[Clang][AST] Track whether template template parameters used the 'typ…

…ename' keyword (#88139) This patch adds a `Typename` bit-field to `TemplateTemplateParmDecl` which stores whether the template template parameter was declared with the `typename` keyword.
llvm · Apr 11, 2024 · 4e6d18f · 4e6d18f
1 parent f626a35
commit 4e6d18f
Show file tree

Hide file tree

Showing 13 changed files with 75 additions and 52 deletions.
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -360,6 +360,9 @@ Improvements to Clang's diagnostics
   Added the ``-Wtentative-definition-array`` warning group to cover this.
   Fixes #GH87766
 
+- Clang now uses the correct type-parameter-key (``class`` or ``typename``) when printing
+  template template parameter declarations.
+
 Improvements to Clang's time-trace
 ----------------------------------
 
@@ -535,6 +538,7 @@ Bug Fixes to C++ Support
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 - Clang now properly preserves ``FoundDecls`` within a ``ConceptReference``. (#GH82628)
+- The presence of the ``typename`` keyword is now stored in ``TemplateTemplateParmDecl``.
 
 Miscellaneous Bug Fixes
 ^^^^^^^^^^^^^^^^^^^^^^^

diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
@@ -1581,26 +1581,36 @@ class TemplateTemplateParmDecl final
       DefaultArgStorage<TemplateTemplateParmDecl, TemplateArgumentLoc *>;
   DefArgStorage DefaultArgument;
 
+  /// Whether this template template parameter was declaration with
+  /// the 'typename' keyword.
+  ///
+  /// If false, it was declared with the 'class' keyword.
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned Typename : 1;
+
   /// Whether this parameter is a parameter pack.
-  bool ParameterPack;
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned ParameterPack : 1;
 
   /// Whether this template template parameter is an "expanded"
   /// parameter pack, meaning that it is a pack expansion and we
   /// already know the set of template parameters that expansion expands to.
-  bool ExpandedParameterPack = false;
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned ExpandedParameterPack : 1;
 
   /// The number of parameters in an expanded parameter pack.
   unsigned NumExpandedParams = 0;
 
-  TemplateTemplateParmDecl(DeclContext *DC, SourceLocation L,
-                           unsigned D, unsigned P, bool ParameterPack,
-                           IdentifierInfo *Id, TemplateParameterList *Params)
+  TemplateTemplateParmDecl(DeclContext *DC, SourceLocation L, unsigned D,
+                           unsigned P, bool ParameterPack, IdentifierInfo *Id,
+                           bool Typename, TemplateParameterList *Params)
       : TemplateDecl(TemplateTemplateParm, DC, L, Id, Params),
-        TemplateParmPosition(D, P), ParameterPack(ParameterPack) {}
+        TemplateParmPosition(D, P), Typename(Typename),
+        ParameterPack(ParameterPack), ExpandedParameterPack(false) {}
 
-  TemplateTemplateParmDecl(DeclContext *DC, SourceLocation L,
-                           unsigned D, unsigned P,
-                           IdentifierInfo *Id, TemplateParameterList *Params,
+  TemplateTemplateParmDecl(DeclContext *DC, SourceLocation L, unsigned D,
+                           unsigned P, IdentifierInfo *Id, bool Typename,
+                           TemplateParameterList *Params,
                            ArrayRef<TemplateParameterList *> Expansions);
 
   void anchor() override;
@@ -1613,14 +1623,13 @@ class TemplateTemplateParmDecl final
   static TemplateTemplateParmDecl *Create(const ASTContext &C, DeclContext *DC,
                                           SourceLocation L, unsigned D,
                                           unsigned P, bool ParameterPack,
-                                          IdentifierInfo *Id,
+                                          IdentifierInfo *Id, bool Typename,
                                           TemplateParameterList *Params);
-  static TemplateTemplateParmDecl *Create(const ASTContext &C, DeclContext *DC,
-                                          SourceLocation L, unsigned D,
-                                          unsigned P,
-                                          IdentifierInfo *Id,
-                                          TemplateParameterList *Params,
-                                 ArrayRef<TemplateParameterList *> Expansions);
+  static TemplateTemplateParmDecl *
+  Create(const ASTContext &C, DeclContext *DC, SourceLocation L, unsigned D,
+         unsigned P, IdentifierInfo *Id, bool Typename,
+         TemplateParameterList *Params,
+         ArrayRef<TemplateParameterList *> Expansions);
 
   static TemplateTemplateParmDecl *CreateDeserialized(ASTContext &C,
                                                       unsigned ID);
@@ -1634,6 +1643,14 @@ class TemplateTemplateParmDecl final
   using TemplateParmPosition::setPosition;
   using TemplateParmPosition::getIndex;
 
