quite messy implementation of generic lambdas, needs reworking; fixes #715

compiler/sem.nim

@@ -333,6 +333,7 @@ proc myOpen(module: PSym): PPassContext =
   c.semOperand = semOperand
   c.semConstBoolExpr = semConstBoolExpr
   c.semOverloadedCall = semOverloadedCall
+  c.semInferredLambda = semInferredLambda
   c.semGenerateInstance = generateInstance
   c.semTypeNode = semTypeNode
   pushProcCon(c, module)

compiler/semdata.nim

@@ -81,6 +81,7 @@ type
     semOverloadedCall*: proc (c: PContext, n, nOrig: PNode,
                               filter: TSymKinds): PNode {.nimcall.}
     semTypeNode*: proc(c: PContext, n: PNode, prev: PType): PType {.nimcall.}
+    semInferredLambda*: proc(c: PContext, pt: TIdTable, n: PNode): PNode
     semGenerateInstance*: proc (c: PContext, fn: PSym, pt: TIdTable,
                                 info: TLineInfo): PSym
     includedFiles*: TIntSet    # used to detect recursive include files

compiler/semexprs.nim

@@ -1829,8 +1829,8 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
       result = symChoice(c, n, s, scClosed)
       if result.kind == nkSym:
         markIndirect(c, result.sym)
-        if isGenericRoutine(result.sym):
+        # if isGenericRoutine(result.sym):
-          localError(n.info, errInstantiateXExplicitely, s.name.s)
+        #   localError(n.info, errInstantiateXExplicitely, s.name.s)
   of nkSym:
     # because of the changed symbol binding, this does not mean that we
     # don't have to check the symbol for semantics here again!

compiler/semstmts.nim

@@ -766,7 +766,7 @@ proc typeSectionRightSidePass(c: PContext, n: PNode) =
 
 proc checkForMetaFields(n: PNode) =
   template checkMeta(t) =
-    if t.isMetaType and tfGenericTypeParam notin t.flags:
+    if t != nil and t.isMetaType and tfGenericTypeParam notin t.flags:
       localError(n.info, errTIsNotAConcreteType, t.typeToString)
   
   case n.kind
@@ -779,8 +779,9 @@ proc checkForMetaFields(n: PNode) =
     case t.kind
     of tySequence, tySet, tyArray, tyOpenArray, tyVar, tyPtr, tyRef,
        tyProc, tyGenericInvokation, tyGenericInst:
-      for s in t.sons:
+      let start = ord(t.kind in {tyGenericInvokation, tyGenericInst})
-        checkMeta(s)
+      for i in start .. <t.sons.len:
+        checkMeta(t.sons[i])
     else:
       checkMeta(t)
   else:
@@ -907,12 +908,19 @@ proc semLambda(c: PContext, n: PNode, flags: TExprFlags): PNode =
     s = n[namePos].sym
   pushOwner(s)
   openScope(c)
-  if n.sons[genericParamsPos].kind != nkEmpty:
+  var gp: PNode
-    illFormedAst(n)           # process parameters:
+  if n.sons[genericParamsPos].kind != nkEmpty: 
+    n.sons[genericParamsPos] = semGenericParamList(c, n.sons[genericParamsPos])
+    gp = n.sons[genericParamsPos]
+  else:
+    gp = newNodeI(nkGenericParams, n.info)
+
   if n.sons[paramsPos].kind != nkEmpty:
-    var gp = newNodeI(nkGenericParams, n.info)
     semParamList(c, n.sons[paramsPos], gp, s)
-    paramsTypeCheck(c, s.typ)
+    # paramsTypeCheck(c, s.typ)
+    if sonsLen(gp) > 0 and n.sons[genericParamsPos].kind == nkEmpty:
+      # we have a list of implicit type parameters:
+      n.sons[genericParamsPos] = gp
   else:
     s.typ = newTypeS(tyProc, c)
     rawAddSon(s.typ, nil)
@@ -924,12 +932,13 @@ proc semLambda(c: PContext, n: PNode, flags: TExprFlags): PNode =
       localError(n.sons[bodyPos].info, errImplOfXNotAllowed, s.name.s)
     #if efDetermineType notin flags:
     # XXX not good enough; see tnamedparamanonproc.nim
-    pushProcCon(c, s)
+    if n.sons[genericParamsPos].kind == nkEmpty:
-    addResult(c, s.typ.sons[0], n.info, skProc)
+      pushProcCon(c, s)
-    let semBody = hloBody(c, semProcBody(c, n.sons[bodyPos]))
+      addResult(c, s.typ.sons[0], n.info, skProc)
-    n.sons[bodyPos] = transformBody(c.module, semBody, s)
+      let semBody = hloBody(c, semProcBody(c, n.sons[bodyPos]))
-    addResultNode(c, n)
+      n.sons[bodyPos] = transformBody(c.module, semBody, s)
-    popProcCon(c)
+      addResultNode(c, n)
+      popProcCon(c)
     sideEffectsCheck(c, s)
   else:
     localError(n.info, errImplOfXexpected, s.name.s)
@@ -937,6 +946,34 @@ proc semLambda(c: PContext, n: PNode, flags: TExprFlags): PNode =
   popOwner()
   result.typ = s.typ
 
