[cmake-developers] Generating buildsystem metadata from CMake

[Stephen Kelly]

Tobias Hunger wrote:
> 
> How about include_directories, compile_definitions and compile_flags?
> 
> So something along the lines of:
> 
> "include_directories" : ["/foo", "/opt"]
> "compile_definitions" : ["DEF=\"Foo\"", "OTHER_DEF=1"]
> "compile_flags": [ "-c" ]

Quoting Anton:

Anton Makeev wrote:
> The other thing that seems troubling to me is that since file, target,
> language compiler options are split into different parts of metadata, the
> IDE need to know exactly how to assemble them back into the compiler’s
> command line (e.g. what flags go first file’s or language’s), duplicating
> CMake's logic that may be different from version to version and from
> compiler to compiler. The exact command line is needed to get the actual
> and precise defines, include search paths etc. from the compiler.

Maybe he can chime in with more. I don't really know why the entire command 
line is needed instead of separate "include_directories" and 
"compile_definitions" arrays as you and I suggested. Perhaps because that 
would not include -fPIC for example, which causes __PIC__ to be defined.

Another item of note is that CMake does not know the compile flags as a 
sequential container of individual flags currently, but it knows them as a 
string (that's also why it appears as a string in my generated json 
currently).

> Parsing things is always error prone. Is that -D for definitions or /D?

As we can define the format, we could always generate -D and define that as 
the answer to your question.

Anyway, let's see if Anton can explain more about the need for the exact 
command line and whether my suggestion of duplicating the 
"include_directories" and "compile_definitions" is fine.

> The compiler flags are definitely needed though. They are used to e.g.
> decide which dialect of a language are used.
> 
> This would keep parsing simple and will also provide all the
> information we need.
> 
> "linker_flags" might also be interesting...

Yes, something like this is also in the goals for this design.

Thanks,

Steve.