fix #25508; the alternative way

compiler/ccgexprs.nim

@@ -216,6 +216,8 @@ proc genOptAsgnTuple(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
       flags
   let t = skipTypes(dest.t, abstractInst).getUniqueType()
   for i, t in t.ikids:
+    # Do not produce code for void types
+    if isEmptyType(t): continue
     let field = "Field$1" % [i.rope]
     genAssignment(p, optAsgnLoc(dest, t, field),
                      optAsgnLoc(src, t, field), newflags)
@@ -3155,6 +3157,8 @@ proc genTupleConstr(p: BProc, n: PNode, d: var TLoc) =
     for i in 0..<n.len:
       var it = n[i]
       if it.kind == nkExprColonExpr: it = it[1]
+      # Do not produce code for void types
+      if it.typ != nil and isEmptyType(it.typ): continue
       rec = initLoc(locExpr, it, dest[].storage)
       rec.snippet = dotField(rdLoc(dest[]), "Field" & rope(i))
       rec.flags.incl(lfEnforceDeref)
@@ -3766,6 +3770,7 @@ proc containsOpaqueImportcField(typ: PType): bool =
       return true
   of tyTuple:
     for i, a in t.ikids:
+      if isEmptyType(a): continue
       if containsOpaqueImportcField(a):
         return true
   of tyArray:
@@ -3819,6 +3824,8 @@ proc getDefaultValue(p: BProc; typ: PType; info: TLineInfo; result: var Builder)
         result.addField(tupleInit, name = "dummy"):
           result.addIntValue(0)
       for i, a in t.ikids:
+        # Do not produce code for void types
+        if isEmptyType(a): continue
         let elemTyp = skipTypes(a, abstractRange+{tyOwned}-{tyTypeDesc})
         if not isOpaqueImportcType(elemTyp):
           result.addField(tupleInit, name = "Field" & $i):
@@ -3993,6 +4000,8 @@ proc genConstTuple(p: BProc, n: PNode; isConst: bool; tup: PType; result: var Bu
       var it = n[i]
       if it.kind == nkExprColonExpr:
         it = it[1]
+      # Do not produce code for void types
+      if isEmptyType(tup[i]): continue
       result.addField(tupleInit, name = "Field" & $i):
         genBracedInit(p, it, isConst, tup[i], result)
 

compiler/ccgtypes.nim

@@ -800,6 +800,8 @@ proc getTupleDesc(m: BModule; typ: PType, name: Rope,
   var res = newBuilder("")
   res.addStruct(m, typ, name, ""):
     for i, a in typ.ikids:
+      # Do not produce code for void types
+      if isEmptyType(a): continue
       res.addField(
         name = "Field" & $i,
         typ = getTypeDescAux(m, a, check, dkField))
@@ -1476,21 +1478,29 @@ proc genTupleInfo(m: BModule; typ, origType: PType, name: Rope; info: TLineInfo)
   genTypeInfoAuxBase(m, typ, typ, name, cIntValue(0), info)
   var expr = getNimNode(m)
   if not typ.isEmptyTupleType:
-    var tmp = getTempName(m) & "_" & $typ.kidsLen
-    genTNimNodeArray(m, tmp, typ.kidsLen)
-    for i, a in typ.ikids:
-      var tmp2 = getNimNode(m)
-      let fieldTypInfo = genTypeInfoV1(m, a, info)
-      m.s[cfsTypeInit3].addSubscriptAssignment(tmp, cIntValue(i), cAddr(tmp2))
-      m.s[cfsTypeInit3].addFieldAssignment(tmp2, "kind", 1)
-      m.s[cfsTypeInit3].addFieldAssignmentWithValue(tmp2, "offset"):
-        m.s[cfsTypeInit3].addOffsetof(getTypeDesc(m, origType, dkVar), "Field" & $i)
-      m.s[cfsTypeInit3].addFieldAssignment(tmp2, "typ", fieldTypInfo)
-      m.s[cfsTypeInit3].addFieldAssignment(tmp2, "name", "\"Field" & $i & "\"")
-    m.s[cfsTypeInit3].addFieldAssignment(expr, "len", typ.kidsLen)
-    m.s[cfsTypeInit3].addFieldAssignment(expr, "kind", 2)
-    m.s[cfsTypeInit3].addFieldAssignment(expr, "sons",
-      cAddr(subscript(tmp, cIntValue(0))))
+    var nonVoidKids = 0
+    for a in typ.kids:
+      if not isEmptyType(a): inc nonVoidKids
+    if nonVoidKids > 0:
+      var tmp = getTempName(m) & "_" & $nonVoidKids
+      genTNimNodeArray(m, tmp, nonVoidKids)
+      var j = 0
+      for i, a in typ.ikids:
+        # Do not produce code for void types
+        if isEmptyType(a): continue
+        var tmp2 = getNimNode(m)
+        let fieldTypInfo = genTypeInfoV1(m, a, info)
+        m.s[cfsTypeInit3].addSubscriptAssignment(tmp, cIntValue(j), cAddr(tmp2))
+        m.s[cfsTypeInit3].addFieldAssignment(tmp2, "kind", 1)
+        m.s[cfsTypeInit3].addFieldAssignmentWithValue(tmp2, "offset"):
+          m.s[cfsTypeInit3].addOffsetof(getTypeDesc(m, origType, dkVar), "Field" & $i)
+        m.s[cfsTypeInit3].addFieldAssignment(tmp2, "typ", fieldTypInfo)
+        m.s[cfsTypeInit3].addFieldAssignment(tmp2, "name", "\"Field" & $i & "\"")
+        inc j
+      m.s[cfsTypeInit3].addFieldAssignment(expr, "len", nonVoidKids)
+      m.s[cfsTypeInit3].addFieldAssignment(expr, "kind", 2)
+      m.s[cfsTypeInit3].addFieldAssignment(expr, "sons",
+        cAddr(subscript(tmp, cIntValue(0))))
   else:
     m.s[cfsTypeInit3].addFieldAssignment(expr, "len", typ.kidsLen)
     m.s[cfsTypeInit3].addFieldAssignment(expr, "kind", 2)

compiler/jsgen.nim

@@ -2018,8 +2018,12 @@ proc createVar(p: PProc, typ: PType, indirect: bool): Rope =
     if indirect: result = "[$1]" % [result]
   of tyTuple:
     result = rope("{")
+    var first = true
     for i in 0..<t.len:
-      if i > 0: result.add(", ")
+      # Do not produce code for void types
+      if isEmptyType(t[i]): continue
+      if not first: result.add(", ")
+      first = false
       result.addf("Field$1: $2", [i.rope,
             createVar(p, t[i], false)])
     result.add("}")

tests/typerel/tvoid.nim

@@ -4,6 +4,7 @@ empty
 he, no return type;
 abc a string
 ha'''
+  target: "c js"
 """
 
 proc ReturnT[T](x: T): T =
@@ -96,3 +97,7 @@ block: # typeof(stmt)
   block:
     template bad2 = echo (nonexistent; discard)
     doAssert not compiles(bad2())
+
+block:
+  discard default(tuple[b: void])
+  discard default((void,))