On targets that return this from cdtors, cxx_eval_call_expression may
flag flowing off the end of a dtor. That's preempted for ctors, and
avoided entirely when dtors return void, but when they return this,
the return value should be conceptually disregarded, without making
room for such internal ABI details to make a program ill-formed, as in
g++.dg/cpp2a/constexpr-dtor12.C on arm-eabi.
Regstrapped on x86_64-linux-gnu, also verified the testcase fix on
arm-eabi. Ok to install?
for gcc/cp/ChangeLog
* constexpr.cc (cxx_eval_call_expression): Disregard dtor
result.
---
gcc/cp/constexpr.cc | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 9c40b0515747d..d8bc864ae6bcc 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -2889,7 +2889,8 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree
t,
else
{
result = *ctx->global->values.get (res);
- if (result == NULL_TREE && !*non_constant_p)
+ if (result == NULL_TREE && !*non_constant_p
+ && !DECL_DESTRUCTOR_P (fun))
{
if (!ctx->quiet)
error ("%<constexpr%> call flows off the end "
--
Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
Free Software Activist GNU Toolchain Engineer
Disinformation flourishes because many people care deeply about injustice
but very few check the facts. Ask me about <https://stallmansupport.org>
