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-rw-r--r--compiler/semexprs.nim969
1 files changed, 683 insertions, 286 deletions
diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index 6070464c9..2885142a7 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -52,12 +52,8 @@ template rejectEmptyNode(n: PNode) =
 proc semOperand(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
   rejectEmptyNode(n)
   # same as 'semExprWithType' but doesn't check for proc vars
-  result = semExpr(c, n, flags + {efOperand})
+  result = semExpr(c, n, flags + {efOperand, efAllowSymChoice})
   if result.typ != nil:
-    # XXX tyGenericInst here?
-    if result.typ.kind == tyProc and hasUnresolvedParams(result, {efOperand}):
-      #and tfUnresolved in result.typ.flags:
-      localError(c.config, n.info, errProcHasNoConcreteType % n.renderTree)
     if result.typ.kind in {tyVar, tyLent}: result = newDeref(result)
   elif {efWantStmt, efAllowStmt} * flags != {}:
     result.typ = newTypeS(tyVoid, c)
@@ -83,39 +79,10 @@ proc semExprCheck(c: PContext, n: PNode, flags: TExprFlags, expectedType: PType
     # do not produce another redundant error message:
     result = errorNode(c, n)
 
-proc ambiguousSymChoice(c: PContext, orig, n: PNode): PNode =
-  let first = n[0].sym
-  if first.kind == skEnumField:
-    # choose the first resolved enum field, i.e. the latest in scope
-    # to mirror behavior before overloadable enums
-    if hintAmbiguousEnum in c.config.notes:
-      var err = "ambiguous enum field '" & first.name.s &
-        "' assumed to be of type " & typeToString(first.typ) &
-        " -- use one of the following:\n"
-      for child in n:
-        let candidate = child.sym
-        err.add "  " & candidate.owner.name.s & "." & candidate.name.s & "\n"
-      message(c.config, orig.info, hintAmbiguousEnum, err)
-    result = n[0]
-  else:
-    var err = "ambiguous identifier '" & first.name.s &
-      "' -- use one of the following:\n"
-    for child in n:
-      let candidate = child.sym
-      err.add "  " & candidate.owner.name.s & "." & candidate.name.s
-      err.add ": " & typeToString(candidate.typ) & "\n"
-    localError(c.config, orig.info, err)
-    n.typ = errorType(c)
-    result = n
-
 proc semExprWithType(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType = nil): PNode =
-  result = semExprCheck(c, n, flags, expectedType)
+  result = semExprCheck(c, n, flags-{efTypeAllowed}, expectedType)
   if result.typ == nil and efInTypeof in flags:
     result.typ = c.voidType
-  elif (result.typ == nil or result.typ.kind == tyNone) and
-      efTypeAllowed in flags and
-      result.kind == nkClosedSymChoice and result.len > 0:
-    result = ambiguousSymChoice(c, n, result)
   elif result.typ == nil or result.typ == c.enforceVoidContext:
     localError(c.config, n.info, errExprXHasNoType %
                 renderTree(result, {renderNoComments}))
@@ -123,6 +90,18 @@ proc semExprWithType(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType
   elif result.typ.kind == tyError:
     # associates the type error to the current owner
     result.typ = errorType(c)
+  elif efTypeAllowed in flags and result.typ.kind == tyProc and
+      hasUnresolvedParams(result, {}):
+    # mirrored with semOperand but only on efTypeAllowed
+    let owner = result.typ.owner
+    let err =
+      # consistent error message with evaltempl/semMacroExpr
+      if owner != nil and owner.kind in {skTemplate, skMacro}:
+        errMissingGenericParamsForTemplate % n.renderTree
+      else:
+        errProcHasNoConcreteType % n.renderTree
+    localError(c.config, n.info, err)
+    result.typ = errorType(c)
   else:
     if result.typ.kind in {tyVar, tyLent}: result = newDeref(result)
 
@@ -136,6 +115,112 @@ proc semExprNoDeref(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
 proc semSymGenericInstantiation(c: PContext, n: PNode, s: PSym): PNode =
   result = symChoice(c, n, s, scClosed)
 
+proc semSym(c: PContext, n: PNode, sym: PSym, flags: TExprFlags): PNode
+
+proc isSymChoice(n: PNode): bool {.inline.} =
+  result = n.kind in nkSymChoices
+
+proc resolveSymChoice(c: PContext, n: var PNode, flags: TExprFlags = {}, expectedType: PType = nil) =
+  ## Attempts to resolve a symchoice `n`, `n` remains a symchoice if
+  ## it cannot be resolved (this is the case even when `n.len == 1`).
+  if expectedType != nil:
+    # resolve from type inference, see paramTypesMatch
+    n = fitNode(c, expectedType, n, n.info)
+  if isSymChoice(n) and efAllowSymChoice notin flags:
+    # some contexts might want sym choices preserved for later disambiguation
+    # in general though they are ambiguous
+    let first = n[0].sym
+    var foundSym: PSym = nil
+    if first.kind == skEnumField and
+        not isAmbiguous(c, first.name, {skEnumField}, foundSym) and
+        foundSym == first:
+      # choose the first resolved enum field, i.e. the latest in scope
+      # to mirror behavior before overloadable enums
+      n = n[0]
+
+proc semOpenSym(c: PContext, n: PNode, flags: TExprFlags, expectedType: PType,
+                warnDisabled = false): PNode =
+  ## sem the child of an `nkOpenSym` node, that is, captured symbols that can be
+  ## replaced by newly injected symbols in generics. `s` must be the captured
+  ## symbol if the original node is an `nkSym` node; and `nil` if it is an
+  ## `nkOpenSymChoice`, in which case only non-overloadable injected symbols
+  ## will be considered.
+  let isSym = n.kind == nkSym
+  let ident = n.getPIdent
+  assert ident != nil
+  let id = newIdentNode(ident, n.info)
+  c.isAmbiguous = false
+  let s2 = qualifiedLookUp(c, id, {})
+  # for `nkSym`, the first found symbol being different and unambiguous is
+  # enough to replace the original
+  # for `nkOpenSymChoice`, the first found symbol must be non-overloadable,
+  # since otherwise we have to use regular `nkOpenSymChoice` functionality
+  # but of the overloadable sym kinds, semExpr does not handle skModule, skMacro, skTemplate
+  # as overloaded in the case where `nkIdent` finds them first
+  if s2 != nil and not c.isAmbiguous and
+      ((isSym and s2 != n.sym) or
+        (not isSym and s2.kind notin OverloadableSyms-{skModule, skMacro, skTemplate})):
+    # only consider symbols defined under current proc:
+    var o = s2.owner
+    while o != nil:
+      if o == c.p.owner:
+        if not warnDisabled:
+          result = semExpr(c, id, flags, expectedType)
+          return
+        else:
+          var msg =
+            "a new symbol '" & ident.s & "' has been injected during " &
+            # msgContext should show what is being instantiated:
+            "template or generic instantiation, however "
+          if isSym:
+            msg.add(
+              getSymRepr(c.config, n.sym) & " captured at " &
+              "the proc declaration will be used instead; " &
+              "either enable --experimental:openSym to use the injected symbol, " &
+              "or `bind` this captured symbol explicitly")
+          else:
+            msg.add(
+              "overloads of " & ident.s & " will be used instead; " &
+              "either enable --experimental:openSym to use the injected symbol, " &
+              "or `bind` this symbol explicitly")
+          message(c.config, n.info, warnIgnoredSymbolInjection, msg)
+          break
+      o = o.owner
+  # nothing found
+  n.flags.excl nfDisabledOpenSym
+  if not warnDisabled and isSym:
+    result = semExpr(c, n, flags, expectedType)
+  else:
+    result = nil
+    if not isSym:
+      # set symchoice node type back to None
+      n.typ = newTypeS(tyNone, c)
+
+proc semSymChoice(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType = nil): PNode =
+  if n.kind == nkOpenSymChoice:
+    result = semOpenSym(c, n, flags, expectedType,
+      warnDisabled = nfDisabledOpenSym in n.flags and
+        genericsOpenSym notin c.features)
+    if result != nil:
+      return
+  result = n
+  resolveSymChoice(c, result, flags, expectedType)
+  if isSymChoice(result) and result.len == 1:
+    # resolveSymChoice can leave 1 sym
+    result = result[0]
+  if isSymChoice(result) and efAllowSymChoice notin flags:
+    var err = "ambiguous identifier: '" & result[0].sym.name.s &
+      "' -- use one of the following:\n"
+    for child in n:
+      let candidate = child.sym
+      err.add "  " & candidate.owner.name.s & "." & candidate.name.s
+      err.add ": " & typeToString(candidate.typ) & "\n"
+    localError(c.config, n.info, err)
+    n.typ = errorType(c)
+    result = n
+  if result.kind == nkSym:
+    result = semSym(c, result, result.sym, flags)
+
 proc inlineConst(c: PContext, n: PNode, s: PSym): PNode {.inline.} =
   result = copyTree(s.astdef)
   if result.isNil:
@@ -173,19 +258,19 @@ proc checkConvertible(c: PContext, targetTyp: PType, src: PNode): TConvStatus =
   var d = skipTypes(targetTyp, abstractVar)
   var s = srcTyp
   if s.kind in tyUserTypeClasses and s.isResolvedUserTypeClass:
-    s = s.lastSon
+    s = s.last
   s = skipTypes(s, abstractVar-{tyTypeDesc, tyOwned})
   if s.kind == tyOwned and d.kind != tyOwned:
-    s = s.lastSon
+    s = s.skipModifier
   var pointers = 0
   while (d != nil) and (d.kind in {tyPtr, tyRef, tyOwned}):
     if s.kind == tyOwned and d.kind != tyOwned:
-      s = s.lastSon
+      s = s.skipModifier
     elif d.kind != s.kind:
       break
     else:
-      d = d.lastSon
-      s = s.lastSon
+      d = d.elementType
+      s = s.elementType
     inc pointers
 
   let targetBaseTyp = skipTypes(targetTyp, abstractVarRange)
@@ -197,14 +282,16 @@ proc checkConvertible(c: PContext, targetTyp: PType, src: PNode): TConvStatus =
     result = checkConversionBetweenObjects(d.skipTypes(abstractInst), s.skipTypes(abstractInst), pointers)
   elif (targetBaseTyp.kind in IntegralTypes) and
       (srcBaseTyp.kind in IntegralTypes):
-    if targetTyp.kind == tyEnum and srcBaseTyp.kind == tyEnum:
+    if targetTyp.kind == tyEnum and srcBaseTyp.kind == tyEnum and
+        not sameType(targetTyp, srcBaseTyp):
       message(c.config, src.info, warnSuspiciousEnumConv, "suspicious code: enum to enum conversion")
     # `elif` would be incorrect here
     if targetTyp.kind == tyBool:
       discard "convOk"
     elif targetTyp.isOrdinalType:
       if src.kind in nkCharLit..nkUInt64Lit and
-          src.getInt notin firstOrd(c.config, targetTyp)..lastOrd(c.config, targetTyp):
+          src.getInt notin firstOrd(c.config, targetTyp)..lastOrd(c.config, targetTyp) and
+          targetTyp.kind notin {tyUInt..tyUInt64}:
         result = convNotInRange
       elif src.kind in nkFloatLit..nkFloat64Lit and
           (classify(src.floatVal) in {fcNan, fcNegInf, fcInf} or
@@ -219,6 +306,9 @@ proc checkConvertible(c: PContext, targetTyp: PType, src: PNode): TConvStatus =
         result = convNotInRange
   else:
     # we use d, s here to speed up that operation a bit:
+    if d.kind == tyFromExpr:
+      result = convNotLegal
+      return
     case cmpTypes(c, d, s)
     of isNone, isGeneric:
       if not compareTypes(targetTyp.skipTypes(abstractVar), srcTyp.skipTypes({tyOwned}), dcEqIgnoreDistinct):
@@ -242,7 +332,7 @@ proc isCastable(c: PContext; dst, src: PType, info: TLineInfo): bool =
   if skipTypes(dst, abstractInst).kind == tyBuiltInTypeClass:
     return false
   let conf = c.config
-  if conf.selectedGC in {gcArc, gcOrc}:
+  if conf.selectedGC in {gcArc, gcOrc, gcAtomicArc}:
     let d = skipTypes(dst, abstractInst)
     let s = skipTypes(src, abstractInst)
     if d.kind == tyRef and s.kind == tyRef and s[0].isFinal != d[0].isFinal:
@@ -261,7 +351,7 @@ proc isCastable(c: PContext; dst, src: PType, info: TLineInfo): bool =
     return false
   elif srcSize < 0:
     return false
-  elif typeAllowed(dst, skParam, c) != nil:
+  elif typeAllowed(dst, skParam, c, {taIsCastable}) != nil:
     return false
   elif dst.kind == tyProc and dst.callConv == ccClosure:
     return src.kind == tyProc and src.callConv == ccClosure
@@ -269,17 +359,9 @@ proc isCastable(c: PContext; dst, src: PType, info: TLineInfo): bool =
     result = (dstSize >= srcSize) or
         (skipTypes(dst, abstractInst).kind in IntegralTypes) or
         (skipTypes(src, abstractInst-{tyTypeDesc}).kind in IntegralTypes)
-    if result and (dstSize > srcSize):
-      var warnMsg = "target type is larger than source type"
-      warnMsg.add("\n  target type: '$1' ($2)" % [$dst, if dstSize == 1: "1 byte" else: $dstSize & " bytes"])
-      warnMsg.add("\n  source type: '$1' ($2)" % [$src, if srcSize == 1: "1 byte" else: $srcSize & " bytes"])
-      message(conf, info, warnCastSizes, warnMsg)
   if result and src.kind == tyNil:
     return dst.size <= conf.target.ptrSize
 
