package/clang: new package

This patch provides Clang tools and libraries for the host and
libclang for the target.

host-clang is needed to build libclc, which is provided in a follow-up
patch.

We need libclang for the target because it is used by most of OpenCL
implementations.

A later patch in this series will enable Clover, the OpenCL
implementation part of Mesa3D, which requires libclang.

clang-tblgen must be copied to HOST_DIR as it is not installed by
default but is needed for cross-compilation:
http://lists.llvm.org/pipermail/cfe-dev/2015-June/043318.html

Signed-off-by: Valentin Korenblit <valentin.korenblit@smile.fr>
[Thomas:
 - Add Config.in comment about BR2_TOOLCHAIN_HAS_GCC_BUG_64735
 - Minor reformatting/rewrapping of comments in .mk file]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

DEVELOPERS

@@ -1912,6 +1912,7 @@ F:	package/dropwatch/
 F:	package/tstools/
 
 N:	Valentin Korenblit <valentin.korenblit@smile.fr>
+F:	package/clang/
 F:	package/llvm/
 
 N:	Vanya Sergeev <vsergeev@gmail.com>

package/Config.in

@@ -1485,6 +1485,7 @@ menu "Other"
 	source "package/bctoolbox/Config.in"
 	source "package/bdwgc/Config.in"
 	source "package/boost/Config.in"
+	source "package/clang/Config.in"
 	source "package/clapack/Config.in"
 	source "package/classpath/Config.in"
 	source "package/cppcms/Config.in"

package/clang/Config.in

@@ -0,0 +1,26 @@
+config BR2_PACKAGE_CLANG
+	bool "clang"
+	depends on BR2_PACKAGE_LLVM_ARCH_SUPPORTS
+	depends on BR2_HOST_GCC_AT_LEAST_4_8
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
+	depends on BR2_TOOLCHAIN_HAS_THREADS
+	depends on BR2_INSTALL_LIBSTDCPP
+	depends on !BR2_TOOLCHAIN_HAS_GCC_BUG_64735 # std::shared_future
+	depends on !BR2_STATIC_LIBS
+	depends on BR2_USE_WCHAR # std::wstring
+	select BR2_PACKAGE_LLVM
+	help
+	  Clang is a C/C++, Objective C/C++ and OpenCL C front-end
+	  for the LLVM compiler.
+
+	  http://clang.llvm.org
+
+comment "clang needs a toolchain w/ wchar, threads, C++, gcc >= 4.8, host gcc >= 4.8, dynamic library"
+	depends on BR2_PACKAGE_LLVM_ARCH_SUPPORTS
+	depends on !BR2_TOOLCHAIN_HAS_THREADS || !BR2_INSTALL_LIBSTDCPP || \
+		!BR2_HOST_GCC_AT_LEAST_4_8 || !BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 \
+		|| BR2_STATIC_LIBS || !BR2_USE_WCHAR
+
+comment "clang needs a toolchain not affected by GCC bug 64735"
+	depends on BR2_PACKAGE_LLVM_ARCH_SUPPORTS
+	depends on BR2_TOOLCHAIN_HAS_GCC_BUG_64735

package/clang/clang.hash

@@ -0,0 +1,3 @@
+# locally calculated
+sha256 135f6c9b0cd2da1aff2250e065946258eb699777888df39ca5a5b4fe5e23d0ff cfe-5.0.1.src.tar.xz
+sha256 de4c79665f0f5688b0ace17cba6f8e0343925bb95e0949d66d47bbd4527310d6 LICENSE.TXT

package/clang/clang.mk

@@ -0,0 +1,74 @@
+################################################################################
+#
+# clang
+#
+################################################################################
+
+CLANG_VERSION = 5.0.1
+CLANG_SITE = http://llvm.org/releases/$(CLANG_VERSION)
+CLANG_SOURCE = cfe-$(CLANG_VERSION).src.tar.xz
+CLANG_LICENSE = NCSA
+CLANG_LICENSE_FILES = LICENSE.TXT
+CLANG_SUPPORTS_IN_SOURCE_BUILD = NO
+CLANG_INSTALL_STAGING = YES
+
+HOST_CLANG_DEPENDENCIES = host-llvm host-libxml2
+CLANG_DEPENDENCIES = llvm host-clang
+
+# This option is needed, otherwise multiple shared libs
+# (libclangAST.so, libclangBasic.so, libclangFrontend.so, etc.) will
+# be generated. As a final shared lib containing all these components
+# (libclang.so) is also generated, this resulted in the following
+# error when trying to use tools that use libclang:
+# $ CommandLine Error: Option 'track-memory' registered more than once!
+# $ LLVM ERROR: inconsistency in registered CommandLine options
+# By setting BUILD_SHARED_LIBS to OFF, we generate multiple static
+# libraries (the same way as host's clang build) and finally
+# libclang.so to be installed on the target.
+CLANG_CONF_OPTS += -DBUILD_SHARED_LIBS=OFF
+
+# Default is Debug build, which requires considerably more disk space
+# and build time. Release build is selected for host and target
+# because the linker can run out of memory in Debug mode.
+HOST_CLANG_CONF_OPTS += -DCMAKE_BUILD_TYPE=Release
+CLANG_CONF_OPTS += -DCMAKE_BUILD_TYPE=Release
+
+CLANG_CONF_OPTS += -DCMAKE_CROSSCOMPILING=1
+
+# We need to build tools because libclang is a tool
+HOST_CLANG_CONF_OPTS += -DCLANG_BUILD_TOOLS=ON
+CLANG_CONF_OPTS += -DCLANG_BUILD_TOOLS=ON
+
+HOST_CLANG_CONF_OPTS += \
+	-DCLANG_BUILD_EXAMPLES=OFF \
+	-DCLANG_INCLUDE_DOCS=OFF \
+	-DCLANG_INCLUDE_TESTS=OFF
+
+CLANG_CONF_OPTS += \
+	-DCLANG_BUILD_EXAMPLES=OFF \
+	-DCLANG_INCLUDE_DOCS=OFF \
+	-DCLANG_INCLUDE_TESTS=OFF
+
+HOST_CLANG_CONF_OPTS += -DLLVM_CONFIG:FILEPATH=$(HOST_DIR)/bin/llvm-config
+CLANG_CONF_OPTS += -DLLVM_CONFIG:FILEPATH=$(STAGING_DIR)/usr/bin/llvm-config \
+	-DCLANG_TABLEGEN:FILEPATH=$(HOST_DIR)/usr/bin/clang-tblgen \
+	-DLLVM_TABLEGEN_EXE:FILEPATH=$(HOST_DIR)/usr/bin/llvm-tblgen
+
+# Clang can't be used as compiler on the target since there are no
+# development files (headers) and other build tools. So remove clang
+# binaries from target.
+define CLANG_DELETE_BINARIES_FROM_TARGET
+	rm -f $(TARGET_DIR)/usr/bin/clang*
+endef
+CLANG_POST_INSTALL_TARGET_HOOKS += CLANG_DELETE_BINARIES_FROM_TARGET
+
+# clang-tblgen is not installed by default, however it is necessary
+# for cross-compiling clang
+define HOST_CLANG_INSTALL_CLANG_TBLGEN
+	$(INSTALL) -D -m 0755 $(HOST_CLANG_BUILDDIR)/bin/clang-tblgen \
+		$(HOST_DIR)/usr/bin/clang-tblgen
+endef
+HOST_CLANG_POST_INSTALL_HOOKS = HOST_CLANG_INSTALL_CLANG_TBLGEN
+
+$(eval $(cmake-package))
+$(eval $(host-cmake-package))