[Clang] Improve getReplacedTemplateParameterList() const correctness (llvm#131165)

Author: bricknerb

clang/include/clang/AST/DeclTemplate.h

@@ -3392,7 +3392,7 @@ inline std::optional<unsigned> getExpandedPackSize(const NamedDecl *Param) {
 
 /// Internal helper used by Subst* nodes to retrieve the parameter list
 /// for their AssociatedDecl.
-TemplateParameterList *getReplacedTemplateParameterList(Decl *D);
+TemplateParameterList *getReplacedTemplateParameterList(const Decl *D);
 
 } // namespace clang
 

clang/lib/AST/DeclTemplate.cpp

@@ -1642,7 +1642,7 @@ void TemplateParamObjectDecl::printAsInit(llvm::raw_ostream &OS,
   getValue().printPretty(OS, Policy, getType(), &getASTContext());
 }
 
-TemplateParameterList *clang::getReplacedTemplateParameterList(Decl *D) {
+TemplateParameterList *clang::getReplacedTemplateParameterList(const Decl *D) {
   switch (D->getKind()) {
   case Decl::Kind::CXXRecord:
     return cast<CXXRecordDecl>(D)