Move -Wkeyword-macro into -pedantic, remove -Wreserved-id-macro.

As discussed on the post-commit review thread for r224012, -Wkeyword-macro fires
mostly on headers trying to set up portable defines and doesn't find much bad
stuff in practice.  But [macro.names]p2 does disallow defining or undefining
keywords, override and final, and alignas, so keep the warning but move it
into -pedantic.

-Wreserved-id-macro warns on

    #define __need_size_t

which is more or less public api for glibc headers. Since this warning isn't
motivated by a standard, remove it.

(See also r223114 for a previous follow-up to r224012.)

llvm-svn: 224371

5 files changed, 21 insertions, 71 deletions

diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 34609b26816..65ff0443c3c 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -338,7 +338,6 @@ def : DiagGroup<"sequence-point", [Unsequenced]>;
 // Preprocessor warnings.
 def AmbiguousMacro : DiagGroup<"ambiguous-macro">;
 def KeywordAsMacro : DiagGroup<"keyword-macro">;
-def ReservedIdAsMacro : DiagGroup<"reserved-id-macro">;
 
 // Just silence warnings about -Wstrict-aliasing for now.
 def : DiagGroup<"strict-aliasing=0">;
diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index 325ab0e4333..65f9f77af49 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -290,12 +290,8 @@ def note_pp_ambiguous_macro_chosen : Note<
   "expanding this definition of %0">;
 def note_pp_ambiguous_macro_other : Note<
   "other definition of %0">;
-def warn_pp_macro_hides_keyword : Warning<
-  "keyword is hidden by macro definition">,
-  InGroup<KeywordAsMacro>;
-def warn_pp_macro_is_reserved_id : Warning<
-  "macro name is a reserved identifier">, DefaultIgnore,
-  InGroup<ReservedIdAsMacro>;
+def warn_pp_macro_hides_keyword : Extension<
+  "keyword is hidden by macro definition">, InGroup<KeywordAsMacro>;
 
 def pp_invalid_string_literal : Warning<
   "invalid string literal, ignoring final '\\'">;
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index e359ea5ec39..7add52661a6 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -100,53 +100,15 @@ void Preprocessor::DiscardUntilEndOfDirective() {
   } while (Tmp.isNot(tok::eod));
 }
 
-/// \brief Enumerates possible cases of #define/#undef a reserved identifier.
-enum MacroDiag {
-  MD_NoWarn,        //> Not a reserved identifier
-  MD_KeywordDef,    //> Macro hides keyword, enabled by default
-  MD_ReservedMacro  //> #define of #undef reserved id, disabled by default
-};
-
-/// \brief Checks if the specified identifier is reserved in the specified
-/// language.
-/// This function does not check if the identifier is a keyword.
-static bool isReservedId(StringRef Text, const LangOptions &Lang) {
-  // C++ [macro.names], C11 7.1.3:
-  // All identifiers that begin with an underscore and either an uppercase
-  // letter or another underscore are always reserved for any use.
-  if (Text.size() >= 2 && Text[0] == '_' &&
-      (isUppercase(Text[1]) || Text[1] == '_'))
-    return true;
-  // C++ [global.names]
-  // Each name that contains a double underscore ... is reserved to the
-  // implementation for any use.
-  if (Lang.CPlusPlus) {
-    if (Text.find("__") != StringRef::npos)
-      return true;
-  }
-  return false;
-}
-
-static MacroDiag shouldWarnOnMacroDef(Preprocessor &PP, IdentifierInfo *II) {
+static bool shouldWarnOnMacroDef(Preprocessor &PP, IdentifierInfo *II) {
   const LangOptions &Lang = PP.getLangOpts();
   StringRef Text = II->getName();
-  if (isReservedId(Text, Lang))
-    return MD_ReservedMacro;
   // Do not warn on keyword undef.  It is generally harmless and widely used.
   if (II->isKeyword(Lang))
-    return MD_KeywordDef;
+    return true;
   if (Lang.CPlusPlus && (Text.equals("override") || Text.equals("final")))
-    return MD_KeywordDef;
-  return MD_NoWarn;
-}
-
-static MacroDiag shouldWarnOnMacroUndef(Preprocessor &PP, IdentifierInfo *II) {
-  const LangOptions &Lang = PP.getLangOpts();
-  StringRef Text = II->getName();
-  // Do not warn on keyword undef.  It is generally harmless and widely used.
-  if (isReservedId(Text, Lang))
-    return MD_ReservedMacro;
-  return MD_NoWarn;
+    return true;
+  return false;
 }
 
