Decouple from the new version of getTemplateInstantiationArgs()

Author: zyn0217

clang/include/clang/Sema/Sema.h

@@ -13033,6 +13033,7 @@ class Sema final : public SemaBase {
   ///
   /// \param SkipForSpecialization when specified, any template specializations
   /// in a traversal would be ignored.
+  ///
   /// \param ForDefaultArgumentSubstitution indicates we should continue looking
   /// when encountering a specialized member function template, rather than
   /// returning immediately.
@@ -13044,6 +13045,17 @@ class Sema final : public SemaBase {
       bool SkipForSpecialization = false,
       bool ForDefaultArgumentSubstitution = false);
 
+  /// Apart from storing the result to \p Result, this behaves the same as
+  /// another overload.
+  void getTemplateInstantiationArgs(
+      MultiLevelTemplateArgumentList &Result, const NamedDecl *D,
+      const DeclContext *DC = nullptr, bool Final = false,
+      std::optional<ArrayRef<TemplateArgument>> Innermost = std::nullopt,
+      bool RelativeToPrimary = false, const FunctionDecl *Pattern = nullptr,
+      bool ForConstraintInstantiation = false,
+      bool SkipForSpecialization = false,
+      bool ForDefaultArgumentSubstitution = false);
+
   /// RAII object to handle the state changes required to synthesize
   /// a function body.
   class SynthesizedFunctionScope {

clang/lib/Sema/SemaConcept.cpp

@@ -1128,12 +1128,18 @@ static bool CheckFunctionConstraintsWithoutInstantiation(
   // Collect the list of template arguments relative to the 'primary'
   // template. We need the entire list, since the constraint is completely
   // uninstantiated at this point.
-  MultiLevelTemplateArgumentList MLTAL =
-      SemaRef.getTemplateInstantiationArgs(FD, /*DC=*/nullptr,
-                                           /*Final=*/false,
-                                           /*Innermost=*/TemplateArgs,
-                                           /*RelativeToPrimary=*/true,
-                                           /*ForConstraintInstantiation=*/true);
+
+  // FIXME: Add TemplateArgs through the 'Innermost' parameter once
+  // the refactoring of getTemplateInstantiationArgs() relands.
+  MultiLevelTemplateArgumentList MLTAL;
+  MLTAL.addOuterTemplateArguments(Template, /*Args=*/TemplateArgs,
+                                  /*Final=*/false);
+  SemaRef.getTemplateInstantiationArgs(
+      MLTAL, /*D=*/nullptr,
+      FD->getFriendObjectKind() ? FD->getLexicalDeclContext()
+                                : FD->getDeclContext(),
+      /*Final=*/false, /*Innermost=*/std::nullopt, /*RelativeToPrimary=*/true,
+      /*Pattern=*/nullptr, /*ForConstraintInstantiation=*/true);
 
   Sema::ContextRAII SavedContext(SemaRef, FD);
   std::optional<Sema::CXXThisScopeRAII> ThisScope;

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -475,6 +475,21 @@ MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs(
   assert((ND || DC) && "Can't find arguments for a decl if one isn't provided");
   // Accumulate the set of template argument lists in this structure.
   MultiLevelTemplateArgumentList Result;
+  getTemplateInstantiationArgs(
+      Result, ND, DC, Final, Innermost, RelativeToPrimary, Pattern,
+      ForConstraintInstantiation, SkipForSpecialization,
+      ForDefaultArgumentSubstitution);
+  return Result;
+}
+
+void Sema::getTemplateInstantiationArgs(
+    MultiLevelTemplateArgumentList &Result, const NamedDecl *ND,
+    const DeclContext *DC, bool Final,
+    std::optional<ArrayRef<TemplateArgument>> Innermost, bool RelativeToPrimary,
+    const FunctionDecl *Pattern, bool ForConstraintInstantiation,
+    bool SkipForSpecialization, bool ForDefaultArgumentSubstitution) {
+  assert((ND || DC) && "Can't find arguments for a decl if one isn't provided");
+  // Accumulate the set of template argument lists in this structure.
 
   using namespace TemplateInstArgsHelpers;
   const Decl *CurDecl = ND;
@@ -535,14 +550,12 @@ MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs(
     }
 
     if (R.IsDone)
-      return Result;
+      return;
     if (R.ClearRelativeToPrimary)
       RelativeToPrimary = false;
     assert(R.NextDecl);
     CurDecl = R.NextDecl;
   }
-
-  return Result;
 }
 
 bool Sema::CodeSynthesisContext::isInstantiationRecord() const {