While bootstrapping GCC on S/390 the following warning is raised:
gcc/fortran/matchexp.c: In function 'match match_level_5(gfc_expr**)':
gcc/fortran/matchexp.c:401:18: error: 'e' may be used uninitialized in this
function [-Werror=maybe-uninitialized]
401 | gfc_free_expr (e);
| ~~~~~~~~~~~~~~^~~
/home/stefansf/devel/gcc/src/gcc/fortran/matchexp.c:353:19: note: 'e' was
declared here
353 | gfc_expr *all, *e, *total;
| ^
In function match_add_operand local variable e gets initialised via
function match_ext_mult_operand if it returns MATCH_YES. In case of the
remaining two return values MATCH_NO and MATCH_ERROR the current
function call is terminated before e may be used. Thus this
warning/error seems to be a false positive analogous to variable e in
function match_mult_operand. Interestingly this warning may be silenced
by initialising variable e of either function match_level_5 or
match_add_operand. Since both variables are unrelated and correspond to
different functions, this endorses the suspicion of a false positive.
Silenced the warning by initializing variable e of function
match_add_operand.
Bootstrapped and regtested on S/390. Ok for master?
gcc/fortran/ChangeLog:
2020-05-04 Stefan Schulze Frielinghaus <stefa...@linux.ibm.com>
* matchexp.c (match_add_operand): Initialize local variable e.
---
gcc/fortran/matchexp.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/gcc/fortran/matchexp.c b/gcc/fortran/matchexp.c
index 6479582d75b..25e675f3d45 100644
--- a/gcc/fortran/matchexp.c
+++ b/gcc/fortran/matchexp.c
@@ -348,7 +348,9 @@ match_ext_mult_operand (gfc_expr **result)
static match
match_add_operand (gfc_expr **result)
{
- gfc_expr *all, *e, *total;
+ /* Workaround -Wmaybe-uninitialized false positive by initializing variable
+ e. */
+ gfc_expr *all, *e = NULL, *total;
locus where, old_loc;
match m;
gfc_intrinsic_op i;
--
2.25.3
