Linker flavors next steps: linker features
This is my understanding of the first step towards `@petrochenkov's` vision for the future of linker flavors, described in https://github.com/rust-lang/rust/pull/119906#issuecomment-1895693162 and the discussion that followed.
To summarize: having `Cc` and `Lld` embedded in linker flavors creates tension about naming, and a combinatorial explosion of flavors for each new linker feature we'd want to use. Linker features are an extension mechanism that is complementary to principal flavors, with benefits described in #119906.
The most immediate use of this flag would be to turn self-contained linking on and off via features instead of flavors. For example, `-Clinker-features=+/-lld` would toggle using lld instead of selecting a precise flavor, and would be "generic" and work cross-platform (whereas linker flavors are currently more tied to targets). Under this scheme, MCP510 is expected to be `-Clink-self-contained=+linker -Zlinker-features=+lld -Zunstable-options` (though for the time being, the original flags using lld-cc flavors still work).
I purposefully didn't add or document CLI support for `+/-cc`, as it would be a noop right now. I only expect that we'd initially want to stabilize `+/-lld` to begin with.
r? `@petrochenkov`
You had requested that minimal churn would be done to the 230 target specs and this does none yet: the linker features are inferred from the flavor since they're currently isomorphic. We of course expect this to change sooner rather than later.
In the future, we can allow targets to define linker features independently from their flavor, and remove the cc and lld components from the flavors to use the features instead, this actually doesn't need to block stabilization, as we discussed.
(Best reviewed per commit)
Detect borrow checker errors where `.clone()` would be an appropriate user action
When a value is moved twice, suggest cloning the earlier move:
```
error[E0509]: cannot move out of type `U2`, which implements the `Drop` trait
--> $DIR/union-move.rs:49:18
|
LL | move_out(x.f1_nocopy);
| ^^^^^^^^^^^
| |
| cannot move out of here
| move occurs because `x.f1_nocopy` has type `ManuallyDrop<RefCell<i32>>`, which does not implement the `Copy` trait
|
help: consider cloning the value if the performance cost is acceptable
|
LL | move_out(x.f1_nocopy.clone());
| ++++++++
```
When a value is borrowed by an `fn` call, consider if cloning the result of the call would be reasonable, and suggest cloning that, instead of the argument:
```
error[E0505]: cannot move out of `a` because it is borrowed
--> $DIR/variance-issue-20533.rs:53:14
|
LL | let a = AffineU32(1);
| - binding `a` declared here
LL | let x = bat(&a);
| -- borrow of `a` occurs here
LL | drop(a);
| ^ move out of `a` occurs here
LL | drop(x);
| - borrow later used here
|
help: consider cloning the value if the performance cost is acceptable
|
LL | let x = bat(&a).clone();
| ++++++++
```
otherwise, suggest cloning the argument:
```
error[E0505]: cannot move out of `a` because it is borrowed
--> $DIR/variance-issue-20533.rs:59:14
|
LL | let a = ClonableAffineU32(1);
| - binding `a` declared here
LL | let x = foo(&a);
| -- borrow of `a` occurs here
LL | drop(a);
| ^ move out of `a` occurs here
LL | drop(x);
| - borrow later used here
|
help: consider cloning the value if the performance cost is acceptable
|
LL - let x = foo(&a);
LL + let x = foo(a.clone());
|
```
This suggestion doesn't attempt to square out the types between what's cloned and what the `fn` expects, to allow the user to make a determination on whether to change the `fn` call or `fn` definition themselves.
Special case move errors caused by `FnOnce`:
```
error[E0382]: use of moved value: `blk`
--> $DIR/once-cant-call-twice-on-heap.rs:8:5
|
LL | fn foo<F:FnOnce()>(blk: F) {
| --- move occurs because `blk` has type `F`, which does not implement the `Copy` trait
LL | blk();
| ----- `blk` moved due to this call
LL | blk();
| ^^^ value used here after move
|
note: `FnOnce` closures can only be called once
--> $DIR/once-cant-call-twice-on-heap.rs:6:10
|
LL | fn foo<F:FnOnce()>(blk: F) {
| ^^^^^^^^ `F` is made to be an `FnOnce` closure here
LL | blk();
| ----- this value implements `FnOnce`, which causes it to be moved when called
```
Account for redundant `.clone()` calls in resulting suggestions:
```
error[E0507]: cannot move out of dereference of `S`
--> $DIR/needs-clone-through-deref.rs:15:18
|
LL | for _ in self.clone().into_iter() {}
| ^^^^^^^^^^^^ ----------- value moved due to this method call
| |
| move occurs because value has type `Vec<usize>`, which does not implement the `Copy` trait
|
note: `into_iter` takes ownership of the receiver `self`, which moves value
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
help: you can `clone` the value and consume it, but this might not be your desired behavior
|
LL | for _ in <Vec<usize> as Clone>::clone(&self).into_iter() {}
| ++++++++++++++++++++++++++++++ ~
```
We use the presence of `&mut` values in a move error as a proxy for the user caring about side effects, so we don't emit a clone suggestion in that case:
```
error[E0505]: cannot move out of `s` because it is borrowed
--> $DIR/borrowck-overloaded-index-move-index.rs:53:7
|
LL | let mut s = "hello".to_string();
| ----- binding `s` declared here
LL | let rs = &mut s;
| ------ borrow of `s` occurs here
...
