Allow dynamic linking for iOS/tvOS targets #73516

Absolucy · 2020-06-19T20:39:09Z

During the development and testing of the Crabapple project, one obstacle was the lack of cdylib target support for iOS. Surprisingly, once dynamic_linking was enabled for iOS targets, it worked seemingly flawlessly.

I could not find any information on why this was initially or still is disabled.

rust-highfive · 2020-06-19T20:39:12Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nikomatsakis (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

nikomatsakis · 2020-06-22T14:30:39Z

OK, cc @simlay @matthiaskrgr and @trevyn as past contributors to this file -- any thoughts?

Absolucy · 2020-06-22T18:46:22Z

In addition, may I ask why aarch64-apple-ios is used over arm64-apple-ios? LLVM uses arm64, apple resources use arm64, most people use arm64.

nikomatsakis · 2020-06-22T21:29:27Z

@Luxxxxy

Specifically, are you saying that that you are not aware of anyone who uses aarch64-apple-ios as the target triple besides Rust? Or that it is used elsewhere, but not for this purpose? Perhaps you can edit your comment to clarify. =)

Absolucy · 2020-06-22T21:55:39Z

@nikomatsakis Alright, sorry for being unclear.

Here's some examples:

If I want to compile linux for ARMv8, I'll do ARCH=arm64 make
Clang takes arm64 in arch/target triples. For example, clang --target=arm64-apple-ios

In addition, the "official" naming for ARM architectures is very confusing. Let's look at the rustc arch names for various ARM architectures:

armv4t
armv5te
armv6
armv7
armv7a
armv7r
armv7s
aarch64

Notice how aarch64 is inconsistent with the rest. We'd call this armv8 or armv8a if we wished to be consistent.

Although I'm not sure if this thread is the proper place for discussing this, but I'm new to contributing to Rust so idk.

trevyn · 2020-06-23T04:52:01Z

AArch64 is the name of the LLVM backend which targets all 64-bit ARM architectures (and indeed is the proper general name for 64-bit ARM architectures); targeting a specific architecture would be incorrect in this case. For why it is called AArch64 instead of arm64, perhaps this link provides some context: https://www.phoronix.com/scan.php?page=news_item&px=MTY5ODk

Back on topic, I don’t know the origin of the dynamic_linking setting in this file, but I do know that iOS has historically not allowed dynamic linking of user code as policy — even though it was technically possible, such binaries could not be made to pass App Store review. This may have changed, and at any rate, we certainly don’t want to limit Rust to the App Store criteria.

That said, I do not know what impact removing that line will have. @Luxxxxy, is it possible to override that setting at build time?

Absolucy · 2020-06-23T04:53:15Z

@trevyn I'm not sure. I've been using iOS dylibs for Cydia Substrate tweaks.

nikomatsakis · 2020-06-23T20:57:36Z

I'd be inclined to land the PR unless we know of a concrete problem it will cause -- after all, we do know of at least one user that is helped by the change.

trevyn · 2020-06-23T23:21:16Z

Sure; I’d be happy to test against my iOS project once it lands in nightly.

Absolucy · 2020-06-24T05:56:06Z

Yeah once this lands in nightly, Crabapple can start using it instead of the current rustc-ios-nbt build I have.

nikomatsakis · 2020-06-24T14:33:44Z

@bors r+ rollup

bors · 2020-06-24T14:33:45Z

📌 Commit 56e115a has been approved by nikomatsakis

nikomatsakis · 2020-06-24T14:33:53Z

OK, I'm going to merge, and we'll see what happens. =)

Absolucy · 2020-06-24T17:57:37Z

👍

…-linking, r=nikomatsakis Allow dynamic linking for iOS/tvOS targets During the development and testing of the [Crabapple project](https://github.com/Crabapple-iOS/Crabapple), one obstacle was the lack of `cdylib` target support for iOS. Surprisingly, once `dynamic_linking` was enabled for iOS targets, it worked seemingly flawlessly. I could not find any information on why this was initially or still is disabled.

