[clang] Implement CWG2398 provisional TTP matching to class templates

clang-tools-extra/clangd/Hover.cpp

@@ -262,7 +262,8 @@ fetchTemplateParameters(const TemplateParameterList *Params,
       if (NTTP->hasDefaultArgument()) {
         P.Default.emplace();
         llvm::raw_string_ostream Out(*P.Default);
-        NTTP->getDefaultArgument()->printPretty(Out, nullptr, PP);
+        NTTP->getDefaultArgument().getArgument().print(PP, Out,
+                                                       /*IncludeType=*/false);
       }
     } else if (const auto *TTPD = dyn_cast<TemplateTemplateParmDecl>(Param)) {
       P.Type = printType(TTPD, PP);

clang/include/clang/AST/ASTNodeTraverser.h

@@ -704,9 +704,9 @@ class ASTNodeTraverser
     if (const auto *E = D->getPlaceholderTypeConstraint())
       Visit(E);
     if (D->hasDefaultArgument())
-      Visit(D->getDefaultArgument(), SourceRange(),
-            D->getDefaultArgStorage().getInheritedFrom(),
-            D->defaultArgumentWasInherited() ? "inherited from" : "previous");
+      dumpTemplateArgumentLoc(
+          D->getDefaultArgument(), D->getDefaultArgStorage().getInheritedFrom(),
+          D->defaultArgumentWasInherited() ? "inherited from" : "previous");
   }
 
   void VisitTemplateTemplateParmDecl(const TemplateTemplateParmDecl *D) {

clang/include/clang/AST/DeclTemplate.h

@@ -1360,7 +1360,8 @@ class NonTypeTemplateParmDecl final
 
   /// The default template argument, if any, and whether or not
   /// it was inherited.
-  using DefArgStorage = DefaultArgStorage<NonTypeTemplateParmDecl, Expr *>;
+  using DefArgStorage =
+      DefaultArgStorage<NonTypeTemplateParmDecl, TemplateArgumentLoc *>;
   DefArgStorage DefaultArgument;
 
   // FIXME: Collapse this into TemplateParamPosition; or, just move depth/index
@@ -1430,7 +1431,10 @@ class NonTypeTemplateParmDecl final
   bool hasDefaultArgument() const { return DefaultArgument.isSet(); }
 
   /// Retrieve the default argument, if any.
-  Expr *getDefaultArgument() const { return DefaultArgument.get(); }
+  const TemplateArgumentLoc &getDefaultArgument() const {
+    static const TemplateArgumentLoc NoneLoc;
+    return DefaultArgument.isSet() ? *DefaultArgument.get() : NoneLoc;
+  }
 
   /// Retrieve the location of the default argument, if any.
   SourceLocation getDefaultArgumentLoc() const;
@@ -1444,7 +1448,8 @@ class NonTypeTemplateParmDecl final
   /// Set the default argument for this template parameter, and
   /// whether that default argument was inherited from another
   /// declaration.
-  void setDefaultArgument(Expr *DefArg) { DefaultArgument.set(DefArg); }
+  void setDefaultArgument(const ASTContext &C,
+                          const TemplateArgumentLoc &DefArg);
   void setInheritedDefaultArgument(const ASTContext &C,
                                    NonTypeTemplateParmDecl *Parm) {
     DefaultArgument.setInherited(C, Parm);

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -2320,7 +2320,7 @@ DEF_TRAVERSE_DECL(NonTypeTemplateParmDecl, {
   // A non-type template parameter, e.g. "S" in template<int S> class Foo ...
   TRY_TO(TraverseDeclaratorHelper(D));
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited())
-    TRY_TO(TraverseStmt(D->getDefaultArgument()));
+    TRY_TO(TraverseTemplateArgumentLoc(D->getDefaultArgument()));
 })
 
 DEF_TRAVERSE_DECL(ParmVarDecl, {

clang/lib/AST/ASTContext.cpp

@@ -6503,8 +6503,10 @@ bool ASTContext::isSameDefaultTemplateArgument(const NamedDecl *X,
     if (!NTTPX->hasDefaultArgument() || !NTTPY->hasDefaultArgument())
       return false;
 
