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re PR c++/89336 (internal compiler error when compiling a constexpr function)

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PR c++/89336
	* constexpr.c (cxx_eval_store_expression): Diagnose changing of active
	union member for -std=c++17 and earlier.

	* g++.dg/cpp1y/constexpr-89336-3.C: New test.

From-SVN: r269052
This commit is contained in:
Jakub Jelinek 2019-02-20 22:16:27 +01:00 committed by Jakub Jelinek
parent 200a8e1a38
commit ed4ec9ceba
4 changed files with 71 additions and 2 deletions
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6
gcc/cp/ChangeLog
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@ -1,3 +1,9 @@
2019-02-20 Jakub Jelinek <jakub@redhat.com>
PR c++/89336
* constexpr.c (cxx_eval_store_expression): Diagnose changing of active
union member for -std=c++17 and earlier.
2019-02-19 Jason Merrill <jason@redhat.com>
PR c++/87513 - 'sorry' mangling PMF template-id.

16
gcc/cp/constexpr.c
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@ -3813,8 +3813,20 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t,
if (code == UNION_TYPE && CONSTRUCTOR_NELTS (*valp)
&& CONSTRUCTOR_ELT (*valp, 0)->index != index)
/* Changing active member. */
vec_safe_truncate (CONSTRUCTOR_ELTS (*valp), 0);
{
if (cxx_dialect < cxx2a)
{
if (!ctx->quiet)
error_at (cp_expr_loc_or_loc (t, input_location),
"change of the active member of a union "
"from %qD to %qD",
CONSTRUCTOR_ELT (*valp, 0)->index,
index);
*non_constant_p = true;
}
/* Changing active member. */
vec_safe_truncate (CONSTRUCTOR_ELTS (*valp), 0);
}
for (idx = 0;
vec_safe_iterate (CONSTRUCTOR_ELTS (*valp), idx, &cep);

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2019-02-20 Jakub Jelinek <jakub@redhat.com>
PR c++/89336
* g++.dg/cpp1y/constexpr-89336-3.C: New test.
2019-02-20 David Malcolm <dmalcolm@redhat.com>
PR c/89410

46
gcc/testsuite/g++.dg/cpp1y/constexpr-89336-3.C Normal file
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@ -0,0 +1,46 @@
// PR c++/89336
// { dg-do compile { target c++14 } }
constexpr int
foo ()
{
union U { int a; long b; };
union V { union U u; short v; };
V w {};
w.u.a = w.v = w.u.b = 5L; // { dg-error "change of the active member of a union from" "" { target c++17_down } }
return w.u.a;
}
static_assert (foo () == 5, ""); // { dg-error "non-constant condition for static assertion" "" { target c++17_down } }
// { dg-message "expansion of" "" { target c++17_down } .-1 }
constexpr int
bar ()
{
union U { int a[5]; long b; };
union V { union U u; short v; };
V w {};
w.v = 5;
w.u.a[3] = w.u.a[1] = w.v; // { dg-error "change of the active member of a union from" "" { target c++17_down } }
return w.u.a[1] + w.u.a[3];
}
static_assert (bar () == 10, ""); // { dg-error "non-constant condition for static assertion" "" { target c++17_down } }
// { dg-message "expansion of" "" { target c++17_down } .-1 }
struct Z { int x, y; };
constexpr Z
baz ()
{
union W { Z a; long long w; };
W w {};
w.a = { 5, 0 };
w.a = { (int) (w.w = 17LL + w.a.x), 2 }; // { dg-error "change of the active member of a union from" "" { target c++17_down } }
return w.a;
}
static_assert (baz ().x == 22, ""); // { dg-error "non-constant condition for static assertion" "" { target c++17_down } }
// { dg-message "expansion of" "" { target c++17_down } .-1 }
static_assert (baz ().y == 2, ""); // { dg-error "non-constant condition for static assertion" "" { target c++17_down } }
// { dg-message "expansion of" "" { target c++17_down } .-1 }