Revert 374882 "[Concepts] Concept Specialization Expressions"

This reverts commit ec87b003823d63f3342cf648f55a134c1522e612.
The test fails on Windows, see e.g.
http://lab.llvm.org:8011/builders/clang-x64-windows-msvc/builds/11533/steps/stage%201%20check/logs/stdio

Also revert follow-up r374893.

llvm-svn: 374899

1 files changed, 7 insertions, 5 deletions

diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index b74a95a3cd4..455d1090218 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -228,16 +228,18 @@ ExprResult Parser::ParseCaseExpression(SourceLocation CaseLoc) {
 /// Parse a constraint-expression.
 ///
 /// \verbatim
-///       constraint-expression: C++2a[temp.constr.decl]p1
+///       constraint-expression: [Concepts TS temp.constr.decl p1]
 ///         logical-or-expression
 /// \endverbatim
 ExprResult Parser::ParseConstraintExpression() {
-  EnterExpressionEvaluationContext ConstantEvaluated(
-      Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+  // FIXME: this may erroneously consume a function-body as the braced
+  // initializer list of a compound literal
+  //
+  // FIXME: this may erroneously consume a parenthesized rvalue reference
+  // declarator as a parenthesized address-of-label expression
   ExprResult LHS(ParseCastExpression(/*isUnaryExpression=*/false));
   ExprResult Res(ParseRHSOfBinaryExpression(LHS, prec::LogicalOr));
-  if (Res.isUsable() && !Actions.CheckConstraintExpression(Res.get()))
-    return ExprError();
+
   return Res;
 }