-proc isSymChoice(n: PNode): bool {.inline.} =
-  result = n.kind in nkSymChoices
-
 proc maybeLiftType(t: var PType, c: PContext, info: TLineInfo) =
   # XXX: liftParamType started to perform addDecl
   # we could do that instead in semTypeNode by snooping for added
@@ -294,7 +376,7 @@ proc isOwnedSym(c: PContext; n: PNode): bool =
   let s = qualifiedLookUp(c, n, {})
   result = s != nil and sfSystemModule in s.owner.flags and s.name.s == "owned"
 
-proc semConv(c: PContext, n: PNode; expectedType: PType = nil): PNode =
+proc semConv(c: PContext, n: PNode; flags: TExprFlags = {}, expectedType: PType = nil): PNode =
   if n.len != 2:
     localError(c.config, n.info, "a type conversion takes exactly one argument")
     return n
@@ -302,7 +384,7 @@ proc semConv(c: PContext, n: PNode; expectedType: PType = nil): PNode =
   result = newNodeI(nkConv, n.info)
 
   var targetType = semTypeNode(c, n[0], nil)
-  case targetType.kind
+  case targetType.skipTypes({tyDistinct}).kind
   of tyTypeDesc:
     internalAssert c.config, targetType.len > 0
     if targetType.base.kind == tyNone:
@@ -319,16 +401,17 @@ proc semConv(c: PContext, n: PNode; expectedType: PType = nil): PNode =
       return evaluated
     else:
       targetType = targetType.base
+  of tyAnything, tyUntyped, tyTyped:
+    localError(c.config, n.info, "illegal type conversion to '$1'" % typeToString(targetType))
   else: discard
 
   maybeLiftType(targetType, c, n[0].info)
 
   if targetType.kind in {tySink, tyLent} or isOwnedSym(c, n[0]):
     let baseType = semTypeNode(c, n[1], nil).skipTypes({tyTypeDesc})
-    let t = newTypeS(targetType.kind, c)
+    let t = newTypeS(targetType.kind, c, baseType)
     if targetType.kind == tyOwned:
       t.flags.incl tfHasOwned
-    t.rawAddSonNoPropagationOfTypeFlags baseType
     result = newNodeI(nkType, n.info)
     result.typ = makeTypeDesc(c, t)
     return
@@ -339,7 +422,10 @@ proc semConv(c: PContext, n: PNode; expectedType: PType = nil): PNode =
   if n[1].kind == nkExprEqExpr and
       targetType.skipTypes(abstractPtrs).kind == tyObject:
     localError(c.config, n.info, "object construction uses ':', not '='")
-  var op = semExprWithType(c, n[1])
+  var op = semExprWithType(c, n[1], flags * {efDetermineType} + {efAllowSymChoice})
+  if isSymChoice(op) and op[0].sym.kind notin routineKinds:
+    # T(foo) disambiguation syntax only allowed for routines
+    op = semSymChoice(c, op)
   if targetType.kind != tyGenericParam and targetType.isMetaType:
     let final = inferWithMetatype(c, targetType, op, true)
     result.add final
@@ -351,7 +437,9 @@ proc semConv(c: PContext, n: PNode; expectedType: PType = nil): PNode =
   # here or needs to be overwritten too then.
   result.add op
 
-  if targetType.kind == tyGenericParam:
+  if targetType.kind == tyGenericParam or
+      (op.typ != nil and op.typ.kind == tyFromExpr and c.inGenericContext > 0):
+    # expression is compiled early in a generic body
     result.typ = makeTypeFromExpr(c, copyTree(result))
     return result
 
@@ -365,7 +453,8 @@ proc semConv(c: PContext, n: PNode; expectedType: PType = nil): PNode =
       elif op.kind in {nkPar, nkTupleConstr} and targetType.kind == tyTuple:
         op = fitNode(c, targetType, op, result.info)
     of convNotNeedeed:
-      message(c.config, n.info, hintConvFromXtoItselfNotNeeded, result.typ.typeToString)
+      if efNoSem2Check notin flags:
+        message(c.config, n.info, hintConvFromXtoItselfNotNeeded, result.typ.typeToString)
     of convNotLegal:
       result = fitNode(c, result.typ, result[1], result.info)
       if result == nil:
@@ -394,6 +483,8 @@ proc semCast(c: PContext, n: PNode): PNode =
   let castedExpr = semExprWithType(c, n[1])
   if castedExpr.kind == nkClosedSymChoice:
     errorUseQualifier(c, n[1].info, castedExpr)
+  if targetType == nil:
+    localError(c.config, n.info, "Invalid usage of cast, cast requires a type to convert to, e.g., cast[int](0d).")
   if tfHasMeta in targetType.flags:
     localError(c.config, n[0].info, "cannot cast to a non concrete type: '$1'" % $targetType)
   if not isCastable(c, targetType, castedExpr.typ, n.info):
@@ -415,7 +506,7 @@ proc semLowHigh(c: PContext, n: PNode, m: TMagic): PNode =
     of tySequence, tyString, tyCstring, tyOpenArray, tyVarargs:
       n.typ = getSysType(c.graph, n.info, tyInt)
     of tyArray:
-      n.typ = typ[0] # indextype
+      n.typ = typ.indexType
       if n.typ.kind == tyRange and emptyRange(n.typ.n[0], n.typ.n[1]): #Invalid range
         n.typ = getSysType(c.graph, n.info, tyInt)
     of tyInt..tyInt64, tyChar, tyBool, tyEnum, tyUInt..tyUInt64, tyFloat..tyFloat64:
@@ -440,7 +531,7 @@ proc fixupStaticType(c: PContext, n: PNode) =
   # apply this measure only in code that is enlightened to work
   # with static types.
   if n.typ.kind != tyStatic:
-    n.typ = newTypeWithSons(getCurrOwner(c), tyStatic, @[n.typ], c.idgen)
+    n.typ = newTypeS(tyStatic, c, n.typ)
     n.typ.n = n # XXX: cycles like the one here look dangerous.
                 # Consider using `n.copyTree`
 
@@ -465,6 +556,7 @@ proc isOpImpl(c: PContext, n: PNode, flags: TExprFlags): PNode =
       res = t.kind == tyProc and
             t.callConv == ccClosure
     of "iterator":
+      # holdover from when `is iterator` didn't work
       let t = skipTypes(t1, abstractRange)
       res = t.kind == tyProc and
             t.callConv == ccClosure and
@@ -492,8 +584,9 @@ proc isOpImpl(c: PContext, n: PNode, flags: TExprFlags): PNode =
   result.typ = n.typ
 
 proc semIs(c: PContext, n: PNode, flags: TExprFlags): PNode =
-  if n.len != 3:
+  if n.len != 3 or n[2].kind == nkEmpty:
     localError(c.config, n.info, "'is' operator takes 2 arguments")
+    return errorNode(c, n)
 
   let boolType = getSysType(c.graph, n.info, tyBool)
   result = n
@@ -527,15 +620,14 @@ proc semIs(c: PContext, n: PNode, flags: TExprFlags): PNode =
       n[1] = makeTypeSymNode(c, lhsType, n[1].info)
       lhsType = n[1].typ
   else:
-    if lhsType.base.kind == tyNone or
-        (c.inGenericContext > 0 and lhsType.base.containsGenericType):
+    if c.inGenericContext > 0 and lhsType.base.containsUnresolvedType:
       # BUGFIX: don't evaluate this too early: ``T is void``
       return
 
   result = isOpImpl(c, n, flags)
 
 proc semOpAux(c: PContext, n: PNode) =
-  const flags = {efDetermineType}
+  const flags = {efDetermineType, efAllowSymChoice}
   for i in 1..<n.len:
     var a = n[i]
     if a.kind == nkExprEqExpr and a.len == 2:
@@ -560,7 +652,14 @@ proc overloadedCallOpr(c: PContext, n: PNode): PNode =
 
 proc changeType(c: PContext; n: PNode, newType: PType, check: bool) =
   case n.kind
-  of nkCurly, nkBracket:
+  of nkCurly:
+    for i in 0..<n.len:
+      if n[i].kind == nkRange:
+        changeType(c, n[i][0], elemType(newType), check)
+        changeType(c, n[i][1], elemType(newType), check)
+      else:
+        changeType(c, n[i], elemType(newType), check)
+  of nkBracket:
     for i in 0..<n.len:
       changeType(c, n[i], elemType(newType), check)
   of nkPar, nkTupleConstr:
@@ -593,14 +692,20 @@ proc changeType(c: PContext; n: PNode, newType: PType, check: bool) =
           a.add m
           changeType(m, tup[i], check)
   of nkCharLit..nkUInt64Lit:
-    if check and n.kind != nkUInt64Lit and not sameType(n.typ, newType):
+    if check and n.kind != nkUInt64Lit and not sameTypeOrNil(n.typ, newType):
       let value = n.intVal
       if value < firstOrd(c.config, newType) or value > lastOrd(c.config, newType):
         localError(c.config, n.info, "cannot convert " & $value &
-                                         " to " & typeToString(newType))
+                                         " to " & typeNameAndDesc(newType))
   of nkFloatLit..nkFloat64Lit:
     if check and not floatRangeCheck(n.floatVal, newType):
-      localError(c.config, n.info, errFloatToString % [$n.floatVal, typeToString(newType)])
+      localError(c.config, n.info, errFloatToString % [$n.floatVal, typeNameAndDesc(newType)])
+  of nkSym:
+    if check and n.sym.kind == skEnumField and not sameTypeOrNil(n.sym.typ, newType):
+      let value = n.sym.position
+      if value < firstOrd(c.config, newType) or value > lastOrd(c.config, newType):
+        localError(c.config, n.info, "cannot convert '" & n.sym.name.s &
+                                         "' to '" & typeNameAndDesc(newType) & "'")
   else: discard
   n.typ = newType
 
