clearify the condition

Author: bung87

compiler/ccgtypes.nim

@@ -700,15 +700,8 @@ proc getTypeDescAux(m: BModule, origTyp: PType, check: var IntSet; kind: TSymKin
     return
   case t.kind
   of tyRef, tyPtr, tyVar, tyLent:
-    var star: string
-    if t.kind in {tyVar} and tfVarIsPtr notin origTyp.flags and
-                    compileToCpp(m): 
-      if isImportedCppType(t.skipTypes({tyVar})):
-        star = ""
-      else:
-        star = "&"
-    else: 
-      star = "*"
+    var star = if t.kind in {tyVar} and tfVarIsPtr notin origTyp.flags and
+                    compileToCpp(m): "&" else: "*"
     var et = origTyp.skipTypes(abstractInst).lastSon
     var etB = et.skipTypes(abstractInst)
     if mapType(m.config, t, kind) == ctPtrToArray and (etB.kind != tyOpenArray or kind == skParam):

compiler/cgen.nim

@@ -491,8 +491,10 @@ proc constructLoc(p: BProc, loc: var TLoc, isTemp = false) =
       nilLoc.r = rope("NIM_NIL")
       genRefAssign(p, loc, nilLoc)
     else:
-      if p.module.compileToCpp and typ.kind == tyVar and isImportedCppType(typ.skipTypes({tyVar})):
-        return
+      if typ.kind == tyVar:
+        let tt = typ.skipTypes({tyVar})
+        if isImportedType(tt) and tfRequiresInit in tt.flags:
+          return
       linefmt(p, cpsStmts, "$1 = ($2)0;$n", [rdLoc(loc),
         getTypeDesc(p.module, typ, mapTypeChooser(loc))])
   else:

compiler/semstmts.nim

@@ -716,9 +716,12 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
         let actualType = v.typ.skipTypes({tyGenericInst, tyAlias,
                                           tyUserTypeClassInst})
         if actualType.kind in {tyObject, tyDistinct} and
-           actualType.requiresInit and not (sfImportc in actualType.sym.flags):
+           actualType.requiresInit:
            # imported type use requiresInit pragma prevent implicit initialization
-          defaultConstructionError(c, v.typ, v.info)
+          if (tfRequiresInit in actualType.flags and sfImportc in actualType.sym.flags):
+            discard
+          else:
+            defaultConstructionError(c, v.typ, v.info)
         else:
           checkNilable(c, v)
         # allow let to not be initialised if imported from C:

tests/cpp/t17982.nim

@@ -9,7 +9,7 @@ type
 proc initString*(): String
     {.importcpp: "std::string()", header: "string".}
 
-proc append*(this: var String, str: String): var String
+proc append*(this: var String, str: String): String
     # bug seems to trigger when `#`, `@`, or `$1` is used inside `importcpp`
     {.importcpp: "#.append(@)", header: "string", discardable.} # <- changed from `importcpp: "append"`