From 3a91abf311dcc399944882004f3e0b29489d31c7 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Tue, 24 Aug 2010 05:27:49 +0000
Subject: [PATCH] Diagnose the presence of multiple initializations of static
 data members, from Faisal Vali! Fixes PR6904.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111900 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDecl.cpp                         | 21 ++++++++++++++++
 lib/Sema/SemaDeclCXX.cpp                      | 19 ++++++++++++++
 .../class.static/class.static.data/p4.cpp     | 25 +++++++++++++++++++
 3 files changed, 65 insertions(+)
 create mode 100644 test/CXX/class/class.static/class.static.data/p4.cpp

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index b2c31916b7..0ed93910c7 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -4077,6 +4077,8 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
     return;
   }
 
+  
+
   // A definition must end up with a complete type, which means it must be
   // complete with the restriction that an array type might be completed by the
   // initializer; note that later code assumes this restriction.
@@ -4103,6 +4105,25 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
     VDecl->setInvalidDecl();
     return;
   }
+  
+  // C++ [class.static.data]p4
+  //   If a static data member is of const integral or const
+  //   enumeration type, its declaration in the class definition can
+  //   specify a constant-initializer which shall be an integral
+  //   constant expression (5.19). In that case, the member can appear
+  //   in integral constant expressions. The member shall still be
+  //   defined in a namespace scope if it is used in the program and the
+  //   namespace scope definition shall not contain an initializer.
+  //
+  // We already performed a redefinition check above, but for static
+  // data members we also need to check whether there was an in-class
+  // declaration with an initializer.
+  const VarDecl* PrevInit = 0;
+  if (VDecl->isStaticDataMember() && VDecl->getAnyInitializer(PrevInit)) {
+    Diag(VDecl->getLocation(), diag::err_redefinition) << VDecl->getDeclName();
+    Diag(PrevInit->getLocation(), diag::note_previous_definition);
+    return;
+  }  
 
   if (getLangOptions().CPlusPlus && VDecl->hasLocalStorage())
     setFunctionHasBranchProtectedScope();
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 9479fac085..d590a3c0e5 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -5533,6 +5533,25 @@ void Sema::AddCXXDirectInitializerToDecl(Decl *RealDecl,
     return;
   }
 
+  // C++ [class.static.data]p4
+  //   If a static data member is of const integral or const
+  //   enumeration type, its declaration in the class definition can
+  //   specify a constant-initializer which shall be an integral
+  //   constant expression (5.19). In that case, the member can appear
+  //   in integral constant expressions. The member shall still be
+  //   defined in a namespace scope if it is used in the program and the
+  //   namespace scope definition shall not contain an initializer.
+  //
+  // We already performed a redefinition check above, but for static
+  // data members we also need to check whether there was an in-class
+  // declaration with an initializer.
+  const VarDecl* PrevInit = 0;
+  if (VDecl->isStaticDataMember() && VDecl->getAnyInitializer(PrevInit)) {
+    Diag(VDecl->getLocation(), diag::err_redefinition) << VDecl->getDeclName();
+    Diag(PrevInit->getLocation(), diag::note_previous_definition);
+    return;
+  } 
+
   // If either the declaration has a dependent type or if any of the
   // expressions is type-dependent, we represent the initialization
   // via a ParenListExpr for later use during template instantiation.
diff --git a/test/CXX/class/class.static/class.static.data/p4.cpp b/test/CXX/class/class.static/class.static.data/p4.cpp
new file mode 100644
index 0000000000..2b1eca7419
--- /dev/null
+++ b/test/CXX/class/class.static/class.static.data/p4.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s 
+struct InClassInitializerOnly {
+  static const int i = 0;
+};
+int const InClassInitializerOnly::i;
+
+struct OutOfClassInitializerOnly {
+  static const int i;
+};
+int const OutOfClassInitializerOnly::i = 0;
+
+struct InClassInitializerAndOutOfClassCopyInitializer {
+  static const int i = 0; // expected-note{{previous definition is here}}
+};
+int const InClassInitializerAndOutOfClassCopyInitializer::i = 0; // expected-error{{redefinition of 'i'}}
+
+struct InClassInitializerAndOutOfClassDirectInitializer {
+  static const int i = 0; // expected-note{{previous definition is here}}
+};
+int const InClassInitializerAndOutOfClassDirectInitializer::i(0); // expected-error{{redefinition of 'i'}}
+
+
+
+int main() { }
+
-- 
2.40.0