@@ -612,34 +717,46 @@ proc arrayConstrType(c: PContext, n: PNode): PType =
   else:
     var t = skipTypes(n[0].typ, {tyGenericInst, tyVar, tyLent, tyOrdinal, tyAlias, tySink})
     addSonSkipIntLit(typ, t, c.idgen)
-  typ[0] = makeRangeType(c, 0, n.len - 1, n.info)
+  typ.setIndexType makeRangeType(c, 0, n.len - 1, n.info)
   result = typ
 
 proc semArrayConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType = nil): PNode =
   result = newNodeI(nkBracket, n.info)
-  result.typ = newTypeS(tyArray, c)
+  # nkBracket nodes can also be produced by the VM as seq constant nodes
+  # in which case, we cannot produce a new array type for the node,
+  # as this might lose type info even when the node has array type
+  let constructType = n.typ.isNil
   var expectedElementType, expectedIndexType: PType = nil
-  if expectedType != nil:
-    let expected = expectedType.skipTypes(abstractRange-{tyDistinct})
-    case expected.kind
+  var expectedBase: PType = nil
+  if constructType:
+    result.typ = newTypeS(tyArray, c)
+    rawAddSon(result.typ, nil)     # index type
+    if expectedType != nil:
+      expectedBase = expectedType.skipTypes(abstractRange-{tyDistinct})
+  else:
+    result.typ = n.typ
+    expectedBase = n.typ.skipTypes(abstractRange) # include tyDistinct this time
+  if expectedBase != nil:
+    case expectedBase.kind
     of tyArray:
-      expectedIndexType = expected[0]
-      expectedElementType = expected[1]
-    of tyOpenArray:
-      expectedElementType = expected[0]
+      expectedIndexType = expectedBase[0]
+      expectedElementType = expectedBase[1]
+    of tyOpenArray, tySequence:
+      # typed bracket expressions can also have seq type
+      expectedElementType = expectedBase[0]
     else: discard
-  rawAddSon(result.typ, nil)     # index type
   var
-    firstIndex, lastIndex: Int128
+    firstIndex, lastIndex: Int128 = Zero
     indexType = getSysType(c.graph, n.info, tyInt)
     lastValidIndex = lastOrd(c.config, indexType)
   if n.len == 0:
-    rawAddSon(result.typ,
-      if expectedElementType != nil and
-          typeAllowed(expectedElementType, skLet, c) == nil:
-        expectedElementType
-      else:
-        newTypeS(tyEmpty, c)) # needs an empty basetype!
+    if constructType:
+      rawAddSon(result.typ,
+        if expectedElementType != nil and
+            typeAllowed(expectedElementType, skLet, c) == nil:
+          expectedElementType
+        else:
+          newTypeS(tyEmpty, c)) # needs an empty basetype!
     lastIndex = toInt128(-1)
   else:
     var x = n[0]
@@ -656,9 +773,13 @@ proc semArrayConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PTyp
         x = x[1]
 
     let yy = semExprWithType(c, x, {efTypeAllowed}, expectedElementType)
-    var typ = yy.typ
-    if expectedElementType == nil:
-      expectedElementType = typ
+    var typ: PType
+    if constructType:
+      typ = yy.typ
+      if expectedElementType == nil:
+        expectedElementType = typ
+    else:
+      typ = expectedElementType
     result.add yy
     #var typ = skipTypes(result[0].typ, {tyGenericInst, tyVar, tyLent, tyOrdinal})
     for i in 1..<n.len:
@@ -678,19 +799,27 @@ proc semArrayConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PTyp
 
       let xx = semExprWithType(c, x, {efTypeAllowed}, expectedElementType)
       result.add xx
-      typ = commonType(c, typ, xx.typ)
+      if constructType:
+        typ = commonType(c, typ, xx.typ)
       #n[i] = semExprWithType(c, x, {})
       #result.add fitNode(c, typ, n[i])
       inc(lastIndex)
-    addSonSkipIntLit(result.typ, typ, c.idgen)
+    if constructType:
+      addSonSkipIntLit(result.typ, typ, c.idgen)
     for i in 0..<result.len:
       result[i] = fitNode(c, typ, result[i], result[i].info)
-  result.typ[0] = makeRangeType(c, toInt64(firstIndex), toInt64(lastIndex), n.info,
-                                     indexType)
+  if constructType:
+    result.typ.setIndexType(
+      makeRangeType(c,
+        toInt64(firstIndex), toInt64(lastIndex),
+        n.info, indexType))
 
 proc fixAbstractType(c: PContext, n: PNode) =
   for i in 1..<n.len:
     let it = n[i]
+    if it == nil:
+      localError(c.config, n.info, "'$1' has nil child at index $2" % [renderTree(n, {renderNoComments}), $i])
+      return
     # do not get rid of nkHiddenSubConv for OpenArrays, the codegen needs it:
     if it.kind == nkHiddenSubConv and
         skipTypes(it.typ, abstractVar).kind notin {tyOpenArray, tyVarargs}:
@@ -708,7 +837,7 @@ proc isUnresolvedSym(s: PSym): bool =
   result = s.kind == skGenericParam
   if not result and s.typ != nil:
     result = tfInferrableStatic in s.typ.flags or
-        (s.kind == skParam and s.typ.isMetaType) or
+        (s.kind == skParam and (s.typ.isMetaType or sfTemplateParam in s.flags)) or
         (s.kind == skType and
         s.typ.flags * {tfGenericTypeParam, tfImplicitTypeParam} != {})
 
@@ -736,7 +865,7 @@ proc hasUnresolvedArgs(c: PContext, n: PNode): bool =
       if hasUnresolvedArgs(c, n[i]): return true
     return false
 
-proc newHiddenAddrTaken(c: PContext, n: PNode): PNode =
+proc newHiddenAddrTaken(c: PContext, n: PNode, isOutParam: bool): PNode =
   if n.kind == nkHiddenDeref and not (c.config.backend == backendCpp or
                                       sfCompileToCpp in c.module.flags):
     checkSonsLen(n, 1, c.config)
@@ -745,13 +874,17 @@ proc newHiddenAddrTaken(c: PContext, n: PNode): PNode =
     result = newNodeIT(nkHiddenAddr, n.info, makeVarType(c, n.typ))
     result.add n
     let aa = isAssignable(c, n)
+    let sym = getRoot(n)
     if aa notin {arLValue, arLocalLValue}:
       if aa == arDiscriminant and c.inUncheckedAssignSection > 0:
         discard "allow access within a cast(unsafeAssign) section"
+      elif strictDefs in c.features and aa == arAddressableConst and
+              sym != nil and sym.kind == skLet and isOutParam:
+        discard "allow let varaibles to be passed to out parameters"
       else:
         localError(c.config, n.info, errVarForOutParamNeededX % renderNotLValue(n))
 
-proc analyseIfAddressTaken(c: PContext, n: PNode): PNode =
+proc analyseIfAddressTaken(c: PContext, n: PNode, isOutParam: bool): PNode =
   result = n
   case n.kind
   of nkSym:
@@ -759,7 +892,7 @@ proc analyseIfAddressTaken(c: PContext, n: PNode): PNode =
     if n.sym.typ != nil and
         skipTypes(n.sym.typ, abstractInst-{tyTypeDesc}).kind notin {tyVar, tyLent}:
       incl(n.sym.flags, sfAddrTaken)
-      result = newHiddenAddrTaken(c, n)
+      result = newHiddenAddrTaken(c, n, isOutParam)
   of nkDotExpr:
     checkSonsLen(n, 2, c.config)
     if n[1].kind != nkSym:
@@ -767,27 +900,35 @@ proc analyseIfAddressTaken(c: PContext, n: PNode): PNode =
       return
     if skipTypes(n[1].sym.typ, abstractInst-{tyTypeDesc}).kind notin {tyVar, tyLent}:
       incl(n[1].sym.flags, sfAddrTaken)
-      result = newHiddenAddrTaken(c, n)
+      result = newHiddenAddrTaken(c, n, isOutParam)
   of nkBracketExpr:
     checkMinSonsLen(n, 1, c.config)
     if skipTypes(n[0].typ, abstractInst-{tyTypeDesc}).kind notin {tyVar, tyLent}:
       if n[0].kind == nkSym: incl(n[0].sym.flags, sfAddrTaken)
-      result = newHiddenAddrTaken(c, n)
+      result = newHiddenAddrTaken(c, n, isOutParam)
   else:
-    result = newHiddenAddrTaken(c, n)
+    result = newHiddenAddrTaken(c, n, isOutParam)
 
-proc analyseIfAddressTakenInCall(c: PContext, n: PNode) =
+proc analyseIfAddressTakenInCall(c: PContext, n: PNode, isConverter = false) =
   checkMinSonsLen(n, 1, c.config)
+  if n[0].typ == nil:
+    # n[0] might be erroring node in nimsuggest
+    return
   const
     FakeVarParams = {mNew, mNewFinalize, mInc, ast.mDec, mIncl, mExcl,
       mSetLengthStr, mSetLengthSeq, mAppendStrCh, mAppendStrStr, mSwap,
-      mAppendSeqElem, mNewSeq, mReset, mShallowCopy, mDeepCopy, mMove,
+      mAppendSeqElem, mNewSeq, mShallowCopy, mDeepCopy, mMove,
       mWasMoved}
 
+  template checkIfConverterCalled(c: PContext, n: PNode) =
+    ## Checks if there is a converter call which wouldn't be checked otherwise
+    # Call can sometimes be wrapped in a deref
+    let node = if n.kind == nkHiddenDeref: n[0] else: n
+    if node.kind == nkHiddenCallConv:
+      analyseIfAddressTakenInCall(c, node, true)
   # get the real type of the callee
   # it may be a proc var with a generic alias type, so we skip over them
   var t = n[0].typ.skipTypes({tyGenericInst, tyAlias, tySink})
-
   if n[0].kind == nkSym and n[0].sym.magic in FakeVarParams:
     # BUGFIX: check for L-Value still needs to be done for the arguments!
     # note sometimes this is eval'ed twice so we check for nkHiddenAddr here:
@@ -802,6 +943,8 @@ proc analyseIfAddressTakenInCall(c: PContext, n: PNode) =
               discard "allow access within a cast(unsafeAssign) section"
             else:
               localError(c.config, it.info, errVarForOutParamNeededX % $it)
+        # Make sure to still check arguments for converters
+        c.checkIfConverterCalled(n[i])
     # bug #5113: disallow newSeq(result) where result is a 'var T':
     if n[0].sym.magic in {mNew, mNewFinalize, mNewSeq}:
       var arg = n[1] #.skipAddr
@@ -813,14 +956,13 @@ proc analyseIfAddressTakenInCall(c: PContext, n: PNode) =
     return
   for i in 1..<n.len:
     let n = if n.kind == nkHiddenDeref: n[0] else: n
-    if n[i].kind == nkHiddenCallConv:
-      # we need to recurse explicitly here as converters can create nested
-      # calls and then they wouldn't be analysed otherwise
-      analyseIfAddressTakenInCall(c, n[i])
+    c.checkIfConverterCalled(n[i])
     if i < t.len and
         skipTypes(t[i], abstractInst-{tyTypeDesc}).kind in {tyVar}:
-      if n[i].kind != nkHiddenAddr:
-        n[i] = analyseIfAddressTaken(c, n[i])
+      # Converters wrap var parameters in nkHiddenAddr but they haven't been analysed yet.
+      # So we need to make sure we are checking them still when in a converter call
+      if n[i].kind != nkHiddenAddr or isConverter:
+        n[i] = analyseIfAddressTaken(c, n[i].skipAddr(), isOutParam(skipTypes(t[i], abstractInst-{tyTypeDesc})))
 
 include semmagic
 
@@ -860,7 +1002,7 @@ proc evalAtCompileTime(c: PContext, n: PNode): PNode =
         if n[i].typ.isNil or n[i].typ.kind != tyStatic or
             tfUnresolved notin n[i].typ.flags:
           break maybeLabelAsStatic
-      n.typ = newTypeWithSons(c, tyStatic, @[n.typ])
+      n.typ = newTypeS(tyStatic, c, n.typ)
       n.typ.flags.incl tfUnresolved
 
   # optimization pass: not necessary for correctness of the semantic pass
@@ -874,7 +1016,8 @@ proc evalAtCompileTime(c: PContext, n: PNode): PNode =
 
     if callee.magic notin ctfeWhitelist: return
 
-    if callee.kind notin {skProc, skFunc, skConverter, skConst} or callee.isGenericRoutine:
+    if callee.kind notin {skProc, skFunc, skConverter, skConst} or
+        callee.isGenericRoutineStrict:
       return
 
     if n.typ != nil and typeAllowed(n.typ, skConst, c) != nil: return
@@ -917,21 +1060,22 @@ proc semStaticExpr(c: PContext, n: PNode; expectedType: PType = nil): PNode =
     result = fixupTypeAfterEval(c, result, a)
 
 proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
-                                     flags: TExprFlags): PNode =
+                                     flags: TExprFlags; expectedType: PType = nil): PNode =
   if flags*{efInTypeof, efWantIterator, efWantIterable} != {}:
     # consider: 'for x in pReturningArray()' --> we don't want the restriction
     # to 'skIterator' anymore; skIterator is preferred in sigmatch already
     # for typeof support.
     # for ``typeof(countup(1,3))``, see ``tests/ttoseq``.
     result = semOverloadedCall(c, n, nOrig,
-      {skProc, skFunc, skMethod, skConverter, skMacro, skTemplate, skIterator}, flags)
+      {skProc, skFunc, skMethod, skConverter, skMacro, skTemplate, skIterator}, flags, expectedType)
   else:
     result = semOverloadedCall(c, n, nOrig,
-      {skProc, skFunc, skMethod, skConverter, skMacro, skTemplate}, flags)
+      {skProc, skFunc, skMethod, skConverter, skMacro, skTemplate}, flags, expectedType)
 
   if result != nil:
     if result[0].kind != nkSym:
-      internalError(c.config, "semOverloadedCallAnalyseEffects")
+      if not (c.inGenericContext > 0): # see generic context check in semOverloadedCall
+        internalError(c.config, "semOverloadedCallAnalyseEffects")
       return
     let callee = result[0].sym
     case callee.kind
@@ -951,41 +1095,70 @@ proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
 
 proc resolveIndirectCall(c: PContext; n, nOrig: PNode;
                          t: PType): TCandidate =
-  initCandidate(c, result, t)
+  result = initCandidate(c, t)
   matches(c, n, nOrig, result)
 
