split the inline and closure iterators into different symbol kinds for easier discrimination between them

compiler/ast.nim

@@ -469,7 +469,8 @@ type
     skResult,             # special 'result' variable
     skProc,               # a proc
     skMethod,             # a method
-    skIterator,           # an iterator
+    skIterator,           # an inline iterator
+    skClosureIterator,    # a resumable closure iterator
     skConverter,          # a type converter
     skMacro,              # a macro
     skTemplate,           # a template; currently also misused for user-defined
@@ -485,8 +486,8 @@ type
   TSymKinds* = set[TSymKind]
 
 const
-  routineKinds* = {skProc, skMethod, skIterator, skConverter,
-    skMacro, skTemplate}
+  routineKinds* = {skProc, skMethod, skIterator, skClosureIterator,
+                   skConverter, skMacro, skTemplate}
   tfIncompleteStruct* = tfVarargs
   skError* = skUnknown
   
@@ -820,8 +821,8 @@ type
 # the poor naming choices in the standard library.
 
 const 
-  OverloadableSyms* = {skProc, skMethod, skIterator, skConverter,
-    skModule, skTemplate, skMacro}
+  OverloadableSyms* = {skProc, skMethod, skIterator, skClosureIterator,
+    skConverter, skModule, skTemplate, skMacro}
 
   GenericTypes*: TTypeKinds = {tyGenericInvokation, tyGenericBody, 
     tyGenericParam}
@@ -843,7 +844,8 @@ const
                                     tyTuple, tySequence}
   NilableTypes*: TTypeKinds = {tyPointer, tyCString, tyRef, tyPtr, tySequence,
     tyProc, tyString, tyError}
-  ExportableSymKinds* = {skVar, skConst, skProc, skMethod, skType, skIterator, 
+  ExportableSymKinds* = {skVar, skConst, skProc, skMethod, skType,
+    skIterator, skClosureIterator,
     skMacro, skTemplate, skConverter, skEnumField, skLet, skStub}
   PersistentNodeFlags*: TNodeFlags = {nfBase2, nfBase8, nfBase16,
                                       nfDotSetter, nfDotField,
@@ -869,7 +871,10 @@ const
   nkStrKinds* = {nkStrLit..nkTripleStrLit}
 
   skLocalVars* = {skVar, skLet, skForVar, skParam, skResult}
-  skProcKinds* = {skProc, skTemplate, skMacro, skIterator, skMethod, skConverter}
+  skProcKinds* = {skProc, skTemplate, skMacro, skIterator, skClosureIterator,
+                  skMethod, skConverter}
+
+  skIterators* = {skIterator, skClosureIterator}
 
   lfFullExternalName* = lfParamCopy # \
     # only used when 'gCmd == cmdPretty': Indicates that the symbol has been
@@ -1479,8 +1484,7 @@ proc originatingModule*(s: PSym): PSym =
   while result.kind != skModule: result = result.owner
 
 proc isRoutine*(s: PSym): bool {.inline.} =
-  result = s.kind in {skProc, skTemplate, skMacro, skIterator, skMethod,
-                      skConverter}
+  result = s.kind in skProcKinds
 
 proc hasPattern*(s: PSym): bool {.inline.} =
   result = isRoutine(s) and s.ast.sons[patternPos].kind != nkEmpty

compiler/ccgexprs.nim

@@ -1803,7 +1803,7 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
       else:
         genProc(p.module, sym)
       putLocIntoDest(p, d, sym.loc)
-    of skProc, skConverter, skIterator:
+    of skProc, skConverter, skIterators:
       genProc(p.module, sym)
       if sym.loc.r == nil or sym.loc.t == nil:
         internalError(n.info, "expr: proc not init " & sym.name.s)

compiler/ccgstmts.nim

@@ -863,7 +863,7 @@ proc genAsmOrEmitStmt(p: BProc, t: PNode, isAsmStmt=false): PRope =
       res.add(t.sons[i].strVal)
     of nkSym:
       var sym = t.sons[i].sym
-      if sym.kind in {skProc, skIterator, skMethod}: 
+      if sym.kind in {skProc, skIterator, skClosureIterator, skMethod}:
         var a: TLoc
         initLocExpr(p, t.sons[i], a)
         res.add(rdLoc(a).ropeToStr)

