Proc macro generating `include!` or `include_str!` is not expanded correctly if including files from the target folder

[tomasol]

rust-analyzer version: rust-analyzer version: 0.4.1801-standalone
rustc version: rustc 1.75.0 (82e1608df 2023-12-21)

Reproducer: https://github.com/tomasol/ra-proc-macro-including-target

I want to use a proc macro which include!s some generated rust files from the target directory. RA cannot expand the macro properly, but only when the included file resides in the target directory. Needed for fixing this issue in cargo-component

Comment from the issue:

From the output of RA:

File with cargo diagnostic not found in VFS: file not found: /Users/peterhuene/demo/target/bindings/proxy/bindings.rs

It seems, for whatever reason when loaded in a workspace, the VFS isn't populated with the bindings file, which I think means RA will give it an empty file to the proc-macro, ultimately resulting in an empty bindings macro.

When reproducing the issue there was no difference between the project being part of a workspace or not.

[Veetaha]

This definitely worked for me in the past, so this must be a regression after some commit in rust-analuzer. I'm sure, because suddenly big percentage of our code that uses code generation in build.rs with prost became entirely unanalyzed.

[Veykril]

Yes this is a known regression (can't find the concrete issue right now) since #15959

[lnicola]

#16109

[Veykril]

That's the one, I thought I left a comment on the issue but I guess I didn't. Closing as duplicate, I think the issue OP reported is of the same cause.