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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
+-----------------
+
+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: ${output}.\n"
+ "PIE link options will not be passed to linker.")
+ endif()
+
+#]=======================================================================]
+
+
+include (Internal/CMakeCheckCompilerFlag)
+
+function (check_pie_supported)
+ cmake_policy(GET CMP0083 cmp0083)
+
+ if (NOT cmp0083)
+ message(FATAL_ERROR "check_pie_supported: Policy CMP0083 is not set")
+ endif()
+
+ if(cmp0083 STREQUAL "OLD")
+ message(FATAL_ERROR "check_pie_supported: Policy CMP0083 set to OLD")
+ endif()
+
+ set(optional)
+ set(one OUTPUT_VARIABLE)
+ set(multiple LANGUAGES)
+
+ cmake_parse_arguments(CHECK_PIE "${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_check_compiler_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}): ${output}\n")
+ endif()
+
+ cmake_check_compiler_flag(${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()