-proc bracketedMacro(n: PNode): PSym =
-  if n.len >= 1 and n[0].kind == nkSym:
-    result = n[0].sym
-    if result.kind notin {skMacro, skTemplate}:
-      result = nil
+proc finishOperand(c: PContext, a: PNode): PNode =
+  if a.typ.isNil:
+    result = c.semOperand(c, a, {efDetermineType})
+  else:
+    result = a
+  # XXX tyGenericInst here?
+  if result.typ.kind == tyProc and hasUnresolvedParams(result, {efOperand}):
+    #and tfUnresolved in result.typ.flags:
+    let owner = result.typ.owner
+    let err =
+      # consistent error message with evaltempl/semMacroExpr
+      if owner != nil and owner.kind in {skTemplate, skMacro}:
+        errMissingGenericParamsForTemplate % a.renderTree
+      else:
+        errProcHasNoConcreteType % a.renderTree
+    localError(c.config, a.info, err)
+  considerGenSyms(c, result)
 
-proc setGenericParams(c: PContext, n: PNode) =
-  for i in 1..<n.len:
-    n[i].typ = semTypeNode(c, n[i], nil)
+proc semFinishOperands(c: PContext; n: PNode; isBracketExpr = false) =
+  # this needs to be called to ensure that after overloading resolution every
+  # argument has been sem'checked
+
+  # skip the first argument for operands of `[]` since it may be an unresolved
+  # generic proc, which is handled in semMagic
+  let start = 1 + ord(isBracketExpr)
+  for i in start..<n.len:
+    n[i] = finishOperand(c, n[i])
 
 proc afterCallActions(c: PContext; n, orig: PNode, flags: TExprFlags; expectedType: PType = nil): PNode =
   if efNoSemCheck notin flags and n.typ != nil and n.typ.kind == tyError:
     return errorNode(c, n)
+  if n.typ != nil and n.typ.kind == tyFromExpr and c.inGenericContext > 0:
+    return n
 
   result = n
+
+  when defined(nimsuggest):
+    if c.config.expandProgress:
+      if c.config.expandLevels == 0:
+        return n
+      else:
+        c.config.expandLevels -= 1
+
   let callee = result[0].sym
   case callee.kind
   of skMacro: result = semMacroExpr(c, result, orig, callee, flags, expectedType)
   of skTemplate: result = semTemplateExpr(c, result, callee, flags, expectedType)
   else:
-    semFinishOperands(c, result)
+    semFinishOperands(c, result, isBracketExpr = callee.magic in {mArrGet, mArrPut})
     activate(c, result)
     fixAbstractType(c, result)
     analyseIfAddressTakenInCall(c, result)
     if callee.magic != mNone:
-      result = magicsAfterOverloadResolution(c, result, flags)
+      result = magicsAfterOverloadResolution(c, result, flags, expectedType)
     when false:
       if result.typ != nil and
-          not (result.typ.kind == tySequence and result.typ[0].kind == tyEmpty):
+          not (result.typ.kind == tySequence and result.elementType.kind == tyEmpty):
         liftTypeBoundOps(c, result.typ, n.info)
     #result = patchResolvedTypeBoundOp(c, result)
-  if c.matchedConcept == nil:
+  if c.matchedConcept == nil and (c.inTypeofContext == 0 or callee.magic != mNone):
+    # don't fold calls in concepts and typeof
     result = evalAtCompileTime(c, result)
 
 proc semIndirectOp(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType = nil): PNode =
@@ -1001,20 +1174,20 @@ proc semIndirectOp(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType
       result.transitionSonsKind(nkCall)
       result.flags.incl nfExplicitCall
       for i in 1..<n.len: result.add n[i]
-      return semExpr(c, result, flags)
+      return semExpr(c, result, flags, expectedType)
+    elif n0.typ.kind == tyFromExpr and c.inGenericContext > 0:
+      # don't make assumptions, entire expression needs to be tyFromExpr
+      result = semGenericStmt(c, n)
+      result.typ = makeTypeFromExpr(c, result.copyTree)
+      return
     else:
       n[0] = n0
   else:
-    n[0] = semExpr(c, n[0], {efInCall})
+    n[0] = semExpr(c, n[0], {efInCall, efAllowSymChoice})
     let t = n[0].typ
     if t != nil and t.kind in {tyVar, tyLent}:
       n[0] = newDeref(n[0])
-    elif n[0].kind == nkBracketExpr:
-      let s = bracketedMacro(n[0])
-      if s != nil:
-        setGenericParams(c, n[0])
-        return semDirectOp(c, n, flags, expectedType)
-    elif isSymChoice(n[0]):
+    elif isSymChoice(n[0]) and nfDotField notin n.flags:
       # overloaded generic procs e.g. newSeq[int] can end up here
       return semDirectOp(c, n, flags, expectedType)
 
@@ -1023,7 +1196,7 @@ proc semIndirectOp(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType
     t = skipTypes(n[0].typ, abstractInst+{tyOwned}-{tyTypeDesc, tyDistinct})
   if t != nil and t.kind == tyTypeDesc:
     if n.len == 1: return semObjConstr(c, n, flags, expectedType)
-    return semConv(c, n)
+    return semConv(c, n, flags)
 
   let nOrig = n.copyTree
   semOpAux(c, n)
@@ -1060,7 +1233,6 @@ proc semIndirectOp(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType
           msg.addDeclaredLocMaybe(c.config, typ)
           localError(c.config, n.info, msg)
         return errorNode(c, n)
-      result = nil
     else:
       result = m.call
       instGenericConvertersSons(c, result, m)
@@ -1092,7 +1264,7 @@ proc semDirectOp(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType =
   # this seems to be a hotspot in the compiler!
   let nOrig = n.copyTree
   #semLazyOpAux(c, n)
-  result = semOverloadedCallAnalyseEffects(c, n, nOrig, flags)
+  result = semOverloadedCallAnalyseEffects(c, n, nOrig, flags, expectedType)
   if result != nil: result = afterCallActions(c, result, nOrig, flags, expectedType)
   else: result = errorNode(c, n)
 
@@ -1203,7 +1375,7 @@ proc readTypeParameter(c: PContext, typ: PType,
             # This seems semantically correct and then we'll be able
             # to return the section symbol directly here
             let foundType = makeTypeDesc(c, def[2].typ)
-            return newSymNode(copySym(def[0].sym, nextSymId c.idgen).linkTo(foundType), info)
+            return newSymNode(copySym(def[0].sym, c.idgen).linkTo(foundType), info)
 
       of nkConstSection:
         for def in statement:
@@ -1214,7 +1386,7 @@ proc readTypeParameter(c: PContext, typ: PType,
         discard
 
   if typ.kind != tyUserTypeClass:
-    let ty = if typ.kind == tyCompositeTypeClass: typ[1].skipGenericAlias
+    let ty = if typ.kind == tyCompositeTypeClass: typ.firstGenericParam.skipGenericAlias
              else: typ.skipGenericAlias
     let tbody = ty[0]
     for s in 0..<tbody.len-1:
@@ -1228,11 +1400,13 @@ proc readTypeParameter(c: PContext, typ: PType,
             return c.graph.emptyNode
         else:
           let foundTyp = makeTypeDesc(c, rawTyp)
-          return newSymNode(copySym(tParam.sym, nextSymId c.idgen).linkTo(foundTyp), info)
+          return newSymNode(copySym(tParam.sym, c.idgen).linkTo(foundTyp), info)
 
   return nil
 
 proc semSym(c: PContext, n: PNode, sym: PSym, flags: TExprFlags): PNode =
+  result = nil
+  assert n.kind in nkIdentKinds + {nkDotExpr}
   let s = getGenSym(c, sym)
   case s.kind
   of skConst:
@@ -1241,7 +1415,7 @@ proc semSym(c: PContext, n: PNode, sym: PSym, flags: TExprFlags): PNode =
     onUse(n.info, s)
     let typ = skipTypes(s.typ, abstractInst-{tyTypeDesc})
     case typ.kind
-    of  tyNil, tyChar, tyInt..tyInt64, tyFloat..tyFloat128,
+    of tyNil, tyChar, tyInt..tyInt64, tyFloat..tyFloat128,
         tyTuple, tySet, tyUInt..tyUInt64:
       if s.magic == mNone: result = inlineConst(c, n, s)
       else: result = newSymNode(s, n.info)
@@ -1267,9 +1441,8 @@ proc semSym(c: PContext, n: PNode, sym: PSym, flags: TExprFlags): PNode =
     else:
       result = newSymNode(s, n.info)
   of skMacro, skTemplate:
-    if efNoEvaluateGeneric in flags and s.ast[genericParamsPos].len > 0 or
-       (n.kind notin nkCallKinds and s.requiredParams > 0) or
-       sfCustomPragma in sym.flags:
+    # check if we cannot use alias syntax (no required args or generic params)
+    if sfNoalias in s.flags:
       let info = getCallLineInfo(n)
       markUsed(c, info, s)
       onUse(info, s)
@@ -1327,6 +1500,12 @@ proc semSym(c: PContext, n: PNode, sym: PSym, flags: TExprFlags): PNode =
     markUsed(c, n.info, s)
     onUse(n.info, s)
     result = newSymNode(s, n.info)
+  of skModule:
+    # make sure type is None and not nil for discard checking
+    if efWantStmt in flags: s.typ = newTypeS(tyNone, c)
+    markUsed(c, n.info, s)
+    onUse(n.info, s)
+    result = newSymNode(s, n.info)
   else:
     let info = getCallLineInfo(n)
     #if efInCall notin flags:
@@ -1336,24 +1515,39 @@ proc semSym(c: PContext, n: PNode, sym: PSym, flags: TExprFlags): PNode =
 
 proc tryReadingGenericParam(c: PContext, n: PNode, i: PIdent, t: PType): PNode =
   case t.kind
-  of tyTypeParamsHolders:
+  of tyGenericInst:
     result = readTypeParameter(c, t, i, n.info)
     if result == c.graph.emptyNode:
-      result = n
-      n.typ = makeTypeFromExpr(c, n.copyTree)
+      if c.inGenericContext > 0:
+        result = semGenericStmt(c, n)
+        result.typ = makeTypeFromExpr(c, result.copyTree)
+      else:
+        result = nil
   of tyUserTypeClasses:
     if t.isResolvedUserTypeClass:
       result = readTypeParameter(c, t, i, n.info)
+    elif c.inGenericContext > 0:
+      result = semGenericStmt(c, n)
+      result.typ = makeTypeFromExpr(c, copyTree(result))
     else:
-      n.typ = makeTypeFromExpr(c, copyTree(n))
-      result = n
-  of tyGenericParam, tyAnything:
-    n.typ = makeTypeFromExpr(c, copyTree(n))
-    result = n
+      result = nil
+  of tyGenericBody, tyCompositeTypeClass:
+    if c.inGenericContext > 0:
+      result = readTypeParameter(c, t, i, n.info)
+      if result != nil:
+        # generic parameter exists, stop here but delay until instantiation
+        result = semGenericStmt(c, n)
+        result.typ = makeTypeFromExpr(c, copyTree(result))
+    else:
+      result = nil
+  elif c.inGenericContext > 0 and t.containsUnresolvedType:
+    result = semGenericStmt(c, n)
+    result.typ = makeTypeFromExpr(c, copyTree(result))
   else:
-    discard
+    result = nil
 
 proc tryReadingTypeField(c: PContext, n: PNode, i: PIdent, ty: PType): PNode =
+  result = nil
   var ty = ty.skipTypes(tyDotOpTransparent)
   case ty.kind
   of tyEnum:
@@ -1362,7 +1556,7 @@ proc tryReadingTypeField(c: PContext, n: PNode, i: PIdent, ty: PType): PNode =
     while ty != nil:
       f = getSymFromList(ty.n, i)
       if f != nil: break
-      ty = ty.sons[0]         # enum inheritance
+      ty = ty[0]         # enum inheritance
     if f != nil:
       result = newSymNode(f)
       result.info = n.info
@@ -1376,7 +1570,7 @@ proc tryReadingTypeField(c: PContext, n: PNode, i: PIdent, ty: PType): PNode =
         n.typ = makeTypeDesc(c, field.typ)
         result = n
   of tyGenericInst:
-    result = tryReadingTypeField(c, n, i, ty.lastSon)
+    result = tryReadingTypeField(c, n, i, ty.skipModifier)
     if result == nil:
       result = tryReadingGenericParam(c, n, i, ty)
   else:
@@ -1405,7 +1599,8 @@ proc builtinFieldAccess(c: PContext; n: PNode; flags: var TExprFlags): PNode =
     onUse(n[1].info, s)
     return
 
