cmake/Modules/Platform/Emscripten.cmake

# This file is a 'toolchain description file' for CMake.
# It teaches CMake about the Emscripten compiler, so that CMake can generate
# makefiles from CMakeLists.txt that invoke emcc.

# To use this toolchain file with CMake, invoke CMake with the following command
# line parameters:
# cmake -DCMAKE_TOOLCHAIN_FILE=<EmscriptenRoot>/cmake/Modules/Platform/Emscripten.cmake
#       -DCMAKE_BUILD_TYPE=<Debug|RelWithDebInfo|Release|MinSizeRel>
#       -G "Unix Makefiles" (Linux and OSX)
#       -G "MinGW Makefiles" (Windows)
#       <path/to/CMakeLists.txt> # Note, pass in here ONLY the path to the file, not the filename 'CMakeLists.txt' itself.

# After that, build the generated Makefile with the command 'make'. On Windows,
# you may download and use 'mingw32-make' instead.

# The following variable describes the target OS we are building to.
set(CMAKE_SYSTEM_NAME Emscripten)
set(CMAKE_SYSTEM_VERSION 1)

set(CMAKE_CROSSCOMPILING TRUE)
set_property(GLOBAL PROPERTY TARGET_SUPPORTS_SHARED_LIBS FALSE)

# Advertise Emscripten as a 32-bit platform (as opposed to
# CMAKE_SYSTEM_PROCESSOR=x86_64 for 64-bit platform), since some projects (e.g.
# OpenCV) use this to detect bitness.
set(CMAKE_SYSTEM_PROCESSOR x86)

# Tell CMake how it should instruct the compiler to generate multiple versions
# of an outputted .so library: e.g. "libfoo.so, libfoo.so.1, libfoo.so.1.4" etc.
# This feature is activated if a shared library project has the property
# SOVERSION defined.
set(CMAKE_SHARED_LIBRARY_SONAME_C_FLAG "-Wl,-soname,")

# In CMake, CMAKE_HOST_WIN32 is set when we are cross-compiling from Win32 to
# Emscripten:
# http://www.cmake.org/cmake/help/v2.8.12/cmake.html#variable:CMAKE_HOST_WIN32
# The variable WIN32 is set only when the target arch that will run the code
# will be WIN32, so unset WIN32 when cross-compiling.
set(WIN32)

# The same logic as above applies for APPLE and CMAKE_HOST_APPLE, so unset
# APPLE.
set(APPLE)

# And for UNIX and CMAKE_HOST_UNIX. However, Emscripten is often able to mimic
# being a Linux/Unix system, in which case a lot of existing CMakeLists.txt
# files can be configured for Emscripten while assuming UNIX build, so this is
# left enabled.
set(UNIX 1)

# Do a no-op access on the CMAKE_TOOLCHAIN_FILE variable so that CMake will not
# issue a warning on it being unused.
if (CMAKE_TOOLCHAIN_FILE)
endif()

# Locate where the Emscripten compiler resides in relative to this toolchain file.
if ("${EMSCRIPTEN_ROOT_PATH}" STREQUAL "")
  get_filename_component(GUESS_EMSCRIPTEN_ROOT_PATH "${CMAKE_CURRENT_LIST_DIR}/../../../" ABSOLUTE)
  if (EXISTS "${GUESS_EMSCRIPTEN_ROOT_PATH}/emranlib")
    set(EMSCRIPTEN_ROOT_PATH "${GUESS_EMSCRIPTEN_ROOT_PATH}")
  endif()
endif()

# If not found by above search, locate using the EMSCRIPTEN environment variable.
if ("${EMSCRIPTEN_ROOT_PATH}" STREQUAL "")
  set(EMSCRIPTEN_ROOT_PATH "$ENV{EMSCRIPTEN}")
endif()

# Abort if not found.
if ("${EMSCRIPTEN_ROOT_PATH}" STREQUAL "")
  message(FATAL_ERROR "Could not locate the Emscripten compiler toolchain directory! Either set the EMSCRIPTEN environment variable, or pass -DEMSCRIPTEN_ROOT_PATH=xxx to CMake to explicitly specify the location of the compiler!")
endif()