compiler/ccgtypes.nim

@@ -69,7 +69,7 @@ proc mangleName(s: PSym): PRope =
   if result == nil: 
     if gCmd == cmdCompileToLLVM: 
       case s.kind
-      of skProc, skMethod, skConverter, skConst, skIterator: 
+      of skProc, skMethod, skConverter, skConst, skIterators:
         result = ~"@"
       of skVar, skForVar, skResult, skLet: 
         if sfGlobal in s.flags: result = ~"@"

compiler/cgen.nim

@@ -705,7 +705,7 @@ proc cgsym(m: BModule, name: string): PRope =
   var sym = magicsys.getCompilerProc(name)
   if sym != nil: 
     case sym.kind
-    of skProc, skMethod, skConverter, skIterator: genProc(m, sym)
+    of skProc, skMethod, skConverter, skIterators: genProc(m, sym)
     of skVar, skResult, skLet: genVarPrototype(m, sym)
     of skType: discard getTypeDesc(m, sym.typ)
     else: internalError("cgsym: " & name)

compiler/docgen.nim

@@ -366,7 +366,7 @@ proc generateJson(d: PDoc, n: PNode, jArray: PJsonNode = nil): PJsonNode =
 proc genSection(d: PDoc, kind: TSymKind) =
   const sectionNames: array[skModule..skTemplate, string] = [
     "Imports", "Types", "Vars", "Lets", "Consts", "Vars", "Procs", "Methods",
-    "Iterators", "Converters", "Macros", "Templates"
+    "Iterators", "Iterators", "Converters", "Macros", "Templates"
   ]
   if d.section[kind] == nil: return
   var title = sectionNames[kind].toRope

compiler/importer.nim

@@ -103,7 +103,7 @@ proc importSymbol(c: PContext, n: PNode, fromMod: PSym) =
       internalError(n.info, "importSymbol: 2")
     # for an enumeration we have to add all identifiers
     case s.kind
-    of skProc, skMethod, skIterator, skMacro, skTemplate, skConverter:
+    of skProcKinds:
       # for a overloadable syms add all overloaded routines
       var it: TIdentIter
       var e = initIdentIter(it, fromMod.tab, s.name)

compiler/jsgen.nim

@@ -1154,7 +1154,7 @@ proc createVar(p: PProc, typ: PType, indirect: bool): PRope =
 
 proc isIndirect(v: PSym): bool = 
   result = (sfAddrTaken in v.flags) and (mapType(v.typ) != etyObject) and
-    v.kind notin {skProc, skConverter, skMethod, skIterator}
+    v.kind notin {skProc, skConverter, skMethod, skIterator, skClosureIterator}
 
 proc genVarInit(p: PProc, v: PSym, n: PNode) = 
   var 

compiler/lambdalifting.nim

@@ -232,9 +232,9 @@ proc newOuterContext(fn: PSym, up: POuterContext = nil): POuterContext =
   initIdNodeTable(result.localsToAccess)
   initIdTable(result.localsToEnv)
   initIdTable(result.lambdasToEnv)
-  result.isIter = fn.kind == skIterator and fn.typ.callConv == ccClosure
+  result.isIter = fn.kind == skClosureIterator
   if result.isIter: initIterContext(result, fn)
-  
+
 proc newInnerContext(fn: PSym): PInnerContext =
   new(result)
   result.fn = fn
@@ -292,8 +292,7 @@ proc newCall(a, b: PSym): PNode =
   result.add newSymNode(b)
 
 proc isInnerProc(s, outerProc: PSym): bool {.inline.} =
-  result = (s.kind in {skProc, skMethod, skConverter} or
-            s.kind == skIterator and s.typ.callConv == ccClosure) and
+  result = s.kind in {skProc, skMethod, skConverter, skClosureIterator} and
            s.skipGenericOwner == outerProc
   #s.typ.callConv == ccClosure
 
@@ -653,7 +652,7 @@ proc outerProcSons(o: POuterContext, n: PNode) =
 proc liftIterSym*(n: PNode): PNode =
   # transforms  (iter)  to  (let env = newClosure[iter](); (iter, env)) 
   let iter = n.sym
-  assert iter.kind == skIterator
+  assert iter.kind == skClosureIterator
 
   result = newNodeIT(nkStmtListExpr, n.info, n.typ)
   
@@ -679,7 +678,7 @@ proc transformOuterProc(o: POuterContext, n: PNode): PNode =
 
     var closure = PEnv(idTableGet(o.lambdasToEnv, local))
 
