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| author | Marek Polacek <polacek@redhat.com> | 2015-05-07 19:36:31 +0000 |
|---|---|---|
| committer | Marek Polacek <mpolacek@gcc.gnu.org> | 2015-05-07 19:36:31 +0000 |
| commit | 0173bd2a038cbeef871b22b312a6856ab1dcda2a (patch) | |
| tree | 12367850915ce482968be36f7c2f4344d74b5ed5 /gcc/c | |
| parent | d57c99458933a21fdf94f508191f145ad8d5ec58 (diff) | |
| download | gcc-0173bd2a038cbeef871b22b312a6856ab1dcda2a.zip gcc-0173bd2a038cbeef871b22b312a6856ab1dcda2a.tar.gz gcc-0173bd2a038cbeef871b22b312a6856ab1dcda2a.tar.bz2 | |
re PR c/65179 (Introduce new C warning: -Wshift-negative-value)
PR c/65179
* c-common.c (c_fully_fold_internal): Warn when left shifting a
negative value.
* c.opt (Wshift-negative-value): New option.
* c-opts.c (c_common_post_options): Set warn_shift_negative_value
when -Wextra and C99/C++11 mode.
* c-typeck.c (build_binary_op): Warn when left shifting a negative
value.
* typeck.c (cp_build_binary_op): Warn when left shifting a negative
value.
* doc/invoke.texi: Document -Wshift-negative-value.
* c-c++-common/Wshift-negative-value-1.c: New test.
* testsuite/c-c++-common/Wshift-negative-value-2.c: New test.
* testsuite/c-c++-common/Wshift-negative-value-3.c: New test.
* testsuite/c-c++-common/Wshift-negative-value-4.c: New test.
* testsuite/c-c++-common/Wshift-negative-value-5.c: New test.
* testsuite/c-c++-common/Wshift-negative-value-6.c: New test.
* testsuite/gcc.dg/c90-left-shift-1.c: New test.
* testsuite/gcc.dg/c99-const-expr-7.c: Add dg-error.
* testsuite/gcc.dg/c99-left-shift-1.c: New test.
From-SVN: r222889
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) |