https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113769
Bug ID: 113769
Summary: GCC fails to warn of integer being used uninitialized
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: symbioticfemale at cumallover dot me
Target Milestone: ---
// The "used uninitialized" warning is not produced on both GCC and Tiny
Compiler. Clang recognizes the error. (-Wall on all compilers). See line
comments for further explanation. The latest version of GCC I've tested with is
13.2.1.
// Version 1: With printf
#include <stdio.h>
#include <stdint.h>
#include <pthread.h>
pthread_rwlock_t necessary_lock = PTHREAD_RWLOCK_INITIALIZER;
void do_nothing(const void *value);
void do_nothing(const void *value)
{
printf("%p\n",value); // do anything on value other than (void) value
}
int main(void) {
pthread_rwlock_rdlock(&necessary_lock);
pthread_rwlock_unlock(&necessary_lock);
// Fun fact: remove either the pthread_rwlock_rdlock +
pthread_rwlock_unlock, or the printf in do_nothing, and GCC catches the lack of
initialization
uint32_t pos;
pos += 1;
do_nothing(&pos);
printf("%u\n",pos);
}
// Version 2: Without printf
#include <stdio.h>
#include <stdint.h>
#include <pthread.h>
pthread_rwlock_t necessary_lock = PTHREAD_RWLOCK_INITIALIZER;
void do_nothing(const void *value);
void do_nothing(const void *value)
{
(void) value;
}
int main(void) {
pthread_rwlock_rdlock(&necessary_lock);
pthread_rwlock_unlock(&necessary_lock);
// Fun fact: remove either the pthread_rwlock_rdlock +
pthread_rwlock_unlock, or the do_nothing function call, and GCC catches the
lack of initialization. Add a printf after do_nothing and GCC will also catch
it.
uint32_t pos;
pos += 1;
do_nothing(&pos);
}