+proc semInferredLambda(c: PContext, pt: TIdTable, n: PNode): PNode =
+  var n = n
+  
+  n = replaceTypesInBody(c, pt, n)
+  result = n
+  
+  n.sons[genericParamsPos] = emptyNode
+  n.sons[paramsPos] = n.typ.n
+  
+  openScope(c)
+  var s = n.sons[namePos].sym
+  addParams(c, n.typ.n, skProc)
+  pushProcCon(c, s)
+  addResult(c, n.typ.sons[0], n.info, skProc)
+  let semBody = hloBody(c, semProcBody(c, n.sons[bodyPos]))
+  n.sons[bodyPos] = transformBody(c.module, semBody, n.sons[namePos].sym)
+  addResultNode(c, n)
+  popProcCon(c)
+  closeScope(c)
+  
+  s.ast = result
+
+  # alternative variant (not quite working):
+  # var prc = arg[0].sym
+  # let inferred = c.semGenerateInstance(c, prc, m.bindings, arg.info)
+  # result = inferred.ast
+  # result.kind = arg.kind
+
 proc activate(c: PContext, n: PNode) =
   # XXX: This proc is part of my plan for getting rid of
   # forward declarations. stay tuned.

compiler/semtypinst.nim

@@ -29,6 +29,7 @@ proc checkConstructedType*(info: TLineInfo, typ: PType) =
     localError(info, errVarVarTypeNotAllowed)
   elif computeSize(t) == szIllegalRecursion:
     localError(info, errIllegalRecursionInTypeX, typeToString(t))
+  
   when false:
     if t.kind == tyObject and t.sons[0] != nil:
       if t.sons[0].kind != tyObject or tfFinal in t.sons[0].flags: 
@@ -409,14 +410,22 @@ proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType =
       
       else: discard
 
+proc initTypeVars(p: PContext, pt: TIdTable, info: TLineInfo): TReplTypeVars =
+  initIdTable(result.symMap)
+  copyIdTable(result.typeMap, pt)
+  initIdTable(result.localCache)
+  result.info = info
+  result.c = p
+
+proc replaceTypesInBody*(p: PContext, pt: TIdTable, n: PNode): PNode =
+  var cl = initTypeVars(p, pt, n.info)
+  pushInfoContext(n.info)
+  result = replaceTypeVarsN(cl, n)
+  popInfoContext()
+  
 proc generateTypeInstance*(p: PContext, pt: TIdTable, info: TLineInfo,
                            t: PType): PType =
-  var cl: TReplTypeVars
+  var cl = initTypeVars(p, pt, info)
-  initIdTable(cl.symMap)
-  copyIdTable(cl.typeMap, pt)
-  initIdTable(cl.localCache)
-  cl.info = info
-  cl.c = p
   pushInfoContext(info)
   result = replaceTypeVarsT(cl, t)
   popInfoContext()

compiler/sigmatch.nim

@@ -1039,10 +1039,11 @@ proc paramTypesMatchAux(m: var TCandidate, f, argType: PType,
     #result = copyTree(arg)
     result = implicitConv(nkHiddenStdConv, f, copyTree(arg), m, c)
   of isInferred, isInferredConvertible:
-    var prc = if arg.kind in nkLambdaKinds: arg[0].sym
+    if arg.kind in {nkProcDef, nkIteratorDef} + nkLambdaKinds:
-              else: arg.sym
+      result = c.semInferredLambda(c, m.bindings, arg)
-    let inferred = c.semGenerateInstance(c, prc, m.bindings, arg.info)
+    else:
-    result = newSymNode(inferred, arg.info)
+      let inferred = c.semGenerateInstance(c, arg.sym, m.bindings, arg.info)
+      result = newSymNode(inferred, arg.info)
     if r == isInferredConvertible:
       result = implicitConv(nkHiddenStdConv, f, result, m, c)
   of isGeneric:

compiler/types.nim

@@ -1042,7 +1042,8 @@ proc typeAllowedAux(marker: var TIntSet, typ: PType, kind: TSymKind,
   of tyEmpty:
     result = taField in flags
   of tyTypeClasses:
-    result = true
+    result = tfGenericTypeParam in t.flags or
+             taField notin flags
   of tyGenericBody, tyGenericParam, tyGenericInvokation,
      tyNone, tyForward, tyFromExpr, tyFieldAccessor:
     result = false

tests/generics/tgenericlambda.nim

@@ -0,0 +1,10 @@
+discard """
+  output: "10\n10"
+"""
+
+proc test(x: proc (a, b: int): int) =
+  echo x(5, 5)
+
+test(proc (a, b): auto = a + b)
+
+test do (a, b) -> auto: a + b

tests/generics/tmetafield.nim

@@ -1,7 +1,7 @@
 discard """
   cmd: "nimrod check $# $#"
   msg: "'proc' is not a concrete type"
-  msg: "'seq[Foo]' is not a concrete type."
+  msg: "'Foo' is not a concrete type."
   msg: "invalid type: 'TBaseMed'"
 """