Don't necessarily enforce file extension of .bc, .ll, .s files

[kinke]

Use the output filename (-of or inferred) directly if a single file is emitted per compiled module.

Fixes issue #1843.

[thewilsonator]

IIUC you mean if more than one of -output-{bc,ll,s,o} is specified them still force the extensions, but not for object files (I need different extensions for object files, don't change this)?
And you mean llvm modules, not d modules,yes?
I'm just trying to think how this will interoperate with my dcompute PRs which will have multiple files being outputted, but they will each come from one distinct llvm module.

Anyway if this is to be merged please also merge ldc-developers:master into ldc-developers:dcompute, so that I can test properly.

[thewilsonator]

This will have merge conflicts with #1840

[kinke]

IIUC you mean if more than one of -output-{bc,ll,s,o} is specified them still force the extensions, but not for object files

Exactly, as the diff clearly shows. Object filenames aren't touched, only bc/ll/s. The point being that we get a single object filename (-of or inferred) per produced object, so the default .o/.obj extension normally needs to be replaced for bc/ll/s files. But in case only one kind is produced, we may use the filename directly (if inferred, it already has the right .bc/.ll/.s extension), and this is how the explicit -of can make it through the front-end to the name of the single bc/ll/s file being produced.

And you mean llvm modules, not d modules,yes?

Yep, i.e., a single or multiple (-singleobj) D modules compiled to an 'object' (incl. bc/ll/s).

In essence, this only affects the output filename of a bc/ll/s file if (1) a single -output-{bc,ll,s} flag is used, (2) -output-o isn't used (also preventing the generation of a static lib/executable/shared lib, as -of would apply to that name then) and (3) -of is specified (implying -singleobj), i.e., a single 'object' file with that name is to be produced. E.g., ldc2 -output-ll -of=bla.IR foo.d [bar.d].

[JohanEngelen]

Is there a way we can test this?
Perhaps %ldc ... -output-s -of=%T/test.A && %remove %T/test.A, relying on failure of %remove when the file is not found?

[kinke]

I added a tiny test, but opted for a textual IR file and an existence check via FileCheck.

[kinke]

@JohanEngelen: I guess this fixes a potential issue wrt. -flto=<something> -output-o -output-bc, as I guess the regular object filename is required for the bitcode file in the LTO case.

[JohanEngelen]

Hm, I think with -output-o -output-bc -flto=.. this codeblock should be executed twice. Two files should be output, right? One for -output-o (bitcode because LTO), and one for output-bc.

[kinke]

I think it's okay not outputting the redundant .bc copy in the LTO case for this exotic cmdline-flags constellation.

[JohanEngelen]

Cool.