# Normalize, convert Windows backslashes to forward slashes or CMake will crash.
get_filename_component(EMSCRIPTEN_ROOT_PATH "${EMSCRIPTEN_ROOT_PATH}" ABSOLUTE)

list(APPEND CMAKE_MODULE_PATH "${EMSCRIPTEN_ROOT_PATH}/cmake/Modules")

if (CMAKE_HOST_WIN32)
  set(EMCC_SUFFIX ".bat")
else()
  set(EMCC_SUFFIX "")
endif()

# Specify the compilers to use for C and C++
if ("${CMAKE_C_COMPILER}" STREQUAL "")
  set(CMAKE_C_COMPILER "${EMSCRIPTEN_ROOT_PATH}/emcc${EMCC_SUFFIX}" CACHE FILEPATH "Emscripten emcc")
endif()
if ("${CMAKE_CXX_COMPILER}" STREQUAL "")
  set(CMAKE_CXX_COMPILER "${EMSCRIPTEN_ROOT_PATH}/em++${EMCC_SUFFIX}" CACHE FILEPATH "Emscripten em++")
endif()

if ("${CMAKE_AR}" STREQUAL "")
  set(CMAKE_AR "${EMSCRIPTEN_ROOT_PATH}/emar${EMCC_SUFFIX}" CACHE FILEPATH "Emscripten ar")
endif()

if ("${CMAKE_RANLIB}" STREQUAL "")
  set(CMAKE_RANLIB "${EMSCRIPTEN_ROOT_PATH}/emranlib${EMCC_SUFFIX}" CACHE FILEPATH "Emscripten ranlib")
endif()

if ("${CMAKE_C_COMPILER_AR}" STREQUAL "")
  set(CMAKE_C_COMPILER_AR "${CMAKE_AR}" CACHE FILEPATH "Emscripten ar")
endif()
if ("${CMAKE_CXX_COMPILER_AR}" STREQUAL "")
  set(CMAKE_CXX_COMPILER_AR "${CMAKE_AR}" CACHE FILEPATH "Emscripten ar")
endif()
if ("${CMAKE_C_COMPILER_RANLIB}" STREQUAL "")
  set(CMAKE_C_COMPILER_RANLIB "${CMAKE_RANLIB}" CACHE FILEPATH "Emscripten ranlib")
endif()
if ("${CMAKE_CXX_COMPILER_RANLIB}" STREQUAL "")
  set(CMAKE_CXX_COMPILER_RANLIB "${CMAKE_RANLIB}" CACHE FILEPATH "Emscripten ranlib")
endif()

# Don't allow CMake to autodetect the compiler, since it does not understand
# Emscripten.
# Pass -DEMSCRIPTEN_FORCE_COMPILERS=OFF to disable (sensible mostly only for
# testing/debugging purposes).
option(EMSCRIPTEN_FORCE_COMPILERS "Force C/C++ compiler" ON)
if (EMSCRIPTEN_FORCE_COMPILERS)

  # Detect version of the 'emcc' executable. Note that for CMake, we tell it the
  # version of the Clang compiler and not the version of Emscripten, because
  # CMake understands Clang better.
  # Toolchain script is interpreted multiple times, so don't rerun the check if
  # already done before.
  if (NOT CMAKE_C_COMPILER_VERSION)
    execute_process(COMMAND "${CMAKE_C_COMPILER}" "-v" RESULT_VARIABLE _cmake_compiler_result ERROR_VARIABLE _cmake_compiler_output OUTPUT_QUIET)
    if (NOT _cmake_compiler_result EQUAL 0)
      message(FATAL_ERROR "Failed to fetch compiler version information with command \"'${CMAKE_C_COMPILER}' -v\"! Process returned with error code ${_cmake_compiler_result}.")
    endif()
    if (NOT "${_cmake_compiler_output}" MATCHES "[Ee]mscripten")
      message(FATAL_ERROR "System LLVM compiler cannot be used to build with Emscripten! Check Emscripten's LLVM toolchain location in .emscripten configuration file, and make sure to point CMAKE_C_COMPILER to where emcc is located. (was pointing to \"${CMAKE_C_COMPILER}\")")
    endif()
    string(REGEX MATCH "clang version ([0-9\\.]+)" _dummy_unused "${_cmake_compiler_output}")
    if (NOT CMAKE_MATCH_1)
      message(FATAL_ERROR "Failed to regex parse Clang compiler version from version string: ${_cmake_compiler_output}")
    endif()

    set(CMAKE_C_COMPILER_VERSION "${CMAKE_MATCH_1}")
    set(CMAKE_CXX_COMPILER_VERSION "${CMAKE_MATCH_1}")
    if (${CMAKE_C_COMPILER_VERSION} VERSION_LESS 3.9.0)
      message(WARNING "CMAKE_C_COMPILER version looks too old. Was ${CMAKE_C_COMPILER_VERSION}, should be at least 3.9.0.")
    endif()
  endif()