+  /// Whether this template template parameter was declared with
+  /// the 'typename' keyword.
+  bool wasDeclaredWithTypename() const { return Typename; }
+
+  /// Set whether this template template parameter was declared with
+  /// the 'typename' or 'class' keyword.
+  void setDeclaredWithTypename(bool withTypename) { Typename = withTypename; }
+
   /// Whether this template template parameter is a template
   /// parameter pack.
   ///

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
@@ -9064,7 +9064,7 @@ class Sema final : public SemaBase {
                                            Expr *DefaultArg);
   NamedDecl *ActOnTemplateTemplateParameter(
       Scope *S, SourceLocation TmpLoc, TemplateParameterList *Params,
-      SourceLocation EllipsisLoc, IdentifierInfo *ParamName,
+      bool Typename, SourceLocation EllipsisLoc, IdentifierInfo *ParamName,
       SourceLocation ParamNameLoc, unsigned Depth, unsigned Position,
       SourceLocation EqualLoc, ParsedTemplateArgument DefaultArg);
 

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
@@ -799,7 +799,7 @@ ASTContext::getCanonicalTemplateTemplateParmDecl(
 
   TemplateTemplateParmDecl *CanonTTP = TemplateTemplateParmDecl::Create(
       *this, getTranslationUnitDecl(), SourceLocation(), TTP->getDepth(),
-      TTP->getPosition(), TTP->isParameterPack(), nullptr,
+      TTP->getPosition(), TTP->isParameterPack(), nullptr, /*Typename=*/false,
       TemplateParameterList::Create(*this, SourceLocation(), SourceLocation(),
                                     CanonParams, SourceLocation(),
                                     /*RequiresClause=*/nullptr));

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
@@ -5952,7 +5952,8 @@ ASTNodeImporter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
           ToD, D, Importer.getToContext(),
           Importer.getToContext().getTranslationUnitDecl(), *LocationOrErr,
           D->getDepth(), D->getPosition(), D->isParameterPack(),
-          (*NameOrErr).getAsIdentifierInfo(), *TemplateParamsOrErr))
+          (*NameOrErr).getAsIdentifierInfo(), D->wasDeclaredWithTypename(),
+          *TemplateParamsOrErr))
     return ToD;
 
   if (D->hasDefaultArgument()) {

diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
@@ -1218,7 +1218,10 @@ void DeclPrinter::VisitTemplateDecl(const TemplateDecl *D) {
 
   if (const TemplateTemplateParmDecl *TTP =
         dyn_cast<TemplateTemplateParmDecl>(D)) {
-    Out << "class";
+    if (TTP->wasDeclaredWithTypename())
+      Out << "typename";
+    else
+      Out << "class";
 
     if (TTP->isParameterPack())
       Out << " ...";

diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
@@ -805,10 +805,10 @@ void TemplateTemplateParmDecl::anchor() {}
 
 TemplateTemplateParmDecl::TemplateTemplateParmDecl(
     DeclContext *DC, SourceLocation L, unsigned D, unsigned P,
-    IdentifierInfo *Id, TemplateParameterList *Params,
+    IdentifierInfo *Id, bool Typename, TemplateParameterList *Params,
     ArrayRef<TemplateParameterList *> Expansions)
     : TemplateDecl(TemplateTemplateParm, DC, L, Id, Params),
-      TemplateParmPosition(D, P), ParameterPack(true),
+      TemplateParmPosition(D, P), Typename(Typename), ParameterPack(true),
       ExpandedParameterPack(true), NumExpandedParams(Expansions.size()) {
   if (!Expansions.empty())
     std::uninitialized_copy(Expansions.begin(), Expansions.end(),
@@ -819,26 +819,26 @@ TemplateTemplateParmDecl *
 TemplateTemplateParmDecl::Create(const ASTContext &C, DeclContext *DC,
                                  SourceLocation L, unsigned D, unsigned P,
                                  bool ParameterPack, IdentifierInfo *Id,
-                                 TemplateParameterList *Params) {
+                                 bool Typename, TemplateParameterList *Params) {
   return new (C, DC) TemplateTemplateParmDecl(DC, L, D, P, ParameterPack, Id,
-                                              Params);
+                                              Typename, Params);
 }
 
