make the current PContext accessible through TCandidate

the goal here is to remove all the hacks from ParamTypeMatch and to handle
all type matching in typeRel (the context there is required to evaluate any static
params and to run the compilation tests of user-defined type classes)

5 files changed, 53 insertions, 46 deletions

diff --git a/compiler/semcall.nim b/compiler/semcall.nim
index 9e9614796..0880f5fde 100644
--- a/compiler/semcall.nim
+++ b/compiler/semcall.nim
@@ -47,14 +47,14 @@ proc pickBestCandidate(c: PContext, headSymbol: PNode,
   var z: TCandidate
   
   if sym == nil: return
-  initCandidate(best, sym, initialBinding, symScope)
-  initCandidate(alt, sym, initialBinding, symScope)
+  initCandidate(c, best, sym, initialBinding, symScope)
+  initCandidate(c, alt, sym, initialBinding, symScope)
   best.state = csNoMatch
   
   while sym != nil:
     if sym.kind in filter:
       determineType(c, sym)
-      initCandidate(z, sym, initialBinding, o.lastOverloadScope)
+      initCandidate(c, z, sym, initialBinding, o.lastOverloadScope)
       z.calleeSym = sym
       matches(c, n, orig, z)
       if errors != nil:
@@ -199,15 +199,15 @@ proc instGenericConvertersSons*(c: PContext, n: PNode, x: TCandidate) =
 
 proc IndexTypesMatch(c: PContext, f, a: PType, arg: PNode): PNode = 
   var m: TCandidate
-  initCandidate(m, f)
-  result = paramTypesMatch(c, m, f, a, arg, nil)
+  initCandidate(c, m, f)
+  result = paramTypesMatch(m, f, a, arg, nil)
   if m.genericConverter and result != nil:
     instGenericConvertersArg(c, result, m)
 
 proc ConvertTo*(c: PContext, f: PType, n: PNode): PNode = 
   var m: TCandidate
-  initCandidate(m, f)
-  result = paramTypesMatch(c, m, f, n.typ, n, nil)
+  initCandidate(c, m, f)
+  result = paramTypesMatch(m, f, n.typ, n, nil)
   if m.genericConverter and result != nil:
     instGenericConvertersArg(c, result, m)
 
@@ -243,9 +243,9 @@ proc explicitGenericInstError(n: PNode): PNode =
   result = n
 
 proc explicitGenericSym(c: PContext, n: PNode, s: PSym): PNode =
-  var x: TCandidate
-  initCandidate(x, s, n)
-  var newInst = generateInstance(c, s, x.bindings, n.info)
+  var m: TCandidate
+  initCandidate(c, m, s, n)
+  var newInst = generateInstance(c, s, m.bindings, n.info)
   markUsed(n, s)
   result = newSymNode(newInst, n.info)
 
diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index a7fd1eaa0..67373c303 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -142,7 +142,7 @@ proc checkConversionBetweenObjects(castDest, src: PType): TConvStatus =
 const 
   IntegralTypes = {tyBool, tyEnum, tyChar, tyInt..tyUInt64}
 
-proc checkConvertible(castDest, src: PType): TConvStatus =
+proc checkConvertible(c: PContext, castDest, src: PType): TConvStatus =
   result = convOK
   if sameType(castDest, src) and castDest.sym == src.sym:
     # don't annoy conversions that may be needed on another processor:
@@ -163,7 +163,7 @@ proc checkConvertible(castDest, src: PType): TConvStatus =
     # accept conversion between integral types
   else:
     # we use d, s here to speed up that operation a bit:
-    case cmpTypes(d, s)
+    case cmpTypes(c, d, s)
     of isNone, isGeneric:
       if not compareTypes(castDest, src, dcEqIgnoreDistinct):
         result = convNotLegal
@@ -202,7 +202,7 @@ proc semConv(c: PContext, n: PNode): PNode =
   var op = result.sons[1]
   