  # Capture the Emscripten version to EMSCRIPTEN_VERSION variable.
  if (NOT EMSCRIPTEN_VERSION)
    execute_process(COMMAND "${CMAKE_C_COMPILER}" "-v" RESULT_VARIABLE _cmake_compiler_result ERROR_VARIABLE _cmake_compiler_output OUTPUT_QUIET)
    if (NOT _cmake_compiler_result EQUAL 0)
      message(FATAL_ERROR "Failed to fetch Emscripten version information with command \"'${CMAKE_C_COMPILER}' -v\"! Process returned with error code ${_cmake_compiler_result}.")
    endif()
    string(REGEX MATCH "emcc \\(.*\\) ([0-9\\.]+)" _dummy_unused "${_cmake_compiler_output}")
    if (NOT CMAKE_MATCH_1)
      message(FATAL_ERROR "Failed to regex parse Emscripten compiler version from version string: ${_cmake_compiler_output}")
    endif()

    set(EMSCRIPTEN_VERSION "${CMAKE_MATCH_1}")
  endif()

  set(CMAKE_C_COMPILER_ID_RUN TRUE)
  set(CMAKE_C_COMPILER_FORCED TRUE)
  set(CMAKE_C_COMPILER_WORKS TRUE)
  set(CMAKE_C_COMPILER_ID Clang)
  set(CMAKE_C_COMPILER_FRONTEND_VARIANT GNU)
  set(CMAKE_C_STANDARD_COMPUTED_DEFAULT 11)

  set(CMAKE_CXX_COMPILER_ID_RUN TRUE)
  set(CMAKE_CXX_COMPILER_FORCED TRUE)
  set(CMAKE_CXX_COMPILER_WORKS TRUE)
  set(CMAKE_CXX_COMPILER_ID Clang)
  set(CMAKE_CXX_COMPILER_FRONTEND_VARIANT GNU)
  set(CMAKE_CXX_STANDARD_COMPUTED_DEFAULT 98)

  set(CMAKE_C_PLATFORM_ID "emscripten")
  set(CMAKE_CXX_PLATFORM_ID "emscripten")

  if ("${CMAKE_VERSION}" VERSION_LESS "3.8")
    set(CMAKE_C_COMPILE_FEATURES "c_function_prototypes;c_restrict;c_variadic_macros;c_static_assert")
    set(CMAKE_C90_COMPILE_FEATURES "c_function_prototypes")
    set(CMAKE_C99_COMPILE_FEATURES "c_restrict;c_variadic_macros")
    set(CMAKE_C11_COMPILE_FEATURES "c_static_assert")

    set(CMAKE_CXX_COMPILE_FEATURES "cxx_template_template_parameters;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates")
    set(CMAKE_CXX98_COMPILE_FEATURES "cxx_template_template_parameters")
    set(CMAKE_CXX11_COMPILE_FEATURES "cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates")
    set(CMAKE_CXX14_COMPILE_FEATURES "cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates")
  else() # 3.8+
    set(CMAKE_C90_COMPILE_FEATURES "c_std_90;c_function_prototypes")
    set(CMAKE_C99_COMPILE_FEATURES "c_std_99;c_restrict;c_variadic_macros")
    set(CMAKE_C11_COMPILE_FEATURES "c_std_11;c_static_assert")

