https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66622
Bug ID: 66622
Summary: -Wsign-conversion does not take advantage of data flow
analysis
Product: gcc
Version: 5.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: john.marshall at sanger dot ac.uk
Target Milestone: ---
With GCC 5.1 built from gcc-5.1.0.tar.bz2 on OS X:
Target: x86_64-apple-darwin13.4.0
Configured with: ../gcc-5.1.0/configure --prefix=...
--enable-languages=c,c++,fortran
Thread model: posix
gcc version 5.1.0 (GCC)
The following C program compiled with -Wsign-conversion produces a warning:
unsigned foo(int i) {
if (i < 0) return 0;
else return i;
}
$ gcc-5.1 -c -Wsign-conversion valueconv.c
valueconv.c: In function ‘foo’:
valueconv.c:3:15: warning: conversion to ‘unsigned int’ from ‘int’ may change
the sign of the result [-Wsign-conversion]
else return i;
However if the compiler took advantage of the fact that i>=0 within the else,
it would realise the warning was a false positive.