 bool Preprocessor::CheckMacroName(Token &MacroNameTok, MacroUse isDefineUndef) {
@@ -193,15 +155,8 @@ bool Preprocessor::CheckMacroName(Token &MacroNameTok, MacroUse isDefineUndef) {
   SourceLocation MacroNameLoc = MacroNameTok.getLocation();
   if (!SourceMgr.isInSystemHeader(MacroNameLoc) &&
       (strcmp(SourceMgr.getBufferName(MacroNameLoc), "<built-in>") != 0)) {
-    MacroDiag D = MD_NoWarn;
-    if (isDefineUndef == MU_Define)
-      D = shouldWarnOnMacroDef(*this, II);
-    else if (isDefineUndef == MU_Undef)
-      D = shouldWarnOnMacroUndef(*this, II);
-    if (D == MD_KeywordDef)
+    if (isDefineUndef == MU_Define && shouldWarnOnMacroDef(*this, II))
       Diag(MacroNameTok, diag::warn_pp_macro_hides_keyword);
-    if (D == MD_ReservedMacro)
-      Diag(MacroNameTok, diag::warn_pp_macro_is_reserved_id);
   }
 
   // Okay, we got a good identifier.
diff --git a/clang/test/Preprocessor/macro-reserved.c b/clang/test/Preprocessor/macro-reserved.c
index 2a0e26f8e3a..a13a37fbddf 100644
--- a/clang/test/Preprocessor/macro-reserved.c
+++ b/clang/test/Preprocessor/macro-reserved.c
@@ -1,5 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only %s -verify
 
+#pragma clang diagnostic warning "-Wkeyword-macro"
+
 #define for 0    // expected-warning {{keyword is hidden by macro definition}}
 #define final 1
 #define __HAVE_X 0
@@ -10,16 +12,14 @@
 #undef _HAVE_X
 #undef X__Y
 
-#pragma clang diagnostic warning "-Wreserved-id-macro"
-
 #define switch if  // expected-warning {{keyword is hidden by macro definition}}
 #define final 1
-#define __HAVE_X 0 // expected-warning {{macro name is a reserved identifier}}
-#define _HAVE_X 0  // expected-warning {{macro name is a reserved identifier}}
+#define __HAVE_X 0
+#define _HAVE_X 0
 #define X__Y
 
-#undef __cplusplus // expected-warning {{macro name is a reserved identifier}}
-#undef _HAVE_X     // expected-warning {{macro name is a reserved identifier}}
+#undef __cplusplus
+#undef _HAVE_X
 #undef X__Y
 
 int x;
diff --git a/clang/test/Preprocessor/macro-reserved.cpp b/clang/test/Preprocessor/macro-reserved.cpp
index 8529ddffa1b..087c27e1ab1 100644
--- a/clang/test/Preprocessor/macro-reserved.cpp
+++ b/clang/test/Preprocessor/macro-reserved.cpp
@@ -1,5 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only %s -verify
 
+#pragma clang diagnostic warning "-Wkeyword-macro"
+
 #define for 0    // expected-warning {{keyword is hidden by macro definition}}
 #define final 1  // expected-warning {{keyword is hidden by macro definition}}
 #define __HAVE_X 0
@@ -10,16 +12,14 @@
 #undef _HAVE_X
 #undef X__Y
 
-#pragma clang diagnostic warning "-Wreserved-id-macro"
-
 #define switch if  // expected-warning {{keyword is hidden by macro definition}}
 #define final 1    // expected-warning {{keyword is hidden by macro definition}}
-#define __HAVE_X 0 // expected-warning {{macro name is a reserved identifier}}
-#define _HAVE_X 0  // expected-warning {{macro name is a reserved identifier}}
-#define X__Y       // expected-warning {{macro name is a reserved identifier}}
+#define __HAVE_X 0
+#define _HAVE_X 0
+#define X__Y
 
-#undef __cplusplus // expected-warning {{macro name is a reserved identifier}}
-#undef _HAVE_X     // expected-warning {{macro name is a reserved identifier}}
-#undef X__Y        // expected-warning {{macro name is a reserved identifier}}
+#undef __cplusplus
+#undef _HAVE_X
+#undef X__Y
 
 int x;