On 3/15/23 10:37, Marek Polacek wrote:
On Fri, Mar 10, 2023 at 01:47:46PM -0500, Jason Merrill wrote:
On 3/10/23 11:17, Marek Polacek wrote:
We crash here since r10-3661, the store_init_value hunk in particular.
Before, we called cp_fully_fold_init, so e.g.
{.str=VIEW_CONVERT_EXPR<char[8]>("")}
was folded into
{.str=""}
but now we don't fold and keep the VCE around, and it causes trouble in
cxx_eval_store_expression: in the !refs->is_empty () loop we descend on
.str's initializer but since it's wrapped in a VCE, we skip the STRING_CST
check and then crash on the CONSTRUCTOR_NO_CLEARING.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/12?
PR c++/107280
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_store_expression): Strip location wrappers.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/constexpr-lambda28.C: New test.
---
gcc/cp/constexpr.cc | 3 ++-
gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C | 15 +++++++++++++++
2 files changed, 17 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 8683c00596a..abf6ee560c5 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -6033,7 +6033,8 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree
t,
*valp = build_constructor (type, NULL);
CONSTRUCTOR_NO_CLEARING (*valp) = no_zero_init;
}
- else if (TREE_CODE (*valp) == STRING_CST)
+ else if (STRIP_ANY_LOCATION_WRAPPER (*valp),
+ TREE_CODE (*valp) == STRING_CST)
Seems like this is stripping the location wrapper when we try to modify the
string; I think we want to strip it earlier, when we first initialize the
array member.
Hmm, I suppose we don't want to do the stripping too early. I could
have put it in get_nsdmi, for instance, but maybe here is good as well?
I guess I was thinking more around the time when the value is imported
into constant evaluation, i.e. this chunk of cxx_eval_constant_expression:
if (tree init = DECL_INITIAL (r))
{
init = cxx_eval_constant_expression (ctx, init, vc_prvalue,
non_constant_p, overflow_p);
/* Don't share a CONSTRUCTOR that might be changed. */
init = unshare_constructor (init);
/* Remember that a constant object's constructor has already
run. */
if (CLASS_TYPE_P (TREE_TYPE (r))
&& CP_TYPE_CONST_P (TREE_TYPE (r)))
TREE_READONLY (init) = true;
ctx->global->put_value (r, init);
}
Feel free to pursue that approach or go ahead and push your first patch,
whichever you prefer.
Jason
