CMake/Tests/Module/ExternalData/Data5/Data5Check.cmake

file(STRINGS "${Data5}" lines LIMIT_INPUT 1024)
if(NOT "x${lines}" STREQUAL "xInput file already transformed.")
  message(SEND_ERROR "Input file:\n  ${Data5}\ndoes not have expected content, but [[${lines}]]")
endif()
ExternalData: Tolerate files duplicated across multiple targets If multiple ExternalData_Target_Add calls generate the same output file then we need to avoid calling add_custom_command multiple times with that output. This was already done within a single target by setting a variable in the local function scope. This will not be visible in other calls though so we need to use a directory property instead to prevent adding a custom command multiple times for one output in a directory. Normally it is not safe to have multiple custom commands that produce the same output file across multiple independent targets, but since we use atomic replacement of outputs the resulting races should not be a problem. For the convenience of projects, tolerate this instead of diagnosing it. In particular, we previously allowed up to two copies of the custom command in one directory because CMake has a fallback from MAIN_DEPENDENCY to an `<output>.rule` file. While at it, add a note to the documentation that typically only one external data target should be needed for a project. Reported-by: David Manthey <david.manthey@kitware.com> 2016-09-07 22:09:19 +03:00			`file(STRINGS "${Data5}" lines LIMIT_INPUT 1024)`
			`if(NOT "x${lines}" STREQUAL "xInput file already transformed.")`
			`message(SEND_ERROR "Input file:\n ${Data5}\ndoes not have expected content, but [[${lines}]]")`
			`endif()`