[Bug c/60036] New: Spurious signedness conversion warning with relational operator

[Bug c/60036] New: Spurious signedness conversion warning with relational operator

[chengniansun at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60036

            Bug ID: 60036
           Summary: Spurious signedness conversion warning with relational
                    operator
           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-trunk emits a signedness conversion warning for the statement "f ^= fn1() >
a;". However, as the value of "fn1() > a" is either 1 or 0, the warning is not
true. 

Moreover, Gcc-4.8 and 4.7 do not output this warning. And if I change the
statement to "f = f ^ (fn1() > a);", gcc-trunk does not emit this warning,
either.



$: cat conversion-for-boolean.c
extern int fn1();
unsigned fn(int a) {
  unsigned f = 9;
  f ^= fn1() > a;
  return f;
}

$: gcc-trunk -c -Wconversion -std=c11 conversion-for-boolean.c
conversion-for-boolean.c: In function ‘fn’:
conversion-for-boolean.c:4:5: warning: conversion to ‘unsigned int’ from ‘int’
may change the sign of the result [-Wsign-conversion]
   f ^= fn1() > a;
     ^
$: gcc-4.8 -c -Wconversion -std=c11 conversion-for-boolean.c
$: gcc-4.7 -c -Wconversion -std=c11 conversion-for-boolean.c
$: gcc-trunk --version
gcc-trunk (GCC) 4.9.0 20140131 (experimental)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idX854

Alexa <alexa.gerancho at hushmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |alexa.gerancho at hushmail dot com

--- Comment #13 from Alexa <alexa.gerancho at hushmail dot com> ---
*** Bug 260998 has been marked as a duplicate of this bug. ***
Seen live from the domain http://volichat.com/adult-chat-rooms
Marked for reference. Resolved as fixed @bugzilla.

[Bug c/60036] Spurious signedness conversion warning with relational operator

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60036

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

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

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
This is so since r206620.

[Bug c/60036] [4.9 Regression] Spurious signedness conversion warning with relational operator

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60036

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2014-02-04
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |4.9.0
            Summary|Spurious signedness         |[4.9 Regression] Spurious
                   |conversion warning with     |signedness conversion
                   |relational operator         |warning with relational
                   |                            |operator
     Ever confirmed|0                           |1

[Bug c/60036] [4.9 Regression] Spurious signedness conversion warning with relational operator

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60036

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Tue Feb  4 18:05:29 2014
New Revision: 207481

URL: http://gcc.gnu.org/viewcvs?rev=207481&root=gcc&view=rev
Log:
    PR c/60036
c-family/
    * c-common.c (conversion_warning): Unwrap C_MAYBE_CONST_EXPR and/or
    SAVE_EXPR.
testsuite/
    * gcc.dg/pr60036.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr60036.c
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-common.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/60036] [4.9 Regression] Spurious signedness conversion warning with relational operator

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60036

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

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

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