    set(CMAKE_CXX98_COMPILE_FEATURES "cxx_std_98;cxx_template_template_parameters")
    set(CMAKE_CXX11_COMPILE_FEATURES "cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates")
    set(CMAKE_CXX14_COMPILE_FEATURES "cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates")
    set(CMAKE_CXX17_COMPILE_FEATURES "cxx_std_17")
    if ("${CMAKE_VERSION}" VERSION_LESS "3.12") # [3.8, 3.12)
      set(CMAKE_C_COMPILE_FEATURES "c_std_90;c_function_prototypes;c_std_99;c_restrict;c_variadic_macros;c_std_11;c_static_assert")
      set(CMAKE_CXX_COMPILE_FEATURES "cxx_std_98;cxx_template_template_parameters;cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates;cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates;cxx_std_17")
    else() # 3.12+
      set(CMAKE_CXX20_COMPILE_FEATURES "cxx_std_20")
      if ("${CMAKE_VERSION}" VERSION_LESS "3.20") # [3.12, 3.20)
        set(CMAKE_C_COMPILE_FEATURES "c_std_90;c_function_prototypes;c_std_99;c_restrict;c_variadic_macros;c_std_11;c_static_assert")
        set(CMAKE_CXX_COMPILE_FEATURES "cxx_std_98;cxx_template_template_parameters;cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates;cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates;cxx_std_17;cxx_std_20")
      else() # 3.20+
        set(CMAKE_CXX23_COMPILE_FEATURES "cxx_std_23")
        set(CMAKE_CXX_COMPILE_FEATURES "cxx_std_98;cxx_template_template_parameters;cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates;cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates;cxx_std_17;cxx_std_20;cxx_std_23")
        if ("${CMAKE_VERSION}" VERSION_LESS "3.21") # 3.20
          set(CMAKE_C_COMPILE_FEATURES "c_std_90;c_function_prototypes;c_std_99;c_restrict;c_variadic_macros;c_std_11;c_static_assert")
        else() # 3.21+
          set(CMAKE_C17_COMPILE_FEATURES "c_std_17")
          set(CMAKE_C23_COMPILE_FEATURES "c_std_23")
          set(CMAKE_C_COMPILE_FEATURES "c_std_90;c_function_prototypes;c_std_99;c_restrict;c_variadic_macros;c_std_11;c_static_assert;c_std_17;c_std_23")
        endif()
      endif()
    endif()
  endif()
endif()

execute_process(COMMAND "${EMSCRIPTEN_ROOT_PATH}/em-config${EMCC_SUFFIX}" "CACHE"
  RESULT_VARIABLE _emcache_result
  OUTPUT_VARIABLE _emcache_output
  OUTPUT_STRIP_TRAILING_WHITESPACE)
if (NOT _emcache_result EQUAL 0)
  message(FATAL_ERROR "Failed to find emscripten cache directory with command \"'${EMSCRIPTEN_ROOT_PATH}/em-config${EMCC_SUFFIX}' CACHE\"! Process returned with error code ${_emcache_result}.")
endif()
set(EMSCRIPTEN_SYSROOT "${_emcache_output}/sysroot")

list(APPEND CMAKE_FIND_ROOT_PATH "${EMSCRIPTEN_SYSROOT}")
list(APPEND CMAKE_SYSTEM_PREFIX_PATH /)

set(CMAKE_LIBRARY_ARCHITECTURE "wasm32-emscripten")

if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
  set(CMAKE_INSTALL_PREFIX "${EMSCRIPTEN_SYSROOT}" CACHE PATH
    "Install path prefix, prepended onto install directories." FORCE)
endif()

# To find programs to execute during CMake run time with find_program(), e.g.
# 'git' or so, we allow looking into system paths.
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

# Since Emscripten is a cross-compiler, we should never look at the
# system-provided directories like /usr/include and so on. Therefore only
# CMAKE_FIND_ROOT_PATH should be used as a find directory. See
# http://www.cmake.org/cmake/help/v3.0/variable/CMAKE_FIND_ROOT_PATH_MODE_INCLUDE.html
if (NOT CMAKE_FIND_ROOT_PATH_MODE_LIBRARY)
  set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
endif()
if (NOT CMAKE_FIND_ROOT_PATH_MODE_INCLUDE)
  set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
endif()
if (NOT CMAKE_FIND_ROOT_PATH_MODE_PACKAGE)
  set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
endif()

option(EMSCRIPTEN_GENERATE_BITCODE_STATIC_LIBRARIES "If set, static library targets generate LLVM bitcode files (.bc). If disabled (default), UNIX ar archives (.a) are generated." OFF)
if (EMSCRIPTEN_GENERATE_BITCODE_STATIC_LIBRARIES)
  message(FATAL_ERROR "EMSCRIPTEN_GENERATE_BITCODE_STATIC_LIBRARIES is not compatible with the llvm backend")
endif()

set(CMAKE_EXECUTABLE_SUFFIX ".js")

