[Bug c/19371] New: Missing uninitialized warning

[axel at zankasoftware dot com]

Consider the following code snippet:

$ cat testcase.c
int bar(int n) {
    return n + 1;
}


int main(void) {
    int a = bar(a);
    int b, c, d;
    b = bar(b);
    (void) bar(c);
    return bar(d);
}

Both a, b, c and d are used before they are initialized. However, we only get a warning from d in gcc 
3.3/3.4.

$ gcc -O2 -Wuninitialized testcase.c 
testcase.c: In function `main':
testcase.c:8: warning: `d' might be used uninitialized in this function

Tested on:
gcc version 3.3 20030304 (Apple Computer, Inc. build 1640)
gcc version 3.4.2 [FreeBSD] 20040728

In gcc 2.95, we get a warning from b, c and d, but not a.

$ gcc -O2 -Wuninitialized testcase.c
testcase.c: In function `main':
testcase.c:8: warning: `b' might be used uninitialized in this function
testcase.c:8: warning: `c' might be used uninitialized in this function
testcase.c:8: warning: `d' might be used uninitialized in this function

Tested on:
gcc version 2.95.3 20010125 (prerelease) (OpenBSD)

-- 
           Summary: Missing uninitialized warning
           Product: gcc
           Version: 3.4.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: axel at zankasoftware dot com
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19371