[NFC, Scoped Enum] Convert Sema::ExpressionEvaluationContext into a scoped Enum

- also replace direct equality checks against the ConstantEvaluated enumerator  with isConstantEvaluted(), in anticipation of adding finer granularity to the various ConstantEvaluated contexts and reinstating certain restrictions on where lambda expressions can occur in C++17.

- update the clang tablegen backend that uses these Enumerators, and add the relevant scope where needed.

llvm-svn: 299316

1 files changed, 9 insertions, 8 deletions

diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index 782a35e56dc..2b13f2af685 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -1127,7 +1127,8 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
 
   // Enter a new evaluation context to insulate the lambda from any
   // cleanups from the enclosing full-expression.
-  PushExpressionEvaluationContext(PotentiallyEvaluated);  
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 }
 
 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
@@ -1605,9 +1606,9 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
     // C++11 [expr.prim.lambda]p2:
     //   A lambda-expression shall not appear in an unevaluated operand
     //   (Clause 5).
-    case Unevaluated:
-    case UnevaluatedList:
-    case UnevaluatedAbstract:
+    case ExpressionEvaluationContext::Unevaluated:
+    case ExpressionEvaluationContext::UnevaluatedList:
+    case ExpressionEvaluationContext::UnevaluatedAbstract:
     // C++1y [expr.const]p2:
     //   A conditional-expression e is a core constant expression unless the
     //   evaluation of e, following the rules of the abstract machine, would
@@ -1617,16 +1618,16 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
     // where this should be allowed.  We should probably fix this when DR1607 is
     // ratified, it lays out the exact set of conditions where we shouldn't
     // allow a lambda-expression.
-    case ConstantEvaluated:
+    case ExpressionEvaluationContext::ConstantEvaluated:
       // We don't actually diagnose this case immediately, because we
       // could be within a context where we might find out later that
       // the expression is potentially evaluated (e.g., for typeid).
       ExprEvalContexts.back().Lambdas.push_back(Lambda);
       break;
 
-    case DiscardedStatement:
-    case PotentiallyEvaluated:
-    case PotentiallyEvaluatedIfUsed:
+    case ExpressionEvaluationContext::DiscardedStatement:
+    case ExpressionEvaluationContext::PotentiallyEvaluated:
+    case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
       break;
     }
   }