Yuki Okushi [Mon, 26 Oct 2020 23:44:41 +0000 (08:44 +0900)]
Rollup merge of #76635 - scottmcm:slice-as-chunks, r=LukasKalbertodt
Add [T]::as_chunks(_mut)
Allows getting the slices directly, rather than just through an iterator as in `array_chunks(_mut)`. The constructors for those iterators are then written in terms of these methods, so the iterator constructors no longer have any `unsafe` of their own.
bors [Mon, 26 Oct 2020 18:50:22 +0000 (18:50 +0000)]
Auto merge of #68965 - eddyb:mir-inline-scope, r=nagisa,oli-obk
rustc_mir: track inlined callees in SourceScopeData.
We now record which MIR scopes are the roots of *other* (inlined) functions's scope trees, which allows us to generate the correct debuginfo in codegen, similar to what LLVM inlining generates.
This PR makes the `ui` test `backtrace-debuginfo` pass, if the MIR inliner is turned on by default.
Also, `#[track_caller]` is now correct in the face of MIR inlining (cc `@anp).`
bors [Mon, 26 Oct 2020 16:31:38 +0000 (16:31 +0000)]
Auto merge of #77975 - bjorn3:cg_clif_subtree3, r=Mark-Simulacrum
Add cg_clif as optional codegen backend
Rustc_codegen_cranelift is an alternative codegen backend for rustc based on Cranelift. It has the potential to improve compilation times in debug mode. In my experience the compile time improvements over debug mode LLVM for a clean build are about 20-30% in most cases.
This PR adds cg_clif as optional codegen backend. By default it is only enabled for `./x.py check`. It can be enabled for `./x.py build` too by adding `cranelift` to the `rust.codegen-backends` array in `config.toml`.
bors [Mon, 26 Oct 2020 11:56:59 +0000 (11:56 +0000)]
Auto merge of #78196 - pietroalbini:shipped-files, r=Mark-Simulacrum
Allow creating a list of files shipped in a release
This PR adds the `BUILD_MANIFEST_SHIPPED_FILES_PATH` environment variable to `build-manifest`, which writes a list of all the files referenced in the manifest to the path defined in the variable. The use for this is for `promote-release` to prune files unused files before publishing a release.
This PR **does not implement any pruning**, it just adds support for it to be implemented in the future on `promote-release`'s side.
This still looks very good, but LLVM does not really translate that to
what would be considered ideal machine code (on any target). For example
that's the codegen we obtain for an unknown alignment:
; x86_64
dec rsi
mov rax, rdi
neg rax
and rax, rsi
add rax, rdi
In particular negating a pointer is not something that’s going to be
optimised for in the design of CISC architectures like x86_64. They
are much better at offsetting pointers. And so we’d love to utilize this
ability and produce code that's more like this:
To achieve this we need to give LLVM an opportunity to apply its
various peep-hole optimisations that it does during DAG selection. In
particular, the `and` instruction appears to be a major inhibitor here.
We cannot, sadly, get rid of this load-bearing operation, but we can
reorder operations such that LLVM has more to work with around this
instruction.
One such ordering is proposed in #75579 and results in LLVM IR that
looks broadly like this:
; using add enables `lea` and similar CISCisms
%offset_ptr = add i64 %address, %a_minus_one
%mask = sub i64 0, %a
%masked = and i64 %offset_ptr, %mask
; can be folded with `gepi` that may follow
%offset = sub i64 %masked, %address
…and generates the intended x86_64 machine code.
One might also wonder how the increased amount of code would impact a
RISC target. Turns out not much:
; aarch64 previous ; aarch64 new
sub x8, x1, #1 add x8, x1, x0
neg x9, x0 sub x8, x8, #1
and x8, x9, x8 neg x9, x1
add x0, x0, x8 and x0, x8, x9
(and similarly for ppc, sparc, mips, riscv, etc)
The only target that seems to do worse is… wasm32.