-    if local.kind == skIterator and local.typ.callConv == ccClosure:
+    if local.kind == skClosureIterator:
       # consider: [i1, i2, i1]  Since we merged the iterator's closure
       # with the captured owning variables, we need to generate the
       # closure generation code again:
@@ -843,10 +842,10 @@ proc liftForLoop*(body: PNode): PNode =
   
   # static binding?
   var env: PSym
-  if call[0].kind == nkSym and call[0].sym.kind == skIterator:
+  if call[0].kind == nkSym and call[0].sym.kind == skClosureIterator:
     # createClosure()
     let iter = call[0].sym
-    assert iter.kind == skIterator
+    assert iter.kind == skClosureIterator
     env = copySym(getHiddenParam(iter))
 
     var v = newNodeI(nkVarSection, body.info)

compiler/lookups.nim

@@ -109,7 +109,7 @@ type
 
 proc getSymRepr*(s: PSym): string = 
   case s.kind
-  of skProc, skMethod, skConverter, skIterator: result = getProcHeader(s)
+  of skProc, skMethod, skConverter, skIterators: result = getProcHeader(s)
   else: result = s.name.s
 
 proc ensureNoMissingOrUnusedSymbols(scope: PScope) =

compiler/pragmas.nim

@@ -772,6 +772,17 @@ proc implictPragmas*(c: PContext, sym: PSym, n: PNode,
       addToLib(lib, sym)
       if sym.loc.r == nil: sym.loc.r = toRope(sym.name.s)
 
+proc hasPragma*(n: PNode, pragma: TSpecialWord): bool =
+  if n == nil or n.sons == nil:
+    return false
+
+  for p in n.sons:
+    var key = if p.kind == nkExprColonExpr: p[0] else: p
+    if key.kind == nkIdent and whichKeyword(key.ident) == pragma:
+      return true
+  
+  return false
+
 proc pragma(c: PContext, sym: PSym, n: PNode, validPragmas: TSpecialWords) =
   if n == nil: return
   for i in countup(0, sonsLen(n) - 1):

compiler/semcall.nim

@@ -64,7 +64,7 @@ proc pickBestCandidate(c: PContext, headSymbol: PNode,
             errors[errors.len - 1].add("\n  " & err)
       if z.state == csMatch:
         # little hack so that iterators are preferred over everything else:
-        if sym.kind == skIterator: inc(z.exactMatches, 200)
+        if sym.kind in skIterators: inc(z.exactMatches, 200)
         case best.state
         of csEmpty, csNoMatch: best = z
         of csMatch:
@@ -289,8 +289,9 @@ proc explicitGenericInstantiation(c: PContext, n: PNode, s: PSym): PNode =
     result = newNodeI(a.kind, n.info)
     for i in countup(0, len(a)-1): 
       var candidate = a.sons[i].sym
-      if candidate.kind in {skProc, skMethod, skConverter, skIterator}: 
-        # if suffices that the candidate has the proper number of generic 
+      if candidate.kind in {skProc, skMethod, skConverter,
+                            skIterator, skClosureIterator}:
+        # it suffices that the candidate has the proper number of generic 
         # type parameters:
         if safeLen(candidate.ast.sons[genericParamsPos]) == n.len-1:
           result.add(explicitGenericSym(c, n, candidate))

compiler/semdata.nim

@@ -274,7 +274,7 @@ proc makeRangeType*(c: PContext; first, last: BiggestInt;
   addSonSkipIntLit(result, intType) # basetype of range
 
 proc markIndirect*(c: PContext, s: PSym) {.inline.} =
-  if s.kind in {skProc, skConverter, skMethod, skIterator}:
+  if s.kind in {skProc, skConverter, skMethod, skIterator, skClosureIterator}:
     incl(s.flags, sfAddrTaken)
     # XXX add to 'c' for global analysis
 