 TemplateTemplateParmDecl *
 TemplateTemplateParmDecl::Create(const ASTContext &C, DeclContext *DC,
                                  SourceLocation L, unsigned D, unsigned P,
-                                 IdentifierInfo *Id,
+                                 IdentifierInfo *Id, bool Typename,
                                  TemplateParameterList *Params,
                                  ArrayRef<TemplateParameterList *> Expansions) {
   return new (C, DC,
               additionalSizeToAlloc<TemplateParameterList *>(Expansions.size()))
-      TemplateTemplateParmDecl(DC, L, D, P, Id, Params, Expansions);
+      TemplateTemplateParmDecl(DC, L, D, P, Id, Typename, Params, Expansions);
 }
 
 TemplateTemplateParmDecl *
 TemplateTemplateParmDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
   return new (C, ID) TemplateTemplateParmDecl(nullptr, SourceLocation(), 0, 0,
-                                              false, nullptr, nullptr);
+                                              false, nullptr, false, nullptr);
 }
 
 TemplateTemplateParmDecl *
@@ -847,7 +847,7 @@ TemplateTemplateParmDecl::CreateDeserialized(ASTContext &C, unsigned ID,
   auto *TTP =
       new (C, ID, additionalSizeToAlloc<TemplateParameterList *>(NumExpansions))
           TemplateTemplateParmDecl(nullptr, SourceLocation(), 0, 0, nullptr,
-                                   nullptr, std::nullopt);
+                                   false, nullptr, std::nullopt);
   TTP->NumExpandedParams = NumExpansions;
   return TTP;
 }
@@ -1469,7 +1469,7 @@ createMakeIntegerSeqParameterList(const ASTContext &C, DeclContext *DC) {
   // template <typename T, ...Ints> class IntSeq
   auto *TemplateTemplateParm = TemplateTemplateParmDecl::Create(
       C, DC, SourceLocation(), /*Depth=*/0, /*Position=*/0,
-      /*ParameterPack=*/false, /*Id=*/nullptr, TPL);
+      /*ParameterPack=*/false, /*Id=*/nullptr, /*Typename=*/false, TPL);
   TemplateTemplateParm->setImplicit(true);
 
   // typename T

diff --git a/clang/lib/Parse/ParseTemplate.cpp b/clang/lib/Parse/ParseTemplate.cpp
@@ -805,10 +805,12 @@ NamedDecl *Parser::ParseTemplateTemplateParameter(unsigned Depth,
   // identifier, comma, or greater. Provide a fixit if the identifier, comma,
   // or greater appear immediately or after 'struct'. In the latter case,
   // replace the keyword with 'class'.
+  bool TypenameKeyword = false;
   if (!TryConsumeToken(tok::kw_class)) {
     bool Replace = Tok.isOneOf(tok::kw_typename, tok::kw_struct);
     const Token &Next = Tok.is(tok::kw_struct) ? NextToken() : Tok;
     if (Tok.is(tok::kw_typename)) {
+      TypenameKeyword = true;
       Diag(Tok.getLocation(),
            getLangOpts().CPlusPlus17
                ? diag::warn_cxx14_compat_template_template_param_typename
@@ -878,10 +880,9 @@ NamedDecl *Parser::ParseTemplateTemplateParameter(unsigned Depth,
     }
   }
 
-  return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
-                                                ParamList, EllipsisLoc,
-                                                ParamName, NameLoc, Depth,
-                                                Position, EqualLoc, DefaultArg);
+  return Actions.ActOnTemplateTemplateParameter(
+      getCurScope(), TemplateLoc, ParamList, TypenameKeyword, EllipsisLoc,
+      ParamName, NameLoc, Depth, Position, EqualLoc, DefaultArg);
 }
 
