On 09/12/2013 04:57 PM, James Bigler wrote:
> This seems kind of confusing when the default for all the other VS
> generators is to link in the output of the custom command. Does
> that not seem like a problem?
The goal is to link all .obj files listed in the target exactly once.
According to Tests/ExternalOBJ/CMakeLists.txt this is tested and
works everywhere:
------------------------------------------------------------------------
# Test creation of external objects by custom commands.
set(CUSTOM_OBJECT
${CMAKE_CURRENT_BINARY_DIR}/custom_object${CMAKE_C_OUTPUT_EXTENSION})
add_custom_command(
OUTPUT ${CUSTOM_OBJECT}
COMMAND ${CMAKE_COMMAND} -E copy ${EXTERNAL_OBJECT} ${CUSTOM_OBJECT}
DEPENDS ${EXTERNAL_OBJECT}
)
message("${EXTERNAL_OBJECT}")
# Build an executable using the external object file.
add_executable(ExternalOBJ executable.cxx ${CUSTOM_OBJECT})
# A bug showed up in VS2010 where an object file that was
# part of a custom commad output worked, but ones that were
# not didn't work. So, repeat the executable using the object
# directly and not from the output of the copy.
add_executable(ExternalOBJ2 executable.cxx ${EXTERNAL_OBJECT})
------------------------------------------------------------------------
Special changes were needed to work around VS 10 and 11 behavior of
automatically linking custom command outputs that are objects.
I do not think that happens with VS < 10. In VS 10 we let it link
the custom command output and reference the .obj as <None>. In
VS 11 we set LinkObjects to false in the custom command and refer
to the .obj with <Object>. This is all tested as shown above.
I do not see how MAIN_DEPENDENCY can influence this. It only affects
where the custom command is attached.
-Brad
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