diff --git a/clang/include/clang/AST/ExprConcepts.h b/clang/include/clang/AST/ExprConcepts.h
--- a/clang/include/clang/AST/ExprConcepts.h
+++ b/clang/include/clang/AST/ExprConcepts.h
@@ -126,7 +126,11 @@
   }
 
   SourceLocation getEndLoc() const LLVM_READONLY {
-    return ArgsAsWritten->RAngleLoc;
+    // If the ConceptSpecializationExpr is the ImmediatelyDeclaredConstraint
+    // of a TypeConstraint written syntactically as a constrained-parameter,
+    // there may not be a template argument list.
+    return ArgsAsWritten->RAngleLoc.isValid() ? ArgsAsWritten->RAngleLoc
+                                              : ConceptName.getEndLoc();
   }
 
   // Iterators
diff --git a/clang/test/AST/ast-dump-concepts.cpp b/clang/test/AST/ast-dump-concepts.cpp
--- a/clang/test/AST/ast-dump-concepts.cpp
+++ b/clang/test/AST/ast-dump-concepts.cpp
@@ -1,5 +1,8 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -std=c++2a -ast-dump -ast-dump-filter Foo %s | FileCheck -strict-whitespace %s
 
+template <typename T>
+concept unary_concept = true;
+
 template <typename T, typename U>
 concept not_same_as = true;
 
@@ -10,4 +13,9 @@
   // CHECK-NEXT: `-TemplateArgument {{.*}} type 'int'
   template <not_same_as<int> R>
   Foo(R) requires(true);
+
+  // CHECK:      TemplateTypeParmDecl {{.*}} referenced Concept {{.*}} 'unary_concept'
+  // CHECK-NEXT: `-ConceptSpecializationExpr {{.*}} <col:13> 'bool'
+  template <unary_concept R>
+  Foo(R);
 };