 /// ParseNonTypeTemplateParameter - Handle the parsing of non-type

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
@@ -1630,26 +1630,20 @@ NamedDecl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
 /// ActOnTemplateTemplateParameter - Called when a C++ template template
 /// parameter (e.g. T in template <template \<typename> class T> class array)
 /// has been parsed. S is the current scope.
-NamedDecl *Sema::ActOnTemplateTemplateParameter(Scope* S,
-                                           SourceLocation TmpLoc,
-                                           TemplateParameterList *Params,
-                                           SourceLocation EllipsisLoc,
-                                           IdentifierInfo *Name,
-                                           SourceLocation NameLoc,
-                                           unsigned Depth,
-                                           unsigned Position,
-                                           SourceLocation EqualLoc,
-                                           ParsedTemplateArgument Default) {
+NamedDecl *Sema::ActOnTemplateTemplateParameter(
+    Scope *S, SourceLocation TmpLoc, TemplateParameterList *Params,
+    bool Typename, SourceLocation EllipsisLoc, IdentifierInfo *Name,
+    SourceLocation NameLoc, unsigned Depth, unsigned Position,
+    SourceLocation EqualLoc, ParsedTemplateArgument Default) {
   assert(S->isTemplateParamScope() &&
          "Template template parameter not in template parameter scope!");
 
   // Construct the parameter object.
   bool IsParameterPack = EllipsisLoc.isValid();
-  TemplateTemplateParmDecl *Param =
-    TemplateTemplateParmDecl::Create(Context, Context.getTranslationUnitDecl(),
-                                     NameLoc.isInvalid()? TmpLoc : NameLoc,
-                                     Depth, Position, IsParameterPack,
-                                     Name, Params);
+  TemplateTemplateParmDecl *Param = TemplateTemplateParmDecl::Create(
+      Context, Context.getTranslationUnitDecl(),
+      NameLoc.isInvalid() ? TmpLoc : NameLoc, Depth, Position, IsParameterPack,
+      Name, Typename, Params);
   Param->setAccess(AS_public);
 
   if (Param->isParameterPack())

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3233,12 +3233,14 @@ TemplateDeclInstantiator::VisitTemplateTemplateParmDecl(
     Param = TemplateTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getLocation(),
         D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
-        D->getPosition(), D->getIdentifier(), InstParams, ExpandedParams);
+        D->getPosition(), D->getIdentifier(), D->wasDeclaredWithTypename(),
+        InstParams, ExpandedParams);
   else
     Param = TemplateTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getLocation(),
         D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
-        D->getPosition(), D->isParameterPack(), D->getIdentifier(), InstParams);
+        D->getPosition(), D->isParameterPack(), D->getIdentifier(),
+        D->wasDeclaredWithTypename(), InstParams);
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
     NestedNameSpecifierLoc QualifierLoc =
         D->getDefaultArgument().getTemplateQualifierLoc();

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2715,6 +2715,7 @@ void ASTDeclReader::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
 
 void ASTDeclReader::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
   VisitTemplateDecl(D);
+  D->setDeclaredWithTypename(Record.readBool());
   // TemplateParmPosition.
   D->setDepth(Record.readInt());
   D->setPosition(Record.readInt());

diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -1921,6 +1921,7 @@ void ASTDeclWriter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
     Record.push_back(D->getNumExpansionTemplateParameters());
 
   VisitTemplateDecl(D);
+  Record.push_back(D->wasDeclaredWithTypename());
   // TemplateParmPosition.
   Record.push_back(D->getDepth());
   Record.push_back(D->getPosition());

diff --git a/clang/unittests/AST/DeclPrinterTest.cpp b/clang/unittests/AST/DeclPrinterTest.cpp
@@ -1220,8 +1220,7 @@ TEST(DeclPrinter, TestTemplateTemplateParameterWrittenWithTypename) {
   ASSERT_TRUE(PrintedDeclCXX17Matches(
       "template <template <typename> typename Z> void A();",
       functionTemplateDecl(hasName("A")).bind("id"),
-      "template <template <typename> class Z> void A()"));
-  // WRONG: We should use typename if the parameter was written with it.
+      "template <template <typename> typename Z> void A()"));
 }
 
 TEST(DeclPrinter, TestTemplateArgumentList1) {