@ghost

Rollup of 6 pull requests Successful merges: - rust-lang#72700 (`improper_ctypes_definitions` lint) - rust-lang#73516 (Allow dynamic linking for iOS/tvOS targets) - rust-lang#73616 (Liballoc minor hash import tweak) - rust-lang#73634 (Add UI test for issue 73592) - rust-lang#73688 (Document the self keyword) - rust-lang#73698 (Add procedure for prioritization notifications on Zulip) Failed merges: r? @ghost

according to various people on tech-pkg@, there are no problems with the Firefox build Version 1.46.0 (2020-08-27) ========================== Language -------- - [`if`, `match`, and `loop` expressions can now be used in const functions.][72437] - [Additionally you are now also able to coerce and cast to slices (`&[T]`) in const functions.][73862] - [The `#[track_caller]` attribute can now be added to functions to use the function's caller's location information for panic messages.][72445] - [Recursively indexing into tuples no longer needs parentheses.][71322] E.g. `x.0.0` over `(x.0).0`. - [`mem::transmute` can now be used in static and constants.][72920] **Note** You currently can't use `mem::transmute` in constant functions. Compiler -------- - [You can now use the `cdylib` target on Apple iOS and tvOS platforms.][73516] - [Enabled static "Position Independent Executables" by default for `x86_64-unknown-linux-musl`.][70740] Libraries --------- - [`mem::forget` is now a `const fn`.][73887] - [`String` now implements `From<char>`.][73466] - [The `leading_ones`, and `trailing_ones` methods have been stabilised for all integer types.][73032] - [`vec::IntoIter<T>` now implements `AsRef<[T]>`.][72583] - [All non-zero integer types (`NonZeroU8`) now implement `TryFrom` for their zero-able equivalent (e.g. `TryFrom<u8>`).][72717] - [`&[T]` and `&mut [T]` now implement `PartialEq<Vec<T>>`.][71660] - [`(String, u16)` now implements `ToSocketAddrs`.][73007] - [`vec::Drain<'_, T>` now implements `AsRef<[T]>`.][72584] Stabilized APIs --------------- - [`Option::zip`] - [`vec::Drain::as_slice`] Cargo ----- Added a number of new environment variables that are now available when compiling your crate. - [`CARGO_BIN_NAME` and `CARGO_CRATE_NAME`][cargo/8270] Providing the name of the specific binary being compiled and the name of the crate. - [`CARGO_PKG_LICENSE`][cargo/8325] The license from the manifest of the package. - [`CARGO_PKG_LICENSE_FILE`][cargo/8387] The path to the license file. Compatibility Notes ------------------- - [The target configuration option `abi_blacklist` has been renamed to `unsupported_abis`.][74150] The old name will still continue to work. - [Rustc will now warn if you cast a C-like enum that implements `Drop`.][72331] This was previously accepted but will become a hard error in a future release. - [Rustc will fail to compile if you have a struct with `#[repr(i128)]` or `#[repr(u128)]`.][74109] This representation is currently only allowed on `enum`s. - [Tokens passed to `macro_rules!` are now always captured.][73293] This helps ensure that spans have the correct information, and may cause breakage if you were relying on receiving spans with dummy information. - [The InnoSetup installer for Windows is no longer available.][72569] This was a legacy installer that was replaced by a MSI installer a few years ago but was still being built. - [`{f32, f64}::asinh` now returns the correct values for negative numbers.][72486] - [Rustc will no longer accept overlapping trait implementations that only differ in how the lifetime was bound.][72493] - [Rustc now correctly relates the lifetime of an existential associated type.][71896] This fixes some edge cases where `rustc` would erroneously allow you to pass a shorter lifetime than expected. - [Rustc now dynamically links to `libz` (also called `zlib`) on Linux.][74420] The library will need to be installed for `rustc` to work, even though we expect it to be already available on most systems. - [Tests annotated with `#[should_panic]` are broken on ARMv7 while running under QEMU.][74820] - [Pretty printing of some tokens in procedural macros changed.][75453] The exact output returned by rustc's pretty printing is an unstable implementation detail: we recommend any macro relying on it to switch to a more robust parsing system. [75453]: rust-lang/rust#75453 [74820]: rust-lang/rust#74820 [74420]: rust-lang/rust#74420 [74109]: rust-lang/rust#74109 [74150]: rust-lang/rust#74150 [73862]: rust-lang/rust#73862 [73887]: rust-lang/rust#73887 [73466]: rust-lang/rust#73466 [73516]: rust-lang/rust#73516 [73293]: rust-lang/rust#73293 [73007]: rust-lang/rust#73007 [73032]: rust-lang/rust#73032 [72920]: rust-lang/rust#72920 [72569]: rust-lang/rust#72569 [72583]: rust-lang/rust#72583 [72584]: rust-lang/rust#72584 [72717]: rust-lang/rust#72717 [72437]: rust-lang/rust#72437 [72445]: rust-lang/rust#72445 [72486]: rust-lang/rust#72486 [72493]: rust-lang/rust#72493 [72331]: rust-lang/rust#72331 [71896]: rust-lang/rust#71896 [71660]: rust-lang/rust#71660 [71322]: rust-lang/rust#71322 [70740]: rust-lang/rust#70740 [cargo/8270]: rust-lang/cargo#8270 [cargo/8325]: rust-lang/cargo#8325 [cargo/8387]: rust-lang/cargo#8387 [`Option::zip`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.zip [`vec::Drain::as_slice`]: https://doc.rust-lang.org/stable/std/vec/struct.Drain.html#method.as_slice

khagesh · 2020-09-03T12:44:35Z

Does this PR mean that default builds will be dynamically linked now?

