update release note

Author: Jinjie-Huang

clang/docs/ReleaseNotes.rst

@@ -404,9 +404,8 @@ Improvements to Clang's diagnostics
 - Clang now emits a diagnostic in case `vector_size` or `ext_vector_type`
  attributes are used with a negative size (#GH165463).
 
-- A new warning, -Wshadow-header, has been added to detect when a header file
- included via quotes (#include "...") is found in multiple distinct search
- directories.
+- A new warning ``-Wshadow-header`` has been added to detect when a header file
+ included via quotes (#include "...") is found in multiple distinct search directories.
 
 Improvements to Clang's time-trace
 ----------------------------------

clang/test/Preprocessor/header-shadowing.c

@@ -19,6 +19,7 @@
 // RUN: %clang_cc1 -fms-compatibility -Wshadow-header -Eonly %t/t.c -I %t -I %t/foo -I %t/foo/bar 2>&1 | FileCheck %s --check-prefix=SHADOWING-MS
 
 // SHADOWING-MS: {{.*}} warning: multiple candidates for header 't3.h' found; directory '{{.*}}foo' chosen, ignoring '{{.*}}' and others [-Wshadow-header]
+// SHADOWING-MS: warning: Found foo/t3.h.
 // SHADOWING-MS-NOT: {{.*}} warning: multiple candidates for header 't3.h' found; directory '{{.*}}foo' chosen, ignoring '{{.*}}' and others [-Wshadow-header]
 
 //--- main.c