Add cargo:rustc-link-arg to pass custom linker arguments #6298

lu-zero · 2018-11-09T21:43:49Z

It is useful to produce correct cdylibs on platforms such as Linux and
MacOS.

Groundwork to address #5045 in the future.

alexcrichton · 2018-11-12T15:46:27Z

Thanks for the PR! I'm personally a bit wary to add this though without more protections and/or safeguards. In addition to the soft feature freeze this is a feature we have intentionally not added historically as it can be tricky to do so.

I would personally prefer at least that this takes the route of a more formal feature proposal such as a discussion on internals or a mini-rfc.

lu-zero · 2018-11-12T17:10:07Z

If you have time to guide me on that I'm more than willing to :)

Keep in mind that we have an env key that already let you pass those values, but it does to all the rustc invocations and my actual need is to pass the right linker flags so the soname is set for cdylibs.

We can restrict it to just cdylibs or just make cargo come up with the os-specific incantations at least for the tier1 platforms.

alexcrichton · 2018-11-18T07:55:18Z

For posterity, there's more info on this in https://internals.rust-lang.org/t/pre-rfc-complete-cdylib-support-in-cargo/8843/12

bors · 2018-11-18T08:44:36Z

☔ The latest upstream changes (presumably #6328) made this pull request unmergeable. Please resolve the merge conflicts.

lu-zero · 2018-11-18T10:12:03Z

Here an attempt on restricting, not sure where is the best place to error out if somebody mixes cdylib and dylib.

alexcrichton · 2018-11-21T18:28:39Z

Thanks, although I think there's still a number of open questions here:

Currently this is ignoring link-args on non-cdylib crates (silently), is that the behavior that we want?
What happens if there's mutliple crate types, where do the link args go?
Do we want to read this from .cargo/config? Is there a use case for that?

lu-zero · 2018-11-21T18:49:33Z

Thanks, although I think there's still a number of open questions here:
* Currently this is ignoring link-args on non-cdylib crates (silently), is that the behavior that we want?

The use-case I'm focusing is to pair it with a build.rs providing the link lines. So non-cdylib or non-cdylib+staticlib could be an hard error.

* What happens if there's mutliple crate types, where do the link args go?

from what I'm seeing for the cdylib+staticlib case it works as expected even if rustc is called only once.

* Do we want to read this from `.cargo/config`? Is there a use case for that?

For my usecase there isn't.

On the other hand this can be reused by cargo-deb/rpm/ebuild later for their distro-specific purposes (e.g. custom rpaths), but I'd rather not conflate it.

bors · 2018-11-28T05:19:25Z

☔ The latest upstream changes (presumably #6352) made this pull request unmergeable. Please resolve the merge conflicts.

alexcrichton · 2019-03-08T15:35:07Z

Sorry for having this fall by the wayside, this fell off my radar by accident!

@lu-zero would you still be willing to help drive this PR forward?

Following up with some of my questions above, for cases where the link-args aren't used I don't really know what the best answer is. I think it's fine for now though to swallow them and document that we swallow them, and if it becomes an issue we can issue warnings or something like that later.

For the many crate types, we probably want to either:

Pass the link args to all linked artifacts (except maybe tests)
Rename these to rustc-cdylib-link-arg or somethig like that (to make it clear it only applies to cdylib and leave space to customize them in the future)

For .cargo/config what I meant was that you can specify build script outputs in .cargo/config in native library overrides. I think I missed though where this was already handled.

So all in all, the remaining items needed for this I think are:

Documentation for this new feature
Decision on where to route link args for multiple artifact (aka ignore for all but cdylib or rename to say it's only going to cdylib)

I think I'd personally lean towards renaming this rustc-cdylib-link-arg which leaves us room to add more flavorful configuration for other output artifacts in the future. For example we could have a mode where you specify binary link args but only for one binary and not others.

lu-zero · 2019-03-08T15:47:03Z

@lu-zero would you still be willing to help drive this PR forward?

Sure. I'll update the PR during the weekend :)

alexcrichton · 2019-03-08T15:54:23Z

Ok sounds great, and sorry again for the delay!

It is useful to produce correct cdylibs on platforms such as Linux and MacOS.

lu-zero · 2019-03-08T19:49:47Z

I renamed the key, regarding the documentation to update, where I should I find it?

src/cargo/core/compiler/mod.rs

alexcrichton · 2019-03-11T18:31:08Z

@rfcbot fcp merge

Ok! This looks great to me, so I'd like to propose that this be merged, but would also like to get a signoff from the rest of the team.

rfcbot · 2019-03-11T18:31:11Z

Team member @alexcrichton has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

joshtriplett · 2019-03-11T22:40:00Z

I personally would like this (and would use this) for binaries, not just cdylib, but cdylib certainly helps.

lu-zero · 2019-03-19T07:50:45Z

I'd relax the constraint later and land it sooner if possible :)

rfcbot · 2019-03-27T10:43:12Z

🔔 This is now entering its final comment period, as per the review above. 🔔

alexcrichton · 2019-03-27T12:03:53Z

@bors: r+

bors · 2019-03-27T12:03:54Z

📌 Commit f608ed6 has been approved by alexcrichton

bors · 2019-03-27T12:04:04Z

⌛ Testing commit f608ed6 with merge 5f3f281...