LL | f[s] = 10;
| ^ move out of `s` occurs here
...
LL | use_mut(rs);
| -- borrow later used here
```
We properly account for `foo += foo;` errors where we *don't* suggest `foo.clone() += foo;`, instead suggesting `foo += foo.clone();`.
---
Each commit can be reviewed in isolation. There are some "cleanup" commits, but kept them separate in order to show *why* specific changes were being made, and their effect on tests' output.
Fix#49693, CC #64167.
Re-enable `has_thread_local` for i686-msvc
A few years back, `has_thread_local` was disabled as a workaround for a compiler issue. While the exact cause was never tracked down, it was suspected to be caused by the compiler inlining a thread local access across a dylib boundary. This should be fixed now so let's try again.
Merge cuviper in the mailmap
These emails are associated with my GitHub account already, but I might as well
combine my activity for stuff like the Thanks page too.
Avoid more NonNull-raw-NonNull roundtrips in Vec
r? the8472
The standard library in general has a lot of these round-trips from niched types to their raw innards and back. Such round-trips have overhead in debug builds since https://github.com/rust-lang/rust/pull/120594. I removed some such round-trips in that initial PR and I've been meaning to come back and hunt down more such examples (this is the last item on https://github.com/rust-lang/rust/issues/120848).
Add `/System/iOSSupport` to the library search path on Mac Catalyst
On macOS, `/System/iOSSupport` contains iOS frameworks like UIKit, which is the whole idea of Mac Catalyst.
To link to these, we need to explicitly tell the linker about the support library stubs provided in the macOS SDK under the same path.
Concretely, when building a binary for Mac Catalyst, Xcode passes the following flags to the linker:
```
-iframework /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/System/iOSSupport/System/Library/Frameworks
-L/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.2.sdk/System/iOSSupport/usr/lib
```
This is not something that can be disabled (it's enabled as soon as you enable `SUPPORTS_MACCATALYST`), so I think it's pretty safe to say that we don't need an option to turn these off.
I've chosen to slightly deviate from what Xcode does and use `-F` instead of `-iframework`, since we don't need to change the header search path, and this way the flags nicely match on all the linkers. From what I could tell by reading Clang sources, there shouldn't be a difference when just running the linker.
CC `@BlackHoleFox,` `@shepmaster` (I accidentally let rustbot choose the reviewer).
zkvm: fix path to cmath in zkvm module
I don't know why the original author decided to use relative paths.
I think it would be better to use `use crate::sys::cmath;`
The according issue can be found here https://github.com/risc0/risc0/issues/1647
Remove `sys_common::thread`
Part of #117276.
The stack size calculation isn't system-specific at all and can just live together with the rest of the spawn logic.
typeck: fix `?` suggestion span
Noticed in <https://github.com/rust-lang/rust/pull/112043#issuecomment-2043565292>, if the
```
use the `?` operator to extract the `Result<(), std::fmt::Error>` value, propagating a `Result::Err` value to the caller
```
suggestion is applied to a macro that comes from a non-local crate (e.g. the stdlib), the suggestion span can become non-local, which will cause newer rustfix versions to fail.
This PR tries to remedy the problem by recursively probing ancestors of the expression span, trying to identify the most ancestor span that is (1) still local, and (2) still shares the same syntax context as the expression.
This is the same strategy used in https://github.com/rust-lang/rust/pull/112043.
The test unfortunately cannot `//@ run-rustfix` because there are two conflicting MaybeIncorrect suggestions that when collectively applied, cause the fixed source file to become non-compilable.
Also avoid running `//@ run-rustfix` for `tests/ui/typeck/issue-112007-leaked-writeln-macro-internals.rs` because that also contains conflicting suggestions.
cc `@ehuss` who noticed this. This question mark span fix + not running rustfix on the tests containing conflicting MaybeIncorrect suggestions should hopefully unblock rustfix from updating.
The suggestion to use `let else` with an uninitialized refutable `let`
statement was erroneous: `let else` cannot be used with deferred
initialization.
Improve diagnostic by suggesting to remove visibility qualifier
Resolves#123529
This PR improve diagnostic by suggesting to remove visibility qualifier.
Update stdarch submodule
`asm_experimental_arch` is required in `core` as we're now using unstable inline assembly when building Arm64EC.
Brings in the fix for <https://github.com/rust-lang/stdarch/issues/1555> (cc `@tslnc04).`
r? `@Amanieu`
Call the panic hook for non-unwind panics in proc-macros
As I suggested in https://github.com/rust-lang/rust/issues/123286#issuecomment-2030344815.
If a proc macro causes a non-unwinding panic, `proc_macro` isn't able to catch the unwind and report the panic as a compile error by passing control back to the compiler. Our only chance to produce any diagnostic is the panic hook, so we should call it.
This scenario has already existed, but has become a lot more interesting now that we're adding more UB-detecting panics to the standard library, and such panics do not unwind.
Fix invalid silencing of parsing error
Given
```rust
macro_rules! a {
( ) => {
impl<'b> c for d {
e::<f'g>
}
};
}
```
ensure an error is emitted.
Fix#123079.
Add a `Debug` impl and some basic functions to `f16` and `f128`
`compiler_builtins` uses some convenience functions like `is_nan` and `is_sign_positive`. Add these, as well as a temporary implementation for `Debug` that prints the bit representation.
