From 834dcab66cfcbd943a17b1fe24c634e3f24cbebd Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Wed, 12 Mar 2025 22:02:29 +0800
Subject: [PATCH] fixes #24760; Noncopyable base type ignored

---
 compiler/injectdestructors.nim |  9 ++++++---
 tests/arc/t24760.nim           | 20 ++++++++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)
 create mode 100644 tests/arc/t24760.nim

diff --git a/compiler/injectdestructors.nim b/compiler/injectdestructors.nim
index ce9164058a..e493cf0a64 100644
--- a/compiler/injectdestructors.nim
+++ b/compiler/injectdestructors.nim
@@ -162,9 +162,12 @@ proc isLastReadImpl(n: PNode; c: var Con; scope: var Scope): bool =
   else:
     result = false
 
-proc isLastRead(n: PNode; c: var Con; s: var Scope): bool =
+template hasDestructorOrAsgn(c: var Con, typ: PType): bool =
   # bug #23354; an object type could have a non-trival assignements when it is passed to a sink parameter
-  if not hasDestructor(c, n.typ) and (n.typ.kind != tyObject or isTrival(getAttachedOp(c.graph, n.typ, attachedAsgn))): return true
+  hasDestructor(c, typ) or (typ.kind == tyObject and not isTrival(getAttachedOp(c.graph, typ, attachedAsgn)))
+
+proc isLastRead(n: PNode; c: var Con; s: var Scope): bool =
+  if not hasDestructorOrAsgn(c, n.typ): return true
 
   let m = skipConvDfa(n)
   result = (m.kind == nkSym and sfSingleUsedTemp in m.sym.flags) or
@@ -449,7 +452,7 @@ proc passCopyToSink(n: PNode; c: var Con; s: var Scope): PNode =
   result = newNodeIT(nkStmtListExpr, n.info, n.typ)
   let nTyp = n.typ.skipTypes(tyUserTypeClasses)
   let tmp = c.getTemp(s, nTyp, n.info)
-  if hasDestructor(c, nTyp):
+  if hasDestructorOrAsgn(c, nTyp):
     let typ = nTyp.skipTypes({tyGenericInst, tyAlias, tySink})
     let op = getAttachedOp(c.graph, typ, attachedDup)
     if op != nil and tfHasOwned notin typ.flags:
diff --git a/tests/arc/t24760.nim b/tests/arc/t24760.nim
new file mode 100644
index 0000000000..4eb65a3774
--- /dev/null
+++ b/tests/arc/t24760.nim
@@ -0,0 +1,20 @@
+discard """
+  matrix: "--mm:refc; --mm:orc"
+  errormsg: "=dup' is not available for type <B>, which is inferred from unavailable '=copy'; requires a copy because it's not the last read of 'b'; another read is done here: t24760.nim(19, 8); routine: g"
+"""
+
+type
+  A {.inheritable.} = object
+  B = object of A
+
+proc `=copy`(a: var A, x: A) {.error.}
+#proc `=copy`(a: var B, x: B) {.error.}
+
+proc ffff(v: sink B) =
+  echo v
+
+proc g() =
+  var b: B
+  ffff(b)
+  ffff(b)
+g()
\ No newline at end of file