simple unit test and better documentation for the user defined type classes

6 files changed, 65 insertions, 46 deletions

diff --git a/compiler/msgs.nim b/compiler/msgs.nim
index 5363442b4..895ba71f3 100644
--- a/compiler/msgs.nim
+++ b/compiler/msgs.nim
@@ -436,7 +436,14 @@ type
                                # only 8 bytes.
     line*, col*: int16
     fileIndex*: int32
-    
+  
+  TErrorOutput* = enum
+    eStdOut
+    eStdErr
+    eInMemory
+
+  TErrorOutputs* = set[TErrorOutput]
+
   ERecoverableError* = object of EInvalidValue
   ESuggestDone* = object of EBase
 
@@ -534,13 +541,27 @@ var
   gHintCounter*: int = 0
   gWarnCounter*: int = 0
   gErrorMax*: int = 1         # stop after gErrorMax errors
-  gSilence*: int              # == 0 if we produce any output at all 
 
 when useCaas:
   var stdoutSocket*: TSocket
 
+proc UnknownLineInfo*(): TLineInfo =
+  result.line = int16(-1)
+  result.col = int16(-1)
+  result.fileIndex = -1
+
+var 
+  msgContext: seq[TLineInfo] = @[]
+  lastError = UnknownLineInfo()
+  bufferedMsgs*: seq[string]
+
+  errorOutputs* = {eStdOut, eStdErr}
+
+proc clearBufferedMsgs* =
+  bufferedMsgs = nil
+
 proc SuggestWriteln*(s: string) =
-  if gSilence == 0:
+  if eStdOut in errorOutputs:
     when useCaas:
       if isNil(stdoutSocket): Writeln(stdout, s)
       else:
@@ -548,6 +569,9 @@ proc SuggestWriteln*(s: string) =
         stdoutSocket.send(s & "\c\L")
     else:
       Writeln(stdout, s)
+  
+  if eInMemory in errorOutputs:
+    bufferedMsgs.safeAdd(s)
 
 proc SuggestQuit*() =
   if not isServing:
@@ -570,14 +594,6 @@ const
   RawWarningFormat* = "Warning: $1"
   RawHintFormat* = "Hint: $1"
 
-proc UnknownLineInfo*(): TLineInfo = 
-  result.line = int16(-1)
-  result.col = int16(-1)
-  result.fileIndex = -1
-
-var 
-  msgContext: seq[TLineInfo] = @[]
-
 proc getInfoContextLen*(): int = return msgContext.len
 proc setInfoContextLen*(L: int) = setLen(msgContext, L)
 
@@ -642,14 +658,18 @@ proc addCheckpoint*(filename: string, line: int) =
 
 proc OutWriteln*(s: string) = 
   ## Writes to stdout. Always.
-  if gSilence == 0: Writeln(stdout, s)
+  if eStdOut in errorOutputs: Writeln(stdout, s)
  
 proc MsgWriteln*(s: string) = 
   ## Writes to stdout. If --stdout option is given, writes to stderr instead.
-  if gSilence == 0:
-    if gCmd == cmdIdeTools and optCDebug notin gGlobalOptions: return
-    if optStdout in gGlobalOptions: Writeln(stderr, s)
-    else: Writeln(stdout, s)
+  if gCmd == cmdIdeTools and optCDebug notin gGlobalOptions: return
+
+  if optStdout in gGlobalOptions:
+    if eStdErr in errorOutputs: Writeln(stderr, s)
+  else:
+    if eStdOut in errorOutputs: Writeln(stdout, s)
+  
+  if eInMemory in errorOutputs: bufferedMsgs.safeAdd(s)
 
 proc coordToStr(coord: int): string = 
   if coord == -1: result = "???"
@@ -736,9 +756,6 @@ proc rawMessage*(msg: TMsgKind, args: openarray[string]) =
 proc rawMessage*(msg: TMsgKind, arg: string) = 
   rawMessage(msg, [arg])
 
