Add explanatory message to linker command output on link failure

[RX14]

When the linker fails to find shared object files, print an explanatory message after the original output to aid users in debugging their problem.

See #5291.

[asterite]

I like this. I always thought about doing this but was lazy to.

Maybe we could show the relevant messages at the end of the compilation? I think having those new messages intermixed with everything else makes them easier to miss. Alternatively, we could show those messages in yellow, similar to did you mean? messages.

Yet another possibility is even checking what lib declarations are attached to the -lflag flags, and saying "development libraries for LibYAML` or something that (but maybe this doesn't help much).

[RX14]

@asterite yeah I think highlighting in yellow is a good idea. I'll do that.

[RX14]

Added colour highlighting.

[asterite]

Just tried this in mac: it doesn't work. The error I get is:

ld: library not found for -lfoo

so we probably need a different path for mac.

[RX14]

On that note: a test file

@[Link("nonexistant")]
lib Nope
  fun bar
end

Nope.bar

Running this should produce the error.

[RX14]

@asterite The difference is lld vs gnu ld. gold and bfd use "cannot find -lfoo" the same as GNU ld.

I'll just replace both strings on all platforms.

[RX14]

Fixed when using lld.

[asterite]

Still doesn't work for me. None of the gsub calls catch the error I get:

ld: library not found for -lfoo

[RX14]

@asterite oh, looks like the strings are different on my lld to yours...

[asterite]

Mmm... I'm using ld on mac, not sure it's GNU-related, gold, or anything like that.

[RX14]

@asterite updated!

[asterite]

Thanks, it works now! 🎉