https://github.com/rust-lang/rust http://git.dreamy.place/mirrors/rust/atom?h=stable 2025-07-16T21:24:32+00:00 2025-07-16T21:24:32+00:00 Folkert de Vries folkert@folkertdev.nl 2025-07-02T09:12:54+00:00 urn:sha1:9c8ab891876b37aac458a7461d904fe593856745 2025-07-16T19:38:58+00:00 Folkert de Vries folkert@folkertdev.nl 2025-07-02T08:46:15+00:00 urn:sha1:ec0ff720d1a89cb51edd90116c6e70051affa95f and use it for naked functions 2025-07-16T19:38:48+00:00 Folkert de Vries folkert@folkertdev.nl 2025-07-01T18:02:31+00:00 urn:sha1:f100767dce1fcc0287047053cc29659ac5321a6b And more broadly only codegen `InstanceKind::Item` using the naked function codegen code. Other instance kinds should follow the normal path. 2025-06-03T10:04:34+00:00 bjorn3 17426603+bjorn3@users.noreply.github.com 2025-05-30T12:51:15+00:00 urn:sha1:0bd7aa1116c42a96d1c692065ae500a3d2d75484 This deduplicates some code between codegen backends and may in the future allow adding extra metadata that is only known at link time. 2025-06-03T10:04:34+00:00 bjorn3 17426603+bjorn3@users.noreply.github.com 2025-05-30T11:55:06+00:00 urn:sha1:badabab01f15f156dbb6ce39df4a339006fbfae1 And move passing it to the linker to the driver code. 2025-05-25T18:51:16+00:00 bjorn3 17426603+bjorn3@users.noreply.github.com 2025-05-25T18:51:16+00:00 urn:sha1:3816385b09db445ab580043ed45218df8c1198ad 2025-04-14T09:38:04+00:00 bjorn3 17426603+bjorn3@users.noreply.github.com 2024-12-13T10:01:09+00:00 urn:sha1:3066da813b66ffe46bbe5ea62c56bd079b158cf8 2025-04-14T09:38:04+00:00 bjorn3 17426603+bjorn3@users.noreply.github.com 2024-12-12T20:31:20+00:00 urn:sha1:f5c93fa3feb29b1161acf07191ff2684776b9abf 2025-04-11T13:59:33+00:00 bors bors@rust-lang.org 2025-04-11T13:59:33+00:00 urn:sha1:e1b06f773063140263558b858cb6e4c99755a763 Prepend temp files with per-invocation random string to avoid temp filename conflicts https://github.com/rust-lang/rust/issues/139407 uncovered a very subtle unsoundness with incremental codegen, failing compilation sessions (due to assembler errors), and the "prefer hard linking over copying files" strategy we use in the compiler for file management. Specifically, imagine we're building a single file 3 times, all with `-Csave-temps -Cincremental=...`. Let's call the object file we're building for the codegen unit for `main` "`XXX.o`" just for clarity since it's probably some gigantic hash name: ``` #[inline(never)] #[cfg(any(rpass1, rpass3))] fn a() -> i32 { 0 } #[cfg(any(cfail2))] fn a() -> i32 { 1 } fn main() { evil::evil(); assert_eq!(a(), 0); } mod evil { #[cfg(any(rpass1, rpass3))] pub fn evil() { unsafe { std::arch::asm!("/* */"); } } #[cfg(any(cfail2))] pub fn evil() { unsafe { std::arch::asm!("missing"); } } } ``` Session 1 (`rpass1`): * Type-check, borrow-check, etc. * Serialize the dep graph to the incremental working directory `.../s-...-working/`. * Codegen object file to a temp file `XXX.rcgu.o` which is spit out in the cwd. * Hard-link[^1] `XXX.rcgu.o` to the incremental working directory `.../s-...-working/XXX.o`. * Save-temps option means we don't delete `XXX.rgcu.o`. * Link the binary and stuff. * Finalize[^2] the working incremental session by renaming `.../s-...-working` to ` s-...-asjkdhsjakd` (some other finalized incr comp session dir name). Session 2 (`cfail2`): * Load artifacts from the previous *finalized* incremental session, namely the dep graph. * Type-check, borrow-check, etc. since the file has changed, so most dep graph nodes are red. * Serialize the dep graph to the incremental working directory `.../s-...-working/`. * Codegen object file to a temp file `XXX.rcgu.o`. **HERE IS THE PROBLEM**: The hard-link is still set up to point to the inode from `XXX.o` from the first session, so this also modifies the `XXX.o` in the previous finalized session directory. * Codegen emits an error b/c `missing` is not an instruction, so we abort before finalizing the incremental session. Specifically, this means that the *previous* session is the last finalized session. Session 3 (`rpass3`): * Load artifacts from the previous *finalized* incremental session, namely the dep graph. NOTE that this is from session 1. * All the dep graph nodes are green since we are basically replaying session 1. * codegen object file `XXX.o`, which is detected as *reused* from session 1 since dep nodes were green. That means we **reuse** `XXX.o` which had been dirtied from session 2. * Link the binary and stuff. This results in a binary which reuses some of the build artifacts from session 2, but thinks it's from session 1. At this point, I hope it's clear to see that the incremental results from session 1 were dirtied from session 2, but we reuse them as if session 1 was the previous (finalized) incremental session we ran. This is at best really buggy, and at worst **unsound**. This isn't limited to `-C save-temps`, since there are other combinations of flags that may keep around temporary files (hard linked) in the working directory (like `-C debuginfo=1 -C split-debuginfo=unpacked` on darwin, for example). --- This PR implements a fix which is to prepend temp filenames with a random string that is generated per invocation of rustc. This string is not *deterministic*, but temporary files are transient anyways, so I don't believe this is a problem. That means that temp files are now something like... `{crate-name}.{cgu}.{invocation_temp}.rcgu.o`, where `{invocation_temp}` is the new temporary string we generate per invocation of rustc. Fixes https://github.com/rust-lang/rust/issues/139407 [^1]: https://github.com/rust-lang/rust/blob/175dcc7773d65c1b1542c351392080f48c05799f/compiler/rustc_fs_util/src/lib.rs#L60 [^2]: https://github.com/rust-lang/rust/blob/175dcc7773d65c1b1542c351392080f48c05799f/compiler/rustc_incremental/src/persist/fs.rs#L1-L40 2025-04-10T20:05:06+00:00 John Kåre Alsaker john.kare.alsaker@gmail.com 2025-03-26T23:19:52+00:00 urn:sha1:02f10d9bfe41c6c6650f72965d74f27e92dc3986