Author: David Blaikie Date: 2021-07-22T14:51:56-07:00 New Revision: 83225936af317e6bdd7103a8a039c51a29ce9f57
URL: https://github.com/llvm/llvm-project/commit/83225936af317e6bdd7103a8a039c51a29ce9f57 DIFF: https://github.com/llvm/llvm-project/commit/83225936af317e6bdd7103a8a039c51a29ce9f57.diff LOG: PR51158: Don't emit -Wswitch or -Wcovered-switch-default for empty enums An empty enum is used to implement C++'s new-ish "byte" type (to make sure it's a separate type for overloading, etc - compared to a typedef) - without any enumerators. Some clang warnings don't make sense in this sort of situation, so let's skip them for empty enums. It's arguable that possibly some situations of enumerations without enumerators might want the previous-to-this-patch behavior (if the enum is autogenerated and in some cases comes up empty, then maybe a default in an empty switch would still be considered problematic - so that when you add the first enumeration you do get a -Wswitch warning). But I think that's niche enough & this std::byte case is mainstream enough that we should prioritize the latter over the former. If someone's got a middle ground proposal to account for both of those situations, I'm open to patches/suggestions/etc. Added: Modified: clang/lib/Sema/SemaStmt.cpp clang/test/SemaCXX/switch.cpp Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp index 2ae27de9b207..64c53d6666f0 100644 --- a/clang/lib/Sema/SemaStmt.cpp +++ b/clang/lib/Sema/SemaStmt.cpp @@ -1461,7 +1461,8 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch, // If switch has default case, then ignore it. if (!CaseListIsErroneous && !CaseListIsIncomplete && !HasConstantCond && - ET && ET->getDecl()->isCompleteDefinition()) { + ET && ET->getDecl()->isCompleteDefinition() && + !empty(ET->getDecl()->enumerators())) { const EnumDecl *ED = ET->getDecl(); EnumValsTy EnumVals; diff --git a/clang/test/SemaCXX/switch.cpp b/clang/test/SemaCXX/switch.cpp index 0c60ce02097b..380f4d559ef8 100644 --- a/clang/test/SemaCXX/switch.cpp +++ b/clang/test/SemaCXX/switch.cpp @@ -130,3 +130,19 @@ void test(Opaque o, OpaqueClass oc, Defined d) { } } + +namespace EmptyEnum { + +enum Empty : int {}; +void test(Empty e) { + switch (e) { + case (Empty)0: + break; + } + switch (e) { + default: + break; + } +} + +} // namespace EmptyEnum _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