-    Expr *DefaultArgumentX = NTTPX->getDefaultArgument()->IgnoreImpCasts();
-    Expr *DefaultArgumentY = NTTPY->getDefaultArgument()->IgnoreImpCasts();
+    Expr *DefaultArgumentX =
+        NTTPX->getDefaultArgument().getArgument().getAsExpr()->IgnoreImpCasts();
+    Expr *DefaultArgumentY =
+        NTTPY->getDefaultArgument().getArgument().getAsExpr()->IgnoreImpCasts();
     llvm::FoldingSetNodeID XID, YID;
     DefaultArgumentX->Profile(XID, *this, /*Canonical=*/true);
     DefaultArgumentY->Profile(YID, *this, /*Canonical=*/true);

clang/lib/AST/ASTDiagnostic.cpp

@@ -1238,7 +1238,7 @@ class TemplateDiff {
           E = Iter->getAsExpr();
       }
     } else if (!Default->isParameterPack()) {
-      E = Default->getDefaultArgument();
+      E = Default->getDefaultArgument().getArgument().getAsExpr();
     }
 
     if (!Iter.hasDesugaredTA()) return;

clang/lib/AST/ASTImporter.cpp

@@ -5949,10 +5949,11 @@ ASTNodeImporter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
     return ToD;
 
   if (D->hasDefaultArgument()) {
-    ExpectedExpr ToDefaultArgOrErr = import(D->getDefaultArgument());
+    Expected<TemplateArgumentLoc> ToDefaultArgOrErr =
+        import(D->getDefaultArgument());
     if (!ToDefaultArgOrErr)
       return ToDefaultArgOrErr.takeError();
-    ToD->setDefaultArgument(*ToDefaultArgOrErr);
+    ToD->setDefaultArgument(Importer.getToContext(), *ToDefaultArgOrErr);
   }
 
   return ToD;

clang/lib/AST/DeclPrinter.cpp

@@ -1898,7 +1898,7 @@ void DeclPrinter::VisitNonTypeTemplateParmDecl(
 
   if (NTTP->hasDefaultArgument()) {
     Out << " = ";
-    NTTP->getDefaultArgument()->printPretty(Out, nullptr, Policy, Indentation,
-                                            "\n", &Context);
+    NTTP->getDefaultArgument().getArgument().print(Policy, Out,
+                                                   /*IncludeType=*/false);
   }
 }

clang/lib/AST/DeclTemplate.cpp

@@ -795,14 +795,21 @@ NonTypeTemplateParmDecl::CreateDeserialized(ASTContext &C, GlobalDeclID ID,
 SourceRange NonTypeTemplateParmDecl::getSourceRange() const {
   if (hasDefaultArgument() && !defaultArgumentWasInherited())
     return SourceRange(getOuterLocStart(),
-                       getDefaultArgument()->getSourceRange().getEnd());
+                       getDefaultArgument().getSourceRange().getEnd());
   return DeclaratorDecl::getSourceRange();
 }
 
 SourceLocation NonTypeTemplateParmDecl::getDefaultArgumentLoc() const {
-  return hasDefaultArgument()
-    ? getDefaultArgument()->getSourceRange().getBegin()
-    : SourceLocation();
+  return hasDefaultArgument() ? getDefaultArgument().getSourceRange().getBegin()
+                              : SourceLocation();
+}
+
+void NonTypeTemplateParmDecl::setDefaultArgument(
+    const ASTContext &C, const TemplateArgumentLoc &DefArg) {
+  if (DefArg.getArgument().isNull())
+    DefaultArgument.set(nullptr);
+  else
+    DefaultArgument.set(new (C) TemplateArgumentLoc(DefArg));
 }
 
 //===----------------------------------------------------------------------===//

clang/lib/AST/JSONNodeDumper.cpp

@@ -1044,7 +1044,7 @@ void JSONNodeDumper::VisitNonTypeTemplateParmDecl(
 
   if (D->hasDefaultArgument())
     JOS.attributeObject("defaultArg", [=] {
-      Visit(D->getDefaultArgument(), SourceRange(),
+      Visit(D->getDefaultArgument().getArgument(), SourceRange(),
             D->getDefaultArgStorage().getInheritedFrom(),
             D->defaultArgumentWasInherited() ? "inherited from" : "previous");
     });

clang/lib/AST/ODRDiagsEmitter.cpp

@@ -1523,8 +1523,11 @@ bool ODRDiagsEmitter::diagnoseMismatch(
         }
 
         if (HasFirstDefaultArgument && HasSecondDefaultArgument) {
-          Expr *FirstDefaultArgument = FirstNTTPD->getDefaultArgument();
-          Expr *SecondDefaultArgument = SecondNTTPD->getDefaultArgument();
+          TemplateArgument FirstDefaultArgument =
+              FirstNTTPD->getDefaultArgument().getArgument();
+          TemplateArgument SecondDefaultArgument =
+              SecondNTTPD->getDefaultArgument().getArgument();
+
           if (computeODRHash(FirstDefaultArgument) !=
               computeODRHash(SecondDefaultArgument)) {
             DiagTemplateError(FunctionTemplateParameterDifferentDefaultArgument)

clang/lib/AST/ODRHash.cpp

@@ -480,7 +480,7 @@ class ODRDeclVisitor : public ConstDeclVisitor<ODRDeclVisitor> {
         D->hasDefaultArgument() && !D->defaultArgumentWasInherited();
     Hash.AddBoolean(hasDefaultArgument);
     if (hasDefaultArgument) {
-      AddStmt(D->getDefaultArgument());
+      AddTemplateArgument(D->getDefaultArgument().getArgument());
     }
     Hash.AddBoolean(D->isParameterPack());
 

