From 716ff93161b4d4a02bd4a29860ddb9375e2fda5d Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Sat, 16 Mar 2024 13:23:15 +0800
Subject: [PATCH] fixes #23401; prevents nrvo for cdecl procs (#23409)

fixes #23401

(cherry picked from commit f639cf063f66a160550bcf8955eb3446ca101cc2)
---
 compiler/ccgtypes.nim | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/compiler/ccgtypes.nim b/compiler/ccgtypes.nim
index 2613df14ad..3bc31e42e7 100644
--- a/compiler/ccgtypes.nim
+++ b/compiler/ccgtypes.nim
@@ -270,7 +270,10 @@ proc isInvalidReturnType(conf: ConfigRef; typ: PType, isProc = true): bool =
           {tyVar, tyLent, tyRef, tyPtr})
     of ctStruct:
       let t = skipTypes(rettype, typedescInst)
-      if rettype.isImportedCppType or t.isImportedCppType: return false
+      if rettype.isImportedCppType or t.isImportedCppType or
+          (typ.callConv == ccCDecl and conf.selectedGC in {gcArc, gcAtomicArc, gcOrc}):
+        # prevents nrvo for cdecl procs; # bug #23401
+        return false
       result = containsGarbageCollectedRef(t) or
           (t.kind == tyObject and not isObjLackingTypeField(t))
     else: result = false