fixes nim-lang#24361 (nim-lang#25179)

Author: Araq

compiler/sem.nim

@@ -321,7 +321,7 @@ proc hasCycle(n: PNode): bool =
       break
   excl n.flags, nfNone
 
-proc fixupTypeAfterEval(c: PContext, evaluated, eOrig: PNode): PNode =
+proc fixupTypeAfterEval(c: PContext, evaluated, eOrig: PNode; producedClosure: var bool): PNode =
   # recompute the types as 'eval' isn't guaranteed to construct types nor
   # that the types are sound:
   when true:
@@ -333,7 +333,7 @@ proc fixupTypeAfterEval(c: PContext, evaluated, eOrig: PNode): PNode =
       if hasCycle(result):
         result = localErrorNode(c, eOrig, "the resulting AST is cyclic and cannot be processed further")
       else:
-        semmacrosanity.annotateType(result, expectedType, c.config)
+        semmacrosanity.annotateType(result, expectedType, c.config, producedClosure)
   else:
     result = semExprWithType(c, evaluated)
     #result = fitNode(c, e.typ, result) inlined with special case:
@@ -370,7 +370,10 @@ proc tryConstExpr(c: PContext, n: PNode; expectedType: PType = nil): PNode =
     if result == nil or result.kind == nkEmpty:
       result = nil
     else:
-      result = fixupTypeAfterEval(c, result, e)
+      var producedClosure = false
+      result = fixupTypeAfterEval(c, result, e, producedClosure)
+      if producedClosure:
+        result = nil
 
   except ERecoverableError:
     result = nil
@@ -407,7 +410,10 @@ proc semConstExpr(c: PContext, n: PNode; expectedType: PType = nil): PNode =
       # error correction:
       result = e
     else:
-      result = fixupTypeAfterEval(c, result, e)
+      var producedClosure = false
+      result = fixupTypeAfterEval(c, result, e, producedClosure)
+      if producedClosure:
+        result = nil
 
 proc semExprFlagDispatched(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType = nil): PNode =
   if efNeedStatic in flags:

compiler/semexprs.nim

@@ -951,11 +951,15 @@ proc evalAtCompileTime(c: PContext, n: PNode): PNode =
         result = evalStaticExpr(c.module, c.idgen, c.graph, call, c.p.owner)
         if result.isNil:
           localError(c.config, n.info, errCannotInterpretNodeX % renderTree(call))
-        else: result = fixupTypeAfterEval(c, result, n)
+        else:
+          var producedClosure = false
+          result = fixupTypeAfterEval(c, result, n, producedClosure)
       else:
         result = evalConstExpr(c.module, c.idgen, c.graph, call)
         if result.isNil: result = n
-        else: result = fixupTypeAfterEval(c, result, n)
+        else:
+          var producedClosure = false
+          result = fixupTypeAfterEval(c, result, n, producedClosure)
     else:
       result = n
     #if result != n:
@@ -973,7 +977,8 @@ proc semStaticExpr(c: PContext, n: PNode; expectedType: PType = nil): PNode =
     localError(c.config, n.info, errCannotInterpretNodeX % renderTree(n))
     result = c.graph.emptyNode
   else:
-    result = fixupTypeAfterEval(c, result, a)
+    var producedClosure = false
+    result = fixupTypeAfterEval(c, result, a, producedClosure)
 
 proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
                                      flags: TExprFlags; expectedType: PType = nil): PNode =
@@ -3070,10 +3075,10 @@ proc semTupleConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PTyp
 
 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) =

compiler/semmacrosanity.nim

@@ -86,7 +86,7 @@ proc ithField(t: PType, field: var FieldTracker): FieldInfo =
     base = b.baseClass
   result = ithField(t.n, field)
 
