diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -5460,6 +5460,13 @@
                                const PrintingPolicy &Policy,
                                const TemplateParameterList *TPL = nullptr);
 
+/// Make a best-effort determination of whether the type T can be produced by
+/// substituting Args into the default argument of Param.
+bool isSubstitutedDefaultArgument(ASTContext &Ctx, TemplateArgument Arg,
+                                  const NamedDecl *Param,
+                                  ArrayRef<TemplateArgument> Args,
+                                  unsigned Depth);
+
 /// The injected class name of a C++ class template or class
 /// template partial specialization.  Used to record that a type was
 /// spelled with a bare identifier rather than as a template-id; the
diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -2044,9 +2044,7 @@
   return false;
 }
 
-/// Make a best-effort determination of whether the type T can be produced by
-/// substituting Args into the default argument of Param.
-static bool isSubstitutedDefaultArgument(ASTContext &Ctx, TemplateArgument Arg,
+bool clang::isSubstitutedDefaultArgument(ASTContext &Ctx, TemplateArgument Arg,
                                          const NamedDecl *Param,
                                          ArrayRef<TemplateArgument> Args,
                                          unsigned Depth) {