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sunfishcode / eyra

Rust programs written entirely in Rust
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Not compatible with `lto = true` or `lto = "thin"` #4

Closed SUPERCILEX closed 1 year ago

SUPERCILEX commented 1 year ago

I get a bunch of linker errors. Let me know if this doesn't repro and I'll add more details.

sunfishcode commented 1 year ago

This repros, and mustang has the same problem. Plain Origin support LTO, but when it's c-scape/c-gull providing lots of C symbols to satisfy std's symbol references, I don't know of a way to tell LTO what's going on.

vi commented 1 year ago

Also does not seem to be compatible with -Zbuild-std, preventing experiments with compact min-sized-rust-style executables.

error[E0464]: multiple candidates for `rlib` dependency `std` found
  |
  = note: candidate #1: /mnt/fluff/rust-targets/udpexchange/x86_64-unknown-linux-gnu/release/deps/libstd-3fb54c1424513f2d.rlib
  = note: candidate #2: /mnt/fluff/rust-targets/udpexchange/x86_64-unknown-linux-gnu/release/deps/libeyra-70919b49f0ae59df.rlib

error: `#[panic_handler]` function required, but not found
sunfishcode commented 1 year ago

@vi Ah, that's a conflict with the new std = { package = "eyra", version = "..." } trick. If you switch Cargo.toml to eyra = "..." and add extern crate eyra; to your code it should work.

Also, on the topic of min-sized-rust, if you don't need std or libc, you can get much smaller by omitting Eyra/c-scape/etc. and using Origin directly. This example shows how to produce quite small executables.

sunfishcode commented 1 year ago

I've now added a mention to the README that LTO is not supported. If anyone has any ideas about how to fix it, please post them!

sunfishcode commented 1 year ago

I've now found the problem blocking LTO; it was c-scape's use of #![no_builtins], which the Rust compiler interprets to mean the library should be excluded from LTO. That's now fixed in Eyra 0.16.1, so LTO is now working!

SUPERCILEX commented 1 year ago

Hell yeah, that's awesome!

vi commented 1 year ago

@vi Ah, that's a conflict with the new std = { package = "eyra", version = "..." } trick. If you switch Cargo.toml to eyra = "..." and add extern crate eyra; to your code it should work.

Shall this be documented in the README?

sunfishcode commented 1 year ago

@vi Sure. I've now added it in #12.