   if not isSymChoice(op):
-    let status = checkConvertible(result.typ, op.typ)
+    let status = checkConvertible(c, result.typ, op.typ)
     case status
     of convOK: nil
     of convNotNeedeed:
@@ -213,7 +213,7 @@ proc semConv(c: PContext, n: PNode): PNode =
   else:
     for i in countup(0, sonsLen(op) - 1):
       let it = op.sons[i]
-      let status = checkConvertible(result.typ, it.typ)
+      let status = checkConvertible(c, result.typ, it.typ)
       if status == convOK:
         markUsed(n, it.sym)
         markIndirect(c, it.sym)
@@ -324,15 +324,15 @@ proc isOpImpl(c: PContext, n: PNode): PNode =
     case t2.kind
     of tyTypeClasses:
       var m: TCandidate
-      InitCandidate(m, t2)
+      InitCandidate(c, m, t2)
       match = matchUserTypeClass(c, m, emptyNode, t2, t1) != nil
     of tyOrdinal:
       var m: TCandidate
-      InitCandidate(m, t2)
+      InitCandidate(c, m, t2)
       match = isOrdinalType(t1)
     of tySequence, tyArray, tySet:
       var m: TCandidate
-      InitCandidate(m, t2)
+      InitCandidate(c, m, t2)
       match = typeRel(m, t2, t1) != isNone
     else:
       match = sameType(t1, t2)
@@ -707,7 +707,7 @@ proc semIndirectOp(c: PContext, n: PNode, flags: TExprFlags): PNode =
   if t != nil and t.kind == tyProc:
     # This is a proc variable, apply normal overload resolution
     var m: TCandidate
-    initCandidate(m, t)
+    initCandidate(c, m, t)
     matches(c, n, nOrig, m)
     if m.state != csMatch:
       if c.inCompilesContext > 0:
diff --git a/compiler/semtypes.nim b/compiler/semtypes.nim
index 85928ee75..7e76e950b 100644
--- a/compiler/semtypes.nim
+++ b/compiler/semtypes.nim
@@ -838,7 +838,7 @@ proc semGeneric(c: PContext, n: PNode, s: PSym, prev: PType): PType =
   else:
     internalAssert s.typ.kind == tyGenericBody
 
-    var m = newCandidate(s, n)
+    var m = newCandidate(c, s, n)
     matches(c, n, copyTree(n), m)
     
     if m.state != csMatch:
diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 87f1decf4..42eefec5a 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -21,7 +21,8 @@ type
   TCandidateState* = enum 
     csEmpty, csMatch, csNoMatch
 
-  TCandidate* {.final.} = object 
+  TCandidate* {.final.} = object
+    c*: PContext
     exactMatches*: int       # also misused to prefer iters over procs
     genericMatches: int      # also misused to prefer constraints
     subtypeMatches: int
@@ -58,7 +59,9 @@ const
     
 proc markUsed*(n: PNode, s: PSym)
 
-proc initCandidateAux(c: var TCandidate, callee: PType) {.inline.} = 
+proc initCandidateAux(ctx: PContext,
+                      c: var TCandidate, callee: PType) {.inline.} =
+  c.c = ctx
   c.exactMatches = 0
   c.subtypeMatches = 0
   c.convMatches = 0
@@ -71,17 +74,17 @@ proc initCandidateAux(c: var TCandidate, callee: PType) {.inline.} =
   c.genericConverter = false
   c.inheritancePenalty = 0
 
-proc initCandidate*(c: var TCandidate, callee: PType) = 
-  initCandidateAux(c, callee)
+proc initCandidate*(ctx: PContext, c: var TCandidate, callee: PType) =
+  initCandidateAux(ctx, c, callee)
   c.calleeSym = nil
   initIdTable(c.bindings)
 
 proc put(t: var TIdTable, key, val: PType) {.inline.} =
   IdTablePut(t, key, val)
 
