[PATCH] Better diagnostic for re-initialization of static data members

[Hans Wennborg]

Hi rsmith,

+richard, because he put in the fixme in test/CXX/drs/dr0xx.cpp:925.

For the following code:
  struct S {
    static const int x = 42;
  };
  const int S::x = 42;

This patch changes the diagnostic from:

  a.cc:4:14: error: redefinition of 'x'
  const int S::x = 42;
               ^
  a.cc:2:20: note: previous definition is here
    static const int x = 42;
                     ^
to:

  a.cc:4:18: error: re-initialization of static data member 'x'
  const int S::x = 42;
                   ^
  a.cc:2:24: note: previous initialization is here
    static const int x = 42;
                         ^

http://llvm-reviews.chandlerc.com/D2235

Files:
  include/clang/Basic/DiagnosticSemaKinds.td
  lib/Sema/SemaDecl.cpp
  test/CXX/class/class.static/class.static.data/p4.cpp
  test/CXX/drs/dr0xx.cpp
  test/SemaCXX/cxx1y-variable-templates_in_class.cpp

Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -3525,6 +3525,8 @@
 def warn_missing_variable_declarations : Warning<
   "no previous extern declaration for non-static variable %0">,
   InGroup<DiagGroup<"missing-variable-declarations">>, DefaultIgnore;
+def err_static_data_member_reinitialization :
+  Error<"re-initialization of static data member %0">;
 def err_redefinition : Error<"redefinition of %0">;
 def err_alias_after_tentative :
   Error<"alias definition of %0 after tentative definition">;
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -8184,9 +8184,8 @@
     // data members we also need to check whether there was an in-class
     // declaration with an initializer.
     if (VDecl->isStaticDataMember() && VDecl->getAnyInitializer(PrevInit)) {
-      Diag(VDecl->getLocation(), diag::err_redefinition) 
-        << VDecl->getDeclName();
-      Diag(PrevInit->getLocation(), diag::note_previous_definition);
+      Diag(Init->getExprLoc(), diag::err_static_data_member_reinitialization) << VDecl->getDeclName();
+      Diag(PrevInit->getInit()->getExprLoc(), diag::note_previous_initializer) << 0;
       return;
     }  
 
Index: test/CXX/class/class.static/class.static.data/p4.cpp
===================================================================
--- test/CXX/class/class.static/class.static.data/p4.cpp
+++ test/CXX/class/class.static/class.static.data/p4.cpp
@@ -10,15 +10,14 @@
 int const OutOfClassInitializerOnly::i = 0;
 
 struct InClassInitializerAndOutOfClassCopyInitializer {
-  static const int i = 0; // expected-note{{previous definition is here}}
+  static const int i = 0; // expected-note{{previous initialization is here}}
 };
-int const InClassInitializerAndOutOfClassCopyInitializer::i = 0; // expected-error{{redefinition of 'i'}}
+int const InClassInitializerAndOutOfClassCopyInitializer::i = 0; // expected-error{{re-initialization of static data member 'i'}}
 
 struct InClassInitializerAndOutOfClassDirectInitializer {
-  static const int i = 0; // expected-note{{previous definition is here}}
+  static const int i = 0; // expected-note{{previous initialization is here}}
 };
-int const InClassInitializerAndOutOfClassDirectInitializer::i(0); // expected-error{{redefinition of 'i'}}
-
+int const InClassInitializerAndOutOfClassDirectInitializer::i(0); // expected-error{{re-initialization of static data member 'i'}}
 
 
 int main() { }
Index: test/CXX/drs/dr0xx.cpp
===================================================================
--- test/CXX/drs/dr0xx.cpp
+++ test/CXX/drs/dr0xx.cpp
@@ -919,11 +919,10 @@
 
 namespace dr88 { // dr88: yes
   template<typename T> struct S {
-    static const int a = 1;
+    static const int a = 1; // expected-note {{previous}}
     static const int b;
   };
-  // FIXME: This diagnostic is pretty bad.
-  template<> const int S<int>::a = 4; // expected-error {{redefinition}} expected-note {{previous}}
+  template<> const int S<int>::a = 4; // expected-error {{re-initialization}}
   template<> const int S<int>::b = 4;
 }
 
Index: test/SemaCXX/cxx1y-variable-templates_in_class.cpp
===================================================================
--- test/SemaCXX/cxx1y-variable-templates_in_class.cpp
+++ test/SemaCXX/cxx1y-variable-templates_in_class.cpp
@@ -39,11 +39,11 @@
   template<typename T> CONST T B1::right<T,int> = T(5);
 
   class B2 {
-    template<typename T, typename T0> static CONST T right = T(100);  // expected-note {{previous definition is here}}
-    template<typename T> static CONST T right<T,int> = T(5);          // expected-note {{previous definition is here}}
+    template<typename T, typename T0> static CONST T right = T(100);  // expected-note {{previous initialization is here}}
+    template<typename T> static CONST T right<T,int> = T(5);          // expected-note {{previous initialization is here}}
   };
-  template<typename T, typename T0> CONST T B2::right = T(100);   // expected-error {{redefinition of 'right'}}
-  template<typename T> CONST T B2::right<T,int> = T(5);           // expected-error {{redefinition of 'right'}}
+  template<typename T, typename T0> CONST T B2::right = T(100);   // expected-error {{re-initialization of static data member 'right'}}
+  template<typename T> CONST T B2::right<T,int> = T(5);           // expected-error {{re-initialization of static data member 'right'}}
 
   class B3 {
     template<typename T, typename T0> static CONST T right = T(100);
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