constexpr: static data members declared constexpr are required to have an

initializer; all other constexpr variables are merely required to be
initialized. In particular, a user-provided constexpr default constructor can be
used for such initialization.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144028 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 26 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index d71cd5f7d5..8419cbebc4 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -6191,17 +6191,6 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
   if (!VDecl->isInvalidDecl())
     checkUnsafeAssigns(VDecl->getLocation(), VDecl->getType(), Init);
 
-  if (VDecl->isConstexpr() && !VDecl->isInvalidDecl() &&
-      !VDecl->getType()->isDependentType() &&
-      !Init->isTypeDependent() && !Init->isValueDependent() &&
-      !Init->isConstantInitializer(Context,
-                                   VDecl->getType()->isReferenceType())) {
-    // FIXME: Improve this diagnostic to explain why the initializer is not
-    // a constant expression.
-    Diag(VDecl->getLocation(), diag::err_constexpr_var_requires_const_init)
-      << VDecl << Init->getSourceRange();
-  }
-  
   Init = MaybeCreateExprWithCleanups(Init);
   // Attach the initializer to the decl.
   VDecl->setInit(Init);
@@ -6266,16 +6255,12 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl,
       return;
     }
 
-    // C++0x [dcl.constexpr]p9: An object or reference declared constexpr must
-    // have an initializer.
     // C++0x [class.static.data]p3: A static data member can be declared with
     // the constexpr specifier; if so, its declaration shall specify
     // a brace-or-equal-initializer.
-    //
-    // A static data member's definition may inherit an initializer from an
-    // in-class declaration.
-    if (Var->isConstexpr() && !Var->getAnyInitializer()) {
-      Diag(Var->getLocation(), diag::err_constexpr_var_requires_init)
+    if (Var->isConstexpr() && Var->isStaticDataMember() &&
+        !Var->isThisDeclarationADefinition()) {
+      Diag(Var->getLocation(), diag::err_constexpr_static_mem_var_requires_init)
         << Var->getDeclName();
       Var->setInvalidDecl();
       return;
@@ -6533,15 +6518,21 @@ void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
     }
   }
 
-  // Check for global constructors.
+  Expr *Init = var->getInit();
+  bool IsGlobal = var->hasGlobalStorage() && !var->isStaticLocal();
+
   if (!var->getDeclContext()->isDependentContext() &&
-      var->hasGlobalStorage() &&
-      !var->isStaticLocal() &&
-      var->getInit() &&
-      !var->getInit()->isConstantInitializer(Context,
-                                             baseType->isReferenceType()))
-    Diag(var->getLocation(), diag::warn_global_constructor)
-      << var->getInit()->getSourceRange();
+      (var->isConstexpr() || IsGlobal) && Init &&
+      !Init->isConstantInitializer(Context, baseType->isReferenceType())) {
+    // FIXME: Improve this diagnostic to explain why the initializer is not
+    // a constant expression.
+    if (var->isConstexpr())
+      Diag(var->getLocation(), diag::err_constexpr_var_requires_const_init)
+        << var << Init->getSourceRange();
+    if (IsGlobal)
+      Diag(var->getLocation(), diag::warn_global_constructor)
+        << Init->getSourceRange();
+  }
 
   // Require the destructor.
   if (const RecordType *recordType = baseType->getAs<RecordType>())