https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93169
Bug ID: 93169
Summary: [10 regression] Variable incorrectly put into readonly
section.
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hubicka at gcc dot gnu.org
Target Milestone: ---
This is testcase by Mark Williams who also bisected it
template <typename a> class b {
struct c {
a h;
constexpr c() {}
~c() {}
} d;
};
struct e {
int g;
e() { g = 2; }
};
main() { static const b<e> f; }
$ /aux/hubicka/trunk-install/bin/g++ -O2 t.C
t.C:12:1: warning: ISO C++ forbids declaration of ‘main’ with no type
[-Wreturn-type]
12 | main() { static const b<e> f; }
| ^~~~
$ ./a.out
Segmentation fault
$ /aux/hubicka/9-install/bin/g++ -O2 t.C
At.C:12:6: warning: ISO C++ forbids declaration of ‘main’ with no type
[-Wreturn-type]
12 | main() { static const b<e> f; }
| ^
$ ./a.out
It is caused by
commit 88bbd5a94e06eb42a5ed84a3ff6da498bea229e9 (HEAD, refs/bisect/bad)
Author: mpolacek <mpolacek@138bc75d-0d04-0410-961f-82ee72b054a4>
AuthorDate: Mon Aug 19 13:59:13 2019 +0000
Commit: mpolacek <mpolacek@138bc75d-0d04-0410-961f-82ee72b054a4>
CommitDate: Mon Aug 19 13:59:13 2019 +0000
PR c++/91264 - detect modifying const objects in constexpr.
* constexpr.c (modifying_const_object_error): New function.
(cxx_eval_call_expression): Set TREE_READONLY on a CONSTRUCTOR of
a const-qualified object after it's been fully constructed.
(modifying_const_object_p): New function.
(cxx_eval_store_expression): Detect modifying a const object
during constant expression evaluation.
(cxx_eval_increment_expression): Use a better location when
building
up the store.
(cxx_eval_constant_expression) <case DECL_EXPR>: Mark a constant
object's constructor TREE_READONLY.
and goes away after reverting the cxx_eval_call_expression hunk.