compiler/semexprs.nim

@@ -662,11 +662,11 @@ proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
                                      flags: TExprFlags): PNode =
   if flags*{efInTypeof, efWantIterator} != {}:
     # consider: 'for x in pReturningArray()' --> we don't want the restriction
-    # to 'skIterator' anymore; skIterator is preferred in sigmatch already for
-    # typeof support.
+    # to 'skIterators' anymore; skIterators are preferred in sigmatch already 
+    # for typeof support.
     # for ``type(countup(1,3))``, see ``tests/ttoseq``.
     result = semOverloadedCall(c, n, nOrig,
-      {skProc, skMethod, skConverter, skMacro, skTemplate, skIterator})
+      {skProc, skMethod, skConverter, skMacro, skTemplate}+skIterators)
   else:
     result = semOverloadedCall(c, n, nOrig, 
       {skProc, skMethod, skConverter, skMacro, skTemplate})
@@ -679,7 +679,7 @@ proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
     case callee.kind
     of skMacro, skTemplate: discard
     else:
-      if (callee.kind == skIterator) and (callee.id == c.p.owner.id): 
+      if (callee.kind in skIterators) and (callee.id == c.p.owner.id): 
         localError(n.info, errRecursiveDependencyX, callee.name.s)
       if sfNoSideEffect notin callee.flags: 
         if {sfImportc, sfSideEffect} * callee.flags != {}:
@@ -1193,7 +1193,7 @@ proc semReturn(c: PContext, n: PNode): PNode =
   result = n
   checkSonsLen(n, 1)
   if c.p.owner.kind in {skConverter, skMethod, skProc, skMacro} or
-     (c.p.owner.kind == skIterator and c.p.owner.typ.callConv == ccClosure):
+     c.p.owner.kind == skClosureIterator:
     if n.sons[0].kind != nkEmpty:
       # transform ``return expr`` to ``result = expr; return``
       if c.p.resultSym != nil: 
@@ -1258,7 +1258,7 @@ proc semYieldVarResult(c: PContext, n: PNode, restype: PType) =
 proc semYield(c: PContext, n: PNode): PNode =
   result = n
   checkSonsLen(n, 1)
-  if c.p.owner == nil or c.p.owner.kind != skIterator:
+  if c.p.owner == nil or c.p.owner.kind notin skIterators:
     localError(n.info, errYieldNotAllowedHere)
   elif c.p.inTryStmt > 0 and c.p.owner.typ.callConv != ccInline:
     localError(n.info, errYieldNotAllowedInTryStmt)
@@ -1266,9 +1266,11 @@ proc semYield(c: PContext, n: PNode): PNode =
     n.sons[0] = semExprWithType(c, n.sons[0]) # check for type compatibility:
     var restype = c.p.owner.typ.sons[0]
     if restype != nil:
-      n.sons[0] = fitNode(c, restype.base, n.sons[0])
+      let adjustedRes = if c.p.owner.kind == skIterator: restype.base
+                        else: restype
+      n.sons[0] = fitNode(c, adjustedRes, n.sons[0])
       if n.sons[0].typ == nil: internalError(n.info, "semYield")
-      semYieldVarResult(c, n, restype)
+      semYieldVarResult(c, n, adjustedRes)
     else:
       localError(n.info, errCannotReturnExpr)
   elif c.p.owner.typ.sons[0] != nil:
@@ -1828,7 +1830,7 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
     var s = lookUp(c, n)
     semCaptureSym(s, c.p.owner)
     result = semSym(c, n, s, flags)
-    if s.kind in {skProc, skMethod, skIterator, skConverter}:
+    if s.kind in {skProc, skMethod, skConverter}+skIterators:
       #performProcvarCheck(c, n, s)
       result = symChoice(c, n, s, scClosed)
       if result.kind == nkSym:
@@ -1918,7 +1920,7 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
           localError(n.info, errUseQualifier, s.name.s)
         elif s.magic == mNone: result = semDirectOp(c, n, flags)
         else: result = semMagic(c, n, s, flags)
-      of skProc, skMethod, skConverter, skIterator: 
+      of skProc, skMethod, skConverter, skIterators:
         if s.magic == mNone: result = semDirectOp(c, n, flags)
         else: result = semMagic(c, n, s, flags)
       else:
@@ -1942,7 +1944,7 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
   of nkBracketExpr:
     checkMinSonsLen(n, 1)
     var s = qualifiedLookUp(c, n.sons[0], {checkUndeclared})
-    if s != nil and s.kind in {skProc, skMethod, skConverter, skIterator}: 
+    if s != nil and s.kind in {skProc, skMethod, skConverter}+skIterators:
       # type parameters: partial generic specialization
       n.sons[0] = semSymGenericInstantiation(c, n.sons[0], s)
       result = explicitGenericInstantiation(c, n, s)

