Why is CMake ignoring assembly files when building static library?

Question

I've set

set(CAN_USE_ASSEMBLER TRUE)

And it's not helping at all. I'm trying to create a static library with a command like:

add_library(${CMAKE_PROJECT_NAME} STATIC
            ../PropWare ../spi ../spi_as.S ../sd)

where the files without extensions are C++ or C files and the .S file is assembly. But when I run cmake and make, it compiles the C/C++ sources and just ignores the assembly file... no warnings, no errors... just skips right over it.

I'd love any ideas. Full source is available on github (do note: this link is to the cmake branch, all others should be ignored). The first line is in this file and the second line is in this file.

Cowled

Cmake still does this a decade later. You tell it about some asm source, it silently ignores it, until you stumble across this post in confusion and raise a PR adding the line 'project'. Thank you for the question - without it I'd have never found this in their docs. – Plasticine

Answer 1

Note that you can enable ASM in the project() command too. For example:

project(abc
        LANGUAGES C CXX ASM)

Uncurl

This is really the right answer to the question :) Not sure why I never came back and updated it lol – Cowled

Answer 2

Update

See this better answer https://mcmap.net/q/1412861/-why-is-cmake-ignoring-assembly-files-when-building-static-library It's not always possible to know what languages you need enabled at the time that the project() command is invoked... but probably 99.9% of the time it is, so go with this route. If, however, you need to programmatically enable different languages, based on some configure-time logic, then my original answer will work for you.

Original Answer

Finally found it. Instead of

set(CAN_USE_ASSEMBLER TRUE)

I should have used

enable_language(ASM)

Cowled

Answer 3

When using gcc, you can compile .S files with your C compiler (no explicit invocation of asm needed). CMake can be told to do so using

set_property(SOURCE <myfile>.S PROPERTY LANGUAGE C)

for each of your .S files. Then they got compiled in...

Chamfron

I suppose that is an option that would work. But why not just enable assembly via the enable_language(ASM) command? – Cowled

And actually, I do have CMake set to use gcc instead of as for building assembly files. – Cowled

I actually had to use this technique with the language set to ASM_NASM so cmake would include my files. Otherwise, it would just ignore the nasm altogether. – Kerianne