set(CMAKE_C_USE_RESPONSE_FILE_FOR_LIBRARIES 1)
set(CMAKE_CXX_USE_RESPONSE_FILE_FOR_LIBRARIES 1)
set(CMAKE_C_USE_RESPONSE_FILE_FOR_OBJECTS 1)
set(CMAKE_CXX_USE_RESPONSE_FILE_FOR_OBJECTS 1)
set(CMAKE_C_USE_RESPONSE_FILE_FOR_INCLUDES 1)
set(CMAKE_CXX_USE_RESPONSE_FILE_FOR_INCLUDES 1)

set(CMAKE_C_RESPONSE_FILE_LINK_FLAG "@")
set(CMAKE_CXX_RESPONSE_FILE_LINK_FLAG "@")

# Set a global EMSCRIPTEN variable that can be used in client CMakeLists.txt to
# detect when building using Emscripten.
set(EMSCRIPTEN 1 CACHE BOOL "If true, we are targeting Emscripten output.")

# Hardwire support for cmake-2.8/Modules/CMakeBackwardsCompatibilityC.cmake
# without having CMake to try complex things to autodetect these:
set(CMAKE_SKIP_COMPATIBILITY_TESTS 1)
set(CMAKE_SIZEOF_CHAR 1)
set(CMAKE_SIZEOF_UNSIGNED_SHORT 2)
set(CMAKE_SIZEOF_SHORT 2)
set(CMAKE_SIZEOF_INT 4)
set(CMAKE_SIZEOF_UNSIGNED_LONG 4)
set(CMAKE_SIZEOF_UNSIGNED_INT 4)
set(CMAKE_SIZEOF_LONG 4)
set(CMAKE_SIZEOF_VOID_P 4)
set(CMAKE_SIZEOF_FLOAT 4)
set(CMAKE_SIZEOF_DOUBLE 8)
set(CMAKE_C_SIZEOF_DATA_PTR 4)
set(CMAKE_CXX_SIZEOF_DATA_PTR 4)
set(CMAKE_HAVE_LIMITS_H 1)
set(CMAKE_HAVE_UNISTD_H 1)
set(CMAKE_HAVE_PTHREAD_H 1)
set(CMAKE_HAVE_SYS_PRCTL_H 1)
set(CMAKE_WORDS_BIGENDIAN 0)
set(CMAKE_DL_LIBS)

function(em_validate_asmjs_after_build target)
  message(WARNING "em_validate_asmjs_after_build no longer exists")
endfunction()

# A global counter to guarantee unique names for js library files.
set(link_js_counter 1)

# Internal function: Do not call from user CMakeLists.txt files. Use one of
# em_link_js_library()/em_link_pre_js()/em_link_post_js() instead.
function(em_add_tracked_link_flag target flagname)

  # User can input list of JS files either as a single list, or as variable
  # arguments to this function, so iterate over varargs, and treat each item in
  # varargs as a list itself, to support both syntax forms.
  foreach(jsFileList ${ARGN})
    foreach(jsfile ${jsFileList})
      # If the user edits the JS file, we want to relink the emscripten
      # application, but unfortunately it is not possible to make a link step
      # depend directly on a source file. Instead, we must make a dummy no-op
      # build target on that source file, and make the project depend on
      # that target.

      # Sanitate the source .js filename to a good symbol name to use as a dummy
      # filename.
      get_filename_component(jsname "${jsfile}" NAME)
      string(REGEX REPLACE "[/:\\\\.\ ]" "_" dummy_js_target ${jsname})
      set(dummy_lib_name ${target}_${link_js_counter}_${dummy_js_target})
      set(dummy_c_name "${CMAKE_BINARY_DIR}/${dummy_js_target}_tracker.c")

      # Create a new static library target that with a single dummy .c file.
      add_library(${dummy_lib_name} STATIC ${dummy_c_name})
      # Make the dummy .c file depend on the .js file we are linking, so that if
      # the .js file is edited, the dummy .c file, and hence the static library
      # will be rebuild (no-op). This causes the main application to be
      # relinked, which is what we want.  This approach was recommended by
      # http://www.cmake.org/pipermail/cmake/2010-May/037206.html
      add_custom_command(OUTPUT ${dummy_c_name} COMMAND ${CMAKE_COMMAND} -E touch ${dummy_c_name} DEPENDS ${jsfile})
      target_link_libraries(${target} ${dummy_lib_name})