Add cargo:rustc-link-arg to pass custom linker arguments It is useful to produce correct `cdylibs` on platforms such as Linux and MacOS. Groundwork to address #5045 in the future.

bors · 2019-03-27T12:26:42Z

☀️ Test successful - checks-travis, status-appveyor
Approved by: alexcrichton
Pushing 5f3f281 to master...

Update cargo Update cargo 22 commits in 0e35bd8af0ec72d3225c4819b330b94628f0e9d0..63231f438a2b5b84ccf319a5de22343ee0316323 2019-03-13 06:52:51 +0000 to 2019-03-27 12:26:45 +0000 - Code cleanup (rust-lang/cargo#6787) - Add cargo:rustc-link-arg to pass custom linker arguments (rust-lang/cargo#6298) - Testsuite: remove some unnecessary is_nightly checks. (rust-lang/cargo#6786) - cargo metadata: Don't show `null` deps. (rust-lang/cargo#6534) - Some fingerprint cleanup. (rust-lang/cargo#6785) - Fix fingerprint for canceled build script. (rust-lang/cargo#6782) - Canonicalize default target if it ends with `.json` (rust-lang/cargo#6778) - Fix setting `panic=unwind` compiling lib a extra time. (rust-lang/cargo#6781) - Always nicely show errors from crates.io if possible (rust-lang/cargo#6771) - Testsuite: Make `cwd()` relative to project root. (rust-lang/cargo#6768) - Allow `cargo fix` if gitignore matches root working dir. (rust-lang/cargo#6767) - Remove redundant imports (rust-lang/cargo#6763) - Handle backcompat hazard with `toml` crate (rust-lang/cargo#6761) - Fix spurious error in dirty_both_lib_and_test. (rust-lang/cargo#6756) - Update toml requirement from 0.4.2 to 0.5.0 (rust-lang/cargo#6760) - Reuse std::env::consts::EXE_SUFFIX (rust-lang/cargo#6758) - Proptest 0.9.1 (rust-lang/cargo#6753) - Don't need extern crate in 2018 (rust-lang/cargo#6752) - Release a jobserver token while locking a file (rust-lang/cargo#6748) - Minor doc fix for publish command synopsis (rust-lang/cargo#6749) - Stricter package change detection. (rust-lang/cargo#6740) - Fix resolving yanked crates when using a local registry. (rust-lang/cargo#6742)

Version 1.35.0 (2019-05-23) ========================== Language -------- - [`FnOnce`, `FnMut`, and the `Fn` traits are now implemented for `Box<FnOnce>`, `Box<FnMut>`, and `Box<Fn>` respectively.][59500] - [You can now coerce closures into unsafe function pointers.][59580] e.g. ```rust unsafe fn call_unsafe(func: unsafe fn()) { func() } pub fn main() { unsafe { call_unsafe(|| {}); } } ``` Compiler -------- - [Added the `armv6-unknown-freebsd-gnueabihf` and `armv7-unknown-freebsd-gnueabihf` targets.][58080] - [Added the `wasm32-unknown-wasi` target.][59464] Libraries --------- - [`Thread` will now show its ID in `Debug` output.][59460] - [`StdinLock`, `StdoutLock`, and `StderrLock` now implement `AsRawFd`.][59512] - [`alloc::System` now implements `Default`.][59451] - [Expanded `Debug` output (`{:#?}`) for structs now has a trailing comma on the last field.][59076] - [`char::{ToLowercase, ToUppercase}` now implement `ExactSizeIterator`.][58778] - [All `NonZero` numeric types now implement `FromStr`.][58717] - [Removed the `Read` trait bounds on the `BufReader::{get_ref, get_mut, into_inner}` methods.][58423] - [You can now call the `dbg!` macro without any parameters to print the file and line where it is called.][57847] - [In place ASCII case conversions are now up to 4× faster.][59283] e.g. `str::make_ascii_lowercase` - [`hash_map::{OccupiedEntry, VacantEntry}` now implement `Sync` and `Send`.][58369] Stabilized APIs --------------- - [`f32::copysign`] - [`f64::copysign`] - [`RefCell::replace_with`] - [`RefCell::map_split`] - [`ptr::hash`] - [`Range::contains`] - [`RangeFrom::contains`] - [`RangeTo::contains`] - [`RangeInclusive::contains`] - [`RangeToInclusive::contains`] - [`Option::copied`] Cargo ----- - [You can now set `cargo:rustc-cdylib-link-arg` at build time to pass custom linker arguments when building a `cdylib`.][cargo/6298] Its usage is highly platform specific. Misc ---- - [The Rust toolchain is now available natively for musl based distros.][58575] [59460]: rust-lang/rust#59460 [59464]: rust-lang/rust#59464 [59500]: rust-lang/rust#59500 [59512]: rust-lang/rust#59512 [59580]: rust-lang/rust#59580 [59283]: rust-lang/rust#59283 [59451]: rust-lang/rust#59451 [59076]: rust-lang/rust#59076 [58778]: rust-lang/rust#58778 [58717]: rust-lang/rust#58717 [58369]: rust-lang/rust#58369 [58423]: rust-lang/rust#58423 [58080]: rust-lang/rust#58080 [57847]: rust-lang/rust#57847 [58575]: rust-lang/rust#58575 [cargo/6298]: rust-lang/cargo#6298 [`f32::copysign`]: https://doc.rust-lang.org/stable/std/primitive.f32.html#method.copysign [`f64::copysign`]: https://doc.rust-lang.org/stable/std/primitive.f64.html#method.copysign [`RefCell::replace_with`]: https://doc.rust-lang.org/stable/std/cell/struct.RefCell.html#method.replace_with [`RefCell::map_split`]: https://doc.rust-lang.org/stable/std/cell/struct.RefCell.html#method.map_split [`ptr::hash`]: https://doc.rust-lang.org/stable/std/ptr/fn.hash.html [`Range::contains`]: https://doc.rust-lang.org/std/ops/struct.Range.html#method.contains [`RangeFrom::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeFrom.html#method.contains [`RangeTo::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeTo.html#method.contains [`RangeInclusive::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html#method.contains [`RangeToInclusive::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeToInclusive.html#method.contains [`Option::copied`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.copied

