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.