-  n[0] = semExprWithType(c, n[0], flags+{efDetermineType, efWantIterable})
+  # extra flags since LHS may become a call operand:
+  n[0] = semExprWithType(c, n[0], flags+{efDetermineType, efWantIterable, efAllowSymChoice})
   #restoreOldStyleType(n[0])
   var i = considerQuotedIdent(c, n[1], n)
   var ty = n[0].typ
@@ -1435,7 +1630,7 @@ proc builtinFieldAccess(c: PContext; n: PNode; flags: var TExprFlags): PNode =
     return nil
 
   if ty.kind in tyUserTypeClasses and ty.isResolvedUserTypeClass:
-    ty = ty.lastSon
+    ty = ty.last
   ty = skipTypes(ty, {tyGenericInst, tyVar, tyLent, tyPtr, tyRef, tyOwned, tyAlias, tySink, tyStatic})
   while tfBorrowDot in ty.flags: ty = ty.skipTypes({tyDistinct, tyGenericInst, tyAlias})
   var check: PNode = nil
@@ -1483,7 +1678,9 @@ proc builtinFieldAccess(c: PContext; n: PNode; flags: var TExprFlags): PNode =
     flags.incl efCannotBeDotCall
 
 proc dotTransformation(c: PContext, n: PNode): PNode =
-  if isSymChoice(n[1]):
+  if isSymChoice(n[1]) or
+      # generics usually leave field names as symchoices, but not types
+      (n[1].kind == nkSym and n[1].sym.kind == skType):
     result = newNodeI(nkDotCall, n.info)
     result.add n[1]
     result.add copyTree(n[0])
@@ -1509,18 +1706,20 @@ proc buildOverloadedSubscripts(n: PNode, ident: PIdent): PNode =
   result.add(newIdentNode(ident, n.info))
   for s in n: result.add s
 
-proc semDeref(c: PContext, n: PNode): PNode =
+proc semDeref(c: PContext, n: PNode, flags: TExprFlags): PNode =
   checkSonsLen(n, 1, c.config)
   n[0] = semExprWithType(c, n[0])
   let a = getConstExpr(c.module, n[0], c.idgen, c.graph)
   if a != nil:
-    if a.kind == nkNilLit:
+    if a.kind == nkNilLit and efInTypeof notin flags:
       localError(c.config, n.info, "nil dereference is not allowed")
     n[0] = a
   result = n
   var t = skipTypes(n[0].typ, {tyGenericInst, tyVar, tyLent, tyAlias, tySink, tyOwned})
   case t.kind
-  of tyRef, tyPtr: n.typ = t.lastSon
+  of tyRef, tyPtr: n.typ = t.elementType
+  of tyMetaTypes, tyFromExpr:
+    n.typ = makeTypeFromExpr(c, n.copyTree)
   else: result = nil
   #GlobalError(n[0].info, errCircumNeedsPointer)
 
@@ -1543,22 +1742,23 @@ proc maybeInstantiateGeneric(c: PContext, n: PNode, s: PSym): PNode =
     result = explicitGenericInstantiation(c, n, s)
     if result == n:
       n[0] = copyTree(result[0])
-    else:
-      n[0] = result
 
 proc semSubscript(c: PContext, n: PNode, flags: TExprFlags): PNode =
   ## returns nil if not a built-in subscript operator; also called for the
   ## checking of assignments
+  result = nil
   if n.len == 1:
-    let x = semDeref(c, n)
+    let x = semDeref(c, n, flags)
     if x == nil: return nil
+    if x.typ.kind == tyFromExpr:
+      # depends on generic type
+      return x
     result = newNodeIT(nkDerefExpr, x.info, x.typ)
     result.add(x[0])
     return
   checkMinSonsLen(n, 2, c.config)
-  # make sure we don't evaluate generic macros/templates
-  n[0] = semExprWithType(c, n[0],
-                              {efNoEvaluateGeneric})
+  # signal that generic parameters may be applied after
+  n[0] = semExprWithType(c, n[0], {efNoEvaluateGeneric, efAllowSymChoice})
   var arr = skipTypes(n[0].typ, {tyGenericInst, tyUserTypeClassInst, tyOwned,
                                       tyVar, tyLent, tyPtr, tyRef, tyAlias, tySink})
   if arr.kind == tyStatic:
@@ -1608,13 +1808,16 @@ proc semSubscript(c: PContext, n: PNode, flags: TExprFlags): PNode =
         {tyInt..tyInt64}:
       let idx = getOrdValue(n[1])
       if idx >= 0 and idx < arr.len: n.typ = arr[toInt(idx)]
-      else: localError(c.config, n.info, "invalid index value for tuple subscript")
+      else:
+        localError(c.config, n.info,
+          "invalid index $1 in subscript for tuple of length $2" %
+            [$idx, $arr.len])
       result = n
     else:
       result = nil
   else:
     let s = if n[0].kind == nkSym: n[0].sym
-            elif n[0].kind in nkSymChoices: n[0][0].sym
+            elif n[0].kind in nkSymChoices + {nkOpenSym}: n[0][0].sym
             else: nil
     if s != nil:
       case s.kind
@@ -1654,7 +1857,7 @@ proc propertyWriteAccess(c: PContext, n, nOrig, a: PNode): PNode =
   # this is ugly. XXX Semantic checking should use the ``nfSem`` flag for
   # nodes?
   let aOrig = nOrig[0]
-  result = newTreeI(nkCall, n.info, setterId, a[0], semExprWithType(c, n[1]))
+  result = newTreeI(nkCall, n.info, setterId, a[0], n[1])
   result.flags.incl nfDotSetter
   let orig = newTreeI(nkCall, n.info, setterId, aOrig[0], nOrig[1])
   result = semOverloadedCallAnalyseEffects(c, result, orig, {})
@@ -1695,6 +1898,8 @@ proc takeImplicitAddr(c: PContext, n: PNode; isLent: bool): PNode =
     else:
       localError(c.config, n.info, errExprHasNoAddress)
   result = newNodeIT(nkHiddenAddr, n.info, if n.typ.kind in {tyVar, tyLent}: n.typ else: makePtrType(c, n.typ))
+  if n.typ.kind in {tyVar, tyLent}:
+    n.typ = n.typ.elementType
   result.add(n)
 
 proc asgnToResultVar(c: PContext, n, le, ri: PNode) {.inline.} =
@@ -1761,6 +1966,39 @@ proc goodLineInfo(arg: PNode): TLineInfo =
   else:
     arg.info
 
+proc makeTupleAssignments(c: PContext; n: PNode): PNode =
+  ## expand tuple unpacking assignment into series of assignments
+  ##
+  ## mirrored with semstmts.makeVarTupleSection
+  let lhs = n[0]
+  let value = semExprWithType(c, n[1], {efTypeAllowed})
+  if value.typ.kind != tyTuple:
+    localError(c.config, n[1].info, errTupleUnpackingTupleExpected %
+      [typeToString(value.typ, preferDesc)])
+  elif lhs.len != value.typ.len:
+    localError(c.config, n.info, errTupleUnpackingDifferentLengths %
+      [$lhs.len, typeToString(value.typ, preferDesc), $value.typ.len])
+  result = newNodeI(nkStmtList, n.info)
+
+  let temp = newSym(skTemp, getIdent(c.cache, "tmpTupleAsgn"), c.idgen, getCurrOwner(c), n.info)
+  temp.typ = value.typ
+  temp.flags.incl(sfGenSym)
+  var v = newNodeI(nkLetSection, value.info)
+  let tempNode = newSymNode(temp) #newIdentNode(getIdent(genPrefix & $temp.id), value.info)
+  var vpart = newNodeI(nkIdentDefs, v.info, 3)
+  vpart[0] = tempNode
+  vpart[1] = c.graph.emptyNode
+  vpart[2] = value
+  v.add vpart
+  result.add(v)
+
+  for i in 0..<lhs.len:
+    if lhs[i].kind == nkIdent and lhs[i].ident.id == ord(wUnderscore):
+      # skip _ assignments if we are using a temp as they are already evaluated
+      discard
+    else:
+      result.add newAsgnStmt(lhs[i], newTupleAccessRaw(tempNode, i))
+
 proc semAsgn(c: PContext, n: PNode; mode=asgnNormal): PNode =
   checkSonsLen(n, 2, c.config)
   var a = n[0]
@@ -1788,8 +2026,8 @@ proc semAsgn(c: PContext, n: PNode; mode=asgnNormal): PNode =
       result = buildOverloadedSubscripts(n[0], getIdent(c.cache, "[]="))
       result.add(n[1])
       if mode == noOverloadedSubscript:
-        bracketNotFoundError(c, result)
-        return n
+        bracketNotFoundError(c, result, {})
+        return errorNode(c, n)
       else:
         result = semExprNoType(c, result)
         return result
@@ -1799,11 +2037,11 @@ proc semAsgn(c: PContext, n: PNode; mode=asgnNormal): PNode =
     result.add(n[1])
     return semExprNoType(c, result)
   of nkPar, nkTupleConstr:
-    if a.len >= 2:
+    if a.len >= 2 or a.kind == nkTupleConstr:
       # unfortunately we need to rewrite ``(x, y) = foo()`` already here so
       # that overloading of the assignment operator still works. Usually we
       # prefer to do these rewritings in transf.nim:
-      return semStmt(c, lowerTupleUnpackingForAsgn(c.graph, n, c.idgen, c.p.owner), {})
+      return semStmt(c, makeTupleAssignments(c, n), {})
     else:
       a = semExprWithType(c, a, {efLValue})
   else:
@@ -1812,11 +2050,16 @@ proc semAsgn(c: PContext, n: PNode; mode=asgnNormal): PNode =
   # a = b # both are vars, means: a[] = b[]
   # a = b # b no 'var T' means: a = addr(b)
   var le = a.typ
+  let assignable = isAssignable(c, a)
+  let root = getRoot(a)
+  let useStrictDefLet = root != nil and root.kind == skLet and
+                       assignable == arAddressableConst and
+                       strictDefs in c.features and isLocalSym(root)
   if le == nil:
     localError(c.config, a.info, "expression has no type")
   elif (skipTypes(le, {tyGenericInst, tyAlias, tySink}).kind notin {tyVar} and
-        isAssignable(c, a) in {arNone, arLentValue, arAddressableConst}) or (
-      skipTypes(le, abstractVar).kind in {tyOpenArray, tyVarargs} and views notin c.features):
+        assignable in {arNone, arLentValue, arAddressableConst} and not useStrictDefLet
+        ) or (skipTypes(le, abstractVar).kind in {tyOpenArray, tyVarargs} and views notin c.features):
     # Direct assignment to a discriminant is allowed!
     localError(c.config, a.info, errXCannotBeAssignedTo %
                renderTree(a, {renderNoComments}))
@@ -1828,14 +2071,16 @@ proc semAsgn(c: PContext, n: PNode; mode=asgnNormal): PNode =
       if c.p.owner.kind != skMacro and resultTypeIsInferrable(lhs.sym.typ):
         var rhsTyp = rhs.typ
         if rhsTyp.kind in tyUserTypeClasses and rhsTyp.isResolvedUserTypeClass:
-          rhsTyp = rhsTyp.lastSon
+          rhsTyp = rhsTyp.last
+        if lhs.sym.typ.kind == tyAnything:
+          rhsTyp = rhsTyp.skipTypes({tySink}).skipIntLit(c.idgen)
         if cmpTypes(c, lhs.typ, rhsTyp) in {isGeneric, isEqual}:
           internalAssert c.config, c.p.resultSym != nil
           # Make sure the type is valid for the result variable
           typeAllowedCheck(c, n.info, rhsTyp, skResult)
           lhs.typ = rhsTyp
           c.p.resultSym.typ = rhsTyp
-          c.p.owner.typ[0] = rhsTyp
+          c.p.owner.typ.setReturnType rhsTyp
         else:
           typeMismatch(c.config, n.info, lhs.typ, rhsTyp, rhs)
     borrowCheck(c, n, lhs, rhs)
@@ -1872,6 +2117,9 @@ proc semReturn(c: PContext, n: PNode): PNode =
     localError(c.config, n.info, "'return' not allowed here")
 
