From 36f8cccda47c3bc6a8e5cc2bd6b914181eefbf73 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Fri, 7 Jun 2024 09:01:30 +0200
Subject: [PATCH] fixes #23354; [backport] (#23685)

(cherry picked from commit 7039b8b5bc5c62cdd608a769e0ea556e23973cc5)
---
 compiler/ccgutils.nim   |  3 +++
 tests/refc/tsinkbug.nim | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 tests/refc/tsinkbug.nim

diff --git a/compiler/ccgutils.nim b/compiler/ccgutils.nim
index ebef00e101..f83014afd1 100644
--- a/compiler/ccgutils.nim
+++ b/compiler/ccgutils.nim
@@ -134,6 +134,9 @@ proc ccgIntroducedPtr*(conf: ConfigRef; s: PSym, retType: PType): bool =
     if s.typ.sym != nil and sfForward in s.typ.sym.flags:
       # forwarded objects are *always* passed by pointers for consistency!
       result = true
+    elif s.typ.kind == tySink and conf.selectedGC notin {gcArc, gcAtomicArc, gcOrc, gcHooks}:
+      # bug #23354:
+      result = false
     elif (optByRef in s.options) or (getSize(conf, pt) > conf.target.floatSize * 3):
       result = true           # requested anyway
     elif (tfFinal in pt.flags) and (pt[0] == nil):
diff --git a/tests/refc/tsinkbug.nim b/tests/refc/tsinkbug.nim
new file mode 100644
index 0000000000..2cd762f405
--- /dev/null
+++ b/tests/refc/tsinkbug.nim
@@ -0,0 +1,17 @@
+discard """
+  matrix: "--gc:refc; --gc:arc"
+  output: '''
+Value is: 42
+Value is: 42'''
+"""
+
+type AnObject* = object of RootObj
+  value*: int
+
+proc mutate(a: sink AnObject) =
+  a.value = 1
+
+var obj = AnObject(value: 42)
+echo "Value is: ", obj.value
+mutate(obj)
+echo "Value is: ", obj.value