Onto actual measurements – the best way to evaluate snipets like these
is to use llvm-mca. Much like Aarch64 assembly would allow to suspect,
there isn’t any performance difference to be found. Both snippets
execute in same number of cycles for the CPUs I tried. On x86_64,
we get throughput improvement of >50%!
bors [Mon, 26 Oct 2020 04:34:46 +0000 (04:34 +0000)]
Auto merge of #78387 - Dylan-DPC:rollup-ch0st6z, r=Dylan-DPC
Rollup of 10 pull requests
Successful merges:
- #74477 (`#[deny(unsafe_op_in_unsafe_fn)]` in sys/wasm)
- #77836 (transmute_copy: explain that alignment is handled correctly)
- #78126 (Properly define va_arg and va_list for aarch64-apple-darwin)
- #78137 (Initialize tracing subscriber in compiletest tool)
- #78161 (Add issue template link to IRLO)
- #78214 (Tweak match arm semicolon removal suggestion to account for futures)
- #78247 (Fix #78192)
- #78252 (Add codegen test for #45964)
- #78268 (Do not try to report on closures to avoid ICE)
- #78295 (Add some regression tests)
Dylan DPC [Mon, 26 Oct 2020 02:09:06 +0000 (03:09 +0100)]
Rollup merge of #78214 - estebank:match-semicolon, r=oli-obk
Tweak match arm semicolon removal suggestion to account for futures
* Tweak and extend "use `.await`" suggestions
* Suggest removal of semicolon on prior match arm
* Account for `impl Future` when suggesting semicolon removal
* Silence some errors when encountering `await foo()?` as can't be certain what the intent was
*Thanks to https://twitter.com/a_hoverbear/status/1318960787105353728 for pointing this out!*
bors [Sun, 25 Oct 2020 11:35:26 +0000 (11:35 +0000)]
Auto merge of #78350 - JohnTitor:rollup-vbbm5wf, r=JohnTitor
Rollup of 8 pull requests
Successful merges:
- #77984 (Compute proper module parent during resolution)
- #78085 (MIR validation should check `SwitchInt` values are valid for the type)
- #78208 (replace `#[allow_internal_unstable]` with `#[rustc_allow_const_fn_unstable]` for `const fn`s)
- #78209 (Update `compiler_builtins` to 0.1.36)
- #78276 (Bump backtrace-rs to enable Mach-O support on iOS.)
- #78320 (Link to cargo's `build-std` feature instead of `xargo` in custom target docs)
- #78322 (BTreeMap: stop mistaking node::MIN_LEN for a node level constraint)
- #78326 (Split out statement attributes changes from #78306)
Yuki Okushi [Sun, 25 Oct 2020 09:43:49 +0000 (18:43 +0900)]
Rollup merge of #78326 - Aaron1011:fix/min-stmt-lints, r=petrochenkov
Split out statement attributes changes from #78306
This is the same as PR https://github.com/rust-lang/rust/pull/78306, but `unused_doc_comments` is modified to explicitly ignore statement items (which preserves the current behavior).
This shouldn't have any user-visible effects, so it can be landed without lang team discussion.
---------
When the 'early' and 'late' visitors visit an attribute target, they
activate any lint attributes (e.g. `#[allow]`) that apply to it.
This can affect warnings emitted on sibiling attributes. For example,
the following code does not produce an `unused_attributes` for
`#[inline]`, since the sibiling `#[allow(unused_attributes)]` suppressed
the warning.
However, we do not do this for statements - instead, the lint attributes
only become active when we visit the struct nested inside `StmtKind`
(e.g. `Item`).
Currently, this is difficult to observe due to another issue - the
`HasAttrs` impl for `StmtKind` ignores attributes for `StmtKind::Item`.
As a result, the `unused_doc_comments` lint will never see attributes on
item statements.