lu-zero force-pushed the rustc-link-args branch from fd3e037 to 104b861 Compare November 18, 2018 09:59

lu-zero mentioned this pull request Dec 10, 2018

Make sure cargo sets the soname in the cdylib lu-zero/crav1e#5

Open

6 tasks

nrc assigned alexcrichton Mar 6, 2019

lu-zero added 3 commits March 8, 2019 16:15

Add cargo:rustc-link-arg to pass custom linker arguments

55205ef

It is useful to produce correct cdylibs on platforms such as Linux and MacOS.

Restrict to cdylib the link arg feature

d426f12

Restrict the link-arg key to rustc-cdylib-link-arg for now

9741016

lu-zero force-pushed the rustc-link-args branch from 104b861 to 9741016 Compare March 8, 2019 19:47

Document the rustc-cdylib-link-arg key

064afa6

alexcrichton added the T-cargo Team: Cargo label Mar 11, 2019

alexcrichton reviewed Mar 11, 2019

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src/cargo/core/compiler/mod.rs Outdated Show resolved Hide resolved

rfcbot added proposed-final-comment-period An FCP proposal has started, but not yet signed off. disposition-merge FCP with intent to merge labels Mar 11, 2019

Rename pass_link_args to pass_cdylib_link_args

f608ed6

rfcbot added the final-comment-period FCP — a period for last comments before action is taken label Mar 27, 2019

rfcbot removed the proposed-final-comment-period An FCP proposal has started, but not yet signed off. label Mar 27, 2019

bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Mar 27, 2019

alexcrichton added the relnotes Release-note worthy label Mar 27, 2019

bors merged commit f608ed6 into rust-lang:master Mar 27, 2019

ehuss mentioned this pull request Mar 29, 2019

Update cargo rust-lang/rust#59516

Merged

rfcbot added finished-final-comment-period FCP complete and removed final-comment-period FCP — a period for last comments before action is taken labels Apr 6, 2019

federicomenaquintero mentioned this pull request May 17, 2019

Support soname for cdylibs #5045

Open

konstin mentioned this pull request Oct 31, 2019

wasmtime-py doesn't build with cargo test bytecodealliance/wasmtime#468

Closed

npmccallum mentioned this pull request Jan 17, 2020

Add rustc-bin-link-arg and rustc-link-arg custom build options #7811

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ehuss added this to the 1.35.0 milestone Feb 6, 2022

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Add cargo:rustc-link-arg to pass custom linker arguments #6298

Add cargo:rustc-link-arg to pass custom linker arguments #6298

lu-zero commented Nov 9, 2018

alexcrichton commented Nov 12, 2018

lu-zero commented Nov 12, 2018

alexcrichton commented Nov 18, 2018

bors commented Nov 18, 2018

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bors commented Mar 27, 2019

Add cargo:rustc-link-arg to pass custom linker arguments #6298

Add cargo:rustc-link-arg to pass custom linker arguments #6298

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