# 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 `POSITION_INDEPENDENT_CODE` target property for executables will be honored at link time.

`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 `CMP0083` is set to `OLD`, so the command will return an error in this case. See 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

    check_pie_supported()
    set_property(TARGET foo PROPERTY POSITION_INDEPENDENT_CODE TRUE)

    # 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()