This commit makes two interrelated fixes to the handling of inert
(non-proc-macro) attributes on statements:
* The `HasAttr` impl for `StmtKind` now returns attributes for
`StmtKind::Item`, treating it just like every other `StmtKind`
variant. The only place relying on the old behavior was macro
which has been updated to explicitly ignore attributes on item
statements. This allows the `unused_doc_comments` lint to fire for
item statements.
* The `early` and `late` lint visitors now activate lint attributes when
invoking the callback for `Stmt`. This ensures that a lint
attribute (e.g. `#[allow(unused_doc_comments)]`) can be applied to
sibiling attributes on an item statement.
For now, the `unused_doc_comments` lint is explicitly disabled on item
statements, which preserves the current behavior. The exact locatiosn
where this lint should fire are being discussed in PR #78306
Yuki Okushi [Sun, 25 Oct 2020 09:43:47 +0000 (18:43 +0900)]
Rollup merge of #78322 - ssomers:btree_no_min_len_at_node_level, r=Mark-Simulacrum
BTreeMap: stop mistaking node::MIN_LEN for a node level constraint
Correcting #77612 that fell into the trap of assuming that node::MIN_LEN is an imposed minimum everywhere, and trying to make it much more clear it is an offered minimum at the node level.
Yuki Okushi [Sun, 25 Oct 2020 09:43:44 +0000 (18:43 +0900)]
Rollup merge of #78276 - cutsoy:bump-backtrace, r=nagisa
Bump backtrace-rs to enable Mach-O support on iOS.
Related to rust-lang/backtrace-rs#378. Fixes backtraces on iOS that were missing in Rust v1.47.0 after switching to gimli because it only enabled Mach-O support on macOS.
Yuki Okushi [Sun, 25 Oct 2020 09:43:42 +0000 (18:43 +0900)]
Rollup merge of #78209 - JohnTitor:compiler-builtins, r=Amanieu
Update `compiler_builtins` to 0.1.36
So, the libc build with cargo's `build-std` feature emits a lot of warnings like:
```
warning: a method with this name may be added to the standard library in the future
--> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.35/src/int/udiv.rs:98:23
|
98 | q = n << (<$ty>::BITS - sr);
| ^^^^^^^^^^^
...
268 | udivmod_inner!(n, d, rem, u128)
| ------------------------------- in this macro invocation
|
= warning: once this method is added to the standard library, the ambiguity may cause an error or change in behavior!
= note: for more information, see issue #48919 <rust-lang/rust/issues/48919>
= help: call with fully qualified syntax `Int::BITS(...)` to keep using the current method
= help: add `#![feature(int_bits_const)]` to the crate attributes to enable `num::<impl u128>::BITS`
= note: this warning originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
```
(You can find the full log in https://github.com/rust-lang/libc/runs/1283695796?check_suite_focus=true for example.)
0.1.36 contains https://github.com/rust-lang/compiler-builtins/pull/332 so this version should remove this warning.
Yuki Okushi [Sun, 25 Oct 2020 09:43:40 +0000 (18:43 +0900)]
Rollup merge of #78208 - liketechnik:issue-69399, r=oli-obk
replace `#[allow_internal_unstable]` with `#[rustc_allow_const_fn_unstable]` for `const fn`s
`#[allow_internal_unstable]` is currently used to side-step feature gate and stability checks.
While it was originally only meant to be used only on macros, its use was expanded to `const fn`s.
This pr adds stricter checks for the usage of `#[allow_internal_unstable]` (only on macros) and introduces the `#[rustc_allow_const_fn_unstable]` attribute for usage on `const fn`s.
This pr does not change any of the functionality associated with the use of `#[allow_internal_unstable]` on macros or the usage of `#[rustc_allow_const_fn_unstable]` (instead of `#[allow_internal_unstable]`) on `const fn`s (see https://github.com/rust-lang/rust/issues/69399#issuecomment-712911540).