-var
-  lastError = UnknownLineInfo()
-
 proc writeSurroundingSrc(info: TLineInfo) =
   const indent = "  "
   MsgWriteln(indent & info.sourceLine.ropeToStr)
diff --git a/compiler/sem.nim b/compiler/sem.nim
index 71951dd3f..ea53afbeb 100644
--- a/compiler/sem.nim
+++ b/compiler/sem.nim
@@ -36,7 +36,8 @@ proc semParamList(c: PContext, n, genericParams: PNode, s: PSym)
 proc addParams(c: PContext, n: PNode, kind: TSymKind)
 proc maybeAddResult(c: PContext, s: PSym, n: PNode)
 proc instGenericContainer(c: PContext, n: PNode, header: PType): PType
-proc tryExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode
+proc tryExpr(c: PContext, n: PNode,
+             flags: TExprFlags = {}, bufferErrors = false): PNode
 proc fixImmediateParams(n: PNode): PNode
 proc activate(c: PContext, n: PNode)
 proc semQuoteAst(c: PContext, n: PNode): PNode
diff --git a/compiler/semdata.nim b/compiler/semdata.nim
index 31d2ce6bd..d02359d4c 100644
--- a/compiler/semdata.nim
+++ b/compiler/semdata.nim
@@ -73,7 +73,8 @@ type
     libs*: TLinkedList         # all libs used by this module
     semConstExpr*: proc (c: PContext, n: PNode): PNode {.nimcall.} # for the pragmas
     semExpr*: proc (c: PContext, n: PNode, flags: TExprFlags = {}): PNode {.nimcall.}
-    semTryExpr*: proc (c: PContext, n: PNode, flags: TExprFlags = {}): PNode {.nimcall.}
+    semTryExpr*: proc (c: PContext, n: PNode,flags: TExprFlags = {},
+                       bufferErrors = false): PNode {.nimcall.}
     semOperand*: proc (c: PContext, n: PNode, flags: TExprFlags = {}): PNode {.nimcall.}
     semConstBoolExpr*: proc (c: PContext, n: PNode): PNode {.nimcall.} # XXX bite the bullet
     semOverloadedCall*: proc (c: PContext, n, nOrig: PNode,
diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index 2cb6f2047..337224aef 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -824,7 +824,7 @@ proc buildEchoStmt(c: PContext, n: PNode): PNode =
 
 proc semExprNoType(c: PContext, n: PNode): PNode =
   result = semExpr(c, n, {efWantStmt})
-  discardCheck(result)
+  discardCheck(c, result)
   
 proc isTypeExpr(n: PNode): bool = 
   case n.kind
@@ -1218,7 +1218,7 @@ proc semProcBody(c: PContext, n: PNode): PNode =
       a.sons[1] = result
       result = semAsgn(c, a)
   else:
-    discardCheck(result)
+    discardCheck(c, result)
   closeScope(c)
 
 proc SemYieldVarResult(c: PContext, n: PNode, restype: PType) =
@@ -1439,12 +1439,12 @@ proc semQuoteAst(c: PContext, n: PNode): PNode =
     newNode(nkCall, n.info, quotes)])
   result = semExpandToAst(c, result)
 
-proc tryExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
+proc tryExpr(c: PContext, n: PNode,
+             flags: TExprFlags = {}, bufferErrors = false): PNode =
   # watch out, hacks ahead:
   let oldErrorCount = msgs.gErrorCounter
   let oldErrorMax = msgs.gErrorMax
   inc c.InCompilesContext
-  inc msgs.gSilence
   # do not halt after first error:
   msgs.gErrorMax = high(int)
   
@@ -1453,6 +1453,8 @@ proc tryExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
   openScope(c)
   let oldOwnerLen = len(gOwners)
   let oldGenerics = c.generics
+  let oldErrorOutputs = errorOutputs
+  errorOutputs = if bufferErrors: {eInMemory} else: {}
   let oldContextLen = msgs.getInfoContextLen()
   
   let oldInGenericContext = c.InGenericContext
@@ -1475,7 +1477,7 @@ proc tryExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
   setlen(gOwners, oldOwnerLen)
   c.currentScope = oldScope
   dec c.InCompilesContext
-  dec msgs.gSilence
+  errorOutputs = oldErrorOutputs
   msgs.gErrorCounter = oldErrorCount
   msgs.gErrorMax = oldErrorMax
 
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index ed6787a16..f514a93d7 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -132,7 +132,7 @@ proc fixNilType(n: PNode) =
     for it in n: fixNilType(it)
   n.typ = nil
 