      # Link the js-library to the target
      # When a linked library starts with a "-" cmake will just add it to the
      # linker command line as it is.  The advantage of doing it this way is
      # that the js-library will also be automatically linked to targets that
      # depend on this target.
      get_filename_component(js_file_absolute_path "${jsfile}" ABSOLUTE )
      target_link_libraries(${target} "${flagname} \"${js_file_absolute_path}\"")

      math(EXPR link_js_counter "${link_js_counter} + 1")
    endforeach()
  endforeach()
endfunction()

# This function links a (list of ) .js library file(s) to the given CMake project.
# Example: em_link_js_library(my_executable "lib1.js" "lib2.js")
#    will result in emcc passing --js-library lib1.js --js-library lib2.js to
#    the emscripten linker, as well as tracking the modification timestamp
#    between the linked .js files and the main project, so that editing the .js
#    file will cause the target project to be relinked.
function(em_link_js_library target)
  em_add_tracked_link_flag(${target} "--js-library" ${ARGN})
endfunction()

# This function is identical to em_link_js_library(), except the .js files will
# be added with '--pre-js file.js' command line flag, which is generally used to
# add some preamble .js code to a generated output file.
function(em_link_pre_js target)
  em_add_tracked_link_flag(${target} "--pre-js" ${ARGN})
endfunction()

# This function is identical to em_link_js_library(), except the .js files will
# be added with '--post-js file.js' command line flag, which is generally used
# to add some postamble .js code to a generated output file.
function(em_link_post_js target)
  em_add_tracked_link_flag(${target} "--post-js" ${ARGN})
endfunction()

# Experimental support for targeting generation of Visual Studio project files
# (vs-tool) of Emscripten projects for Windows.  To use this, pass the
# combination -G "Visual Studio 10" -DCMAKE_TOOLCHAIN_FILE=Emscripten.cmake
if ("${CMAKE_GENERATOR}" MATCHES "^Visual Studio.*")
  # By default, CMake generates VS project files with a
  # <GenerateManifest>true</GenerateManifest> directive.
  # This causes VS to attempt to invoke rc.exe during the build, which will fail
  # since app manifests are meaningless for Emscripten.  To disable this, add
  # the following linker flag. This flag will not go to emcc, since the Visual
  # Studio CMake generator will swallow it.
  set(EMSCRIPTEN_VS_LINKER_FLAGS "/MANIFEST:NO")
  # CMake is hardcoded to write a ClCompile directive
  # <ObjectFileName>$(IntDir)</ObjectFileName> in all VS project files it
  # generates.  This makes VS pass emcc a -o param that points to a directory
  # instead of a file, which causes emcc autogenerate the output filename.
  # CMake is hardcoded to assume all object files have the suffix .obj, so
  # adjust the emcc-autogenerated default suffix name to match.
  set(EMSCRIPTEN_VS_LINKER_FLAGS "${EMSCRIPTEN_VS_LINKER_FLAGS} --default-obj-ext .obj")
  # Also hint CMake that it should not hardcode <ObjectFileName> generation.
  # Requires a custom CMake build for this to work (ignored on others)
  # See http://www.cmake.org/Bug/view.php?id=14673 and https://github.com/juj/CMake
  set(CMAKE_VS_NO_DEFAULT_OBJECTFILENAME 1)

  # Apply and cache Emscripten Visual Studio IDE-specific linker flags.
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${EMSCRIPTEN_VS_LINKER_FLAGS}" CACHE STRING "")
  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${EMSCRIPTEN_VS_LINKER_FLAGS}" CACHE STRING "")
  set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${EMSCRIPTEN_VS_LINKER_FLAGS}" CACHE STRING "")
endif()

if (NOT DEFINED CMAKE_CROSSCOMPILING_EMULATOR)
  find_program(NODE_JS_EXECUTABLE NAMES nodejs node)
  if(NODE_JS_EXECUTABLE)
    set(CMAKE_CROSSCOMPILING_EMULATOR "${NODE_JS_EXECUTABLE}" CACHE FILEPATH "Path to the emulator for the target system.")
  endif()
endif()

# No-op on CMAKE_CROSSCOMPILING_EMULATOR so older versions of cmake do not
# complain about unused CMake variable.
if (CMAKE_CROSSCOMPILING_EMULATOR)
endif()