[CMake] Does the echo command use the system shell?

[Óscar Fuentes]

Michael Wild <themiwi at gmail.com> writes:

> The problem is, CMake has to go through the system shell. Of course,
> CMake could write the command to a file and then invoke a custom
> interpreter from the system shell, but that would probably be very
> inefficient and would require CMake to implement a full shell
> language.

Another option for cmake is to appropriately quote the string so the
system shell does not alter it. Consider

cmake -E echo "#hello"

cmake would put on the Unix makefile something like

cmake -E echo "\#hello"

and on windows MinGW makefile or VS project it would be

cmake -E echo "#hello"

[snip]

> But we still don't know what your general goal is, WHY you need this
> and why e.g. a simple add_definitions() isn't enough (because so far I
> haven't seen anything that requires you to do this stuff dynamically
> at build-time).

This is not the issue. As mentioned on the previous posts, the question
is how much confidence can I have on the platform independence of the -E
commands. The stated goal is to provide platform isolation. We have seen
that this is not completely true.

But if you insist on knowing the context that raised the issue, it
consisted on the requirement of creating a header file containing a
#define with a quoted list of the names of the source files of the
project. configure_file is a solution, but requires having a
pre-existing .in file and I'll like to avoid polluting the source tree
as much as possible. Then add_custom_command seemed a good fit.
Maintenance-wise, it is simpler than configure_file+file.in or
file(WRITE+configure_file and has the added feature of regenerating the
file if it is deleted by mistake.

So here we are.