Absolucy · 2020-09-03T13:08:15Z

Does this PR mean that default builds will be dynamically linked now?

don't think so? this just means rustc can compile dylib/cdylib crates for iOS/tvOS

Pkgsrc changes: * Portability patches for Illumos have been intregrated upstream, so are no longer needed in pkgsrc. * Adjust one other patch, and update vendor/libc cargo checksum. Upstream changes: Version 1.46.0 (2020-08-27) ========================== Language -------- - [`if`, `match`, and `loop` expressions can now be used in const functions.] [72437] - [Additionally you are now also able to coerce and cast to slices (`&[T]`) in const functions.][73862] - [The `#[track_caller]` attribute can now be added to functions to use the function's caller's location information for panic messages.][72445] - [Recursively indexing into tuples no longer needs parentheses.][71322] E.g. `x.0.0` over `(x.0).0`. - [`mem::transmute` can now be used in static and constants.][72920] **Note** You currently can't use `mem::transmute` in constant functions. Compiler -------- - [You can now use the `cdylib` target on Apple iOS and tvOS platforms.][73516] - [Enabled static "Position Independent Executables" by default for `x86_64-unknown-linux-musl`.][70740] Libraries --------- - [`mem::forget` is now a `const fn`.][73887] - [`String` now implements `From<char>`.][73466] - [The `leading_ones`, and `trailing_ones` methods have been stabilised for all integer types.][73032] - [`vec::IntoIter<T>` now implements `AsRef<[T]>`.][72583] - [All non-zero integer types (`NonZeroU8`) now implement `TryFrom` for their zero-able equivalent (e.g. `TryFrom<u8>`).][72717] - [`&[T]` and `&mut [T]` now implement `PartialEq<Vec<T>>`.][71660] - [`(String, u16)` now implements `ToSocketAddrs`.][73007] - [`vec::Drain<'_, T>` now implements `AsRef<[T]>`.][72584] Stabilized APIs --------------- - [`Option::zip`] - [`vec::Drain::as_slice`] Cargo ----- Added a number of new environment variables that are now available when compiling your crate. - [`CARGO_BIN_NAME` and `CARGO_CRATE_NAME`][cargo/8270] Providing the name of the specific binary being compiled and the name of the crate. - [`CARGO_PKG_LICENSE`][cargo/8325] The license from the manifest of the package. - [`CARGO_PKG_LICENSE_FILE`][cargo/8387] The path to the license file. Compatibility Notes ------------------- - [The target configuration option `abi_blacklist` has been renamed to `unsupported_abis`.][74150] The old name will still continue to work. - [Rustc will now warn if you have a C-like enum that implements `Drop`.][72331] This was previously accepted but will become a hard error in a future release. - [Rustc will fail to compile if you have a struct with `#[repr(i128)]` or `#[repr(u128)]`.][74109] This representation is currently only allowed on `enum`s. - [Tokens passed to `macro_rules!` are now always captured.][73293] This helps ensure that spans have the correct information, and may cause breakage if you were relying on receiving spans with dummy information. - [The InnoSetup installer for Windows is no longer available.][72569] This was a legacy installer that was replaced by a MSI installer a few years ago but was still being built. - [`{f32, f64}::asinh` now returns the correct values for negative numbers.] [72486] - [Rustc will no longer accept overlapping trait implementations that only differ in how the lifetime was bound.][72493] - [Rustc now correctly relates the lifetime of an existential associated type.][71896] This fixes some edge cases where `rustc` would erroneously allow you to pass a shorter lifetime than expected. - [Rustc now dynamically links to `libz` (also called `zlib`) on Linux.][74420] The library will need to be installed for `rustc` to work, even though we expect it to be already available on most systems. - [Tests annotated with `#[should_panic]` are broken on ARMv7 while running under QEMU.][74820] - [Pretty printing of some tokens in procedural macros changed.][75453] The exact output returned by rustc's pretty printing is an unstable implementation detail: we recommend any macro relying on it to switch to a more robust parsing system. [75453]: rust-lang/rust#75453 [74820]: rust-lang/rust#74820 [74420]: rust-lang/rust#74420 [74109]: rust-lang/rust#74109 [74150]: rust-lang/rust#74150 [73862]: rust-lang/rust#73862 [73887]: rust-lang/rust#73887 [73466]: rust-lang/rust#73466 [73516]: rust-lang/rust#73516 [73293]: rust-lang/rust#73293 [73007]: rust-lang/rust#73007 [73032]: rust-lang/rust#73032 [72920]: rust-lang/rust#72920 [72569]: rust-lang/rust#72569 [72583]: rust-lang/rust#72583 [72584]: rust-lang/rust#72584 [72717]: rust-lang/rust#72717 [72437]: rust-lang/rust#72437 [72445]: rust-lang/rust#72445 [72486]: rust-lang/rust#72486 [72493]: rust-lang/rust#72493 [72331]: rust-lang/rust#72331 [71896]: rust-lang/rust#71896 [71660]: rust-lang/rust#71660 [71322]: rust-lang/rust#71322 [70740]: rust-lang/rust#70740 [cargo/8270]: rust-lang/cargo#8270 [cargo/8325]: rust-lang/cargo#8325 [cargo/8387]: rust-lang/cargo#8387 [`Option::zip`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.zip [`vec::Drain::as_slice`]: https://doc.rust-lang.org/stable/std/vec/struct.Drain.html#method.as_slice

