[Bug c/50459] New: alignof doesn't work on plain old constant, works with expressions containing it

[Bug c/50459] New: alignof doesn't work on plain old constant, works with expressions containing it

[b.r.longbons at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459

             Bug #: 50459
           Summary: alignof doesn't work on plain old constant, works with
                    expressions containing it
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: b.r.longbons@gmail.com


For certain types of constant, the exact form:

__attribute__((aligned(align)))

fails, even though 'align' can be used in other constant expressions.

Types of constants that fail:
// C
enum { align = 8 };
// C++
const int align = 8;
class Foo { static const int align = 8; };
// and lots of nasty template stuff

Anything that forms an expression succeeds, even if it's just (align).
sizeof() or a C++11 constexpr function also work.

Bad versions: 4.2.4, 4.3.6, 4.4.6, 4.5.3, 4.6.0, 4.6.1, and a couple of recent
builds from git.

Minimal testcase:
enum { align = 8 };
int succeeds __attribute__((aligned((align)) ));
int fails __attribute__((aligned(align) ));

[Bug c/50459] alignof doesn't work on plain old constant, works with expressions containing it

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459

Marc Glisse <glisse at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-04-12
   Target Milestone|---                         |4.10.0
     Ever confirmed|0                           |1
      Known to fail|                            |4.9.0

[Bug c/50459] alignof doesn't work on plain old constant, works with expressions containing it

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Created attachment 32594
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32594&action=edit
pr50459

Yeah.  This is regtested patch that covers even other attributes.  If this
approach is ok then I can take this bug & post to ML.

[Bug c/50459] alignof doesn't work on plain old constant, works with expressions containing it

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Sure, thanks.  I'll give it another round of testing and post to ML.

[Bug c/50459] alignof doesn't work on plain old constant, works with expressions containing it

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Fri May  9 08:24:37 2014
New Revision: 210262

URL: http://gcc.gnu.org/viewcvs?rev=210262&root=gcc&view=rev
Log:
    PR c/50459
c-family/
    * c-common.c (check_user_alignment): Return -1 if alignment is error
    node.
    (handle_aligned_attribute): Don't call default_conversion on
    FUNCTION_DECLs.
    (handle_vector_size_attribute): Likewise.
    (handle_tm_wrap_attribute): Handle case when wrap_decl is error node.
    (handle_sentinel_attribute): Call default_conversion and allow even
    integral types as an argument.
c/
    * c-parser.c (c_parser_attributes): Parse the arguments as an
    expression-list if the attribute takes identifier.
testsuite/
    * c-c++-common/attributes-1.c: Move test line to a new test.
    * c-c++-common/attributes-2.c: New test.
    * c-c++-common/pr50459.c: New test.
    * c-c++-common/pr59280.c: Add "undeclared" to dg-error.
    * gcc.dg/nonnull-2.c: Likewise.
    * gcc.dg/pr55570.c: Modify dg-error.
    * gcc.dg/tm/wrap-2.c: Likewise.

Added:
    trunk/gcc/testsuite/c-c++-common/attributes-2.c
    trunk/gcc/testsuite/c-c++-common/pr50459.c
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-common.c
    trunk/gcc/c/ChangeLog
    trunk/gcc/c/c-parser.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/c-c++-common/attributes-1.c
    trunk/gcc/testsuite/c-c++-common/pr59280.c
    trunk/gcc/testsuite/gcc.dg/nonnull-2.c
    trunk/gcc/testsuite/gcc.dg/pr55570.c
    trunk/gcc/testsuite/gcc.dg/tm/wrap-2.c

[Bug c/50459] alignof doesn't work on plain old constant, works with expressions containing it

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459

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

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

--- Comment #7 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.

[Bug c/50459] alignof doesn't work on plain old constant, works with expressions containing it

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459
Bug 50459 depends on bug 61137, which changed state.

Bug 61137 Summary: [5 regression] FAIL: gcc.target/ia64/small-addr-1.c (test for excess errors)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61137

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