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Fix missing -Wimplicit-fallthrough warning
- From: Marek Polacek <polacek at redhat dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 29 Sep 2016 18:10:27 +0200
- Subject: Fix missing -Wimplicit-fallthrough warning
- Authentication-results: sourceware.org; auth=none
Here, a missing -Wimplicit-fallthrough warning was caused by a misplaced
FALLTHROUGH_LABEL_P check. As it is now, for FALLTHROUGH_LABEL_P we'd
never gotten around to
1933 /* So that next warn_implicit_fallthrough_r will start looking for
1934 a new sequence starting with this label. */
1935 gsi_prev (gsi_p);
The fix is to move the check to should_warn_for_implicit_fallthrough.
Bootstrapped/regtested on x86_64-linux and ppc64-linux, ok for trunk?
2016-09-29 Marek Polacek <polacek@redhat.com>
* gimplify.c (should_warn_for_implicit_fallthrough): Check for
FALLTHROUGH_LABEL_P here...
(warn_implicit_fallthrough_r): ...not here.
* c-c++-common/Wimplicit-fallthrough-22.c: New test.
diff --git gcc/gimplify.c gcc/gimplify.c
index 66bb8be..e077a7e 100644
--- gcc/gimplify.c
+++ gcc/gimplify.c
@@ -1817,6 +1817,10 @@ should_warn_for_implicit_fallthrough (gimple_stmt_iterator *gsi_p, tree label)
{
gimple_stmt_iterator gsi = *gsi_p;
+ /* Don't warn if the label is marked with a "falls through" comment. */
+ if (FALLTHROUGH_LABEL_P (label))
+ return false;
+
/* Don't warn for a non-case label followed by a statement:
case 0:
foo ();
@@ -1903,7 +1907,6 @@ warn_implicit_fallthrough_r (gimple_stmt_iterator *gsi_p, bool *handled_ops_p,
if (gimple_code (next) == GIMPLE_LABEL
&& gimple_has_location (next)
&& (label = gimple_label_label (as_a <glabel *> (next)))
- && !FALLTHROUGH_LABEL_P (label)
&& prev != NULL)
{
struct label_entry *l;
diff --git gcc/testsuite/c-c++-common/Wimplicit-fallthrough-22.c gcc/testsuite/c-c++-common/Wimplicit-fallthrough-22.c
index e69de29..7a81e47 100644
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-22.c
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-22.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-Wimplicit-fallthrough" } */
+
+void bar (int);
+
+void
+foo (int i)
+{
+ switch (i)
+ {
+ case 1:
+ bar (1);
+ /* FALLTHROUGH */
+ case 2:
+ bar (2); /* { dg-warning "statement may fall through" } */
+ case 3:
+ bar (3); /* { dg-warning "statement may fall through" } */
+ case 4:
+ bar (4);
+ default:
+ break;
+ }
+}
Marek