Alan W. Irwin wrote:
> The following CMake logic fragment illustrates the issue:
>
> add_executable(plhershey-unicode-gen ${plhershey-unicode-gen_SRCS})
>
> add_custom_command(
> OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/plhershey-unicode.h
> COMMAND plhershey-unicode-gen
> ${CMAKE_SOURCE_DIR}/fonts/plhershey-unicode.csv
> ${CMAKE_CURRENT_BINARY_DIR}/plhershey-unicode.h
> DEPENDS
> plhershey-unicode-gen
> ${CMAKE_SOURCE_DIR}/fonts/plhershey-unicode.csv
> )
>
> add_custom_target(
> plhershey-unicode.h_built
> DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/plhershey-unicode.h
> )
>
> If I touch the source for plhershey-unicode-gen and run "make
> plhershey-unicode.h_built", then plhershey-unicode-gen gets rebuilt but the
> custom command is not re-run. Apparently, a target is ignored as a DEPENDS
> if it is also used as a COMMAND. That doesn't seem correct to me.
>
> The workaround is to replace the COMMAND by the location of the
> plhershey-unicode-gen executable. In that case, if I touch the source for
> plhershey-unicode-gen and run "make plhershey-unicode.h_built", then
> plhershey-unicode-gen gets rebuilt, and so does plhershey-unicode.h.
>
> According to the documentation you should be able to use targets for
> COMMANDs, and targets for DEPENDS. Furthermore according to the
> documention, in the former case the file depends are not taken care of, but
> in the latter case they should be (for add_executable or add_library
> targets). I believe it is a bug in the implemention that the latter
> case is
> ignored when the target is also used for the COMMAND.
CMake has a test for this (BuildDepends), and it has this code:
add_custom_command(
OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/regen.h
COMMAND generator ${CMAKE_CURRENT_BINARY_DIR}/regen.h regen
DEPENDS generator # adds file-level dependency to re-run rule
)
The test passes, and if I comment out the DEPENDS line it fails.
What version of CMake are you using? What generator? What platform?
-Brad
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