From 6e34aea93c71e3ac1667f93357695551e2ced09d Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Wed, 19 Sep 2012 14:04:13 -0400
Subject: [PATCH 1/2] Clang: Split Compiler/Clang* modules out from GNU
 (#13550)

While Clang presents an almost identical interface to GNU there will be
some differences.  Split the compiler information modules to allow
separate rules for Clang.  Start by loading the GNU rules but leave a
place to add Clang-specific information.
---
 Modules/Compiler/Clang-ASM.cmake |  6 +++++-
 Modules/Compiler/Clang-C.cmake   |  3 ++-
 Modules/Compiler/Clang-CXX.cmake |  3 ++-
 Modules/Compiler/Clang.cmake     | 25 +++++++++++++++++++++++++
 4 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 Modules/Compiler/Clang.cmake

diff --git a/Modules/Compiler/Clang-ASM.cmake b/Modules/Compiler/Clang-ASM.cmake
index a908b609f..16c9c159c 100644
--- a/Modules/Compiler/Clang-ASM.cmake
+++ b/Modules/Compiler/Clang-ASM.cmake
@@ -1 +1,5 @@
-include(Compiler/GNU-ASM)
+include(Compiler/Clang)
+
+set(CMAKE_ASM_SOURCE_FILE_EXTENSIONS s;S;asm)
+
+__compiler_clang(ASM)
diff --git a/Modules/Compiler/Clang-C.cmake b/Modules/Compiler/Clang-C.cmake
index f7baf686a..98fcd0b3f 100644
--- a/Modules/Compiler/Clang-C.cmake
+++ b/Modules/Compiler/Clang-C.cmake
@@ -1 +1,2 @@
-include(Compiler/GNU-C)
+include(Compiler/Clang)
+__compiler_clang(C)
diff --git a/Modules/Compiler/Clang-CXX.cmake b/Modules/Compiler/Clang-CXX.cmake
index d3c403a69..486e2af88 100644
--- a/Modules/Compiler/Clang-CXX.cmake
+++ b/Modules/Compiler/Clang-CXX.cmake
@@ -1 +1,2 @@
-include(Compiler/GNU-CXX)
+include(Compiler/Clang)
+__compiler_clang(CXX)
diff --git a/Modules/Compiler/Clang.cmake b/Modules/Compiler/Clang.cmake
new file mode 100644
index 000000000..f7be864f8
--- /dev/null
+++ b/Modules/Compiler/Clang.cmake
@@ -0,0 +1,25 @@
+
+#=============================================================================
+# Copyright 2002-2012 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+# This module is shared by multiple languages; use include blocker.
+if(__COMPILER_CLANG)
+  return()
+endif()
+set(__COMPILER_CLANG 1)
+
+include(Compiler/GNU)
+
+macro(__compiler_clang lang)
+  __compiler_gnu(${lang})
+endmacro()

From ada9efd3afb710a982f28f46196d5ec53ade199b Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Wed, 19 Sep 2012 14:04:23 -0400
Subject: [PATCH 2/2] Clang: All versions know about -fPIE (#13550)

The GNU compiler information file tests for GNU >= 3.4 because earlier
versions do not have the flag.  The version number test is not valid for
Clang compiler versions, but we know Clang supports the flag.
---
 Modules/Compiler/Clang.cmake | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Modules/Compiler/Clang.cmake b/Modules/Compiler/Clang.cmake
index f7be864f8..75a971dd7 100644
--- a/Modules/Compiler/Clang.cmake
+++ b/Modules/Compiler/Clang.cmake
@@ -22,4 +22,5 @@ include(Compiler/GNU)
 
 macro(__compiler_clang lang)
   __compiler_gnu(${lang})
+  set(CMAKE_${lang}_COMPILE_OPTIONS_PIE "-fPIE")
 endmacro()