Note: The check for `#[rustc_allow_const_fn_unstable]` currently only validates that the attribute is used on a function, because I don't know how I would check if the function is a `const fn` at the place of the check. I therefore openend this as a 'draft pull request'.
bors [Sun, 25 Oct 2020 09:23:45 +0000 (09:23 +0000)]
Auto merge of #77476 - tgnottingham:buffered_siphasher128, r=nnethercote
perf: buffer SipHasher128
This is an attempt to improve Siphasher128 performance by buffering input. Although it reduces instruction count, I'm not confident the effect on wall times, or lack-thereof, is worth the change.
---
Additional notes not reflected in source comments:
* Implementation choices were guided by a combination of results from rustc-perf and micro-benchmarks, mostly the former.
* ~~I tried a couple of different struct layouts that might be more cache friendly with no obvious effect.~~ Update: a particular struct layout was chosen, but it's not critical to performance. See comments in source and discussion below.
* I suspect that buffering would be important to a SIMD-accelerated algorithm, but from what I've read and my own tests, SipHash does not seem very amenable to SIMD acceleration, at least by SSE.
bors [Sun, 25 Oct 2020 04:48:37 +0000 (04:48 +0000)]
Auto merge of #77398 - wesleywiser:measureme_0_8, r=Mark-Simulacrum
Upgrade to measureme 9.0.0
I believe I did this correctly but there's still a reference to `measureme@0.7.1` coming from `rustc-ap-rustc_data_structures` and I'm not sure how to resolve that.
r? `@Mark-Simulacrum`
We'll also need to deploy the new version of the tools on perf.rlo.
bors [Sun, 25 Oct 2020 02:27:09 +0000 (02:27 +0000)]
Auto merge of #77526 - RalfJung:dont-promote-unions, r=lcnr
stop promoting union field accesses in 'const'
Turns out that promotion of union field accesses is the only difference between "promotion in `const`/`static` bodies" and "explicit promotion". So if we can remove this, we have finally achieved what I thought to already be the case -- that the bodies of `const`/`static` initializers behave the same as explicit promotion contexts.
The reason we do not want to promote union field accesses is that they can introduce UB, i.e., they can go wrong. We want to [minimize the ways promoteds can fail to evaluate](https://github.com/rust-lang/const-eval/issues/53). Also this change makes things more consistent overall, removing a special case that was added without much consideration (as far as I can tell).
bors [Sat, 24 Oct 2020 21:42:39 +0000 (21:42 +0000)]
Auto merge of #78334 - jonas-schievink:rollup-z0gzbmm, r=jonas-schievink
Rollup of 12 pull requests
Successful merges:
- #75115 (`#[deny(unsafe_op_in_unsafe_fn)]` in sys/cloudabi)
- #76614 (change the order of type arguments on ControlFlow)
- #77610 (revise Hermit's mutex interface to support the behaviour of StaticMutex)
- #77830 (Simplify query proc-macros)
- #77930 (Do not ICE with TraitPredicates containing [type error])
- #78069 (Fix const core::panic!(non_literal_str).)
- #78072 (Cleanup constant matching in exhaustiveness checking)
- #78119 (Throw core::panic!("message") as &str instead of String.)
- #78191 (Introduce a temporary for discriminant value in MatchBranchSimplification)
- #78272 (const_evaluatable_checked: deal with unused nodes + div)
- #78318 (TyCtxt: generate single impl block with `slice_interners` macro)
- #78327 (resolve: Relax macro resolution consistency check to account for any errors)
Jonas Schievink [Sat, 24 Oct 2020 20:40:00 +0000 (22:40 +0200)]
Rollup merge of #78327 - petrochenkov:inconsist, r=Aaron1011
resolve: Relax macro resolution consistency check to account for any errors
The check was previously omitted only when ambiguity errors or `Res::Err` were encountered, but the "macro-expanded `extern crate` items cannot shadow..." error (at least) can cause same inconsistencies as well.
