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, 4 insertions, 18 deletions

diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index 78a7afdbf09..325400e4630 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -566,21 +566,6 @@ void DeclPrinter::VisitEnumConstantDecl(EnumConstantDecl *D) {
   }
 }
 
-static void printExplicitSpecifier(ExplicitSpecifier ES, llvm::raw_ostream &Out,
-                                   PrintingPolicy &Policy,
-                                   unsigned Indentation) {
-  std::string Proto = "explicit";
-  llvm::raw_string_ostream EOut(Proto);
-  if (ES.getExpr()) {
-    EOut << "(";
-    ES.getExpr()->printPretty(EOut, nullptr, Policy, Indentation);
-    EOut << ")";
-  }
-  EOut << " ";
-  EOut.flush();
-  Out << EOut.str();
-}
-
 void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
   if (!D->getDescribedFunctionTemplate() &&
       !D->isFunctionTemplateSpecialization())
@@ -611,9 +596,10 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
     if (D->isVirtualAsWritten()) Out << "virtual ";
     if (D->isModulePrivate())    Out << "__module_private__ ";
     if (D->isConstexpr() && !D->isExplicitlyDefaulted()) Out << "constexpr ";
-    ExplicitSpecifier ExplicitSpec = ExplicitSpecifier::getFromDecl(D);
-    if (ExplicitSpec.isSpecified())
-      printExplicitSpecifier(ExplicitSpec, Out, Policy, Indentation);
+    if ((CDecl && CDecl->isExplicitSpecified()) ||
+        (ConversionDecl && ConversionDecl->isExplicitSpecified()) ||
+        (GuideDecl && GuideDecl->isExplicitSpecified()))
+      Out << "explicit ";
   }
 
   PrintingPolicy SubPolicy(Policy);