 proc semProcBody(c: PContext, n: PNode; expectedType: PType = nil): PNode =
+  when defined(nimsuggest):
+    if c.graph.config.expandDone():
+      return n
   openScope(c)
   result = semExpr(c, n, expectedType = expectedType)
   if c.p.resultSym != nil and not isEmptyType(result.typ):
@@ -1898,12 +2146,12 @@ proc semProcBody(c: PContext, n: PNode; expectedType: PType = nil): PNode =
     if isEmptyType(result.typ):
       # we inferred a 'void' return type:
       c.p.resultSym.typ = errorType(c)
-      c.p.owner.typ[0] = nil
+      c.p.owner.typ.setReturnType nil
     else:
       localError(c.config, c.p.resultSym.info, errCannotInferReturnType %
         c.p.owner.name.s)
-  if isInlineIterator(c.p.owner.typ) and c.p.owner.typ[0] != nil and
-      c.p.owner.typ[0].kind == tyUntyped:
+  if isIterator(c.p.owner.typ) and c.p.owner.typ.returnType != nil and
+      c.p.owner.typ.returnType.kind == tyAnything:
     localError(c.config, c.p.owner.info, errCannotInferReturnType %
       c.p.owner.name.s)
   closeScope(c)
@@ -1929,6 +2177,8 @@ proc semYieldVarResult(c: PContext, n: PNode, restype: PType) =
             tupleConstr[i] = takeImplicitAddr(c, tupleConstr[i], e.kind == tyLent)
         else:
           localError(c.config, n[0].info, errXExpected, "tuple constructor")
+      elif e.kind == tyEmpty:
+        localError(c.config, n[0].info, errTypeExpected)
   else:
     when false:
       # XXX investigate what we really need here.
@@ -1941,12 +2191,10 @@ proc semYield(c: PContext, n: PNode): PNode =
   if c.p.owner == nil or c.p.owner.kind != skIterator:
     localError(c.config, n.info, errYieldNotAllowedHere)
   elif n[0].kind != nkEmpty:
-    n[0] = semExprWithType(c, n[0]) # check for type compatibility:
     var iterType = c.p.owner.typ
     let restype = iterType[0]
+    n[0] = semExprWithType(c, n[0], {}, restype) # check for type compatibility:
     if restype != nil:
-      if restype.kind != tyUntyped:
-        n[0] = fitNode(c, restype, n[0], n.info)
       if n[0].typ == nil: internalError(c.config, n.info, "semYield")
 
       if resultTypeIsInferrable(restype):
@@ -1954,11 +2202,13 @@ proc semYield(c: PContext, n: PNode): PNode =
         iterType[0] = inferred
         if c.p.resultSym != nil:
           c.p.resultSym.typ = inferred
+      else:
+        n[0] = fitNode(c, restype, n[0], n.info)
 
       semYieldVarResult(c, n, restype)
     else:
       localError(c.config, n.info, errCannotReturnExpr)
-  elif c.p.owner.typ[0] != nil:
+  elif c.p.owner.typ.returnType != nil:
     localError(c.config, n.info, errGenerated, "yield statement must yield a value")
 
 proc considerQuotedIdentOrDot(c: PContext, n: PNode, origin: PNode = nil): PIdent =
@@ -2005,6 +2255,8 @@ proc lookUpForDeclared(c: PContext, n: PNode, onlyCurrentScope: bool): PSym =
     result = n.sym
   of nkOpenSymChoice, nkClosedSymChoice:
     result = n[0].sym
+  of nkOpenSym:
+    result = lookUpForDeclared(c, n[0], onlyCurrentScope)
   else:
     localError(c.config, n.info, "identifier expected, but got: " & renderTree(n))
     result = nil
@@ -2040,10 +2292,11 @@ proc expectString(c: PContext, n: PNode): string =
   if n.kind in nkStrKinds:
     return n.strVal
   else:
+    result = ""
     localError(c.config, n.info, errStringLiteralExpected)
 
 proc newAnonSym(c: PContext; kind: TSymKind, info: TLineInfo): PSym =
-  result = newSym(kind, c.cache.idAnon, nextSymId c.idgen, getCurrOwner(c), info)
+  result = newSym(kind, c.cache.idAnon, c.idgen, getCurrOwner(c), info)
 
 proc semExpandToAst(c: PContext, n: PNode): PNode =
   let macroCall = n[1]
@@ -2064,7 +2317,7 @@ proc semExpandToAst(c: PContext, n: PNode): PNode =
     let headSymbol = macroCall[0]
     var cands = 0
     var cand: PSym = nil
-    var o: TOverloadIter
+    var o: TOverloadIter = default(TOverloadIter)
     var symx = initOverloadIter(o, c, headSymbol)
     while symx != nil:
       if symx.kind in {skTemplate, skMacro} and symx.typ.len == macroCall.len:
@@ -2172,10 +2425,14 @@ proc semQuoteAst(c: PContext, n: PNode): PNode =
   if ids.len > 0:
     dummyTemplate[paramsPos] = newNodeI(nkFormalParams, n.info)
     dummyTemplate[paramsPos].add getSysSym(c.graph, n.info, "untyped").newSymNode # return type
-    ids.add getSysSym(c.graph, n.info, "untyped").newSymNode # params type
-    ids.add c.graph.emptyNode # no default value
-    dummyTemplate[paramsPos].add newTreeI(nkIdentDefs, n.info, ids)
-
+    dummyTemplate[paramsPos].add newTreeI(nkIdentDefs, n.info, ids[0], getSysSym(c.graph, n.info, "typed").newSymNode, c.graph.emptyNode)
+    for i in 1..<ids.len:
+      let exp = semExprWithType(c, quotes[i+1], {})
+      let typ = exp.typ
+      if tfTriggersCompileTime notin typ.flags and typ.kind != tyStatic and exp.kind == nkSym and exp.sym.kind notin routineKinds + {skType}:
+        dummyTemplate[paramsPos].add newTreeI(nkIdentDefs, n.info, ids[i], newNodeIT(nkType, n.info, typ), c.graph.emptyNode)
+      else:
+        dummyTemplate[paramsPos].add newTreeI(nkIdentDefs, n.info, ids[i], getSysSym(c.graph, n.info, "typed").newSymNode, c.graph.emptyNode)
   var tmpl = semTemplateDef(c, dummyTemplate)
   quotes[0] = tmpl[namePos]
   # This adds a call to newIdentNode("result") as the first argument to the template call
@@ -2231,7 +2488,7 @@ proc tryExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
     if c.config.errorCounter != oldErrorCount:
       result = nil
   except ERecoverableError:
-    discard
+    result = nil
   # undo symbol table changes (as far as it's possible):
   c.compilesContextId = oldCompilesId
   c.generics = oldGenerics
@@ -2270,7 +2527,7 @@ proc semShallowCopy(c: PContext, n: PNode, flags: TExprFlags): PNode =
     result = semDirectOp(c, n, flags)
 
 proc createFlowVar(c: PContext; t: PType; info: TLineInfo): PType =
-  result = newType(tyGenericInvocation, nextTypeId c.idgen, c.module)
+  result = newType(tyGenericInvocation, c.idgen, c.module)
   addSonSkipIntLit(result, magicsys.getCompilerProc(c.graph, "FlowVar").typ, c.idgen)
   addSonSkipIntLit(result, t, c.idgen)
   result = instGenericContainer(c, info, result, allowMetaTypes = false)
@@ -2280,15 +2537,14 @@ proc instantiateCreateFlowVarCall(c: PContext; t: PType;
   let sym = magicsys.getCompilerProc(c.graph, "nimCreateFlowVar")
   if sym == nil:
     localError(c.config, info, "system needs: nimCreateFlowVar")
-  var bindings: TIdTable
-  initIdTable(bindings)
+  var bindings = initTypeMapping()
   bindings.idTablePut(sym.ast[genericParamsPos][0].typ, t)
   result = c.semGenerateInstance(c, sym, bindings, info)
   # since it's an instantiation, we unmark it as a compilerproc. Otherwise
   # codegen would fail:
   if sfCompilerProc in result.flags:
     result.flags.excl {sfCompilerProc, sfExportc, sfImportc}
-    result.loc.r = ""
+    result.loc.snippet = ""
 
 proc setMs(n: PNode, s: PSym): PNode =
   result = n
@@ -2311,9 +2567,7 @@ proc semMagic(c: PContext, n: PNode, s: PSym, flags: TExprFlags; expectedType: P
   of mAddr:
     markUsed(c, n.info, s)
     checkSonsLen(n, 2, c.config)
-    result[0] = newSymNode(s, n[0].info)
-    result[1] = semAddrArg(c, n[1])
-    result.typ = makePtrType(c, result[1].typ)
+    result = semAddr(c, n[1])
   of mTypeOf:
     markUsed(c, n.info, s)
     result = semTypeOf(c, n)
@@ -2425,12 +2679,12 @@ proc semMagic(c: PContext, n: PNode, s: PSym, flags: TExprFlags; expectedType: P
         let expected = expectedType.skipTypes(abstractRange-{tyDistinct});
         expected.kind in {tySequence, tyOpenArray}):
       # seq type inference
-      var arrayType = newType(tyOpenArray, nextTypeId(c.idgen), expected.owner)
+      var arrayType = newType(tyOpenArray, c.idgen, expected.owner)
       arrayType.rawAddSon(expected[0])
       if n[0].kind == nkSym and sfFromGeneric in n[0].sym.flags:
         # may have been resolved to `@`[empty] at some point,
         # reset to `@` to deal with this
-        n[0] = newSymNode(n[0].sym.owner, n[0].info)
+        n[0] = newSymNode(n[0].sym.instantiatedFrom, n[0].info)
       n[1] = semExpr(c, n[1], flags, arrayType)
     result = semDirectOp(c, n, flags, expectedType)
   else:
@@ -2440,9 +2694,10 @@ proc semWhen(c: PContext, n: PNode, semCheck = true): PNode =
   # If semCheck is set to false, ``when`` will return the verbatim AST of
   # the correct branch. Otherwise the AST will be passed through semStmt.
   result = nil
+  let flags = if semCheck: {efWantStmt} else: {}
 
   template setResult(e: untyped) =
-    if semCheck: result = semExpr(c, e) # do not open a new scope!
+    if semCheck: result = semExpr(c, e, flags) # do not open a new scope!
     else: result = e
 
   # Check if the node is "when nimvm"
@@ -2454,13 +2709,16 @@ proc semWhen(c: PContext, n: PNode, semCheck = true): PNode =
   var typ = commonTypeBegin
   if n.len in 1..2 and n[0].kind == nkElifBranch and (
       n.len == 1 or n[1].kind == nkElse):
-    let exprNode = n[0][0]
+    var exprNode = n[0][0]
+    if exprNode.kind == nkOpenSym:
+      exprNode = exprNode[0]
     if exprNode.kind == nkIdent:
       whenNimvm = lookUp(c, exprNode).magic == mNimvm
     elif exprNode.kind == nkSym:
       whenNimvm = exprNode.sym.magic == mNimvm
     if whenNimvm: n.flags.incl nfLL
 
