https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79374
Bug ID: 79374
Summary: missing sometimes-uninitialized warning in switch
statement
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: hermantenbrugge at home dot nl
Target Milestone: ---
The code below:
int tst(int);
int
tst (int sel)
{
int rv;
switch (sel) {
case 1: break;
default: rv = 0;
break;
}
return rv;
}
compiled with 'gcc -S -O3 -Wall tst.c' results in no warning in gcc 6.3.1 and
gcc 7.0.1 (head)
When compiled with clang 3.8.1 with same compiler options I get:
tst.c:9:8: warning: variable 'rv' is used uninitialized whenever switch case is
taken [-Wsometimes-uninitialized]
case 1: break;
^
tst.c:13:10: note: uninitialized use occurs here
return rv;
^~
tst.c:6:9: note: initialize the variable 'rv' to silence this warning
int rv;
^
= 0
1 warning generated.
This is a very reduced test case and in the real code it was much harder to see
that rv was uninitialized.
I now that bug '44042' was closed as 'RESOLVED WONTFIX' but clang gives the
correct warning.