Jonas Schievink [Sat, 24 Oct 2020 20:39:55 +0000 (22:39 +0200)]
Rollup merge of #78191 - tmiasko:temp-match-branch-simplification, r=oli-obk
Introduce a temporary for discriminant value in MatchBranchSimplification
The optimization introduces additional uses of the discriminant operand, but
does not ensure that it is still valid to evaluate it or that it still
evaluates to the same value.
Evaluate it once at original position, and store the result in a new temporary.
Follow up on #78151. The optimization remains disabled by default.
Jonas Schievink [Sat, 24 Oct 2020 20:39:53 +0000 (22:39 +0200)]
Rollup merge of #78119 - fusion-engineering-forks:panic-use-as-str, r=Amanieu
Throw core::panic!("message") as &str instead of String.
This makes `core::panic!("message")` consistent with `std::panic!("message")`, which throws a `&str` and not a `String`.
This also makes any other panics from `core::panicking::panic` result in a `&str` rather than a `String`, which includes compiler-generated panics such as the panics generated for `mem::zeroed()`.
fn check(msg: &(dyn Any + Send)) {
if let Some(s) = msg.downcast_ref::<String>() {
println!("Got a String: {:?}", s);
} else if let Some(s) = msg.downcast_ref::<&str>() {
println!("Got a &str: {:?}", s);
}
}
```
Before:
```
Got a String: "core"
Got a String: "core"
Got a &str: "std"
Got a &str: "std"
```
After:
```
Got a &str: "core"
Got a &str: "core"
Got a &str: "std"
Got a &str: "std"
```
Jonas Schievink [Sat, 24 Oct 2020 20:39:51 +0000 (22:39 +0200)]
Rollup merge of #78072 - Nadrieril:cleanup-constant-matching, r=varkor
Cleanup constant matching in exhaustiveness checking
This supercedes https://github.com/rust-lang/rust/pull/77390. I made the `Opaque` constructor work.
I have opened two issues https://github.com/rust-lang/rust/issues/78071 and https://github.com/rust-lang/rust/issues/78057 from the discussion we had on the previous PR. They are not regressions nor directly related to the current PR so I thought we'd deal with them separately.
I left a FIXME somewhere because I didn't know how to compare string constants for equality. There might even be some unicode things that need to happen there. In the meantime I preserved previous behavior.
Jonas Schievink [Sat, 24 Oct 2020 20:39:49 +0000 (22:39 +0200)]
Rollup merge of #78069 - fusion-engineering-forks:core-const-panic-str, r=RalfJung
Fix const core::panic!(non_literal_str).
Invocations of `core::panic!(x)` where `x` is not a string literal expand to `panic!("{}", x)`, which is not understood by the const panic logic right now. This adds `panic_str` as a lang item, and modifies the const eval implementation to hook into this item as well.
This fixes the issue mentioned here: https://github.com/rust-lang/rust/issues/51999#issuecomment-687604248
Jonas Schievink [Sat, 24 Oct 2020 20:39:44 +0000 (22:39 +0200)]
Rollup merge of #77610 - hermitcore:dtors, r=m-ou-se
revise Hermit's mutex interface to support the behaviour of StaticMutex
rust-lang/rust#77147 simplifies things by splitting this Mutex type into two types matching the two use cases: StaticMutex and MovableMutex. To support the new behavior of StaticMutex, we move part of the mutex implementation into libstd.
The interface to the OS changed. Consequently, I removed a few functions, which aren't longer needed.
bors [Sat, 24 Oct 2020 19:23:32 +0000 (19:23 +0000)]
Auto merge of #77255 - Aaron1011:feature/collect-attr-tokens, r=petrochenkov
Unconditionally capture tokens for attributes.
This allows us to avoid synthesizing tokens in `prepend_attr`, since we
have the original tokens available.
We still need to synthesize tokens when expanding `cfg_attr`,
but this is an unavoidable consequence of the syntax of `cfg_attr` -
the user does not supply the `#` and `[]` tokens that a `cfg_attr`
expands to.