-proc discardCheck(result: PNode) =
+proc discardCheck(c: PContext, result: PNode) =
   if result.typ != nil and result.typ.kind notin {tyStmt, tyEmpty}:
     if result.kind == nkNilLit:
       result.typ = nil
@@ -142,6 +142,10 @@ proc discardCheck(result: PNode) =
       while n.kind in skipForDiscardable:
         n = n.lastSon
         n.typ = nil
+    elif c.InTypeClass > 0 and result.typ.kind == tyBool:
+      let verdict = semConstExpr(c, result)
+      if verdict.intVal == 0:
+        localError(result.info, "type class predicate failed.")
     elif result.typ.kind != tyError and gCmd != cmdInteractive:
       if result.typ.kind == tyNil:
         fixNilType(result)
@@ -169,7 +173,7 @@ proc semIf(c: PContext, n: PNode): PNode =
       typ = commonType(typ, it.sons[0].typ)
     else: illFormedAst(it)
   if isEmptyType(typ) or typ.kind == tyNil or not hasElse:
-    for it in n: discardCheck(it.lastSon)
+    for it in n: discardCheck(c, it.lastSon)
     result.kind = nkIfStmt
     # propagate any enforced VoidContext:
     if typ == EnforceVoidContext: result.typ = EnforceVoidContext
@@ -230,7 +234,7 @@ proc semCase(c: PContext, n: PNode): PNode =
       localError(n.info, errNotAllCasesCovered)
   closeScope(c)
   if isEmptyType(typ) or typ.kind == tyNil or not hasElse:
-    for i in 1..n.len-1: discardCheck(n.sons[i].lastSon)
+    for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon)
     # propagate any enforced VoidContext:
     if typ == EnforceVoidContext:
       result.typ = EnforceVoidContext
@@ -275,8 +279,8 @@ proc semTry(c: PContext, n: PNode): PNode =
     typ = commonType(typ, a.sons[length-1].typ)
   dec c.p.inTryStmt
   if isEmptyType(typ) or typ.kind == tyNil:
-    discardCheck(n.sons[0])
-    for i in 1..n.len-1: discardCheck(n.sons[i].lastSon)
+    discardCheck(c, n.sons[0])
+    for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon)
     if typ == EnforceVoidContext:
       result.typ = EnforceVoidContext
   else:
@@ -1221,7 +1225,7 @@ proc semStmtList(c: PContext, n: PNode): PNode =
         voidContext = true
         n.typ = EnforceVoidContext
       if i != last or voidContext:
-        discardCheck(n.sons[i])
+        discardCheck(c, n.sons[i])
       else:
         n.typ = n.sons[i].typ
         if not isEmptyType(n.typ):
diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 1d502a205..00f3b2b10 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -85,6 +85,7 @@ proc initCandidate*(c: var TCandidate, callee: PSym, binding: PNode,
   c.calleeSym = callee
   c.calleeScope = calleeScope
   initIdTable(c.bindings)
+  c.errors = nil
   if binding != nil and callee.kind in RoutineKinds:
     var typeParams = callee.ast[genericParamsPos]
     for i in 1..min(sonsLen(typeParams), sonsLen(binding)-1):
@@ -774,23 +775,16 @@ proc matchUserTypeClass*(c: PContext, m: var TCandidate,
     addDecl(c, dummyParam)
 
   for stmt in f.n[3]:
-    var e = c.semTryExpr(c, copyTree(stmt))
-    if e == nil:
-      let expStr = renderTree(stmt, {renderNoComments})
-      m.errors.safeAdd("can't compile " & expStr & "  for " & a.typeToString)
-      return nil
+    var e = c.semTryExpr(c, copyTree(stmt), bufferErrors = false)
+    m.errors = bufferedMsgs
+    clearBufferedMsgs()
+    if e == nil: return nil
+
     case e.kind
-    of nkReturnStmt:
-      nil
+    of nkReturnStmt: nil
     of nkTypeSection: nil
     of nkConstDef: nil
-    else:
-      if e.typ != nil and e.typ.kind == tyBool:
-        let verdict = c.semConstExpr(c, e)
-        if verdict.intVal == 0:
-          let expStr = renderTree(stmt, {renderNoComments})
-          m.errors.safeAdd(expStr & " doesn't hold for " & a.typeToString)
-          return nil
+    else: nil
   
   result = arg
   put(m.bindings, f, a)