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.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@222889 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 12 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/c90-left-shift-1.c b/gcc/testsuite/gcc.dg/c90-left-shift-1.c
new file mode 100644
index 00000000000..755595f5c27
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c90-left-shift-1.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1990 -pedantic-errors" } */
+
+enum E { A = -2 << 1 };
+int i = -1 << 0;
+
+int
+f (int i)
+{
+  switch (i)
+  case -1 << 0: break;
+}