-proc annotateType*(n: PNode, t: PType; conf: ConfigRef) =
+proc annotateType*(n: PNode, t: PType; conf: ConfigRef; producedClosure: var bool) =
   let x = t.skipTypes(abstractInst+{tyRange})
   # Note: x can be unequal to t and we need to be careful to use 't'
   # to not to skip tyGenericInst
@@ -102,7 +102,7 @@ proc annotateType*(n: PNode, t: PType; conf: ConfigRef) =
         globalError conf, n.info, "invalid field at index " & $i
       else:
         internalAssert(conf, n[i].kind == nkExprColonExpr)
-        annotateType(n[i][1], field.sym.typ, conf)
+        annotateType(n[i][1], field.sym.typ, conf, producedClosure)
         if field.delete:
           # only codegen fields from active case branches
           incl(n[i].flags, nfPreventCg)
@@ -111,9 +111,11 @@ proc annotateType*(n: PNode, t: PType; conf: ConfigRef) =
       n.typ() = t
       for i in 0..<n.len:
         if i >= x.kidsLen: globalError conf, n.info, "invalid field at index " & $i
-        else: annotateType(n[i], x[i], conf)
+        else: annotateType(n[i], x[i], conf, producedClosure)
     elif x.kind == tyProc and x.callConv == ccClosure:
       n.typ() = t
+      if n.len > 1 and n[1].kind notin {nkEmpty, nkNilLit}:
+        producedClosure = true
     elif x.kind == tyOpenArray: # `opcSlice` transforms slices into tuples
       if n.kind == nkTupleConstr:
         let
@@ -125,11 +127,11 @@ proc annotateType*(n: PNode, t: PType; conf: ConfigRef) =
         of nkStrKinds:
           for i in left..right:
             bracketExpr.add newIntNode(nkCharLit, BiggestInt n[0].strVal[i])
-            annotateType(bracketExpr[^1], x.elementType, conf)
+            annotateType(bracketExpr[^1], x.elementType, conf, producedClosure)
         of nkBracket:
           for i in left..right:
             bracketExpr.add n[0][i]
-            annotateType(bracketExpr[^1], x.elementType, conf)
+            annotateType(bracketExpr[^1], x.elementType, conf, producedClosure)
         else:
           globalError(conf, n.info, "Incorrectly generated tuple constr")
         n[] = bracketExpr[]
@@ -140,18 +142,18 @@ proc annotateType*(n: PNode, t: PType; conf: ConfigRef) =
   of nkBracket:
     if x.kind in {tyArray, tySequence, tyOpenArray}:
       n.typ() = t
-      for m in n: annotateType(m, x.elemType, conf)
+      for m in n: annotateType(m, x.elemType, conf, producedClosure)
     else:
       globalError(conf, n.info, "[] must have some form of array type")
   of nkCurly:
     if x.kind in {tySet}:
       n.typ() = t
       for m in n:
         if m.kind == nkRange:
-          annotateType(m[0], x.elemType, conf)
-          annotateType(m[1], x.elemType, conf)
+          annotateType(m[0], x.elemType, conf, producedClosure)
+          annotateType(m[1], x.elemType, conf, producedClosure)
         else:
-          annotateType(m, x.elemType, conf)
+          annotateType(m, x.elemType, conf, producedClosure)
     else:
       globalError(conf, n.info, "{} must have the set type")
   of nkFloatLit..nkFloat128Lit:

compiler/vm.nim

@@ -859,9 +859,9 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
     of opcLdObj:
       # a = b.c
       decodeBC(rkNode)
-      if rb >= regs.len or regs[rb].kind == rkNone or 
+      if rb >= regs.len or regs[rb].kind == rkNone or
         (regs[rb].kind == rkNode and regs[rb].node == nil) or
-        (regs[rb].kind == rkNodeAddr and regs[rb].nodeAddr[] == nil): 
+        (regs[rb].kind == rkNodeAddr and regs[rb].nodeAddr[] == nil):
         stackTrace(c, tos, pc, errNilAccess)
       else:
         let src = if regs[rb].kind == rkNode: regs[rb].node else: regs[rb].nodeAddr[]
@@ -1472,7 +1472,8 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
           let node = regs[rb+i].regToNode
           node.info = c.debug[pc]
           if prc.typ[i].kind notin {tyTyped, tyUntyped}:
-            node.annotateType(prc.typ[i], c.config)
+            var producedClosure = false
+            node.annotateType(prc.typ[i], c.config, producedClosure)
 
           macroCall.add(node)
         var a = evalTemplate(macroCall, prc, genSymOwner, c.config, c.cache, c.templInstCounter, c.idgen)