compiler/semgnrc.nim

@@ -42,7 +42,7 @@ proc semGenericStmtSymbol(c: PContext, n: PNode, s: PSym): PNode =
   of skUnknown: 
     # Introduced in this pass! Leave it as an identifier.
     result = n
-  of skProc, skMethod, skIterator, skConverter: 
+  of skProc, skMethod, skIterators, skConverter:
     result = symChoice(c, n, s, scOpen)
   of skTemplate:
     if macroToExpand(s):
@@ -141,7 +141,7 @@ proc semGenericStmt(c: PContext, n: PNode,
         # symbol lookup ...
       of skUnknown, skParam: 
         # Leave it as an identifier.
-      of skProc, skMethod, skIterator, skConverter: 
+      of skProc, skMethod, skIterators, skConverter:
         result.sons[0] = symChoice(c, n.sons[0], s, scOption)
         first = 1
       of skGenericParam:

compiler/semstmts.nim

@@ -76,8 +76,8 @@ proc performProcvarCheck(c: PContext, n: PNode, s: PSym) =
 
 proc semProcvarCheck(c: PContext, n: PNode) =
   let n = n.skipConv
-  if n.kind == nkSym and n.sym.kind in {skProc, skMethod, skIterator,
-                                        skConverter}:
+  if n.kind == nkSym and n.sym.kind in {skProc, skMethod, skConverter,
+                                        skIterator, skClosureIterator}:
     performProcvarCheck(c, n, n.sym)
 
 proc semProc(c: PContext, n: PNode): PNode
@@ -665,7 +665,7 @@ proc semFor(c: PContext, n: PNode): PNode =
     # first class iterator:
     result = semForVars(c, n)
   elif call.kind notin nkCallKinds or call.sons[0].kind != nkSym or
-      call.sons[0].sym.kind != skIterator: 
+      call.sons[0].sym.kind notin skIterators:
     if length == 3:
       n.sons[length-2] = implicitIterator(c, "items", n.sons[length-2])
     elif length == 4:
@@ -998,8 +998,7 @@ proc activate(c: PContext, n: PNode) =
       discard
 
 proc maybeAddResult(c: PContext, s: PSym, n: PNode) =
-  if s.typ.sons[0] != nil and
-      (s.kind != skIterator or s.typ.callConv == ccClosure):
+  if s.typ.sons[0] != nil and s.kind != skIterator:
     addResult(c, s.typ.sons[0], n.info, s.kind)
     addResultNode(c, n)
 
@@ -1074,12 +1073,12 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
     rawAddSon(s.typ, nil)
   if n.sons[patternPos].kind != nkEmpty:
     n.sons[patternPos] = semPattern(c, n.sons[patternPos])
-  if s.kind == skIterator: 
+  if s.kind in skIterators:
     s.typ.flags.incl(tfIterator)
   
   var proto = searchForProc(c, s.scope, s)
-  if proto == nil: 
-    if s.kind == skIterator and isAnon: s.typ.callConv = ccClosure
+  if proto == nil:
+    if s.kind == skClosureIterator: s.typ.callConv = ccClosure
     else: s.typ.callConv = lastOptionEntry(c).defaultCC
     # add it here, so that recursive procs are possible:
     if sfGenSym in s.flags: discard
@@ -1139,7 +1138,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
         n.sons[bodyPos] = transformBody(c.module, semBody, s)
       popProcCon(c)
     else:
-      if s.typ.sons[0] != nil and kind != skIterator:
+      if s.typ.sons[0] != nil and kind notin skIterators:
         addDecl(c, newSym(skUnknown, getIdent"result", nil, n.info))
       var toBind = initIntSet()
       n.sons[bodyPos] = semGenericStmtScope(c, n.sons[bodyPos], {}, toBind)
@@ -1166,7 +1165,10 @@ proc determineType(c: PContext, s: PSym) =
   discard semProcAux(c, s.ast, s.kind, {}, stepDetermineType)
 
 proc semIterator(c: PContext, n: PNode): PNode =
-  result = semProcAux(c, n, skIterator, iteratorPragmas)
+  let kind = if hasPragma(n[pragmasPos], wClosure) or
+                n[namePos].kind == nkEmpty: skClosureIterator
+             else: skIterator
+  result = semProcAux(c, n, kind, iteratorPragmas)
   var s = result.sons[namePos].sym
   var t = s.typ
   if t.sons[0] == nil and s.typ.callConv != ccClosure:

