[patch c++]: Fix PR/63996

[patch c++]: Fix PR/63996

[Kai Tietz]

Hi,

The loop-expression loops endless in c++14's case for cases the
statement-list isn't constant.

Bug 63996 - Infinite loop in invalid C++14 constexpr fn

ChangeLog

2014-12-12  Kai Tietz  <ktietz@redhat.com>

    PR c++/63996
    * constexpr.c (cxx_eval_loop_expr): Don't loop
    endless on none-constant expression.


2014-12-12  Kai Tietz  <ktietz@redhat.com>

    PR c++/63996
    * g++.dg/cpp1y/pr63996.C: New file.

Tested for x86_64-w64-mingw32.  Ok for apply?

Regards,
Kai

New testcase in g++.dg/cpp1y as pr63996.C

// { dg-do compile { target c++14 } }

constexpr int
foo (int i)
{
  int a[i] = { };
}

constexpr int j = foo (1); // { dg-error "is not a constant expression" }


Index: constexpr.c
===================================================================
--- constexpr.c (Revision 218570)
+++ constexpr.c (Arbeitskopie)
@@ -2841,7 +2870,7 @@ cxx_eval_loop_expr (const constexpr_ctx *ctx, tree
     {
       cxx_eval_statement_list (ctx, body,
                               non_constant_p, overflow_p, jump_target);
-      if (returns (jump_target) || breaks (jump_target))
+      if (returns (jump_target) || breaks (jump_target) || *non_constant_p)
        break;
     }
   if (breaks (jump_target))

Re: [patch c++]: Fix PR/63996

[Jason Merrill]

OK.

Jason

Re: [patch c++]: Fix PR/63996

[Paolo Carlini]

Hi,

On 12/12/2014 11:58 AM, Kai Tietz wrote:
> New testcase in g++.dg/cpp1y as pr63996.C
>
> // { dg-do compile { target c++14 } }
>
> constexpr int
> foo (int i)
> {
>    int a[i] = { };
> }
>
> constexpr int j = foo (1); // { dg-error "is not a constant expression" }
The testcase fails spuriously because of Jason's VLA reversion commit, 
please adjust it.

Thanks,
Paolo.

Re: [patch c++]: Fix PR/63996

[Andreas Schwab]

Kai Tietz <ktietz70@googlemail.com> writes:

> New testcase in g++.dg/cpp1y as pr63996.C
>
> // { dg-do compile { target c++14 } }
>
> constexpr int
> foo (int i)
> {
>   int a[i] = { };
> }
>
> constexpr int j = foo (1); // { dg-error "is not a constant expression" }

FAIL: g++.dg/cpp1y/pr63996.C  -std=c++14 (test for excess errors)
Excess errors:
/usr/local/gcc/gcc-20141214/gcc/testsuite/g++.dg/cpp1y/pr63996.C:6:10: error: ISO C++ forbids variable length array 'a' [-Wvla]

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: [patch c++]: Fix PR/63996

[Paolo Carlini]

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... committed as obvious the below.

Paolo.

/////////////////////

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2014-12-15  Paolo Carlini  <paolo.carlini@oracle.com>

	* g++.dg/cpp1y/pr63996.C: Fix.

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Index: g++.dg/cpp1y/pr63996.C
===================================================================
--- g++.dg/cpp1y/pr63996.C	(revision 218737)
+++ g++.dg/cpp1y/pr63996.C	(working copy)
@@ -3,7 +3,7 @@
 constexpr int
 foo (int i)
 {
-  int a[i] = { };
+  int a[i] = { }; // { dg-error "forbids variable length" }
 }
 
 constexpr int j = foo (1); // { dg-error "is not a constant expression" }

Re: [patch c++]: Fix PR/63996

[Kai Tietz]

2014-12-15 11:48 GMT+01:00 Paolo Carlini <paolo.carlini@oracle.com>:
> ... committed as obvious the below.
>
> Paolo.
>
> /////////////////////

Thanks
Kai