r359800 - Do not warn on switches over enums that do not use [[maybe_unused]] enumerators

[David Blaikie via cfe-commits]

Author: dblaikie
Date: Thu May  2 09:30:49 2019
New Revision: 359800

URL: http://llvm.org/viewvc/llvm-project?rev=359800&view=rev
Log:
Do not warn on switches over enums that do not use [[maybe_unused]] enumerators

PR36231, [dcl.attr.unused]p3

Reviewers: aaron.ballman

Differential Revision: https://reviews.llvm.org/D61444

Modified:
    cfe/trunk/lib/Sema/SemaStmt.cpp
    cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.unused/p3.cpp

Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=359800&r1=359799&r2=359800&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
+++ cfe/trunk/lib/Sema/SemaStmt.cpp Thu May  2 09:30:49 2019
@@ -1162,6 +1162,9 @@ Sema::ActOnFinishSwitchStmt(SourceLocati
           break;
         }
 
+        if (EI->second->hasAttr<UnusedAttr>())
+          continue;
+
         // Drop unneeded case values
         while (CI != CaseVals.end() && CI->first < EI->first)
           CI++;

Modified: cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.unused/p3.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.unused/p3.cpp?rev=359800&r1=359799&r2=359800&view=diff
==============================================================================
--- cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.unused/p3.cpp (original)
+++ cfe/trunk/test/CXX/dcl.dcl/dcl.attr/dcl.attr.unused/p3.cpp Thu May  2 09:30:49 2019
@@ -5,9 +5,17 @@ static_assert(__has_cpp_attribute(maybe_
 
 struct [[maybe_unused]] S {};
 
+enum E1 {
+  EnumVal [[maybe_unused]],
+  UsedEnumVal,
+};
+
 void f() {
   int x; // expected-warning {{unused variable}}
   typedef int I; // expected-warning {{unused typedef 'I'}}
+  E1 e;
+  switch (e) { // expected-warning {{enumeration value 'UsedEnumVal' not handled in switch}}
+  }
 
   // Should not warn about these due to not being used.
   [[maybe_unused]] int y;
@@ -17,10 +25,16 @@ void f() {
   S s;
   maybe_unused_int test;
   y = 12;
+  switch (e) {
+  case UsedEnumVal:
+    break;
+  }
 }
 
 #ifdef EXT
 // expected-warning at 6 {{use of the 'maybe_unused' attribute is a C++17 extension}}
-// expected-warning at 13 {{use of the 'maybe_unused' attribute is a C++17 extension}}
-// expected-warning at 14 {{use of the 'maybe_unused' attribute is a C++17 extension}}
+// expected-warning at 9 {{use of the 'maybe_unused' attribute is a C++17 extension}}
+// expected-warning at 9 {{attributes on an enumerator declaration are a C++17 extension}}
+// expected-warning at 21 {{use of the 'maybe_unused' attribute is a C++17 extension}}
+// expected-warning at 22 {{use of the 'maybe_unused' attribute is a C++17 extension}}
 #endif