# Copyright 2021 Nikita Kniazev
#  Copyright 2020 Rene Rivera
#  Copyright (c) 2003      Michael Stevens
#  Copyright (c) 2010-2011 Bryce Lelbach (blelbach@cct.lsu.edu, maintainer)
#
#  Use, modification and distribution is subject to the Boost Software
#  License Version 1.0. (See accompanying file LICENSE.txt or
#  https://www.bfgroup.xyz/b2/LICENSE.txt)

#| tag::doc[]

[[b2.reference.tools.compiler.clang-linux]]
= Clang (GCC frontend)

The `clang-linux` module supports Clang with GCC frontend and has the same
options as link:#b2.reference.tools.compiler.gcc[`gcc`] toolset, with the
addition of `<triple>` option.

The value of that option is passed as the value of `--target=` flag, unless
provided as `<triple>none`. In that case the flag is not passed to the build
tools. If the option is not provided the build system may try to guess the
correct target triple.

|# # end::doc[]

import args ;
import common ;
import toolset ;
import feature ;
import toolset : flags ;
import clang ;
import gcc ;
import common ;
import errors ;
import generators ;
import type ;
import numbers ;
import os ;
import property ;
import rc ;
import set ;

feature.extend-subfeature toolset clang : platform : linux ;

toolset.inherit-generators clang-linux
    <toolset>clang <toolset-clang:platform>linux : gcc
  : gcc.mingw.link gcc.mingw.link.dll gcc.cygwin.link gcc.cygwin.link.dll ;

local all-os = [ feature.values <target-os> ] ;
local all-arch = [ feature.values <architecture> ] ;

toolset.inherit-rules clang-linux : gcc ;
toolset.inherit-flags clang-linux : gcc
  : <inlining>full
    <lto>on/<lto-mode>full
    <lto>on/<lto-mode>fat
    <target-os>$(all-os)/<address-model>32
    <target-os>$(all-os)/<address-model>64
    <target-os>$(all-os)/<architecture>$(all-arch)/<address-model>32
    <target-os>$(all-os)/<architecture>$(all-arch)/<address-model>64
  : INCLUDE-GCH
  ;

.debug-configuration = [ args.get-arg debug-configuration ] ;

rule init ( version ? :  command * : options * ) {
  command = [ common.find-compiler clang-linux : clang++ : $(version) : $(command) ] ;
  local command-string = [ common.make-command-string $(command) ] ;
  if ! $(version) { # ?= operator does not short-circuit
  version ?= [ get-short-version $(command-string) ] ;
  }

  local condition = [ common.check-init-parameters clang-linux
    : version $(version) ] ;

  common.handle-options clang-linux : $(condition) : $(command) : $(options) ;
  clang.init-flags clang-linux : $(condition) : $(version) :
      [ feature.get-values <triple> : $(options) ] ;

  # Support for gcc root as the backend, this is mainly useful for clang/gcc on Windows
  # since on Linux gcc will be the default compiler already located on the PATH.
  # On Windows it is possible to have multiple versions of mingw(-64)/gcc installed
  # in different directories. The <root>option can be given so that the gcc backend
  # can be found at runtime, while the $(command) can be a script that sets the
  # PATH for both the clang directory and the backende gcc directory
  # before calling clang++ when compiling/linking.

  local root = [ feature.get-values <root> : $(options) ] ;

  if $(root)
    {
        # On multilib 64-bit boxes, there are both 32-bit and 64-bit libraries
        # and all must be added to LD_LIBRARY_PATH. The linker will pick the
        # right onces. Note that we do not provide a clean way to build a 32-bit
        # binary using a 64-bit compiler, but user can always pass -m32
        # manually.
        local lib_path = $(root)/bin $(root)/lib $(root)/lib32 $(root)/lib64 ;
        if $(.debug-configuration)
        {
            ECHO "notice:" using gcc libraries with clang"::" $(condition) "::" $(lib_path) ;
        }
        toolset.flags clang-linux.link RUN_PATH $(condition) : $(lib_path) ;
    }

  # - Archive builder.
  local archiver = [ feature.get-values <archiver> : $(options) ] ;
  if ( ! $(archiver) ) && $(root)
    {
    archiver = $(root)/bin/ar ;
    }
  toolset.flags clang-linux.archive .AR $(condition) : $(archiver[1]) ;

    # - Resource compiler.
    local rc = [ common.get-invocation-command-nodefault clang-linux : windres :
        [ feature.get-values <rc> : $(options) ] : $(bin) : search-path ] ;
    local rc-type = [ feature.get-values <rc-type> : $(options) ] ;
    rc-type ?= windres ;
    if ! $(rc)
    {
        # If we can not find an RC compiler we fallback to a null one that
        # creates empty object files. This allows the same Jamfiles to work
        # across the board. The null RC uses assembler to create the empty
        # objects, so configure that.
        rc = [ common.get-invocation-command clang-linux : as : : $(bin) : search-path ]
            ;
        rc-type = null ;
    }
    rc.configure $(rc) : $(condition) : <rc-type>$(rc-type) ;
}

rule get-full-version ( command-string )
{
    return [ common.match-command-output version : "version ([0-9.]+)"
           : "$(command-string) --version" ] ;
}

rule get-short-version ( command-string : single-digit-since ? )
{
    local version = [ get-full-version $(command-string) ] ;
    version = [ SPLIT_BY_CHARACTERS $(version) : . ] ;

    import version ;
    if [ version.version-less $(version) : $(single-digit-since:E=4) ]
    {
        return $(version[1-2]:J=.) ;
    }

    return $(version[1]) ;
}

local rule compile-link-flags ( * )
{
    toolset.flags clang-linux.compile OPTIONS $(1) : $(2) ;
    toolset.flags clang-linux.link OPTIONS $(1) : $(2) ;
}

###############################################################################
# Flags

toolset.flags clang-linux.compile INCLUDE-PCH : -include-pch ;

# note: clang silently ignores some of these inlining options
# For clang, 'on' and 'full' are identical.
toolset.flags clang-linux.compile OPTIONS <inlining>full : -Wno-inline ;

compile-link-flags <address-model>32 : -m32 ;
compile-link-flags <address-model>64 : -m64 ;

# LTO
toolset.flags clang-linux.compile OPTIONS <lto>on/<lto-mode>thin : -flto=thin ;
toolset.flags clang-linux.link OPTIONS <lto>on/<lto-mode>thin : -flto=thin ;

toolset.flags clang-linux.compile OPTIONS <lto>on/<lto-mode>full : -flto=full ;
toolset.flags clang-linux.link OPTIONS <lto>on/<lto-mode>full : -flto=full ;

# stdlib selection
toolset.flags clang-linux.compile.c++ OPTIONS <stdlib>gnu <stdlib>gnu11 <stdlib>libstdc++ : -stdlib=libstdc++ ;
toolset.flags clang-linux.link OPTIONS <stdlib>gnu <stdlib>gnu11 <stdlib>libstdc++ : -stdlib=libstdc++ ;

toolset.flags clang-linux.compile.c++ OPTIONS <stdlib>libc++ : -stdlib=libc++ ;
toolset.flags clang-linux.link OPTIONS <stdlib>libc++ : -stdlib=libc++ ;