clang/lib/AST/TypePrinter.cpp

@@ -2281,8 +2281,9 @@ bool clang::isSubstitutedDefaultArgument(ASTContext &Ctx, TemplateArgument Arg,
                Ctx, Arg, TTPD->getDefaultArgument().getArgument(), Args, Depth);
   } else if (auto *NTTPD = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
     return NTTPD->hasDefaultArgument() &&
-           isSubstitutedTemplateArgument(Ctx, Arg, NTTPD->getDefaultArgument(),
-                                         Args, Depth);
+           isSubstitutedTemplateArgument(
+               Ctx, Arg, NTTPD->getDefaultArgument().getArgument(), Args,
+               Depth);
   }
   return false;
 }

clang/lib/ExtractAPI/DeclarationFragments.cpp

@@ -1023,8 +1023,9 @@ DeclarationFragmentsBuilder::getFragmentsForTemplateParameters(
       if (NTP->hasDefaultArgument()) {
         SmallString<8> ExprStr;
         raw_svector_ostream Output(ExprStr);
-        NTP->getDefaultArgument()->printPretty(
-            Output, nullptr, NTP->getASTContext().getPrintingPolicy());
+        NTP->getDefaultArgument().getArgument().print(
+            NTP->getASTContext().getPrintingPolicy(), Output,
+            /*IncludeType=*/false);
         Fragments.append(" = ", DeclarationFragments::FragmentKind::Text)
             .append(ExprStr, DeclarationFragments::FragmentKind::Text);
       }

clang/lib/Index/IndexDecl.cpp

@@ -711,7 +711,8 @@ class IndexingDeclVisitor : public ConstDeclVisitor<IndexingDeclVisitor, bool> {
       } else if (const auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(TP)) {
         IndexCtx.indexTypeSourceInfo(NTTP->getTypeSourceInfo(), Parent);
         if (NTTP->hasDefaultArgument())
-          IndexCtx.indexBody(NTTP->getDefaultArgument(), Parent);
+          handleTemplateArgumentLoc(NTTP->getDefaultArgument(), Parent,
+                                    TP->getLexicalDeclContext());
       } else if (const auto *TTPD = dyn_cast<TemplateTemplateParmDecl>(TP)) {
         if (TTPD->hasDefaultArgument())
           handleTemplateArgumentLoc(TTPD->getDefaultArgument(), Parent,

clang/lib/Sema/HLSLExternalSemaSource.cpp

@@ -442,10 +442,12 @@ void HLSLExternalSemaSource::defineHLSLVectorAlias() {
       AST, HLSLNamespace, SourceLocation(), SourceLocation(), 0, 1,
       &AST.Idents.get("element_count", tok::TokenKind::identifier), AST.IntTy,
       false, AST.getTrivialTypeSourceInfo(AST.IntTy));
-  Expr *LiteralExpr =
-      IntegerLiteral::Create(AST, llvm::APInt(AST.getIntWidth(AST.IntTy), 4),
-                             AST.IntTy, SourceLocation());
-  SizeParam->setDefaultArgument(LiteralExpr);
+  llvm::APInt Val(AST.getIntWidth(AST.IntTy), 4);
+  TemplateArgument Default(AST, llvm::APSInt(std::move(Val)), AST.IntTy,
+                           /*IsDefaulted=*/true);
+  SizeParam->setDefaultArgument(
+      AST, SemaPtr->getTrivialTemplateArgumentLoc(Default, AST.IntTy,
+                                                  SourceLocation(), SizeParam));
   TemplateParams.emplace_back(SizeParam);
 
   auto *ParamList =

clang/lib/Sema/SemaTemplate.cpp

@@ -1599,7 +1599,9 @@ NamedDecl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
     if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
       return Param;
 
-    Param->setDefaultArgument(Default);
+    Param->setDefaultArgument(
+        Context, getTrivialTemplateArgumentLoc(TemplateArgument(Default),
+                                               QualType(), SourceLocation()));
   }
 
   return Param;
@@ -1805,6 +1807,8 @@ static void SetNestedNameSpecifier(Sema &S, TagDecl *T,
 // Returns the template parameter list with all default template argument
 // information.
 static TemplateParameterList *GetTemplateParameterList(TemplateDecl *TD) {
+  if (TD->isImplicit())
+    return TD->getTemplateParameters();
   // Make sure we get the template parameter list from the most
   // recent declaration, since that is the only one that is guaranteed to
   // have all the default template argument information.
@@ -1825,7 +1829,8 @@ static TemplateParameterList *GetTemplateParameterList(TemplateDecl *TD) {
   //    template <class = void> friend struct C;
   //  };
   //  template struct S<int>;
-  while (D->getFriendObjectKind() != Decl::FriendObjectKind::FOK_None &&
+  while ((D->isImplicit() ||
+          D->getFriendObjectKind() != Decl::FriendObjectKind::FOK_None) &&
          D->getPreviousDecl())
     D = D->getPreviousDecl();
   return cast<TemplateDecl>(D)->getTemplateParameters();
@@ -3630,9 +3635,9 @@ bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
 
