sys-devel/llvm: Fix bogus flags and paths in llvm-config, #565358

Fix llvm-config to avoid bogus results. In particular:

1. Limit --cflags and --cxxflags to package-specific flags. Do not
output the whole flag-string used during the build. This fixes libclc
build issues when LLVM build flags were not tolerated by clang.

2. Fix library names and paths to use shared library suffix rather than
static library suffix, especially that we do not install static
libraries.

3. Wipe out --system-libs since they should not be required for dynamic
linking.

4. Ban --obj-root and --src-root when running outside source tree, since
we are not installing any sources and therefore their results would
always be bogus.

Based on patch provided by Steven Newbury.

Fixes: https://bugs.gentoo.org/565358

1 files changed, 113 insertions, 0 deletions

diff --git a/sys-devel/llvm/files/llvm-3.7-llvm-config.patch b/sys-devel/llvm/files/llvm-3.7-llvm-config.patch
new file mode 100644
index 000000000000..932c92b36cca
--- /dev/null
+++ b/sys-devel/llvm/files/llvm-3.7-llvm-config.patch
@@ -0,0 +1,113 @@
+From 8a51e9673859eb3fb819f0d1dad5e2a60d1a3c0a Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Micha=C5=82=20G=C3=B3rny?= <mgorny@gentoo.org>
+Date: Wed, 2 Dec 2015 16:04:56 +0100
+Subject: [PATCH] llvm-config: Clean up exported values, update for shared
+ linking
+
+Gentoo-specific fixup for llvm-config, including:
+- wiping build-specific CFLAGS, CXXFLAGS,
+- updating library suffixes for shared libs,
+- wiping --system-libs for shared linking,
+- banning --obj-root and --src-root due to no sources installed.
+
+Thanks to Steven Newbury for the initial patch.
+
+Bug: https://bugs.gentoo.org/565358
+Bug: https://bugs.gentoo.org/501684
+---
+ tools/llvm-config/CMakeLists.txt    |  11 ++++++++---
+ tools/llvm-config/llvm-config.cpp   |  22 ++++++++++++++++------
+ utils/llvm-build/llvmbuild/main.py  |   4 +++-
+ 4 files changed, 27 insertions(+), 10 deletions(-)
+
+diff --git a/tools/llvm-config/CMakeLists.txt b/tools/llvm-config/CMakeLists.txt
+index edbd8c9..9a801bd 100644
+--- a/tools/llvm-config/CMakeLists.txt
++++ b/tools/llvm-config/CMakeLists.txt
+@@ -22,12 +22,17 @@ 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}} ${LLVM_DEFINITIONS}")
+ # Use the C++ link flags, since they should be a superset of C link flags.
+ set(LLVM_LDFLAGS "${CMAKE_CXX_LINK_FLAGS}")
+ set(LLVM_BUILDMODE ${CMAKE_BUILD_TYPE})
+-set(LLVM_SYSTEM_LIBS ${SYSTEM_LIBS})
++# We don't do static libs, so we don't need to supply any system-libs
++set(LLVM_SYSTEM_LIBS "")
+ string(REPLACE ";" " " LLVM_TARGETS_BUILT "${LLVM_TARGETS_TO_BUILD}")
+ configure_file(${BUILDVARIABLES_SRCPATH} ${BUILDVARIABLES_OBJPATH} @ONLY)
+ 
+diff --git a/tools/llvm-config/llvm-config.cpp b/tools/llvm-config/llvm-config.cpp
+index 879b9ab..d2c43fa 100644
+--- a/tools/llvm-config/llvm-config.cpp
++++ b/tools/llvm-config/llvm-config.cpp
+@@ -323,10 +323,19 @@ int main(int argc, char **argv) {
+ #else
+         OS << "ON\n";
+ #endif
+-      } else if (Arg == "--obj-root") {
+-        OS << ActivePrefix << '\n';
+-      } else if (Arg == "--src-root") {
+-        OS << LLVM_SRC_ROOT << '\n';
++      } else if (Arg == "--obj-root" || Arg == "--src-root") {
++        if (IsInDevelopmentTree) {
++          if (Arg == "--obj-root") {
++            OS << ActivePrefix << '\n';
++          } else {
++            OS << LLVM_SRC_ROOT << '\n';
++          }
++        } else {
++          // sources are not installed
++          llvm::errs() << "llvm-config: sources not installed, "
++                       << Arg << " not available\n";
++          exit(1);
++        }
+       } else {
+         usage();
+       }
+@@ -360,8 +369,9 @@ int main(int argc, char **argv) {
+           OS << ActiveLibDir << '/' << Lib;
+         } else if (PrintLibs) {
+           // If this is a typical library name, include it using -l.
+-          if (Lib.startswith("lib") && Lib.endswith(".a")) {
+-            OS << "-l" << Lib.slice(3, Lib.size()-2);
++          if (Lib.startswith("lib") && Lib.endswith(LTDL_SHLIB_EXT)) {
++            // sizeof counts trailing NUL
++            OS << "-l" << Lib.slice(3, Lib.size()-sizeof(LTDL_SHLIB_EXT)+1);
+             continue;
+           }
+ 
+diff --git a/utils/llvm-build/llvmbuild/main.py b/utils/llvm-build/llvmbuild/main.py
+index 353741f..4ba5e91 100644
+--- a/utils/llvm-build/llvmbuild/main.py
++++ b/utils/llvm-build/llvmbuild/main.py
+@@ -393,6 +393,8 @@ subdirectories = %s
+ //
+ //===----------------------------------------------------------------------===//
+ 
++#include "llvm/Config/config.h"
++
+ """)
+         f.write('struct AvailableComponent {\n')
+         f.write('  /// The name of the component.\n')
+@@ -413,7 +415,7 @@ subdirectories = %s
+             if library_name is None:
+                 library_name_as_cstr = '0'
+             else:
+-                library_name_as_cstr = '"lib%s.a"' % library_name
++                library_name_as_cstr = '"lib%s" LTDL_SHLIB_EXT' % library_name
+             f.write('  { "%s", %s, %d, { %s } },\n' % (
+                 name, library_name_as_cstr, is_installed,
+                 ', '.join('"%s"' % dep
+
+-- 
+2.6.3
+