Revert r359949 "[clang] adding explicit(bool) from c++2a"

This caused Clang to start erroring on the following:

  struct S {
    template <typename = int> explicit S();
  };

  struct T : S {};

  struct U : T {
    U();
  };
  U::U() {}

  $ clang -c /tmp/x.cc
  /tmp/x.cc:10:4: error: call to implicitly-deleted default constructor of 'T'
  U::U() {}
     ^
  /tmp/x.cc:5:12: note: default constructor of 'T' is implicitly deleted
    because base class 'S' has no default constructor
  struct T : S {};
             ^
  1 error generated.

See discussion on the cfe-commits email thread.

This also reverts the follow-ups r359966 and r359968.

> this patch adds support for the explicit bool specifier.
>
> Changes:
> - The parsing for the explicit(bool) specifier was added in ParseDecl.cpp.
> - The storage of the explicit specifier was changed. the explicit specifier was stored as a boolean value in the FunctionDeclBitfields and in the DeclSpec class. now it is stored as a PointerIntPair<Expr*, 2> with a flag and a potential expression in CXXConstructorDecl, CXXDeductionGuideDecl, CXXConversionDecl and in the DeclSpec class.
> - Following the AST change, Serialization, ASTMatchers, ASTComparator and ASTPrinter were adapted.
> - Template instantiation was adapted to instantiate the potential expressions of the explicit(bool) specifier When instantiating their associated declaration.
> - The Add*Candidate functions were adapted, they now take a Boolean indicating if the context allowing explicit constructor or conversion function and this boolean is used to remove invalid overloads that required template instantiation to be detected.
> - Test for Semantic and Serialization were added.
>
> This patch is not yet complete. I still need to check that interaction with CTAD and deduction guides is correct. and add more tests for AST operations. But I wanted first feedback.
> Perhaps this patch should be spited in smaller patches, but making each patch testable as a standalone may be tricky.
>
> Patch by Tyker
>
> Differential Revision: https://reviews.llvm.org/D60934

llvm-svn: 360024

1 files changed, 5 insertions, 4 deletions

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 27fcc9e40b5..ffe0e8bd74e 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -858,6 +858,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
   FD->setStorageClass(static_cast<StorageClass>(Record.readInt()));
   FD->setInlineSpecified(Record.readInt());
   FD->setImplicitlyInline(Record.readInt());
+  FD->setExplicitSpecified(Record.readInt());
   FD->setVirtualAsWritten(Record.readInt());
   FD->setPure(Record.readInt());
   FD->setHasInheritedPrototype(Record.readInt());
@@ -1976,7 +1977,6 @@ ASTDeclReader::VisitCXXRecordDeclImpl(CXXRecordDecl *D) {
 }
 
 void ASTDeclReader::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
-  D->setExplicitSpecifier(Record.readExplicitSpec());
   VisitFunctionDecl(D);
   D->setIsCopyDeductionCandidate(Record.readInt());
 }
@@ -2002,7 +2002,6 @@ void ASTDeclReader::VisitCXXMethodDecl(CXXMethodDecl *D) {
 void ASTDeclReader::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
   // We need the inherited constructor information to merge the declaration,
   // so we have to read it before we call VisitCXXMethodDecl.
-  D->setExplicitSpecifier(Record.readExplicitSpec());
   if (D->isInheritingConstructor()) {
     auto *Shadow = ReadDeclAs<ConstructorUsingShadowDecl>();
     auto *Ctor = ReadDeclAs<CXXConstructorDecl>();
@@ -2028,7 +2027,6 @@ void ASTDeclReader::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
 }
 
 void ASTDeclReader::VisitCXXConversionDecl(CXXConversionDecl *D) {
-  D->setExplicitSpecifier(Record.readExplicitSpec());
   VisitCXXMethodDecl(D);
 }
 
@@ -3752,7 +3750,10 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
     D = CXXMethodDecl::CreateDeserialized(Context, ID);
     break;
   case DECL_CXX_CONSTRUCTOR:
-    D = CXXConstructorDecl::CreateDeserialized(Context, ID, Record.readInt());
+    D = CXXConstructorDecl::CreateDeserialized(Context, ID, false);
+    break;
+  case DECL_CXX_INHERITED_CONSTRUCTOR:
+    D = CXXConstructorDecl::CreateDeserialized(Context, ID, true);
     break;
   case DECL_CXX_DESTRUCTOR:
     D = CXXDestructorDecl::CreateDeserialized(Context, ID);