+  var cannotResolve = false
   for i in 0..<n.len:
     var it = n[i]
     case it.kind
@@ -2468,9 +2726,22 @@ proc semWhen(c: PContext, n: PNode, semCheck = true): PNode =
       checkSonsLen(it, 2, c.config)
       if whenNimvm:
         if semCheck:
-          it[1] = semExpr(c, it[1])
+          it[1] = semExpr(c, it[1], flags)
           typ = commonType(c, typ, it[1].typ)
         result = n # when nimvm is not elimited until codegen
+      elif c.inGenericContext > 0:
+        let e = semExprWithType(c, it[0])
+        if e.typ.kind == tyFromExpr:
+          it[0] = makeStaticExpr(c, e)
+          cannotResolve = true
+        else:
+          it[0] = forceBool(c, e)
+          let val = getConstExpr(c.module, it[0], c.idgen, c.graph)
+          if val == nil or val.kind != nkIntLit:
+            cannotResolve = true
+          elif not cannotResolve and val.intVal != 0 and result == nil:
+            setResult(it[1])
+            return # we're not in nimvm and we already have a result
       else:
         let e = forceBool(c, semConstExpr(c, it[0]))
         if e.kind != nkIntLit:
@@ -2482,13 +2753,21 @@ proc semWhen(c: PContext, n: PNode, semCheck = true): PNode =
           return # we're not in nimvm and we already have a result
     of nkElse, nkElseExpr:
       checkSonsLen(it, 1, c.config)
-      if result == nil or whenNimvm:
+      if cannotResolve:
+        discard
+      elif result == nil or whenNimvm:
         if semCheck:
-          it[0] = semExpr(c, it[0])
+          it[0] = semExpr(c, it[0], flags)
           typ = commonType(c, typ, it[0].typ)
+          if typ != nil and typ.kind != tyUntyped:
+            it[0] = fitNode(c, typ, it[0], it[0].info)
         if result == nil:
           result = it[0]
     else: illFormedAst(n, c.config)
+  if cannotResolve:
+    result = semGenericStmt(c, n)
+    result.typ = makeTypeFromExpr(c, result.copyTree)
+    return
   if result == nil:
     result = newNodeI(nkEmpty, n.info)
   if whenNimvm:
@@ -2516,34 +2795,39 @@ proc semSetConstr(c: PContext, n: PNode, expectedType: PType = nil): PNode =
     # only semantic checking for all elements, later type checking:
     var typ: PType = nil
     for i in 0..<n.len:
+      let doSetType = typ == nil
       if isRange(n[i]):
         checkSonsLen(n[i], 3, c.config)
         n[i][1] = semExprWithType(c, n[i][1], {efTypeAllowed}, expectedElementType)
         n[i][2] = semExprWithType(c, n[i][2], {efTypeAllowed}, expectedElementType)
-        if typ == nil:
+        if doSetType:
           typ = skipTypes(n[i][1].typ,
                           {tyGenericInst, tyVar, tyLent, tyOrdinal, tyAlias, tySink})
-          if expectedElementType == nil:
-            expectedElementType = typ
         n[i].typ = n[i][2].typ # range node needs type too
       elif n[i].kind == nkRange:
         # already semchecked
-        if typ == nil:
+        if doSetType:
           typ = skipTypes(n[i][0].typ,
                           {tyGenericInst, tyVar, tyLent, tyOrdinal, tyAlias, tySink})
-          if expectedElementType == nil:
-            expectedElementType = typ
       else:
         n[i] = semExprWithType(c, n[i], {efTypeAllowed}, expectedElementType)
-        if typ == nil:
+        if doSetType:
           typ = skipTypes(n[i].typ, {tyGenericInst, tyVar, tyLent, tyOrdinal, tyAlias, tySink})
-          if expectedElementType == nil:
-            expectedElementType = typ
-    if not isOrdinalType(typ, allowEnumWithHoles=true):
-      localError(c.config, n.info, errOrdinalTypeExpected % typeToString(typ, preferDesc))
-      typ = makeRangeType(c, 0, MaxSetElements-1, n.info)
-    elif lengthOrd(c.config, typ) > MaxSetElements:
-      typ = makeRangeType(c, 0, MaxSetElements-1, n.info)
+      if doSetType:
+        if not isOrdinalType(typ, allowEnumWithHoles=true):
+          localError(c.config, n.info, errOrdinalTypeExpected % typeToString(typ, preferDesc))
+          typ = makeRangeType(c, 0, MaxSetElements-1, n.info)
+        elif isIntLit(typ):
+          # set of int literal, use a default range smaller than the max range
+          typ = makeRangeType(c, 0, DefaultSetElements-1, n.info)
+        elif lengthOrd(c.config, typ) > MaxSetElements:
+          message(c.config, n.info, warnAboveMaxSizeSet, "type '" &
+            typeToString(typ, preferDesc) & "' is too big to be a `set` element, " &
+            "assuming a range of 0.." & $(MaxSetElements - 1) &
+            ", explicitly write this range to get rid of warning")
+          typ = makeRangeType(c, 0, MaxSetElements-1, n.info)
+        if expectedElementType == nil:
+          expectedElementType = typ
     addSonSkipIntLit(result.typ, typ, c.idgen)
     for i in 0..<n.len:
       var m: PNode
@@ -2625,13 +2909,19 @@ proc semTupleFieldsConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType
     # can check if field name matches expected type here
     let expectedElemType = if expected != nil: expected[i] else: nil
     n[i][1] = semExprWithType(c, n[i][1], {}, expectedElemType)
+    if expectedElemType != nil and
+        (expectedElemType.kind != tyNil and not hasEmpty(expectedElemType)):
+      # hasEmpty/nil check is to not break existing code like
+      # `const foo = [(1, {}), (2, {false})]`,
+      # `const foo = if true: (0, nil) else: (1, new(int))`
+      n[i][1] = fitNode(c, expectedElemType, n[i][1], n[i][1].info)
 
     if n[i][1].typ.kind == tyTypeDesc:
       localError(c.config, n[i][1].info, "typedesc not allowed as tuple field.")
       n[i][1].typ = errorType(c)
 
     var f = newSymS(skField, n[i][0], c)
-    f.typ = skipIntLit(n[i][1].typ, c.idgen)
+    f.typ = skipIntLit(n[i][1].typ.skipTypes({tySink}), c.idgen)
     f.position = i
     rawAddSon(typ, f.typ)
     typ.n.add newSymNode(f)
@@ -2651,7 +2941,13 @@ proc semTuplePositionsConstr(c: PContext, n: PNode, flags: TExprFlags; expectedT
   for i in 0..<n.len:
     let expectedElemType = if expected != nil: expected[i] else: nil
     n[i] = semExprWithType(c, n[i], {}, expectedElemType)
-    addSonSkipIntLit(typ, n[i].typ, c.idgen)
+    if expectedElemType != nil and
+        (expectedElemType.kind != tyNil and not hasEmpty(expectedElemType)):
+      # hasEmpty/nil check is to not break existing code like
+      # `const foo = [(1, {}), (2, {false})]`,
+      # `const foo = if true: (0, nil) else: (1, new(int))`
+      n[i] = fitNode(c, expectedElemType, n[i], n[i].info)
+    addSonSkipIntLit(typ, n[i].typ.skipTypes({tySink}), c.idgen)
   result.typ = typ
 
 include semobjconstr
@@ -2706,7 +3002,7 @@ proc semExport(c: PContext, n: PNode): PNode =
   result = newNodeI(nkExportStmt, n.info)
   for i in 0..<n.len:
     let a = n[i]
-    var o: TOverloadIter
+    var o: TOverloadIter = default(TOverloadIter)
     var s = initOverloadIter(o, c, a)
     if s == nil:
       localError(c.config, a.info, errGenerated, "cannot export: " & renderTree(a))
@@ -2742,7 +3038,7 @@ proc semExport(c: PContext, n: PNode): PNode =
 
 proc semTupleConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType = nil): PNode =
   var tupexp = semTuplePositionsConstr(c, n, flags, expectedType)
-  var isTupleType: bool
+  var isTupleType: bool = false
   if tupexp.len > 0: # don't interpret () as type
     isTupleType = tupexp[0].typ.kind == tyTypeDesc
     # check if either everything or nothing is tyTypeDesc
@@ -2756,24 +3052,50 @@ proc semTupleConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PTyp
   else:
     result = tupexp
 
-proc shouldBeBracketExpr(n: PNode): bool =
+proc isExplicitGenericCall(c: PContext, n: PNode): bool =
+  ## checks if a call node `n` is a routine call with explicit generic params
+  ## 
+  ## the callee node needs to be either an nkBracketExpr or a call to a
+  ## symchoice of `[]` in which case it will be transformed into nkBracketExpr
+  ## 
+  ## the LHS of the bracket expr has to either be a symchoice or resolve to
+  ## a routine symbol
+  template checkCallee(n: PNode) =
+    # check subscript LHS, `n` must be mutable
+    if isSymChoice(n):
+      result = true
+    else:
+      let s = qualifiedLookUp(c, n, {})
+      if s != nil and s.kind in routineKinds:
+        result = true
+        n = semSymGenericInstantiation(c, n, s)
   assert n.kind in nkCallKinds
+  result = false
   let a = n[0]
-  if a.kind in nkCallKinds:
+  case a.kind
+  of nkBracketExpr:
+    checkCallee(a[0])
+  of nkCallKinds:
     let b = a[0]
     if b.kind in nkSymChoices:
-      for i in 0..<b.len:
-        if b[i].kind == nkSym and b[i].sym.magic == mArrGet:
-          let be = newNodeI(nkBracketExpr, n.info)
+      let name = b.getPIdent
+      if name != nil and name.s == "[]":
+        checkCallee(a[1])
+        if result:
+          # transform callee into normal bracket expr, only on success
+          let be = newNodeI(nkBracketExpr, a.info)
           for i in 1..<a.len: be.add(a[i])
           n[0] = be
-          return true
+  else:
+    result = false
 
 proc asBracketExpr(c: PContext; n: PNode): PNode =
   proc isGeneric(c: PContext; n: PNode): bool =
     if n.kind in {nkIdent, nkAccQuoted}:
       let s = qualifiedLookUp(c, n, {})
       result = s != nil and isGenericRoutineStrict(s)
+    else:
+      result = false
 
   assert n.kind in nkCallKinds
   if n.len > 1 and isGeneric(c, n[1]):
@@ -2786,6 +3108,18 @@ proc asBracketExpr(c: PContext; n: PNode): PNode =
           return result
   return nil
 
+proc isOpenArraySym(x: PNode): bool =
+  var x = x
+  while true:
+    case x.kind
+    of {nkAddr, nkHiddenAddr}:
+      x = x[0]
+    of {nkHiddenStdConv, nkHiddenDeref}:
+      x = x[1]
+    else:
+      break
+  result = x.kind == nkSym
+
 proc hoistParamsUsedInDefault(c: PContext, call, letSection, defExpr: var PNode) =
   # This takes care of complicated signatures such as:
   # proc foo(a: int, b = a)
@@ -2803,11 +3137,18 @@ proc hoistParamsUsedInDefault(c: PContext, call, letSection, defExpr: var PNode)
   # duty is activated by returning a non-nil value. The caller is responsible
   # for replacing the input to the function with the returned non-nil value.
   # (which is the hoisted symbol)
-  if defExpr.kind == nkSym and defExpr.sym.kind == skParam and defExpr.sym.owner == call[0].sym:
+  if defExpr.kind == nkSym and defExpr.sym.kind == skParam and
+      (defExpr.sym.owner == call[0].sym or
+        # symbol was resolved before proc was instantiated:
+        (sfFromGeneric in call[0].sym.flags and
+          defExpr.sym.owner == call[0].sym.instantiatedFrom)):
     let paramPos = defExpr.sym.position + 1
 
-    if call[paramPos].kind != nkSym:
-      let hoistedVarSym = newSym(skLet, getIdent(c.graph.cache, genPrefix), nextSymId c.idgen,
+    if call[paramPos].skipAddr.kind != nkSym and not (
+      skipTypes(call[paramPos].typ, abstractVar).kind in {tyOpenArray, tyVarargs} and
+      isOpenArraySym(call[paramPos])
+    ):
+      let hoistedVarSym = newSym(skLet, getIdent(c.graph.cache, genPrefix), c.idgen,
                                  c.p.owner, letSection.info, c.p.owner.options)
       hoistedVarSym.typ = call[paramPos].typ
 
@@ -2818,7 +3159,7 @@ proc hoistParamsUsedInDefault(c: PContext, call, letSection, defExpr: var PNode)
 
       call[paramPos] = newSymNode(hoistedVarSym) # Refer the original arg to its hoisted sym
 
-    # arg we refer to is a sym, wether introduced by hoisting or not doesn't matter, we simply reuse it
+    # arg we refer to is a sym, whether introduced by hoisting or not doesn't matter, we simply reuse it
     defExpr = call[paramPos]
   else:
     for i in 0..<defExpr.safeLen:
@@ -2832,8 +3173,8 @@ proc getNilType(c: PContext): PType =
     result.align = c.config.target.ptrSize.int16
     c.nilTypeCache = result
 
-proc enumFieldSymChoice(c: PContext, n: PNode, s: PSym): PNode =
-  var o: TOverloadIter
+proc enumFieldSymChoice(c: PContext, n: PNode, s: PSym; flags: TExprFlags): PNode =
+  var o: TOverloadIter = default(TOverloadIter)
   var i = 0
   var a = initOverloadIter(o, c, n)
   while a != nil:
@@ -2845,7 +3186,7 @@ proc enumFieldSymChoice(c: PContext, n: PNode, s: PSym): PNode =
   if i <= 1:
     if sfGenSym notin s.flags:
       result = newSymNode(s, info)
-      markUsed(c, info, s)
+      markUsed(c, info, s, efInCall notin flags)
       onUse(info, s)
     else:
       result = n
@@ -2866,6 +3207,55 @@ proc semPragmaStmt(c: PContext; n: PNode) =
   else:
     pragma(c, c.p.owner, n, stmtPragmas, true)
 
