fixes #23354; [backport] (#23685)

2 files changed, 20 insertions, 0 deletions

diff --git a/compiler/ccgutils.nim b/compiler/ccgutils.nim
index 6b106984c..c0e574186 100644
--- a/compiler/ccgutils.nim
+++ b/compiler/ccgutils.nim
@@ -90,6 +90,9 @@ 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 000000000..2cd762f40
--- /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