[CMake] Unneeded escaping: how to stop it?

[Brad King]

Steven Van Ingelgem wrote:
> The problem in fact is in cmcommand.h @ line 67: "InvokeInitialPass"
> 
> Here there is done the pass through "ExpandArguments", which removes
> the knowledge of the quoted/unquoted nature of the arguments... Before
> is known if it's VERBATIM or not...
> 
> I think this is a deep problem, and rather difficult to solve.
> 
> Do you want me to submit it to the bug tracker?

No.  This is not a CMake bug.  The VERBATIM option is a feature of 
add_custom_command, not of the CMake language.  In fact the only reason 
it is there is to implement the correct behavior of add_custom_command 
without breaking compatibility with older code that tried to add all the 
shell escapes directly.  The option does not indicate that the text 
following it will be placed in the build system verbatim.

It's the CMakeLists.txt file writer's job to get the text that should 
appear in the command through the CMake language and given to 
add_custom_command as arguments.  Each argument to the COMMAND option of 
add_custom_command becomes one argument in the generated build system. 
The VERBATIM option just tells it to implement proper escaping for the 
arguments.

Placing shell code directly in a custom command is not a good idea.  It 
will not work for non-Unix makes.  Even if you want to run a unix shell 
script and don't care about other platforms, you should just run the 
shell with the script as part of the custom command instead of depending 
on the implementation detail that make tools run the commands in a shell.

add_custom_command(
   OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/test.txt
   COMMAND /bin/sh ${CMAKE_CURRENT_SOURCE_DIR}/myscript.sh 
${CMAKE_CURRENT_BINARY_DIR}/test.txt
   )
add_custom_target(
   DriveTest ALL
   DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/test.txt
   )

Then put your code in myscript.sh and refer to "$1" for the output file.

-Brad