[Bug c/66066] New: [6 Regression] r222889 causes bogus error: initializer element is not constant

[Bug c/66066] New: [6 Regression] r222889 causes bogus error: initializer element is not constant

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

            Bug ID: 66066
           Summary: [6 Regression] r222889 causes bogus error: initializer
                    element is not constant
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
  Target Milestone: ---

% cat decode.i
int a = -1 << 0 | 0;

 % gcc -c decode.i
decode.i:1:9: error: initializer element is not constant
 int a = -1 << 0 | 0;
         ^

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Yes, that is expected (in C99!).  See
<https://gcc.gnu.org/ml/gcc-patches/2015-04/msg01946.html>.  New tests
c90-left-shift-1.c and c99-left-shift-1.c explicitly test such behavior.

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
The reason is that -1 << 0 is UB in C99, and we should reject the program only
when the invalid shift is happening in a context where a constant expression is
required.

But if it turns out to break too many packages, I guess we'll have to revisit
;(.

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |6.0

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
You can always make it a -pedantic error only...

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[kugan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

kugan at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kugan at gcc dot gnu.org

--- Comment #5 from kugan at gcc dot gnu.org ---
I ran into this today when I created a cross compiler for aarch64-linux-gnu. It
also happens with arm. As Richard Biener suggested, -pedantic helps. How about
this:

diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 3fcb7c2..d5d82fd 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -10702,7 +10702,7 @@ build_binary_op (location_t location, enum tree_code
code,
            {
              /* Don't reject a left shift of a negative value in a context
                 where a constant expression is needed in C90.  */
-             if (flag_isoc99)
+             if (flag_isoc99 && pedantic)
                int_const = false;
              if (c_inhibit_evaluation_warnings == 0)
                warning_at (location, OPT_Wshift_negative_value,

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[vp at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

Vidya Praveen <vp at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vp at gcc dot gnu.org

--- Comment #6 from Vidya Praveen <vp at gcc dot gnu.org> ---
glibc build fails as well (i observed for arm and aarch64).

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[rohitarulraj at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

Rohit <rohitarulraj at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rohitarulraj at gmail dot com

--- Comment #7 from Rohit <rohitarulraj at gmail dot com> ---
glibc build for PowerPC fails too.

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[clyon at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #8 from clyon at gcc dot gnu.org ---
Can we consider moving this to -pedantic as suggested by Richard in comment #4?

Full compiler builds are broken because of this.

Thanks

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-05-12
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #10 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Working on this, but it isn't a simple matter of adding "pedantic".

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |manu at gcc dot gnu.org

--- Comment #11 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #10)
> Working on this, but it isn't a simple matter of adding "pedantic".

Joseph, would testing global_dc->pedantic_errors be an acceptable work-around
(with a big ??? note) while a better solution is found?
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Subject: [Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idf066

--- Comment #12 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Tue, 12 May 2015, manu at gcc dot gnu.org wrote:

> > Working on this, but it isn't a simple matter of adding "pedantic".
>
> Joseph, would testing global_dc->pedantic_errors be an acceptable work-around
> (with a big ??? note) while a better solution is found?

If you want a workaround, a test for "pedantic" would be the natural
workaround, but I think the proper fix is folding as I described at
<https://gcc.gnu.org/ml/gcc-patches/2015-05/msg01015.html> to allow these
cases to reach the existing pedwarn-if-pedantic logic.

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #13 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I expect to have a proper fix (additional folding in c_fully_fold_internal)
today or tomorrow, depends on how many issues I hit along the way (see e.g.
PR66127).  The tzdata issue seems to be being worked on, so I think the
"pedantic" stopgap isn't needed right now.

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #14 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #13)
> I expect to have a proper fix (additional folding in c_fully_fold_internal)
> today or tomorrow, depends on how many issues I hit along the way (see e.g.
> PR66127).  The tzdata issue seems to be being worked on, so I think the
> "pedantic" stopgap isn't needed right now.

