fixes #22679 Nim zero clear an object contains C++ imported class when a proc return it (#22681)

compiler/cgen.nim

@@ -498,9 +498,10 @@ proc resetLoc(p: BProc, loc: var TLoc) =
     else:
       # array passed as argument decayed into pointer, bug #7332
       # so we use getTypeDesc here rather than rdLoc(loc)
-      linefmt(p, cpsStmts, "#nimZeroMem((void*)$1, sizeof($2));$n",
-              [addrLoc(p.config, loc),
-              getTypeDesc(p.module, loc.t, descKindFromSymKind mapTypeChooser(loc))])
+      if not isOrHasImportedCppType(typ): #bug 22679
+        linefmt(p, cpsStmts, "#nimZeroMem((void*)$1, sizeof($2));$n",
+                [addrLoc(p.config, loc),
+                getTypeDesc(p.module, loc.t, descKindFromSymKind mapTypeChooser(loc))])
       # XXX: We can be extra clever here and call memset only
       # on the bytes following the m_type field?
       genObjectInit(p, cpsStmts, loc.t, loc, constructObj)

tests/cpp/t22679.nim

@@ -0,0 +1,50 @@
+discard """
+  cmd: "nim cpp $file"
+  output:'''
+cppNZ.x = 123
+cppNZInit.x = 123
+hascpp.cppnz.x = 123
+hasCppInit.cppnz.x = 123
+hasCppCtor.cppnz.x = 123
+'''
+"""
+{.emit:"""/*TYPESECTION*/
+struct CppNonZero {
+  int x = 123;
+};
+""".}
+
+import sugar
+type
+  CppNonZero {.importcpp, inheritable.} = object
+    x: cint
+
+  HasCpp = object
+    cppnz: CppNonZero
+
+proc initCppNonZero: CppNonZero =
+  CppNonZero()
+
+proc initHasCpp: HasCpp =
+  HasCpp()
+
+proc ctorHasCpp: HasCpp {.constructor.} =
+  discard
+
+proc main =
+  var cppNZ: CppNonZero
+  dump cppNZ.x
+
+  var cppNZInit = initCppNonZero()
+  dump cppNZInit.x
+
+  var hascpp: HasCpp
+  dump hascpp.cppnz.x
+
+  var hasCppInit = initHasCpp()
+  dump hasCppInit.cppnz.x
+
+  var hasCppCtor = ctorHasCpp()
+  dump hasCppCtor.cppnz.x
+
+main()