From 4025061b8a31e612af17bd9548b35e1918135291 Mon Sep 17 00:00:00 2001
From: NAKAMURA Takumi <geek4civic@gmail.com>
Date: Sun, 16 Oct 2011 02:54:33 +0000
Subject: [PATCH] CMake: Introduce LLVM_CLANG_SOURCE_DIR, "tools/clang" by
 default. Clang will not be built if LLVM_CLANG_SOURCE_DIR="" or
 ${LLVM_CLANG_SOURCE_DIR}/CMakeLists.txt is not found.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142103 91177308-0d34-0410-b5e6-96231b3b80d8
---
 docs/CMake.html      | 5 +++++
 tools/CMakeLists.txt | 7 +++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/docs/CMake.html b/docs/CMake.html
index 6389c7f22af..ac07b0d6d44 100644
--- a/docs/CMake.html
+++ b/docs/CMake.html
@@ -351,6 +351,11 @@
     Function Interface library. If the library or its headers are
     installed on a custom location, you can set the variables
     FFI_INCLUDE_DIR and FFI_LIBRARY_DIR. Defaults to OFF.</dd>
+
+  <dt><b>LLVM_CLANG_SOURCE_DIR</b>:PATH</dt>
+  <dd>Path to Clang's source directory. Defaults to tools/clang.
+    Clang will not be built when it is empty or it does not point valid
+    path.</dd>
 </dl>
 
 </div>
diff --git a/tools/CMakeLists.txt b/tools/CMakeLists.txt
index e66648bee1e..3c679b82d3b 100644
--- a/tools/CMakeLists.txt
+++ b/tools/CMakeLists.txt
@@ -59,11 +59,14 @@ if( LLVM_ENABLE_PIC )
   endif()
 endif()
 
-if( EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/clang/CMakeLists.txt )
+set(LLVM_CLANG_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/clang" CACHE PATH "Path to Clang source directory")
+
+if (NOT ${LLVM_CLANG_SOURCE_DIR} STREQUAL ""
+    AND EXISTS ${LLVM_CLANG_SOURCE_DIR}/CMakeLists.txt)
   option(LLVM_BUILD_CLANG "Whether to build Clang as part of LLVM" ON)
   if (${LLVM_BUILD_CLANG})
     add_subdirectory( ${CMAKE_CURRENT_SOURCE_DIR}/clang )
   endif()
-endif( EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/clang/CMakeLists.txt )
+endif ()
 
 set(LLVM_COMMON_DEPENDS ${LLVM_COMMON_DEPENDS} PARENT_SCOPE)
-- 
2.34.1