compiler/semtempl.nim

@@ -171,7 +171,7 @@ proc semTemplSymbol(c: PContext, n: PNode, s: PSym): PNode =
   of skUnknown: 
     # Introduced in this pass! Leave it as an identifier.
     result = n
-  of skProc, skMethod, skIterator, skConverter, skTemplate, skMacro:
+  of OverloadableSyms:
     result = symChoice(c, n, s, scOpen)
   of skGenericParam: 
     result = newSymNodeTypeDesc(s, n.info)
@@ -348,7 +348,7 @@ proc semTemplBody(c: var TemplCtx, n: PNode): PNode =
   of nkMethodDef:
     result = semRoutineInTemplBody(c, n, skMethod)
   of nkIteratorDef:
-    result = semRoutineInTemplBody(c, n, skIterator)
+    result = semRoutineInTemplBody(c, n, n[namePos].sym.kind)
   of nkTemplateDef:
     result = semRoutineInTemplBody(c, n, skTemplate)
   of nkMacroDef:

compiler/semtypes.nim

@@ -953,6 +953,23 @@ proc semTypeClass(c: PContext, n: PNode, prev: PType): PType =
       let typ = semTypeNode(c, n, nil)
       result.sons.safeAdd(typ)
 
+proc semProcTypeWithScope(c: PContext, n: PNode,
+                        prev: PType, kind: TSymKind): PType =
+  checkSonsLen(n, 2)
+  openScope(c)
+  result = semProcTypeNode(c, n.sons[0], nil, prev, kind)
+  # dummy symbol for `pragma`:
+  var s = newSymS(kind, newIdentNode(getIdent("dummy"), n.info), c)
+  s.typ = result
+  if n.sons[1].kind == nkEmpty or n.sons[1].len == 0:
+    if result.callConv == ccDefault:
+      result.callConv = ccClosure
+      #Message(n.info, warnImplicitClosure, renderTree(n))
+  else:
+    pragma(c, s, n.sons[1], procTypePragmas)
+    when useEffectSystem: setEffectsForProcType(result, n.sons[1])
+  closeScope(c)
+
 proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
   result = nil
   if gCmd == cmdIdeTools: suggestExpr(c, n)
@@ -1075,27 +1092,18 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
     var base = semTypeNode(c, n.sons[0], nil)
     result.rawAddSon(base)
     result.flags.incl tfHasStatic
-  of nkProcTy, nkIteratorTy:
+  of nkIteratorTy:
+    if n.sonsLen == 0:
+      result = newConstraint(c, tyIter)
+    else:
+      result = semProcTypeWithScope(c, n, prev, skClosureIterator)
+      result.flags.incl(tfIterator)
+      result.callConv = ccClosure
+  of nkProcTy:
     if n.sonsLen == 0:
       result = newConstraint(c, tyProc)
     else:
-      checkSonsLen(n, 2)
-      openScope(c)
-      result = semProcTypeNode(c, n.sons[0], nil, prev, skProc)
-      # dummy symbol for `pragma`:
-      var s = newSymS(skProc, newIdentNode(getIdent("dummy"), n.info), c)
-      s.typ = result
-      if n.sons[1].kind == nkEmpty or n.sons[1].len == 0:
-        if result.callConv == ccDefault:
-          result.callConv = ccClosure
-          #Message(n.info, warnImplicitClosure, renderTree(n))
-      else:
-        pragma(c, s, n.sons[1], procTypePragmas)
-        when useEffectSystem: setEffectsForProcType(result, n.sons[1])
-      closeScope(c)
-    if n.kind == nkIteratorTy:
-      result.flags.incl(tfIterator)
-      result.callConv = ccClosure
+      result = semProcTypeWithScope(c, n, prev, skProc)
   of nkEnumTy: result = semEnum(c, n, prev)
   of nkType: result = n.typ
   of nkStmtListType: result = semStmtListType(c, n, prev)

compiler/sigmatch.nim

@@ -1142,7 +1142,7 @@ proc paramTypesMatch*(m: var TCandidate, f, a: PType,
     z.calleeSym = m.calleeSym
     var best = -1
     for i in countup(0, sonsLen(arg) - 1): 
-      if arg.sons[i].sym.kind in {skProc, skIterator, skMethod, skConverter}: 
+      if arg.sons[i].sym.kind in {skProc, skMethod, skConverter}+skIterators:
         copyCandidate(z, m)
         var r = typeRel(z, f, arg.sons[i].typ)
         if r != isNone: 

