diff options
Diffstat (limited to 'gcc/c')
| -rw-r--r-- | gcc/c/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/c/c-typeck.c | 11 |
2 files changed, 17 insertions, 0 deletions
diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog index 2ef895a..ccd1e72 100644 --- a/gcc/c/ChangeLog +++ b/gcc/c/ChangeLog @@ -1,3 +1,9 @@ +2015-05-07 Marek Polacek <polacek@redhat.com> + + PR c/65179 + * c-typeck.c (build_binary_op): Warn when left shifting a negative + value. + 2015-04-30 Marek Polacek <polacek@redhat.com> * c-typeck.c (set_init_label): Call error_at instead of error and diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c index 328f294..73275aa 100644 --- a/gcc/c/c-typeck.c +++ b/gcc/c/c-typeck.c @@ -10697,6 +10697,17 @@ build_binary_op (location_t location, enum tree_code code, && code1 == INTEGER_TYPE) { doing_shift = true; + if (TREE_CODE (op0) == INTEGER_CST + && tree_int_cst_sgn (op0) < 0) + { + /* Don't reject a left shift of a negative value in a context + where a constant expression is needed in C90. */ + if (flag_isoc99) + int_const = false; + if (c_inhibit_evaluation_warnings == 0) + warning_at (location, OPT_Wshift_negative_value, + "left shift of negative value"); + } if (TREE_CODE (op1) == INTEGER_CST) { if (tree_int_cst_sgn (op1) < 0) |