-proc initCandidate*(c: var TCandidate, callee: PSym, binding: PNode, 
-                    calleeScope = -1) =
-  initCandidateAux(c, callee.typ)
+proc initCandidate*(ctx: PContext, c: var TCandidate, callee: PSym,
+                    binding: PNode, calleeScope = -1) =
+  initCandidateAux(ctx, c, callee.typ)
   c.calleeSym = callee
   c.calleeScope = calleeScope
   initIdTable(c.bindings)
@@ -93,10 +96,12 @@ proc initCandidate*(c: var TCandidate, callee: PSym, binding: PNode,
       #debug(formalTypeParam)
       put(c.bindings, formalTypeParam, binding[i].typ)
 
-proc newCandidate*(callee: PSym, binding: PNode, calleeScope = -1): TCandidate =
-  initCandidate(result, callee, binding, calleeScope)
+proc newCandidate*(ctx: PContext, callee: PSym,
+                   binding: PNode, calleeScope = -1): TCandidate =
+  initCandidate(ctx, result, callee, binding, calleeScope)
 
 proc copyCandidate(a: var TCandidate, b: TCandidate) = 
+  a.c = b.c
   a.exactMatches = b.exactMatches
   a.subtypeMatches = b.subtypeMatches
   a.convMatches = b.convMatches
@@ -762,10 +767,10 @@ proc typeRel(c: var TCandidate, f, a: PType, doBind = true): TTypeRelation =
     result = isEqual
   else: internalError("typeRel: " & $f.kind)
   
-proc cmpTypes*(f, a: PType): TTypeRelation = 
-  var c: TCandidate
-  InitCandidate(c, f)
-  result = typeRel(c, f, a)
+proc cmpTypes*(c: PContext, f, a: PType): TTypeRelation = 
+  var m: TCandidate
+  InitCandidate(c, m, f)
+  result = typeRel(m, f, a)
 
 proc getInstantiatedType(c: PContext, arg: PNode, m: TCandidate, 
                          f: PType): PType = 
@@ -887,13 +892,14 @@ proc matchUserTypeClass*(c: PContext, m: var TCandidate,
   result = arg
   put(m.bindings, f, a)
 
-proc ParamTypesMatchAux(c: PContext, m: var TCandidate, f, argType: PType,
+proc ParamTypesMatchAux(m: var TCandidate, f, argType: PType,
                         argSemantized, argOrig: PNode): PNode =
   var
     r: TTypeRelation
     arg = argSemantized
 
   let
+    c = m.c
     a0 = if c.InTypeClass > 0: argType.skipTypes({tyTypeDesc})
          else: argType
     a = if a0 != nil: a0.skipTypes({tyStatic}) else: a0
@@ -1007,19 +1013,20 @@ proc ParamTypesMatchAux(c: PContext, m: var TCandidate, f, argType: PType,
         else:
           result = userConvMatch(c, m, base(f), a, arg)
 
-proc ParamTypesMatch*(c: PContext, m: var TCandidate, f, a: PType, 
+proc ParamTypesMatch*(m: var TCandidate, f, a: PType,
                       arg, argOrig: PNode): PNode =
   if arg == nil or arg.kind notin nkSymChoices:
-    result = ParamTypesMatchAux(c, m, f, a, arg, argOrig)
+    result = ParamTypesMatchAux(m, f, a, arg, argOrig)
   else: 
     # CAUTION: The order depends on the used hashing scheme. Thus it is
     # incorrect to simply use the first fitting match. However, to implement
     # this correctly is inefficient. We have to copy `m` here to be able to
     # roll back the side effects of the unification algorithm.
+    let c = m.c
     var x, y, z: TCandidate
-    initCandidate(x, m.callee)
-    initCandidate(y, m.callee)
-    initCandidate(z, m.callee)
+    initCandidate(c, x, m.callee)
+    initCandidate(c, y, m.callee)
+    initCandidate(c, z, m.callee)
     x.calleeSym = m.calleeSym
     y.calleeSym = m.calleeSym
     z.calleeSym = m.calleeSym
@@ -1051,7 +1058,7 @@ proc ParamTypesMatch*(c: PContext, m: var TCandidate, f, a: PType,
     else: 
       # only one valid interpretation found:
       markUsed(arg, arg.sons[best].sym)
-      result = ParamTypesMatchAux(c, m, f, arg.sons[best].typ, arg.sons[best],
+      result = ParamTypesMatchAux(m, f, arg.sons[best].typ, arg.sons[best],
                                   argOrig)
 