vimmerru · 2020-11-24T08:51:12Z

@aspenluxxxy This PR added a lot of headache for iOS builds. cdylib target is near impossible to build if you are using any crate with native dependencies (ex. openssl, libsodium, zmq). You can't just find .so files for all architectures to perform correct linking. Usual workflow is the following:

You build staticlib and rely that native dependencies will be linked as frameworks later
You setup right cocoapods in ObjectiveC/Swift wrapper.

As cargo doesn't support platform-dependent crate types rust-lang/cargo#4881 as a result a lot of projects now broken on Rust 1.46

trevyn · 2020-11-24T09:13:30Z

@vimmerru Did this PR in any way inhibit your ability to build a staticlib? This should almost always be the only way you ever need to build an iOS project; the cdylib target is only for very unique use-cases (such as Cydia tweaks, apparently), and you shouldn’t normally need to touch it.

vimmerru · 2020-11-24T09:32:19Z

@trevyn

Did this PR in any way inhibit your ability to build a staticlib?

Yes. It affects all cross-platform crates that require cdylib for desktop target. There is no way to skip crate type for specific platform in Cargo.toml. Builds that worked before now require at least additional flags. For example, i spend one day to understand what is broken in CI/CD for this project https://github.com/hyperledger/indy-sdk

Absolucy · 2020-11-24T13:52:04Z

@vimmerru That is a problem with cargo, not the aarch64-apple-ios target

vimmerru · 2020-11-24T14:01:41Z

@aspenluxxxy The problem is a lot of projects can't build for iOS now due broken tooling, but value of cdlyb for iOS is small as it is useful only for few Cydia-style hackers.

Partially it is the issue in cargo, but there is no easy fix for projects that require iOS builds. As i can see this PR is already reverted in nightly due a lot of complains.

Diatrus · 2021-05-28T21:45:15Z

@aspenluxxxy The problem is a lot of projects can't build for iOS now due broken tooling, but value of cdlyb for iOS is small as it is useful only for few Cydia-style hackers.

I'm late to this, but I'm not entirely sure why you think dynamic libraries are useless excepting "Cydia-style hackers" when they have worked in stock since iOS 8.

Allow dynamic linking for iOS/tvOS targets.

56e115a

rust-highfive assigned nikomatsakis Jun 19, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 19, 2020

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 24, 2020

This was referenced Jun 25, 2020

Rollup of 6 pull requests #73710

Closed

Rollup of 6 pull requests #73711

Merged

bors merged commit d6c674b into rust-lang:master Jun 25, 2020

Absolucy deleted the feature/apple-dynamic-linking branch June 25, 2020 16:30

francesca64 mentioned this pull request Oct 8, 2020

Revert "Allow dynamic linking for iOS/tvOS targets." #77716

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This was referenced Nov 24, 2020

Ability to set crate-type depending on target rust-lang/cargo#4881

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Support of cdylib crate types on iOS in Rust 1.46 breaks usual build workflows #79373

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vimmerru mentioned this pull request Nov 24, 2020

Support skipping of crate types TimNN/cargo-lipo#39

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jonas-schievink added the O-ios Operating system: iOS label Nov 24, 2020

holzschu mentioned this pull request Feb 11, 2021

Support dylib on iOS #21727

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Torrekie mentioned this pull request Aug 18, 2021

Allow iOS dynamic linking #88130

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