compiler/transf.nim

@@ -113,7 +113,7 @@ proc newAsgnStmt(c: PTransf, le: PNode, ri: PTransNode): PTransNode =
   result[1] = ri
 
 proc transformSymAux(c: PTransf, n: PNode): PNode =
-  #if n.sym.kind == skIterator and n.sym.typ.callConv == ccClosure:
+  #if n.sym.kind == skClosureIterator:
   #  return liftIterSym(n)
   var b: PNode
   var tc = c.transCon
@@ -434,7 +434,6 @@ proc transformFor(c: PTransf, n: PNode): PTransNode =
   var length = sonsLen(n)
   var call = n.sons[length - 2]
   if call.kind notin nkCallKinds or call.sons[0].kind != nkSym or 
-      call.sons[0].typ.callConv == ccClosure or
       call.sons[0].sym.kind != skIterator:
     n.sons[length-1] = transformLoopBody(c, n.sons[length-1]).PNode
     return lambdalifting.liftForLoop(n).PTransNode
@@ -454,7 +453,7 @@ proc transformFor(c: PTransf, n: PNode): PTransNode =
   var newC = newTransCon(getCurrOwner(c))
   newC.forStmt = n
   newC.forLoopBody = loopBody
-  if iter.kind != skIterator: internalError(call.info, "transformFor") 
+  internalAssert iter.kind == skIterator
   # generate access statements for the parameters (unless they are constant)
   pushTransCon(c, newC)
   for i in countup(1, sonsLen(call) - 1): 
@@ -741,7 +740,7 @@ proc transformBody*(module: PSym, n: PNode, prc: PSym): PNode =
     var c = openTransf(module, "")
     result = processTransf(c, n, prc)
     result = liftLambdas(prc, result)
-    #if prc.kind == skIterator and prc.typ.callConv == ccClosure:
+    #if prc.kind == skClosureIterator:
     #  result = lambdalifting.liftIterator(prc, result)
     incl(result.flags, nfTransf)
     when useEffectSystem: trackProc(prc, result)

compiler/types.nim

@@ -1247,7 +1247,7 @@ proc computeSize(typ: PType): BiggestInt =
 
 proc getReturnType*(s: PSym): PType =
   # Obtains the return type of a iterator/proc/macro/template
-  assert s.kind in {skProc, skTemplate, skMacro, skIterator}
+  assert s.kind in skProcKinds
   result = s.typ.sons[0]
 
 proc getSize(typ: PType): BiggestInt = 

compiler/vmgen.nim

@@ -1311,7 +1311,7 @@ proc gen(c: PCtx; n: PNode; dest: var TDest; flags: TGenFlags = {}) =
     case s.kind
     of skVar, skForVar, skTemp, skLet, skParam, skResult:
       genRdVar(c, n, dest, flags)
-    of skProc, skConverter, skMacro, skTemplate, skMethod, skIterator:
+    of skProc, skConverter, skMacro, skTemplate, skMethod, skIterators:
       # 'skTemplate' is only allowed for 'getAst' support:
       if sfImportc in s.flags: c.importcSym(n.info, s)
       genLit(c, n, dest)

doc/idetools.txt

@@ -279,8 +279,8 @@ skForVar
         col 7: ""
 
 
-skIterator
-----------
+skIterator, skClosureIterator
+-----------------------------
 
 The fourth column will be the empty string if the iterator is being
 defined, since at that point in the file the parser hasn't processed

lib/core/macros.nim

@@ -88,7 +88,7 @@ type
     nskUnknown, nskConditional, nskDynLib, nskParam,
     nskGenericParam, nskTemp, nskModule, nskType, nskVar, nskLet, 
     nskConst, nskResult,
-    nskProc, nskMethod, nskIterator,
+    nskProc, nskMethod, nskIterator, nskClosureIterator,
     nskConverter, nskMacro, nskTemplate, nskField,
     nskEnumField, nskForVar, nskLabel,
     nskStub

tests/exprs/texprstmt.nim

@@ -1,6 +1,6 @@
 discard """
   line: 10
-  errormsg: "value returned by statement has to be discarded"
+  errormsg: "value of type 'string' has to be discarded"
 """
 
 # bug #578

tests/iter/tanoniter1.nim

@@ -8,7 +8,7 @@ discard """
 """
 
 proc factory(a, b: int): iterator (): int =
-  iterator foo(): int =
+  iterator foo(): int {.closure.} =
     var x = a
     while x <= b:
       yield x