From: Eli Friedman <eli.friedman@gmail.com>
Date: Sat, 21 Jan 2012 04:44:06 +0000 (+0000)
Subject: Fix some comments relating to ExpressionEvaluationContexts.  Get rid of a couple... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=78a542478dd63c2789816dcc1cdab5c9a6eef99b;p=clang

Fix some comments relating to ExpressionEvaluationContexts.  Get rid of a couple of uses of ConstantEvaluated which don't make sense.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148624 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 9735a09598..48d118a397 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -521,9 +521,9 @@ public:
     /// run time.
     Unevaluated,
 
-    /// \brief The current expression and its subexpressions occur within a
-    /// constant expression. Such a context is not potentially-evaluated in
-    /// C++98, but is potentially-evaluated in C++11.
+    /// \brief The current context is "potentially evaluated" in C++11 terms,
+    /// but the expression is evaluated at compile-time (like the values of
+    /// cases in a switch statment).
     ConstantEvaluated,
 
     /// \brief The current expression is potentially evaluated at run time,
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index fc16b9bbaf..d68c851d63 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -10751,8 +10751,7 @@ void Sema::MarkVTableUsed(SourceLocation Loc, CXXRecordDecl *Class,
   // not have a vtable.
   if (!Class->isDynamicClass() || Class->isDependentContext() ||
       CurContext->isDependentContext() ||
-      ExprEvalContexts.back().Context == Unevaluated ||
-      ExprEvalContexts.back().Context == ConstantEvaluated)
+      ExprEvalContexts.back().Context == Unevaluated)
     return;
 
   // Try to insert this class into the map.
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 613fb73c95..9649666250 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -9477,21 +9477,16 @@ void Sema::MarkDeclarationReferenced(SourceLocation Loc, Decl *D) {
   switch (ExprEvalContexts.back().Context) {
     case Unevaluated:
       // We are in an expression that is not potentially evaluated; do nothing.
+      // (Depending on how you read the standard, we actually do need to do
+      // something here for null pointer constants, but the standard's
+      // definition of a null pointer constant is completely crazy.)
       return;
 
     case ConstantEvaluated:
-      // We are in an expression that will be evaluated during translation; in
-      // C++11, we need to define any functions which are used in case they're
-      // constexpr, whereas in C++98, we only need to define static data members
-      // of class templates.
-      if (!getLangOptions().CPlusPlus ||
-          (!getLangOptions().CPlusPlus0x && !isa<VarDecl>(D)))
-        return;
-      break;
-
     case PotentiallyEvaluated:
-      // We are in a potentially-evaluated expression, so this declaration is
-      // "used"; handle this below.
+      // We are in a potentially evaluated expression (or a constant-expression
+      // in C++03); we need to do implicit template instantiation, implicitly
+      // define class members, and mark most declarations as used.
       break;
 
     case PotentiallyEvaluatedIfUsed:
@@ -9616,6 +9611,8 @@ void Sema::MarkDeclarationReferenced(SourceLocation Loc, Decl *D) {
     // Keep track of used but undefined variables.  We make a hole in
     // the warning for static const data members with in-line
     // initializers.
+    // FIXME: The hole we make for static const data members is too wide!
+    // We need to implement the C++11 rules for odr-used.
     if (Var->hasDefinition() == VarDecl::DeclarationOnly
         && Var->getLinkage() != ExternalLinkage
         && !(Var->isStaticDataMember() && Var->hasInit())) {
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index e1bd813955..e7b899278f 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -1059,8 +1059,7 @@ static QualType inferARCLifetimeForPointee(Sema &S, QualType type,
 
   // If we are in an unevaluated context, like sizeof, skip adding a
   // qualification.
-  } else if (S.ExprEvalContexts.back().Context == Sema::Unevaluated ||
-             S.ExprEvalContexts.back().Context == Sema::ConstantEvaluated) {
+  } else if (S.ExprEvalContexts.back().Context == Sema::Unevaluated) {
     return type;
 
   // If that failed, give an error and recover using __autoreleasing.