+proc resolveIdentToSym(c: PContext, n: PNode, resultNode: var PNode,
+                       flags: TExprFlags, expectedType: PType): PSym =
+  # result is nil on error or if a node that can't produce a sym is resolved
+  let ident = considerQuotedIdent(c, n)
+  var filter = {low(TSymKind)..high(TSymKind)}
+  if efNoEvaluateGeneric in flags or expectedType != nil:
+    # `a[...]` where `a` is a module or package is not possible
+    filter.excl {skModule, skPackage}
+  let includePureEnum = expectedType != nil and
+    expectedType.skipTypes(abstractRange-{tyDistinct}).kind == tyEnum
+  let candidates = lookUpCandidates(c, ident, filter,
+    includePureEnum = includePureEnum)
+  if candidates.len == 0:
+    result = errorUndeclaredIdentifierHint(c, ident, n.info)
+  elif candidates.len == 1 or {efNoEvaluateGeneric, efInCall} * flags != {}:
+    # unambiguous, or we don't care about ambiguity
+    result = candidates[0]
+  else:
+    # ambiguous symbols have 1 last chance as a symchoice
+    var choice = newNodeIT(nkClosedSymChoice, n.info, newTypeS(tyNone, c))
+    for cand in candidates:
+      case cand.kind
+      of skModule, skPackage:
+        discard
+      of skType:
+        choice.add newSymNodeTypeDesc(cand, c.idgen, n.info)
+      else:
+        choice.add newSymNode(cand, n.info)
+    if choice.len == 0:
+      # we know candidates.len > 1, we just couldn't put any in a symchoice
+      errorUseQualifier(c, n.info, candidates)
+      return nil
+    resolveSymChoice(c, choice, flags, expectedType)
+    # choice.len == 1 can be true here but as long as it's a symchoice
+    # it's still not resolved
+    if isSymChoice(choice):
+      result = nil
+      if efAllowSymChoice in flags:
+        resultNode = choice
+      else:
+        errorUseQualifier(c, n.info, candidates)
+    else:
+      if choice.kind == nkSym:
+        result = choice.sym
+      else:
+        # resolution could have generated nkHiddenStdConv etc
+        resultNode = semExpr(c, choice, flags, expectedType)
+        result = nil
+
 proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType = nil): PNode =
   when defined(nimCompilerStacktraceHints):
     setFrameMsg c.config$n.info & " " & $n.kind
@@ -2875,7 +3265,6 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
     defer:
       if isCompilerDebug():
         echo ("<", c.config$n.info, n, ?.result.typ)
-
   template directLiteral(typeKind: TTypeKind) =
     if result.typ == nil:
       if expectedType != nil and (
@@ -2887,27 +3276,27 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
         result.typ = getSysType(c.graph, n.info, typeKind)
 
   result = n
+  when defined(nimsuggest):
+    var expandStarted = false
+    if c.config.ideCmd == ideExpand and not c.config.expandProgress and
+        ((n.kind in {nkFuncDef, nkProcDef, nkIteratorDef, nkTemplateDef, nkMethodDef, nkConverterDef} and
+          n.info.exactEquals(c.config.expandPosition)) or
+         (n.kind in {nkCall, nkCommand} and
+          n[0].info.exactEquals(c.config.expandPosition))):
+      expandStarted = true
+      c.config.expandProgress = true
+      if c.config.expandLevels == 0:
+        c.config.expandNodeResult = $n
+        suggestQuit()
+
   if c.config.cmd == cmdIdeTools: suggestExpr(c, n)
   if nfSem in n.flags: return
   case n.kind
   of nkIdent, nkAccQuoted:
-    var s: PSym
-    if expectedType != nil and (
-        let expected = expectedType.skipTypes(abstractRange-{tyDistinct});
-        expected.kind == tyEnum):
-      let nameId = considerQuotedIdent(c, n).id
-      for f in expected.n:
-        if f.kind == nkSym and f.sym.name.id == nameId:
-          s = f.sym
-          break
+    let s = resolveIdentToSym(c, n, result, flags, expectedType)
     if s == nil:
-      let checks = if efNoEvaluateGeneric in flags:
-          {checkUndeclared, checkPureEnumFields}
-        elif efInCall in flags:
-          {checkUndeclared, checkModule, checkPureEnumFields}
-        else:
-          {checkUndeclared, checkModule, checkAmbiguity, checkPureEnumFields}
-      s = qualifiedLookUp(c, n, checks)
+      # resolveIdentToSym either errored or gave a result node
+      return
     if c.matchedConcept == nil: semCaptureSym(s, c.p.owner)
     case s.kind
     of skProc, skFunc, skMethod, skConverter, skIterator:
@@ -2921,23 +3310,35 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
       if optOwnedRefs in c.config.globalOptions:
         result.typ = makeVarType(c, result.typ, tyOwned)
     of skEnumField:
-      result = enumFieldSymChoice(c, n, s)
+      result = enumFieldSymChoice(c, n, s, flags)
     else:
       result = semSym(c, n, s, flags)
-    if expectedType != nil and isSymChoice(result):
-      result = fitNode(c, expectedType, result, n.info)
-      if result.kind == nkSym:
-        result = semSym(c, result, result.sym, flags)
+    if isSymChoice(result):
+      result = semSymChoice(c, result, flags, expectedType)
+  of nkClosedSymChoice, nkOpenSymChoice:
+    result = semSymChoice(c, n, flags, expectedType)
   of nkSym:
+    let s = n.sym
+    if nfDisabledOpenSym in n.flags:
+      let override = genericsOpenSym in c.features
+      let res = semOpenSym(c, n, flags, expectedType,
+        warnDisabled = not override)
+      if res != nil:
+        assert override
+        return res
     # because of the changed symbol binding, this does not mean that we
     # don't have to check the symbol for semantics here again!
-    result = semSym(c, n, n.sym, flags)
+    result = semSym(c, n, s, flags)
+  of nkOpenSym:
+    assert n.len == 1
+    let inner = n[0]
+    result = semOpenSym(c, inner, flags, expectedType)
   of nkEmpty, nkNone, nkCommentStmt, nkType:
     discard
   of nkNilLit:
     if result.typ == nil:
       result.typ = getNilType(c)
-      if expectedType != nil:
+      if expectedType != nil and expectedType.kind notin {tyUntyped, tyTyped}:
         var m = newCandidate(c, result.typ)
         if typeRel(m, expectedType, result.typ) >= isSubtype:
           result.typ = expectedType
@@ -2949,7 +3350,6 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
           expected.kind in {tyInt..tyInt64,
             tyUInt..tyUInt64,
             tyFloat..tyFloat128}):
-        result.typ = expected
         if expected.kind in {tyFloat..tyFloat128}:
           n.transitionIntToFloatKind(nkFloatLit)
         changeType(c, result, expectedType, check=true)
@@ -2989,7 +3389,7 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
     result = semFieldAccess(c, n, flags)
     if result.kind == nkDotCall:
       result.transitionSonsKind(nkCall)
-      result = semExpr(c, result, flags)
+      result = semExpr(c, result, flags, expectedType)
   of nkBind:
     message(c.config, n.info, warnDeprecated, "bind is deprecated")
     result = semExpr(c, n[0], flags, expectedType)
@@ -2998,7 +3398,7 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
       let modifier = n.modifierTypeKindOfNode
       if modifier != tyNone:
         var baseType = semExpr(c, n[0]).typ.skipTypes({tyTypeDesc})
-        result.typ = c.makeTypeDesc(c.newTypeWithSons(modifier, @[baseType]))
+        result.typ = c.makeTypeDesc(newTypeS(modifier, c, baseType))
         return
     var typ = semTypeNode(c, n, nil).skipTypes({tyTypeDesc})
     result.typ = makeTypeDesc(c, typ)
@@ -3014,33 +3414,28 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
     c.isAmbiguous = false
     var s = qualifiedLookUp(c, n[0], mode)
     if s != nil:
-      #if c.config.cmd == cmdNimfix and n[0].kind == nkDotExpr:
-      #  pretty.checkUse(n[0][1].info, s)
       case s.kind
       of skMacro, skTemplate:
         result = semDirectOp(c, n, flags, expectedType)
       of skType:
         # XXX think about this more (``set`` procs)
         let ambig = c.isAmbiguous
-        if not (n[0].kind in {nkClosedSymChoice, nkOpenSymChoice, nkIdent} and ambig) and n.len == 2:
-          result = semConv(c, n, expectedType)
-        elif ambig and n.len == 1:
-          errorUseQualifier(c, n.info, s)
+        if not (n[0].kind in nkSymChoices + {nkIdent, nkDotExpr} and ambig) and n.len == 2:
+          result = semConv(c, n, flags, expectedType)
         elif n.len == 1:
-          result = semObjConstr(c, n, flags, expectedType)
+          if ambig:
+            errorUseQualifier(c, n.info, s)
+          else:
+            result = semObjConstr(c, n, flags, expectedType)
         elif s.magic == mNone: result = semDirectOp(c, n, flags, expectedType)
         else: result = semMagic(c, n, s, flags, expectedType)
       of skProc, skFunc, skMethod, skConverter, skIterator:
-        if s.magic == mNone: result = semDirectOp(c, n, flags)
+        if s.magic == mNone: result = semDirectOp(c, n, flags, expectedType)
         else: result = semMagic(c, n, s, flags, expectedType)
       else:
         #liMessage(n.info, warnUser, renderTree(n));
         result = semIndirectOp(c, n, flags, expectedType)
-    elif (n[0].kind == nkBracketExpr or shouldBeBracketExpr(n)) and
-        isSymChoice(n[0][0]):
-      # indirectOp can deal with explicit instantiations; the fixes
-      # the 'newSeq[T](x)' bug
-      setGenericParams(c, n[0])
+    elif isExplicitGenericCall(c, n): # this modifies `n` if true
       result = semDirectOp(c, n, flags, expectedType)
     elif nfDotField in n.flags:
       result = semDirectOp(c, n, flags, expectedType)
@@ -3105,12 +3500,11 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
     result = semArrayConstr(c, n, flags, expectedType)
   of nkObjConstr: result = semObjConstr(c, n, flags, expectedType)
   of nkLambdaKinds: result = semProcAux(c, n, skProc, lambdaPragmas, flags)
-  of nkDerefExpr: result = semDeref(c, n)
+  of nkDerefExpr: result = semDeref(c, n, flags)
   of nkAddr:
     result = n
     checkSonsLen(n, 1, c.config)
-    result[0] = semAddrArg(c, n[0])
-    result.typ = makePtrType(c, result[0].typ)
+    result = semAddr(c, n[0])
   of nkHiddenAddr, nkHiddenDeref:
     checkSonsLen(n, 1, c.config)
     n[0] = semExpr(c, n[0], flags, expectedType)
@@ -3130,10 +3524,6 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
     considerGenSyms(c, n)
   of nkTableConstr:
     result = semTableConstr(c, n, expectedType)
-  of nkClosedSymChoice, nkOpenSymChoice:
-    # handling of sym choices is context dependent
-    # the node is left intact for now
-    discard
   of nkStaticExpr: result = semStaticExpr(c, n[0], expectedType)
   of nkAsgn, nkFastAsgn: result = semAsgn(c, n)
   of nkBlockStmt, nkBlockExpr: result = semBlock(c, n, flags, expectedType)
@@ -3193,7 +3583,9 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
   of nkDefer:
     if c.currentScope == c.topLevelScope:
       localError(c.config, n.info, "defer statement not supported at top level")
+    openScope(c)
     n[0] = semExpr(c, n[0])
+    closeScope(c)
     if not n[0].typ.isEmptyType and not implicitlyDiscardable(n[0]):
       localError(c.config, n.info, "'defer' takes a 'void' expression")
     #localError(c.config, n.info, errGenerated, "'defer' not allowed in this context")
@@ -3214,3 +3606,8 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType
     localError(c.config, n.info, "invalid expression: " &
                renderTree(n, {renderNoComments}))
   if result != nil: incl(result.flags, nfSem)
+
+  when defined(nimsuggest):
+    if expandStarted:
+      c.config.expandNodeResult = $result
+      suggestQuit()