[PATCH] D31069: Don't warn about an unreachable fallthrough annotation in a template function
Ahmed Asadi via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Thu Mar 16 21:46:29 PDT 2017
ahmedasadi updated this revision to Diff 92104.
ahmedasadi added a comment.
Added a test case.
https://reviews.llvm.org/D31069
Files:
lib/Sema/AnalysisBasedWarnings.cpp
test/SemaCXX/P30636.cpp
Index: test/SemaCXX/P30636.cpp
===================================================================
--- test/SemaCXX/P30636.cpp
+++ test/SemaCXX/P30636.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -Wimplicit-fallthrough %s
+// expected-no-diagnostics
+
+template<bool param>
+int fallthrough_template(int i)
+{
+ switch (i) {
+ case 1:
+ if (param)
+ return 3;
+ [[clang::fallthrough]]; // no warning here, for an unreachable annotation (in the fallthrough_template<true> case) in a template function
+ case 2:
+ return 4;
+ default:
+ return 5;
+ }
+}
+
+template int fallthrough_template<true>(int);
+
Index: lib/Sema/AnalysisBasedWarnings.cpp
===================================================================
--- lib/Sema/AnalysisBasedWarnings.cpp
+++ lib/Sema/AnalysisBasedWarnings.cpp
@@ -972,7 +972,7 @@
}
}
- bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt) {
+ bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt, bool isTemplateInstantiation) {
assert(!ReachableBlocks.empty() && "ReachableBlocks empty");
int UnannotatedCnt = 0;
@@ -1002,8 +1002,12 @@
ElemIt != ElemEnd; ++ElemIt) {
if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>()) {
if (const AttributedStmt *AS = asFallThroughAttr(CS->getStmt())) {
- S.Diag(AS->getLocStart(),
- diag::warn_fallthrough_attr_unreachable);
+ // Don't issue a warning for an unreachable fallthrough
+ // attribute in template instantiations as it may not be
+ // unreachable in all instantiations of the template
+ if (!isTemplateInstantiation)
+ S.Diag(AS->getLocStart(),
+ diag::warn_fallthrough_attr_unreachable);
markFallthroughVisited(AS);
++AnnotatedCnt;
break;
@@ -1164,7 +1168,10 @@
int AnnotatedCnt;
- if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt))
+ bool isTemplateInstantiation = false;
+ if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(AC.getDecl()))
+ isTemplateInstantiation = Function->isTemplateInstantiation();
+ if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt, isTemplateInstantiation))
continue;
S.Diag(Label->getLocStart(),
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