fixes #25441; fixes #7355; deletes void args from the argument list (#25455)

fixes #25441; fixes #7355

---------

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
(cherry picked from commit 81610095e6)

compiler/semcall.nim

@@ -830,6 +830,21 @@ proc inheritBindings(c: PContext, x: var TCandidate, expectedType: PType) =
   for i in 0 ..< flatUnbound.len():
     x.bindings.put(flatUnbound[i], flatBound[i])
 
+proc compactVoidArgs(n: PNode): PNode =
+  # deletes void args from the argument list, which are created by `setSon`
+  var hasNil = false
+  for i in 0..<n.len:
+    if n[i] == nil:
+      hasNil = true
+      break
+  if not hasNil:
+    result = n
+  else:
+    result = copyNode(n)
+    for i in 0..<n.len:
+      if n[i] != nil:
+        result.add n[i]
+
 proc semResolvedCall(c: PContext, x: var TCandidate,
                      n: PNode, flags: TExprFlags;
                      expectedType: PType = nil): PNode =
@@ -880,7 +895,7 @@ proc semResolvedCall(c: PContext, x: var TCandidate,
   markUsed(c, info, finalCallee, isGenericInstance = true)
   onUse(info, finalCallee, isGenericInstance = true)
 
-  result = x.call
+  result = compactVoidArgs(x.call)
   instGenericConvertersSons(c, result, x)
   markConvertersUsed(c, result)
   result[0] = newSymNode(finalCallee, getCallLineInfo(result[0]))

compiler/semexprs.nim

@@ -832,9 +832,6 @@ proc semArrayConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PTyp
 proc fixAbstractType(c: PContext, n: PNode) =
   for i in 1..<n.len:
     let it = n[i]
-    if it == nil:
-      localError(c.config, n.info, "'$1' has nil child at index $2" % [renderTree(n, {renderNoComments}), $i])
-      return
     # do not get rid of nkHiddenSubConv for OpenArrays, the codegen needs it:
     if it.kind == nkHiddenSubConv and
         skipTypes(it.typ, abstractVar).kind notin {tyOpenArray, tyVarargs}:
@@ -1155,7 +1152,7 @@ proc semIndirectOp(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType
           localError(c.config, n.info, msg)
         return errorNode(c, n)
     else:
-      result = m.call
+      result = compactVoidArgs(m.call)
       instGenericConvertersSons(c, result, m)
       markConvertersUsed(c, result)
 

compiler/sigmatch.nim

@@ -3093,6 +3093,7 @@ proc matches*(c: PContext, n, nOrig: PNode, m: var TCandidate) =
             put(m, formal.typ, defaultValue.typ)
         defaultValue.flags.incl nfDefaultParam
         setSon(m.call, formal.position + 1, defaultValue)
+
   # forget all inferred types if the overload matching failed
   if m.state == csNoMatch:
     for t in m.inferredTypes:

tests/generics/tvoids.nim

@@ -0,0 +1,19 @@
+block: # bug #25441
+  func foo[T](x: T, y: int) =
+    discard
+
+  foo[void](10)
+
+block:
+  func foo[T: void|float](e: openArray[int], x: T, y: int) =
+    discard
+
+  var x: seq[int]
+  foo[void] x, 2
+
+block: # bug #7355
+  proc gen[A: void, T: void|int](a: A, b: T) = discard
+
+  gen[void, void]()     # Works
+  gen[void, int] 0      # Crash
+  gen[void, int](b = 0) # Crash

tests/macros/t16758.nim

@@ -1,7 +1,3 @@
-discard """
-errormsg: "'blk.p(a)' has nil child at index 1"
-action: reject
-"""
 import macros
 
 type BlockLiteral[T] = object