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C++ PATCH to add __integer_pack built-in for std::make_integer_sequence (c++/80396)

Message ID 20170524150823.GK8499@tucnak
State New
Headers show

Commit Message

Jakub Jelinek May 24, 2017, 3:08 p.m. UTC 
On Wed, May 24, 2017 at 04:16:30PM +0200, Andreas Schwab wrote:
> FAIL: g++.dg/ext/integer-pack2.C  -std=gnu++11 (test for excess errors)
> Excess errors:
> /daten/aranym/gcc/gcc-20170524/gcc/testsuite/g++.dg/ext/integer-pack2.C:10:48: error: overflow in constant expression [-fpermissive]
> /daten/aranym/gcc/gcc-20170524/gcc/testsuite/g++.dg/ext/integer-pack2.C:10:48: error: overflow in constant expression [-fpermissive]

To be precise, it fails only on 32-bit targets.

If we at that point want some wider integer that when cast to int
is 0 (or small enough positive number?), shall we use something like
this, or say 1LL << (sizeof (int) * __CHAR_BIT__), or 2LL * INT_MIN,
something else?  Do we need to include <limits.h>?  Or can we replace
INT_MAX with __INT_MAX__?
Not sure about that -2147483650 for 16-bit int targets (perhaps the test can
be guarded with int32 effective target).

2017-05-24  Jakub Jelinek  <jakub@redhat.com>

	* g++.dg/ext/integer-pack2.C (w): Use -9223372036854775807LL - 1
	instead of -9223372036854775808.



	Jakub

Comments

Jason Merrill May 24, 2017, 6:47 p.m. UTC | #1 
On Wed, May 24, 2017 at 11:08 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Wed, May 24, 2017 at 04:16:30PM +0200, Andreas Schwab wrote:
>> FAIL: g++.dg/ext/integer-pack2.C  -std=gnu++11 (test for excess errors)
>> Excess errors:
>> /daten/aranym/gcc/gcc-20170524/gcc/testsuite/g++.dg/ext/integer-pack2.C:10:48: error: overflow in constant expression [-fpermissive]
>> /daten/aranym/gcc/gcc-20170524/gcc/testsuite/g++.dg/ext/integer-pack2.C:10:48: error: overflow in constant expression [-fpermissive]
>
> To be precise, it fails only on 32-bit targets.

> If we at that point want some wider integer that when cast to int
> is 0 (or small enough positive number?), shall we use something like
> this, or say 1LL << (sizeof (int) * __CHAR_BIT__), or 2LL * INT_MIN,
> something else?

This is fine.

> Do we need to include <limits.h>?  Or can we replace
> INT_MAX with __INT_MAX__?

__INT_MAX__ sounds good.

> Not sure about that -2147483650 for 16-bit int targets (perhaps the test can
> be guarded with int32 effective target).

Yes, restricting the test to int32 seems like the easiest fix.

Jason
diff mbox

Patch

--- gcc/testsuite/g++.dg/ext/integer-pack2.C.jj	2017-05-24 11:59:01.000000000 +0200
+++ gcc/testsuite/g++.dg/ext/integer-pack2.C	2017-05-24 16:24:18.341421124 +0200
@@ -7,6 +7,6 @@  template<typename T, T...> struct intege
 template<typename T, T num>
  using make_integer_sequence = integer_sequence<T, __integer_pack(num)...>; // { dg-error "argument" }
 
-make_integer_sequence<int, -9223372036854775808> w;
+make_integer_sequence<int, -9223372036854775807LL - 1> w;
 make_integer_sequence<int, INT_MAX> x;	   // { dg-message "required" }
 make_integer_sequence<int, -2147483650> y; // { dg-message "required" }