On 2/20/26 2:49 AM, Marek Polacek wrote:
dg.exp=reflect/* passed on x86_64-linux so far. Ok for trunk?
-- >8 --
As discussed in
<https://gcc.gnu.org/pipermail/gcc-patches/2026-January/705756.html>,
we shouldn't walk BIND_EXPR_VARS in check_out_of_consteval_use_r, but
BIND_EXPR_BODY should still be walked.
The IF_STMT is there so that we don't emit bogus errors in "if consteval"
branches, as tested in expr12.C.
gcc/cp/ChangeLog:
* reflect.cc (check_out_of_consteval_use_r): Walk BIND_EXPR_BODY.
For IF_STMT_CONSTEVAL_P, only walk the ELSE_CLAUSE.
gcc/testsuite/ChangeLog:
* g++.dg/reflect/expr11.C: Adjust dg-error.
* g++.dg/reflect/expr12.C: Adjust test.
---
gcc/cp/reflect.cc | 24 ++++++++++++++++++++++--
gcc/testsuite/g++.dg/reflect/expr11.C | 2 +-
gcc/testsuite/g++.dg/reflect/expr12.C | 18 ++++++++++++++++++
3 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/gcc/cp/reflect.cc b/gcc/cp/reflect.cc
index 46355251bcd..0e9118129be 100644
--- a/gcc/cp/reflect.cc
+++ b/gcc/cp/reflect.cc
@@ -8108,8 +8108,6 @@ check_out_of_consteval_use_r (tree *tp, int
*walk_subtrees, void *pset)
/* Don't walk INIT_EXPRs, because we'd emit bogus errors about
member initializers. */
|| TREE_CODE (t) == INIT_EXPR
- /* Don't walk BIND_EXPR_VARS. */
- || TREE_CODE (t) == BIND_EXPR
/* And don't recurse on DECL_EXPRs. */
|| TREE_CODE (t) == DECL_EXPR)
{
@@ -8139,6 +8137,28 @@ check_out_of_consteval_use_r (tree *tp, int
*walk_subtrees, void *pset)
return ret;
}
+ if (TREE_CODE (t) == BIND_EXPR)
+ {
+ if (tree r = cp_walk_tree (&BIND_EXPR_BODY (t),
+ check_out_of_consteval_use_r, pset,
+ static_cast<hash_set<tree> *>(pset)))
+ return r;
+ /* Don't walk BIND_EXPR_VARS. */
+ *walk_subtrees = false;
+ return NULL_TREE;
+ }
+
+ if (TREE_CODE (t) == IF_STMT && IF_STMT_CONSTEVAL_P (t))
+ {
+ if (tree r = cp_walk_tree (&ELSE_CLAUSE (t),
+ check_out_of_consteval_use_r, pset,
+ static_cast<hash_set<tree> *>(pset)))
+ return r;
+ /* Don't walk the consteval branch. */
+ *walk_subtrees = false;
+ return NULL_TREE;
+ }
+
/* Now check the type to see if we are dealing with a consteval-only
expression. */
if (!consteval_only_p (t))
diff --git a/gcc/testsuite/g++.dg/reflect/expr11.C
b/gcc/testsuite/g++.dg/reflect/expr11.C
index 20af4bc07ae..9691ceb07c7 100644
--- a/gcc/testsuite/g++.dg/reflect/expr11.C
+++ b/gcc/testsuite/g++.dg/reflect/expr11.C
@@ -15,7 +15,7 @@ f ()
constexpr auto cr = ^^int;
}
if constexpr (auto r = ^^int; // { dg-error "consteval-only variable .r." }
- r == ^^int); // { dg-error "the value of .r. is not usable"
}
+ r == ^^int); // { dg-error "consteval-only expressions|the value
of .r. is not usable" }
This change seems wrong, since the condition of an "if constexpr" is
manifestly constant-evaluated.
Jason