This is based on PR https://github.com/rust-lang/rust/pull/77250 - this PR exposes a bug in the current `collect_tokens` implementation, which is fixed by the rewrite.
bors [Sat, 24 Oct 2020 16:12:01 +0000 (16:12 +0000)]
Auto merge of #78319 - jonas-schievink:rollup-vzj8a6l, r=jonas-schievink
Rollup of 15 pull requests
Successful merges:
- #76649 (Add a spin loop hint for Arc::downgrade)
- #77392 (add `insert` to `Option`)
- #77716 (Revert "Allow dynamic linking for iOS/tvOS targets.")
- #78109 (Check for exhaustion in RangeInclusive::contains and slicing)
- #78198 (Simplify assert terminator only if condition evaluates to expected value)
- #78243 (--test-args flag description)
- #78249 (improve const infer error)
- #78250 (Document inline-const)
- #78264 (Add regression test for issue-77475)
- #78274 (Update description of Empty Enum for accuracy)
- #78278 (move `visit_predicate` into `TypeVisitor`)
- #78292 (Loop instead of recursion)
- #78293 (Always store Rustdoc theme when it's changed)
- #78300 (Make codegen coverage_context optional, and check)
- #78307 (Revert "Set .llvmbc and .llvmcmd sections as allocatable")
Aaron Hill [Fri, 23 Oct 2020 22:17:00 +0000 (18:17 -0400)]
Fix inconsistencies in handling of inert attributes on statements
When the 'early' and 'late' visitors visit an attribute target, they
activate any lint attributes (e.g. `#[allow]`) that apply to it.
This can affect warnings emitted on sibiling attributes. For example,
the following code does not produce an `unused_attributes` for
`#[inline]`, since the sibiling `#[allow(unused_attributes)]` suppressed
the warning.
However, we do not do this for statements - instead, the lint attributes
only become active when we visit the struct nested inside `StmtKind`
(e.g. `Item`).
Currently, this is difficult to observe due to another issue - the
`HasAttrs` impl for `StmtKind` ignores attributes for `StmtKind::Item`.
As a result, the `unused_doc_comments` lint will never see attributes on
item statements.
This commit makes two interrelated fixes to the handling of inert
(non-proc-macro) attributes on statements:
* The `HasAttr` impl for `StmtKind` now returns attributes for
`StmtKind::Item`, treating it just like every other `StmtKind`
variant. The only place relying on the old behavior was macro
which has been updated to explicitly ignore attributes on item
statements. This allows the `unused_doc_comments` lint to fire for
item statements.
* The `early` and `late` lint visitors now activate lint attributes when
invoking the callback for `Stmt`. This ensures that a lint
attribute (e.g. `#[allow(unused_doc_comments)]`) can be applied to
sibiling attributes on an item statement.
For now, the `unused_doc_comments` lint is explicitly disabled on item
statements, which preserves the current behavior. The exact locatiosn
where this lint should fire are being discussed in PR #78306
Jonas Schievink [Sat, 24 Oct 2020 12:12:18 +0000 (14:12 +0200)]
Rollup merge of #78300 - richkadel:coverage-cx, r=wesleywiser
Make codegen coverage_context optional, and check
Addresses Issue #78286
Libraries compiled with coverage and linked with out enabling coverage
would fail when attempting to add the library's coverage statements to
the codegen coverage context (None).
Now, if coverage statements are encountered while compiling / linking
with `-Z instrument-coverage` disabled, codegen will *not* attempt to
add code regions to a coverage map, and it will not inject the LLVM
instrprof_increment intrinsic calls.
Jonas Schievink [Sat, 24 Oct 2020 12:12:16 +0000 (14:12 +0200)]
Rollup merge of #78293 - nasso:master, r=GuillaumeGomez
Always store Rustdoc theme when it's changed
`switchTheme` (too) lazily updated the value of `rustdoc-theme` in `localStorage`, leading to an incorrect stored value when the system theme is the same as the default (`light`) theme.
