[C++20] add Basic consteval specifier

Summary:
this revision adds Lexing, Parsing and Basic Semantic for the consteval specifier as specified by http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1073r3.html

with this patch, the consteval specifier is treated as constexpr but can only be applied to function declaration.

Changes:
 - add the consteval keyword.
 - add parsing of consteval specifier for normal declarations and lambdas expressions.
 - add the whether a declaration is constexpr is now represented by and enum everywhere except for variable because they can't be consteval.
 - adapt diagnostic about constexpr to print constexpr or consteval depending on the case.
 - add tests for basic semantic.

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: eraman, efriedma, rnkovacs, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D61790

llvm-svn: 363362

1 files changed, 8 insertions, 7 deletions

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 14bccd77115..b43491d061a 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -3093,7 +3093,7 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
             ExplicitSpecifier(
                 ExplicitExpr,
                 FromConstructor->getExplicitSpecifier().getKind()),
-            D->isInlineSpecified(), D->isImplicit(), D->isConstexpr()))
+            D->isInlineSpecified(), D->isImplicit(), D->getConstexprKind()))
       return ToFunction;
   } else if (CXXDestructorDecl *FromDtor = dyn_cast<CXXDestructorDecl>(D)) {
 
@@ -3131,19 +3131,20 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
             ToInnerLocStart, NameInfo, T, TInfo, D->isInlineSpecified(),
             ExplicitSpecifier(ExplicitExpr,
                               FromConversion->getExplicitSpecifier().getKind()),
-            D->isConstexpr(), SourceLocation()))
+            D->getConstexprKind(), SourceLocation()))
       return ToFunction;
   } else if (auto *Method = dyn_cast<CXXMethodDecl>(D)) {
     if (GetImportedOrCreateDecl<CXXMethodDecl>(
             ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
             ToInnerLocStart, NameInfo, T, TInfo, Method->getStorageClass(),
-            Method->isInlineSpecified(), D->isConstexpr(), SourceLocation()))
+            Method->isInlineSpecified(), D->getConstexprKind(),
+            SourceLocation()))
       return ToFunction;
   } else {
-    if (GetImportedOrCreateDecl(ToFunction, D, Importer.getToContext(), DC,
-                                ToInnerLocStart, NameInfo, T, TInfo,
-                                D->getStorageClass(), D->isInlineSpecified(),
-                                D->hasWrittenPrototype(), D->isConstexpr()))
+    if (GetImportedOrCreateDecl(
+            ToFunction, D, Importer.getToContext(), DC, ToInnerLocStart,
+            NameInfo, T, TInfo, D->getStorageClass(), D->isInlineSpecified(),
+            D->hasWrittenPrototype(), D->getConstexprKind()))
       return ToFunction;
   }