On Tue, Jan 21, 2025 at 11:00:13AM -0500, Jason Merrill wrote:
> On 1/21/25 9:54 AM, Jason Merrill wrote:
> > On 1/20/25 5:58 PM, Marek Polacek wrote:
> > > @@ -9087,7 +9092,9 @@ cxx_eval_outermost_constant_expr (tree t, bool
> > > allow_non_constant,
> > > return r;
> > > else if (non_constant_p && TREE_CONSTANT (r))
> > > r = mark_non_constant (r);
> > > - else if (non_constant_p)
> > > + else if (non_constant_p
> > > + /* Check we are not trying to return the wrong type. */
> > > + || !same_type_ignoring_top_level_qualifiers_p (type,
> > > TREE_TYPE (r)))
> > > return t;
>
> Actually, I guess we also want to give an error if !allow_non_constant.
Like so?
(It would not have triggered before pre-r15-7103 because there we're called
from maybe_constant_init, thus allow_non_constant=true.)
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
This patch adds an error in a !allow_non_constant case when the
initializer/object types don't match.
PR c++/118396
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_outermost_constant_expr): Add an error call
when !allow_non_constant.
---
gcc/cp/constexpr.cc | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 9f950ffed74..85d469b055e 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -9092,11 +9092,19 @@ cxx_eval_outermost_constant_expr (tree t, bool
allow_non_constant,
return r;
else if (non_constant_p && TREE_CONSTANT (r))
r = mark_non_constant (r);
- else if (non_constant_p
- /* Check we are not trying to return the wrong type. */
- || !same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (r)))
+ else if (non_constant_p)
return t;
+ /* Check we are not trying to return the wrong type. */
+ if (!same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (r)))
+ {
+ /* If so, this is not a constant expression. */
+ if (!allow_non_constant)
+ error ("%qE is not a constant expression because it initializes "
+ "the wrong object", t);
+ return t;
+ }
+
if (should_unshare)
r = unshare_expr (r);
base-commit: 16d778239397b2f70a1e0680c0b82ae6ee98fe9e
--
2.48.1
