Compress target directory files

[A4-Tacks]

The compilation products of Rust often make the target directory very large

If compressed after compilation, sacrificing some speed can significantly reduce space usage

I hope to have an unstable feature to compress intermediate files and decompress them during use

$ cargo clean
     Removed 0 files
$ cargo test -p ide-assists -- -q
   Compiling proc-macro2 v1.0.101
...
test result: ok. 2644 passed; 0 failed; 3 ignored; 0 measured; 0 filtered out; finished in 16.80s

$ du -sh target
3.0G    target
$ cargo check -p ide-assists
    Checking once_cell v1.21.3
    Checking ide-db v0.0.0 (/rust-analyzer/crates/ide-db)
...
    Checking ide-assists v0.0.0 (/rust-analyzer/crates/ide-assists)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1m 02s
$ du -sh target
3.3G    target
$ find target -type f -exec gzip {} +
$ du -sh target
883M    target

Possible problem

• Compression and decompression have worsened disk IO
• The lifetime of temporarily decompressed files
• May not be aware of compiler requests for intermediate files
• Is it worthwhile to introduce a compression algorithm library into cargo dependencies
• Is the hard link file compressed

@rustbot label +C-feature-request

[epage]

Most likely this would be done on rustc's side so it compresses and decompresses in memory rather than cargo decompressing, having rustc use it, and then deleting the result. This would be compressing each rlib/rmeta or incremental cache entry individually.
This would likely start as a compiler MCP, then an unstable impl in rustc. We'd then need to decide how to expose this in Cargo.

Would be good to evaluate how much benefit this would provide.

Also, would build-dir GC be more beneficial?

[A4-Tacks]

Would be good to evaluate how much benefit this would provide.

If all files is compressed, the space occupation is reduced to 1/4

Also, would build-dir GC be more beneficial?

Mainly to reduce the file size generated by one-time build.
Repeatedly built files can be cleared with cargo clean and rebuild

[epage]

If all files is compressed, the space occupation is reduced to 1/4

Is that to a single compressed file or individually compressing the files?

[epage]

Also, for incremental build cache, my suspicion is that it will be better to disable that (https://doc.rust-lang.org/cargo/reference/config.html#buildincremental) than to compress it but testing would need to be done to check where the line is on that.

[A4-Tacks]

Is that to a single compressed file or individually compressing the files?

The command in the example creates compressed files for each file and deletes old files after compression

Such as gzip a b -> a.gz and b.gz