 proc setSon(father: PNode, at: int, son: PNode) = 
@@ -1142,7 +1149,7 @@ proc matchesAux(c: PContext, n, nOrig: PNode,
       m.baseTypeMatch = false
       n.sons[a].sons[1] = prepareOperand(c, formal.typ, n.sons[a].sons[1])
       n.sons[a].typ = n.sons[a].sons[1].typ
-      var arg = ParamTypesMatch(c, m, formal.typ, n.sons[a].typ,
+      var arg = ParamTypesMatch(m, formal.typ, n.sons[a].typ,
                                 n.sons[a].sons[1], nOrig.sons[a].sons[1])
       if arg == nil:
         m.state = csNoMatch
@@ -1172,7 +1179,7 @@ proc matchesAux(c: PContext, n, nOrig: PNode,
         elif formal != nil:
           m.baseTypeMatch = false
           n.sons[a] = prepareOperand(c, formal.typ, n.sons[a])
-          var arg = ParamTypesMatch(c, m, formal.typ, n.sons[a].typ,
+          var arg = ParamTypesMatch(m, formal.typ, n.sons[a].typ,
                                     n.sons[a], nOrig.sons[a])
           if (arg != nil) and m.baseTypeMatch and (container != nil):
             addSon(container, arg)
@@ -1195,7 +1202,7 @@ proc matchesAux(c: PContext, n, nOrig: PNode,
           return 
         m.baseTypeMatch = false
         n.sons[a] = prepareOperand(c, formal.typ, n.sons[a])
-        var arg = ParamTypesMatch(c, m, formal.typ, n.sons[a].typ,
+        var arg = ParamTypesMatch(m, formal.typ, n.sons[a].typ,
                                   n.sons[a], nOrig.sons[a])
         if arg == nil:
           m.state = csNoMatch
@@ -1249,8 +1256,8 @@ proc matches*(c: PContext, n, nOrig: PNode, m: var TCandidate) =
 
 proc argtypeMatches*(c: PContext, f, a: PType): bool =
   var m: TCandidate
-  initCandidate(m, f)
-  let res = paramTypesMatch(c, m, f, a, ast.emptyNode, nil)
+  initCandidate(c, m, f)
+  let res = paramTypesMatch(m, f, a, ast.emptyNode, nil)
   #instantiateGenericConverters(c, res, m)
   # XXX this is used by patterns.nim too; I think it's better to not
   # instantiate generic converters for that
@@ -1312,7 +1319,7 @@ tests:
 
     setup:
       var c: TCandidate
-      InitCandidate(c, nil)
+      InitCandidate(nil, c, nil)
 
     template yes(x, y) =
       test astToStr(x) & " is " & astToStr(y):
diff --git a/compiler/suggest.nim b/compiler/suggest.nim
index 76a6c21d9..04a222db4 100644
--- a/compiler/suggest.nim
+++ b/compiler/suggest.nim
@@ -119,7 +119,7 @@ proc argsFit(c: PContext, candidate: PSym, n, nOrig: PNode): bool =
   case candidate.kind 
   of OverloadableSyms:
     var m: TCandidate
-    initCandidate(m, candidate, nil)
+    initCandidate(c, m, candidate, nil)
     sigmatch.partialMatch(c, n, nOrig, m)
     result = m.state != csNoMatch
   else: