On 1/20/25 10:27 AM, Marek Polacek wrote:
On Fri, Jan 17, 2025 at 06:38:45PM -0500, Jason Merrill wrote:
On 1/17/25 1:31 PM, Marek Polacek wrote:
On Fri, Jan 17, 2025 at 08:10:24AM -0500, Jason Merrill wrote:
On 1/16/25 8:04 PM, Marek Polacek wrote:
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
The recent r15-6369 unfortunately caused a bad wrong-code issue.
Here we have
TARGET_EXPR <D.2996, (void) (D.2996 = {.status=0, .data={._vptr.Foo=&_ZTV3Foo
+ 16}})>
and call cp_fold_r -> maybe_constant_init with object=D.2996. In
cxx_eval_outermost_constant_expr we now take the type of the object
if present. An object can't have type 'void' and so we continue to
evaluate the initializer. That evaluates into a VOID_CST, meaning
we disregard the whole initializer, and terrible things ensue.
In that case, I'd think we want to use the value of 'object' (which should
be in ctx.ctor?) instead of the return value of
cxx_eval_constant_expression.
Ah, I'm sorry I didn't choose that approach. Maybe like this, then?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
OK. Maybe also add an assert that TREE_TYPE (r) is close enough to type?
Thanks. dg.exp passed with this extra assert:
@@ -8986,7 +8986,11 @@ cxx_eval_outermost_constant_expr (tree t, bool
allow_non_constant,
/* If we got a non-simple TARGET_EXPR, the initializer was a sequence
of statements, and the result ought to be stored in ctx.ctor. */
if (r == void_node && !constexpr_dtor && ctx.ctor)
- r = ctx.ctor;
+ {
+ r = ctx.ctor;
+ gcc_checking_assert (same_type_ignoring_top_level_qualifiers_p
+ (TREE_TYPE (r), type));
+ }
I was thinking to add that assert in general, not just in this case, to
catch any other instances of trying to return the wrong type.
Jason
