http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55060
Bug #: 55060
Summary: False un-initialized variable warnings
Classification: Unclassified
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: shen...@google.com
Compiler version - trunk @ 192770
Compilation option - -c -O2 -Wall
Source -
static void a(int *i) { }
static void b(int p) { }
int main(int argc, char *argv[]) {
int i;
a(&i);
b(i);
return 0;
}
Compilation output -
/home/shenhan/test.c: In function ‘main’:
/home/shenhan/test.c:7:4: warning: ‘i’ is used uninitialized in this function
[-Wuninitialized]
b(i);
^
A quick diagnose by David (Xingliang) Li is copied below -
"The early uninitialized variable warning happens before inlining phase. Before
4.7, compiler does not warn this because the call to a(&i) which may initialize
'i' (the analysis is only intra-procedural).
In 4.7 (and above), the SRA optimization pass which happens before the analysis
is smart enough to replace the call to 'a' into a clone of 'a' which takes no
argument. However the second access to 'i' still remains, thus the warning."
