-C no-integrated-as completely unusable

[MagaTailor]

So many issues, so little time...

• the option produces an .o file whereas .0.o is expected by gcc for linking. After passing --emit asm manually we proceed to find out:
• -C codegen-units produces asm chunks that leads to another failure as just one file is expected
• running through cargo build fails cryptically (deps directory contains .d and .o files but not the rlib) with:

`error: failed to build archive: No such file or directory
Could not compile `typed-arena`

Man page seems to imply (by omission?) it's a transparent change with no caveats.

[MagaTailor]

Adding to the confusion (but explaining the last point) is the fact --emit asm + -C no-integrated-as disables linking of object files. Normally --emit on its own doesn't produce any object files at all, so it seems the combination can't serve as a workaround.

Cross-compilation seems to be affected too.

I managed to induce the following error:

error: could not copy "main.0.s" to "main.s": Permission denied (os error 13)

which means the required file is being generated initially and then renamed.