[Bug c/59846] New: Imprecise column number for -Wtype-limits

[Bug c/59846] New: Imprecise column number for -Wtype-limits

[chengniansun at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59846

            Bug ID: 59846
           Summary: Imprecise column number for -Wtype-limits
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chengniansun at gmail dot com

GCC outputs a wrong column number of a type-limit (comparison between 0 and
unsigned) warning. 

$ gcc-trunk -Wall -Wextra -c -std=c11 -pedantic s.c
s.c: In function ‘fn1’:
s.c:33:3: warning: comparison is always false due to limited range of data type
[-Wtype-limits]
   return b ^= (   b    <        (0UL > p));
   ^

$ clang-trunk -Wall -Wextra -c -std=c11 -pedantic s.c
s.c:33:38: warning: comparison of 0 > unsigned expression is always false
[-Wtautological-compare]
  return b ^= (   b    <        (0UL > p));
                                 ~~~ ^ ~
1 warning generated.

$ cat s.c
int fn1(unsigned p) {
  int b = 99;
  return b ^= (   b    <        (0UL > p));
}
>From gcc-bugs-return-440596-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Thu Jan 16 18:18:18 2014
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From: "jason at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/59821] __builtin_LINE and __builtin_FILE for new'd objects is wrong
Date: Thu, 16 Jan 2014 18:18:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idY821

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #4)
> While I agree with that, for _builtin_{LINE,FILE,FUNCTION} (), those were
> added specifically for the use in default arguments and were I think from
> the start meant to give you the location of the call, not of the token where
> it appears, otherwise those builtins don't make much sense (you could use
> __LINE__, __FILE__ or __FUNCTION__ instead).

Ah, I see.  In that case, I agree that adjusting their locations in
break_out_target_exprs is the way to go.

[Bug c/59846] Imprecise column number for -Wtype-limits

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59846

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-01-23
                 CC|                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.
Extended testcase (locus is imprecise), use -Wlogical-op -Wtype-limits.

_Bool
fn1 (unsigned int p)
{
  return 0UL > p;
}

_Bool
fn2 (unsigned int p)
{
  return 0UL <= p;
}

_Bool
fn3 (unsigned int p)
{
  return p >= 0U;
}

_Bool
fn4 (unsigned int p)
{
  return p < 0U;
}

_Bool
fn5 (_Bool p)
{
  return p || !p;
}

_Bool
fn6 (_Bool p)
{
  return p && !p;
}

[Bug c/59846] Imprecise column number for -Wtype-limits

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59846

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

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

[Bug c/59846] Imprecise column number for -Wtype-limits

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59846

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Thu Jan 23 21:01:08 2014
New Revision: 207008

URL: http://gcc.gnu.org/viewcvs?rev=207008&root=gcc&view=rev
Log:
    PR c/59846
c-family/
    * c-common.c (shorten_compare): Add location_t parameter.
    * c-common.h (shorten_binary_op): Adjust declaration.
cp/
    * typeck.c (cp_build_binary_op): Pass location to shorten_compare.
c/
    * c-typeck.c (parser_build_binary_op): Use location instead of
    input_location.
    (build_binary_op): Pass location to shorten_compare.
testsuite/
    * gcc.dg/pr59846.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr59846.c
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-common.c
    trunk/gcc/c-family/c-common.h
    trunk/gcc/c/ChangeLog
    trunk/gcc/c/c-typeck.c
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/typeck.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/59846] Imprecise column number for -Wtype-limits

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59846

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.9.0

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.