       // Check the presence of a default argument here.
       if (NewNonTypeParm->hasDefaultArgument() &&
-          DiagnoseDefaultTemplateArgument(*this, TPC,
-                                          NewNonTypeParm->getLocation(),
-                    NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
+          DiagnoseDefaultTemplateArgument(
+              *this, TPC, NewNonTypeParm->getLocation(),
+              NewNonTypeParm->getDefaultArgument().getSourceRange())) {
         NewNonTypeParm->removeDefaultArgument();
       }
 
@@ -6107,16 +6112,17 @@ static bool SubstDefaultTemplateArgument(
 /// parameters that precede \p Param in the template parameter list.
 ///
 /// \returns the substituted template argument, or NULL if an error occurred.
-static ExprResult SubstDefaultTemplateArgument(
+static bool SubstDefaultTemplateArgument(
     Sema &SemaRef, TemplateDecl *Template, SourceLocation TemplateLoc,
     SourceLocation RAngleLoc, NonTypeTemplateParmDecl *Param,
     ArrayRef<TemplateArgument> SugaredConverted,
-    ArrayRef<TemplateArgument> CanonicalConverted) {
+    ArrayRef<TemplateArgument> CanonicalConverted,
+    TemplateArgumentLoc &Output) {
   Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc, Param, Template,
                                    SugaredConverted,
                                    SourceRange(TemplateLoc, RAngleLoc));
   if (Inst.isInvalid())
-    return ExprError();
+    return true;
 
   // Only substitute for the innermost template argument list.
   MultiLevelTemplateArgumentList TemplateArgLists(Template, SugaredConverted,
@@ -6127,7 +6133,8 @@ static ExprResult SubstDefaultTemplateArgument(
   Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
   EnterExpressionEvaluationContext ConstantEvaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
-  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
+  return SemaRef.SubstTemplateArgument(Param->getDefaultArgument(),
+                                       TemplateArgLists, Output);
 }
 
 /// Substitute template arguments into the default template argument for
@@ -6219,14 +6226,12 @@ TemplateArgumentLoc Sema::SubstDefaultTemplateArgumentIfAvailable(
       return TemplateArgumentLoc();
 
     HasDefaultArg = true;
-    ExprResult Arg = SubstDefaultTemplateArgument(
-        *this, Template, TemplateLoc, RAngleLoc, NonTypeParm, SugaredConverted,
-        CanonicalConverted);
-    if (Arg.isInvalid())
+    TemplateArgumentLoc Output;
+    if (SubstDefaultTemplateArgument(*this, Template, TemplateLoc, RAngleLoc,
+                                     NonTypeParm, SugaredConverted,
+                                     CanonicalConverted, Output))
       return TemplateArgumentLoc();
-
-    Expr *ArgE = Arg.getAs<Expr>();
-    return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
+    return Output;
   }
 
   TemplateTemplateParmDecl *TempTempParm
@@ -6803,14 +6808,10 @@ bool Sema::CheckTemplateArgumentList(
         return diagnoseMissingArgument(*this, TemplateLoc, Template, NTTP,
                                        NewArgs);
 
-      ExprResult E = SubstDefaultTemplateArgument(
-          *this, Template, TemplateLoc, RAngleLoc, NTTP, SugaredConverted,
-          CanonicalConverted);
-      if (E.isInvalid())
+      if (SubstDefaultTemplateArgument(*this, Template, TemplateLoc, RAngleLoc,
+                                       NTTP, SugaredConverted,
+                                       CanonicalConverted, Arg))
         return true;
-
-      Expr *Ex = E.getAs<Expr>();
-      Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
     } else {
       TemplateTemplateParmDecl *TempParm
         = cast<TemplateTemplateParmDecl>(*Param);
@@ -9523,10 +9524,10 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
         }
       } else if (NonTypeTemplateParmDecl *NTTP
                    = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
-        if (Expr *DefArg = NTTP->getDefaultArgument()) {
+        if (NTTP->hasDefaultArgument()) {
           Diag(NTTP->getDefaultArgumentLoc(),
                diag::err_default_arg_in_partial_spec)
-            << DefArg->getSourceRange();
+              << NTTP->getDefaultArgument().getSourceRange();
           NTTP->removeDefaultArgument();
         }
       } else {