Per discussion on cfe-dev, re-enable suppression of -Wimplicit-fallthrough on C, but also include dialects of C++ earlier than C++11.
There was enough consensus that we *can* get a good language solution
to have an annotation outside of C++11, and without this annotation
this warning doesn't quite mean's completeness criteria for this
kind of warning. For now, restrict this warning to C++11 (where an
annotation exists), and make this the behavior for the LLVM 3.2 release.
Afterwards, we will hammer out a language solution that we are all
happy with.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@167749 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index a20817f..801a1b1 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -818,6 +818,18 @@
static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
bool PerFunction) {
+ // Only perform this analysis when using C++11. There is no good workflow
+ // for this warning when not using C++11. There is no good way to silence
+ // the warning (no attribute is available) unless we are using C++11's support
+ // for generalized attributes. Once could use pragmas to silence the warning,
+ // but as a general solution that is gross and not in the spirit of this
+ // warning.
+ //
+ // NOTE: This an intermediate solution. There are on-going discussions on
+ // how to properly support this warning outside of C++11 with an annotation.
+ if (!AC.getASTContext().getLangOpts().CPlusPlus0x)
+ return;
+
FallthroughMapper FM(S);
FM.TraverseStmt(AC.getBody());
diff --git a/test/SemaCXX/switch-implicit-fallthrough-cxx98.cpp b/test/SemaCXX/switch-implicit-fallthrough-cxx98.cpp
index 14ffcef..8b24c4a 100644
--- a/test/SemaCXX/switch-implicit-fallthrough-cxx98.cpp
+++ b/test/SemaCXX/switch-implicit-fallthrough-cxx98.cpp
@@ -1,5 +1,8 @@
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 -Wimplicit-fallthrough %s
+// XFAIL: *
+// NOTE: This test is marked XFAIL until we come up with a good language design
+// for a worfklow to use this warning outside of C++11.
int fallthrough(int n) {
switch (n / 10) {
