fixes #24760; Noncopyable base type ignored (#24777)

fixes #24760

I tried `incl` `tfHasAsgn` to nontrivial assignment, but that solution
seems to break too many things. Instead, in this PR, `passCopyToSink`
now checks nontrivial assignment

Author: ringabout

compiler/injectdestructors.nim

@@ -163,9 +163,13 @@ proc isLastReadImpl(n: PNode; c: var Con; scope: var Scope): bool =
   else:
     result = false
 
+template hasDestructorOrAsgn(c: var Con, typ: PType): bool =
+  # bug #23354; an object type could have a non-trivial assignements when it is passed to a sink parameter
+  hasDestructor(c, typ) or (c.graph.config.selectedGC in {gcArc, gcOrc, gcAtomicArc} and
+        typ.kind == tyObject and not isTrivial(getAttachedOp(c.graph, typ, attachedAsgn)))
+
 proc isLastRead(n: PNode; c: var Con; s: var Scope): 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
+  if not hasDestructorOrAsgn(c, n.typ): return true
 
   let m = skipConvDfa(n)
   result = isLastReadImpl(n, c, s)
@@ -456,7 +460,7 @@ 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:

compiler/liftdestructors.nim

@@ -1286,7 +1286,7 @@ proc inst(g: ModuleGraph; c: PContext; t: PType; kind: TTypeAttachedOp; idgen: I
     else:
       localError(g.config, info, "unresolved generic parameter")
 
-proc isTrival*(s: PSym): bool {.inline.} =
+proc isTrivial*(s: PSym): bool {.inline.} =
   s == nil or (s.ast != nil and s.ast[bodyPos].len == 0)
 
 proc createTypeBoundOps(g: ModuleGraph; c: PContext; orig: PType; info: TLineInfo;
@@ -1341,8 +1341,8 @@ proc createTypeBoundOps(g: ModuleGraph; c: PContext; orig: PType; info: TLineInf
     if canon != orig:
       setAttachedOp(g, idgen.module, orig, k, getAttachedOp(g, canon, k))
 
-  if not isTrival(getAttachedOp(g, orig, attachedDestructor)):
-    #or not isTrival(orig.assignment) or
-    # not isTrival(orig.sink):
+  if not isTrivial(getAttachedOp(g, orig, attachedDestructor)):
+    #or not isTrivial(orig.assignment) or
+    # not isTrivial(orig.sink):
     orig.flags.incl tfHasAsgn
     # ^ XXX Breaks IC!

compiler/sempass2.nim

@@ -707,7 +707,7 @@ proc isNoEffectList(n: PNode): bool {.inline.} =
   assert n.kind == nkEffectList
   n.len == 0 or (n[tagEffects] == nil and n[exceptionEffects] == nil and n[forbiddenEffects] == nil)
 
-proc isTrival(caller: PNode): bool {.inline.} =
+proc isTrivial(caller: PNode): bool {.inline.} =
   result = caller.kind == nkSym and caller.sym.magic in {mEqProc, mIsNil, mMove, mWasMoved, mSwap}
 
 proc trackOperandForIndirectCall(tracked: PEffects, n: PNode, formals: PType; argIndex: int; caller: PNode) =
@@ -716,7 +716,7 @@ proc trackOperandForIndirectCall(tracked: PEffects, n: PNode, formals: PType; ar
   let param = if formals != nil and formals.n != nil and argIndex < formals.n.len: formals.n[argIndex].sym else: nil
   # assume indirect calls are taken here:
   if op != nil and op.kind == tyProc and n.skipConv.kind != nkNilLit and
-      not isTrival(caller) and
+      not isTrivial(caller) and
       ((param != nil and sfEffectsDelayed in param.flags) or laxEffects in tracked.c.config.legacyFeatures):
 
     internalAssert tracked.config, op.n[0].kind == nkEffectList

tests/arc/t24760.nim

@@ -0,0 +1,20 @@
+discard """
+  matrix: "--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()