diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -553,6 +553,10 @@
   (`#48512 <https://github.com/llvm/llvm-project/issues/48512>`_).
 - Fixed a failing assertion when parsing incomplete destructor.
   (`#63503 <https://github.com/llvm/llvm-project/issues/63503>`_)
+- Fix C++17 mode assert when parsing malformed code and the compiler is
+  attempting to see if it could be type template for class template argument
+  deduction. This fixes
+  (`Issue 57495 <https://github.com/llvm/llvm-project/issues/57495>`_)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Parse/ParseTentative.cpp b/clang/lib/Parse/ParseTentative.cpp
--- a/clang/lib/Parse/ParseTentative.cpp
+++ b/clang/lib/Parse/ParseTentative.cpp
@@ -1656,7 +1656,10 @@
             if (getLangOpts().CPlusPlus17) {
               if (TryAnnotateTypeOrScopeToken())
                 return TPResult::Error;
-              if (Tok.isNot(tok::identifier))
+              // If we annotated then the current token should not still be ::
+              // FIXME we may want to also check for tok::annot_typename but
+              // currently don't have a test case.
+              if (Tok.isNot(tok::annot_cxxscope))
                 break;
             }
 
diff --git a/clang/test/Parser/cxx1z-class-template-argument-deduction.cpp b/clang/test/Parser/cxx1z-class-template-argument-deduction.cpp
--- a/clang/test/Parser/cxx1z-class-template-argument-deduction.cpp
+++ b/clang/test/Parser/cxx1z-class-template-argument-deduction.cpp
@@ -247,3 +247,11 @@
 };
 
 }
+
+namespace GH57495 {
+template <typename T> struct vector{};
+
+void f() {
+  GH57495::vector.d; // expected-error {{cannot use dot operator on a type}}
+}
+}