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PR c++/93143 - incorrect tree sharing with constexpr.

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We don't unshare CONSTRUCTORs as often during constexpr evaluation, so we
need to unshare them here.

	* constexpr.c (cxx_eval_outermost_constant_expr): Don't assume
	CONSTRUCTORs are already unshared.

From-SVN: r280127
This commit is contained in:
Jason Merrill 2020-01-10 13:47:02 -05:00 committed by Jason Merrill
parent 640b23d7ff
commit e0804c9b5e
3 changed files with 34 additions and 3 deletions
gcc
cp
ChangeLogconstexpr.c
testsuite/g++.dg/cpp0x
constexpr-array22.C

4
gcc/cp/ChangeLog

@ -1,5 +1,9 @@
2020-01-10 Jason Merrill <jason@redhat.com>
PR c++/93143 - incorrect tree sharing with constexpr.
* constexpr.c (cxx_eval_outermost_constant_expr): Don't assume
CONSTRUCTORs are already unshared.
PR c++/93173 - incorrect tree sharing.
PR c++/93033
* cp-gimplify.c (cp_gimplify_init_expr, cp_gimplify_expr): Use

6
gcc/cp/constexpr.c

@ -6347,10 +6347,10 @@ cxx_eval_outermost_constant_expr (tree t, bool allow_non_constant,
if (!non_constant_p && overflow_p)
non_constant_p = true;
/* Unshare the result unless it's a CONSTRUCTOR in which case it's already
unshared. */
/* Unshare the result. */
bool should_unshare = true;
if (r == t || TREE_CODE (r) == CONSTRUCTOR)
if (r == t || (TREE_CODE (t) == TARGET_EXPR
&& TARGET_EXPR_INITIAL (t) == r))
should_unshare = false;
if (non_constant_p && !allow_non_constant)

27
gcc/testsuite/g++.dg/cpp0x/constexpr-array22.C Normal file

@ -0,0 +1,27 @@
// PR c++/93143
// { dg-do run { target c++11 } }
struct A { char a[2]; };
static constexpr A foo () { return A{1}; }
void bar ()
{
A a = foo ();
if (a.a[0] != 1)
__builtin_abort();
}
void foobar ()
{
A x[] = { foo (), foo () };
A a = foo ();
if (a.a[0] != 1)
__builtin_abort();
}
int main()
{
bar();
foobar();
}