From 628b899be14a6bab4b32dbd53aabd447dcc16cb7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20G=C3=B3rny?= <mgorny@gentoo.org>
Date: Sat, 20 Aug 2016 23:47:41 +0200
Subject: [PATCH] llvm-config: Clean up exported values, update for shared
 linking

Gentoo-specific fixup for llvm-config, including:
- wiping build-specific CFLAGS, CXXFLAGS,
- making --src-root return invalid path (/dev/null).

Thanks to Steven Newbury for the initial patch.

Bug: https://bugs.gentoo.org/565358
Bug: https://bugs.gentoo.org/501684

diff --git a/tools/llvm-config/CMakeLists.txt b/tools/llvm-config/CMakeLists.txt
index 744fa4e44d1..593788aaef3 100644
--- a/tools/llvm-config/CMakeLists.txt
+++ b/tools/llvm-config/CMakeLists.txt
@@ -32,8 +32,12 @@ get_property(COMPILE_FLAGS TARGET llvm-config PROPERTY COMPILE_FLAGS)
 set(LLVM_SRC_ROOT ${LLVM_MAIN_SRC_DIR})
 set(LLVM_OBJ_ROOT ${LLVM_BINARY_DIR})
 set(LLVM_CPPFLAGS "${CMAKE_CPP_FLAGS} ${CMAKE_CPP_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
-set(LLVM_CFLAGS "${CMAKE_C_FLAGS} ${CMAKE_C_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
-set(LLVM_CXXFLAGS "${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${COMPILE_FLAGS} ${LLVM_DEFINITIONS}")
+# Just use CMAKE_CPP_FLAGS for CFLAGS and CXXFLAGS, otherwise compiler
+# specific flags will be set when we don't know what compiler will be used
+# with external project utilising llvm-config.  C++ Standard is required.
+# TODO: figure out if we can remove -std=c++11 and move it to revdeps.
+set(LLVM_CFLAGS "${CMAKE_CPP_FLAGS} ${CMAKE_C_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
+set(LLVM_CXXFLAGS "${CMAKE_CPP_FLAGS} -std=c++11 ${CMAKE_CXX_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
 set(LLVM_BUILD_SYSTEM cmake)
 set(LLVM_HAS_RTTI ${LLVM_CONFIG_HAS_RTTI})
 set(LLVM_DYLIB_VERSION "${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}${LLVM_VERSION_SUFFIX}")
diff --git a/tools/llvm-config/llvm-config.cpp b/tools/llvm-config/llvm-config.cpp
index d780094861c..c61c72ff48c 100644
--- a/tools/llvm-config/llvm-config.cpp
+++ b/tools/llvm-config/llvm-config.cpp
@@ -549,7 +550,11 @@ int main(int argc, char **argv) {
       } else if (Arg == "--obj-root") {
         OS << ActivePrefix << '\n';
       } else if (Arg == "--src-root") {
-        OS << LLVM_SRC_ROOT << '\n';
+        if (IsInDevelopmentTree) {
+          OS << LLVM_SRC_ROOT << '\n';
+        } else {
+          OS << "/dev/null\n";
+        }
       } else if (Arg == "--ignore-libllvm") {
         LinkDyLib = false;
         LinkMode = BuiltSharedLibs ? LinkModeShared : LinkModeAuto;
-- 
2.11.0