OK, great. That seems a step in the right direction. Thanks for fixing this!
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Subject: [Bug fortran/66128] ICE for some intrinsics with zero sized array parameter
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idf128

--- Comment #1 from Gerhard Steinmetz <gerhard.steinmetz.fortran@t-online.de> ---
Some more examples with other error messages.

This one ...
   program p
      integer, parameter :: z(0) = 0
      print *, count(z > 0)
   end

yields :
internal compiler error: in gfc_conv_intrinsic_count, at
fortran/trans-intrinsic.c:3233

This one ...
   program p
      integer, parameter :: z(0) = 0
      print *, iall(z, z > 0)
      print *, iany(z, z > 0)
      print *, iparity(z, z > 0)
      print *, parity(z > 0)
      print *, product(z, z > 0)
      print *, sum(z, z > 0)
   end

yields :
internal compiler error: in gfc_conv_intrinsic_arith, at
fortran/trans-intrinsic.c:3357

This one ...
   program p
      integer, parameter :: z(0) = 0
      print *, minval(z, z > 0)
      print *, maxval(z, z > 0)
   end

yields :
internal compiler error: in gfc_conv_intrinsic_minmaxval, at
fortran/trans-intrinsic.c:4253

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #15 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Created attachment 35534
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35534&action=edit
gcc6-pr66066

Untested patch without a test

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[sje at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #16 from Steve Ellcey <sje at gcc dot gnu.org> ---
I tried Marek's patch and it fixed the build issue with glibc.  I did get a few
new errors that I think are caused by this change:

FAIL: g++.dg/warn/overflow-warn-1.C  -std=gnu++98 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-1.C  -std=gnu++11 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-1.C  -std=gnu++14 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-3.C  -std=gnu++98 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-3.C  -std=gnu++11 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-3.C  -std=gnu++14 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-4.C  -std=gnu++98 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-4.C  -std=gnu++11 (test for excess errors)
FAIL: g++.dg/warn/overflow-warn-4.C  -std=gnu++14 (test for excess errors)

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #17 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Yeah, fixing PR66127 in some way is a prerequisite for the patch to go in. 
PR66127 is being discussed in the ML, where I've posted an updated version of
the patch for this PR.

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

--- Comment #18 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Thu May 14 11:42:53 2015
New Revision: 223193

URL: https://gcc.gnu.org/viewcvs?rev=223193&root=gcc&view=rev
Log:
        PR c/66066
        PR c/66127
        * c-common.c (c_fully_fold): Pass false down to c_fully_fold_internal.
        (c_fully_fold_internal): Fold C_MAYBE_CONST_EXPRs with
        C_MAYBE_CONST_EXPR_INT_OPERANDS set.  Add FOR_INT_CONST argument and
        use it.  If FOR_INT_CONST, require that all evaluated operands be
        INTEGER_CSTs.

        * c-typeck.c (digest_init): Call pedwarn_init with OPT_Wpedantic
        rather than with 0.

        * gcc.dg/pr14649-1.c: Add -Wpedantic.
        * gcc.dg/pr19984.c: Likewise.
        * gcc.dg/pr66066-1.c: New test.
        * gcc.dg/pr66066-2.c: New test.
        * gcc.dg/pr66066-3.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr66066-1.c
    trunk/gcc/testsuite/gcc.dg/pr66066-2.c
    trunk/gcc/testsuite/gcc.dg/pr66066-3.c
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-common.c
    trunk/gcc/c/ChangeLog
    trunk/gcc/c/c-typeck.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/pr14649-1.c
    trunk/gcc/testsuite/gcc.dg/pr19984.c

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066
Bug 66066 depends on bug 66127, which changed state.

Bug 66127 Summary: Division by zero gets folded away
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66127

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

[Bug c/66066] [6 Regression] r222889 causes bogus error: initializer element is not constant

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #19 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Ought to be fixed.