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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
CheckPIESupported
-----------------
.. versionadded:: 3.14
Check whether the linker supports Position Independent Code (PIE) or No
Position Independent Code (NO_PIE) for executables.
Use this to ensure that the :prop_tgt:`POSITION_INDEPENDENT_CODE` target
property for executables will be honored at link time.
.. command:: check_pie_supported
::
check_pie_supported([OUTPUT_VARIABLE <output>]
[LANGUAGES <lang>...])
Options are:
``OUTPUT_VARIABLE <output>``
Set ``<output>`` variable with details about any error.
``LANGUAGES <lang>...``
Check the linkers used for each of the specified languages.
Supported languages are ``C``, ``CXX``, and ``Fortran``.
It makes no sense to use this module when :policy:`CMP0083` is set to ``OLD``,
so the command will return an error in this case. See policy :policy:`CMP0083`
for details.
Variables
^^^^^^^^^
For each language checked, two boolean cache variables are defined.
``CMAKE_<lang>_LINK_PIE_SUPPORTED``
Set to ``YES`` if ``PIE`` is supported by the linker and ``NO`` otherwise.
``CMAKE_<lang>_LINK_NO_PIE_SUPPORTED``
Set to ``YES`` if ``NO_PIE`` is supported by the linker and ``NO`` otherwise.
Examples
^^^^^^^^
.. code-block:: cmake
check_pie_supported()
set_property(TARGET foo PROPERTY POSITION_INDEPENDENT_CODE TRUE)
.. code-block:: cmake
# Retrieve any error message.
check_pie_supported(OUTPUT_VARIABLE output LANGUAGES C)
set_property(TARGET foo PROPERTY POSITION_INDEPENDENT_CODE TRUE)
if(NOT CMAKE_C_LINK_PIE_SUPPORTED)
message(WARNING "PIE is not supported at link time: ${output}.\n"
"PIE link options will not be passed to linker.")
endif()
#]=======================================================================]
include (Internal/CMakeTryCompilerOrLinkerFlag)
function (check_pie_supported)
cmake_policy(GET CMP0083 cmp0083)
if (NOT cmp0083)
message(FATAL_ERROR "check_pie_supported: Policy CMP0083 is not set")
endif()
if(cmp0083 STREQUAL "OLD")
message(FATAL_ERROR "check_pie_supported: Policy CMP0083 set to OLD")
endif()
set(optional)
set(one OUTPUT_VARIABLE)
set(multiple LANGUAGES)
cmake_parse_arguments(CHECK_PIE "${optional}" "${one}" "${multiple}" "${ARGN}")
if(CHECK_PIE_UNPARSED_ARGUMENTS)
message(FATAL_ERROR "check_pie_supported: Unparsed arguments: ${CHECK_PIE_UNPARSED_ARGUMENTS}")
endif()
if (CHECK_PIE_LANGUAGES)
set (unsupported_languages "${CHECK_PIE_LANGUAGES}")
list (REMOVE_ITEM unsupported_languages "C" "CXX" "Fortran")
if(unsupported_languages)
message(FATAL_ERROR "check_pie_supported: language(s) '${unsupported_languages}' not supported")
endif()
else()
# User did not set any languages, use defaults
get_property (enabled_languages GLOBAL PROPERTY ENABLED_LANGUAGES)
if (NOT enabled_languages)
return()
endif()
list (FILTER enabled_languages INCLUDE REGEX "^(C|CXX|Fortran)$")
if (NOT enabled_languages)
return()
endif()
set (CHECK_PIE_LANGUAGES ${enabled_languages})
endif()
set (outputs)
foreach(lang IN LISTS CHECK_PIE_LANGUAGES)
if(_CMAKE_${lang}_PIE_MAY_BE_SUPPORTED_BY_LINKER)
cmake_try_compiler_or_linker_flag(${lang}
"${CMAKE_${lang}_LINK_OPTIONS_PIE}"
CMAKE_${lang}_LINK_PIE_SUPPORTED
OUTPUT_VARIABLE output)
if (NOT CMAKE_${lang}_LINK_PIE_SUPPORTED)
string (APPEND outputs "PIE (${lang}): ${output}\n")
endif()
cmake_try_compiler_or_linker_flag(${lang}
"${CMAKE_${lang}_LINK_OPTIONS_NO_PIE}"
CMAKE_${lang}_LINK_NO_PIE_SUPPORTED
OUTPUT_VARIABLE output)
if (NOT CMAKE_${lang}_LINK_NO_PIE_SUPPORTED)
string (APPEND outputs "NO_PIE (${lang}): ${output}\n")
endif()
else()
# no support at link time. Set cache variables to NO
set(CMAKE_${lang}_LINK_PIE_SUPPORTED NO CACHE INTERNAL "PIE (${lang})")
set(CMAKE_${lang}_LINK_NO_PIE_SUPPORTED NO CACHE INTERNAL "NO_PIE (${lang})")
string (APPEND outputs "PIE and NO_PIE are not supported by linker for ${lang}")
endif()
endforeach()
if (CHECK_PIE_OUTPUT_VARIABLE)
set (${CHECK_PIE_OUTPUT_VARIABLE} "${outputs}" PARENT_SCOPE)
endif()
endfunction()
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