Jonas Schievink [Sat, 24 Oct 2020 12:12:13 +0000 (14:12 +0200)]
Rollup merge of #78278 - lcnr:predicate-visit, r=matthewjasper
move `visit_predicate` into `TypeVisitor`
Seems easier than dealing with `PredicateVisitor` for me which I needed for object safety checks for `PredicateAtom::ConstEvaluatable`. Is there a reason I am missing for this split?
Jonas Schievink [Sat, 24 Oct 2020 12:12:06 +0000 (14:12 +0200)]
Rollup merge of #78249 - lcnr:ct-infer-origin, r=varkor
improve const infer error
For type inference we probably have to be careful about subtyping and stuff but considering that subtyping shouldn't be relevant for constants I don't really see a reason why we may not want to reuse the const origin here.
Jonas Schievink [Sat, 24 Oct 2020 12:11:59 +0000 (14:11 +0200)]
Rollup merge of #77716 - francesca64:revert-ios-dynamic-linking, r=jonas-schievink
Revert "Allow dynamic linking for iOS/tvOS targets."
This reverts PR #73516.
On macOS I compile static libs for iOS, automated using [cargo-mobile](https://github.com/BrainiumLLC/cargo-mobile), which has worked smoothly for the past 2 years. However, upon updating to Rust 1.46.0, I was no longer able to use Rust on iOS. I've bisected this to the PR referenced above.
For most projects tested, apps now immediately crash with a message like this:
```
dyld: Library not loaded: /Users/francesca/Projects/example/target/aarch64-apple-ios/debug/deps/libexample.dylib
Referenced from: /private/var/containers/Bundle/Application/745912AF-A928-465C-B340-872BD1C9F368/example.app/example
Reason: image not found
dyld: launch, loading dependent libraries
DYLD_LIBRARY_PATH=/usr/lib/system/introspection
DYLD_INSERT_LIBRARIES=/Developer/usr/lib/libBacktraceRecording.dylib:/Developer/usr/lib/libMainThreadChecker.dylib:/Developer/Library/PrivateFrameworks/DTDDISupport.framework/libViewDebuggerSupport.dylib:/Developer/Library/PrivateFrameworks/GPUTools.framework/libglInterpose.dylib:/usr/lib/libMTLCapture.dylib
```
This can be reproduced by using cargo-mobile to generate a winit example project, and then attempting to run it on an iOS device (`cargo mobile init && cargo apple open`).
In our projects that depend on DisplayLink, the build instead fails with a linker error:
```
= note: Undefined symbols for architecture arm64:
"_CACurrentMediaTime", referenced from:
display_link::ios::run_callback_ios10::hda81197ff46aedbd in libapp-4f0abc1d7684103f.rlib(app-4f0abc1d7684103f.40d4iro0yz1iy487.rcgu.o)
display_link::ios::run_callback_pre_ios10::h91f085da19374320 in libapp-4f0abc1d7684103f.rlib(app-4f0abc1d7684103f.40d4iro0yz1iy487.rcgu.o)
ld: symbol(s) not found for architecture arm64
```
After reverting the change to enable dynamic linking on iOS, everything works the same as it did on Rust 1.45.2 for me.
In the future, would it be possible for me to be pinged when iOS-related PRs are made? I work for a company that intends on using Rust on iOS in production, so I'd gladly provide testing.
It's also useful in contexts not requiring the mutability of the reference.
Here's a typical cache example:
```
let checked_cache = cache.as_ref().filter(|e| e.is_valid());
let content = match checked_cache {
Some(e) => &e.content,
None => {
cache = Some(compute_cache_entry());
// unwrap is OK because we just filled the option
&cache.as_ref().unwrap().content
}
};
```
It can be changed into
```
let checked_cache = cache.as_ref().filter(|e| e.is_valid());
let content = match checked_cache {
Some(e) => &e.content,
None => &cache.insert(compute_cache_entry()).content,
};
```
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