Output of gcc -v:
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.0.0/configure --prefix=/home/williamg/local/x86_64-40
--enable-__cxa_atexit --enable-languages=c,c++
Thread model: posix
gcc version 4.0.0
Command line:
~/local/x86_64-40/bin/gcc -O1 -Wall -Werror -c 3.c -o 3.o
Output:
cc1: warnings being treated as errors
3.c: In function ‘main’:
3.c:6: warning: ‘initialised_when_a_is_non_zero’ may be used uninitialized
in
this function
Preprocessed source:
# 1 "3.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "3.c"
extern int g (int);
int main () {
const int a = g (0);
int initialised_when_a_is_non_zero;
if (a)
initialised_when_a_is_non_zero = 10;
g (1);
if (a)
g (initialised_when_a_is_non_zero);
return 0;
}
It's clearly impossible that we use initialised_when_a_is_non_zero unless it
has been initialised.
The warning does not appear with -O0.
Removing the line "g (1);" also makes the warning disappear.
--
Summary: Erroneous warning: " ... may be used uninitialized in
this function"
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: william at gallaf dot net
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21357
