From 2e4fdbdda1a5ffba53ed025e6d04a16d40003325 Mon Sep 17 00:00:00 2001
From: Chih-Hung Hsieh <chh@google.com>
Date: Wed, 10 Feb 2021 22:15:31 -0800
Subject: [PATCH] Do not append empty DEFAULT_TIDY_HEADER_DIRS

* Default value will be empty and not work in -header-filter.

Bug: 179530304
Test: make with WITH_TIDY=1 and various setting of DEFAULT_TIDY_HEADER_DIRS
Change-Id: I3f784f545acd12285a5bf6dcae1bab42c9185fe7
---
 core/clang/tidy.mk | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/core/clang/tidy.mk b/core/clang/tidy.mk
index 868f7bc88..8a408785f 100644
--- a/core/clang/tidy.mk
+++ b/core/clang/tidy.mk
@@ -36,7 +36,7 @@ $(lastword \
 )
 endef
 
-# Default filter contains current directory $1 and DEFAULT_TIDY_HEADER_DIRS.
+# Default filter contains current directory $1 and optional DEFAULT_TIDY_HEADER_DIRS.
 define default_tidy_header_filter
-  -header-filter="($(subst $(space),,$1|$(DEFAULT_TIDY_HEADER_DIRS)))"
+  -header-filter=$(if $(DEFAULT_TIDY_HEADER_DIRS),"($1/|$(DEFAULT_TIDY_HEADER_DIRS))",$1/)
 endef