Revert "fix treatment of local types in "remote coherence" mode"
That commit had accidentally snuck in into #44884 and it causes regressions. Revert it.
This reverts commit c48650ec25.
@bors p=10 - fixes breakage in nightly
r? @eddyb
Implement the special repr(C)-non-clike-enum layout
This is the second half of https://github.com/rust-lang/rfcs/pull/2195
which specifies that
```rust
#[repr(C, u8)]
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
enum MyEnum {
A(u32), // Single primitive value
B { x: u8, y: i16 }, // Composite, and the offset of `y` depends on tag being internal
C, // Empty
D(Option<u32>), // Contains an enum
E(Duration), // Contains a struct
}
```
Has the same layout as
```rust
#[repr(C)]
struct MyEnumRepr {
tag: MyEnumTag,
payload: MyEnumPayload,
}
#[repr(C)]
#[allow(non_snake_case)]
union MyEnumPayload {
A: MyEnumVariantA,
B: MyEnumVariantB,
D: MyEnumVariantD,
E: MyEnumVariantE,
}
#[repr(u8)] #[derive(Copy, Clone)] enum MyEnumTag { A, B, C, D, E }
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantA(u32);
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantB {x: u8, y: i16 }
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantD(Option<u32>);
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantE(Duration);
```
Make accesses to fields of packed structs unsafe
To handle packed structs with destructors (which you'll think are a rare
case, but the `#[repr(packed)] struct Packed<T>(T);` pattern is
ever-popular, which requires handling packed structs with destructors to
avoid monomorphization-time errors), drops of subfields of packed
structs should drop a local move of the field instead of the original
one.
That's it, I think I'll use a strategy suggested by @Zoxc, where this mir
```
drop(packed_struct.field)
```
is replaced by
```
tmp0 = packed_struct.field;
drop tmp0
```
cc #27060 - this should deal with that issue after codegen of drop glue
is updated.
The new errors need to be changed to future-compatibility warnings, but
I'll rather do a crater run first with them as errors to assess the
impact.
cc @eddyb
Things which still need to be done for this:
- [ ] - handle `repr(packed)` structs in `derive` the same way I did in `Span`, and use derive there again
- [ ] - implement the "fix packed drops" pass and call it in both the MIR shim and validated MIR pipelines
- [ ] - do a crater run
- [ ] - convert the errors to compatibility warnings
Add a MIR-borrowck-only output mode
Removes the `-Z borrowck-mir` flag in favour of a `-Z borrowck=mode` flag where mode can be `mir`, `ast`, or `compare`.
* The `ast` mode represents the current default, passing `-Z borrowck=ast` is equivalent to not passing it at all.
* The `compare` mode outputs both the output of the MIR borrow checker and the AST borrow checker, each error with `(Ast)` and `(Mir)` appended. This mode has the same behaviour as `-Z borrowck-mir` had before this commit.
* The `mir` mode only outputs the results of the MIR borrow checker, while suppressing the errors of the ast borrow checker
The PR also updates the tests to use the new flags.
closes #46097
introduce macros for type-foldable and lift, convert stuff to use them
A random commit from a branch I've shelved for the time being that made `TypeFoldable` stuff a bit less annoying to write.
r? @eddyb
rustc: don't mark lifetimes as early-bound in the presence of impl Trait.
This hack from the original implementation shouldn't be needed anymore, thanks to @cramertj.
r? @nikomatsakis
incr.comp.: Make sure we don't lose unused green results from the query cache.
In its current implementation, the query result cache works by bulk-writing the results of all cacheable queries into a monolithic binary file on disk. Prior to this PR, we would potentially lose query results during this process because only results that had already been loaded into memory were serialized. In contrast, results that were not needed during the given compilation session were not serialized again.
This PR will do one pass over all green `DepNodes` that represent a cacheable query and execute the corresponding query in order to make sure that the query result gets loaded into memory before cache serialization.
In the future we might want to look into a serialization format the can be updated in-place so that we don't have to load unchanged results just for immediately storing them again.
r? @nikomatsakis
Add a MIR pass to lower 128-bit operators to lang item calls
Runs only with `-Z lower_128bit_ops` since it's not hooked into targets yet.
This isn't really useful on its own, but the declarations for the lang items need to be in the compiler before compiler-builtins can be updated to define them, so this is part 1 of at least 3.
cc https://github.com/rust-lang/rust/issues/45676 @est31 @nagisa
typeck aggregate rvalues in MIR type checker
This branch is an attempt to land content by @spastorino and @Nashenas88 that was initially landed on nll-master while we waited for https://github.com/rust-lang/rust/pull/45825 to land.
The biggest change it contains is that it extends the MIR type-checker to also type-check MIR aggregate rvalues (at least partially). Specifically, it checks that the operands provided for each field have the right type.
It does not yet check that their well-formedness predicates are met. That is https://github.com/rust-lang/rust/issues/45827. It also does not check other kinds of rvalues (that is https://github.com/rust-lang/rust/issues/45959). @spastorino is working on those issues now.
r? @arielb1
Implement in-band lifetime bindings
TODO (perhaps in a future PR): Should we ban explicit instantiation of generics with in-band lifetimes, or is it uncontroversial to just append them to the end of the lifetimes list?
Fixes#46042, cc #44524.
r? @nikomatsakis
Use the proper term when using non-existing variant
When using a non-existing variant, function or associated item, refer to
the proper term, instead of defaulting to "associated item" in
diagnostics.
Fix#28972.
```
error[E0599]: no variant named `Quux` found for type `Foo` in the current scope
--> file.rs:7:9
|
7 | Foo::Quux(..) =>(),
| ^^^^^^^^^^^^^
```
move closure kind, signature into `ClosureSubsts`
Instead of using side-tables, store the closure-kind and signature in the substitutions themselves. This has two key effects:
- It means that the closure's type changes as inference finds out more things, which is very nice.
- As a result, it avoids the need for the `freshen_closure_like` code (though we still use it for generators).
- It avoids cyclic closures calls.
- These were never meant to be supported, precisely because they make a lot of the fancy inference that we do much more complicated. However, due to an oversight, it was previously possible -- if challenging -- to create a setup where a closure *directly* called itself (see e.g. #21410).
We have to see what the effect of this change is, though. Needs a crater run. Marking as [WIP] until that has been assessed.
r? @arielb1
clean the Debug impl for CrateNum and DefId
Just a tiny quality-of-life improvement because I got tired of noisy debug logs.
```
before: DefId { krate: CrateNum(11), index: DefIndex(0:6) => foo[8787]::Mapper[0]::OtherType[0] } }
after: {crate11:0:6 ~ foo[8787]::Mapper[0]::OtherType[0]})
```
r? @michaelwoerister
dead code lint to say "never constructed" for variants
As reported in #19140, #44083, and #44565, some users were confused when
the dead-code lint reported an enum variant to be "unused" when it was
matched on (but not constructed). This wording change makes it clearer
that the lint is in fact checking for construction.
We continue to say "used" for all other items (it's tempting to say
"called" for functions and methods, but this turns out not to be
correct: functions can be passed as arguments and the dead-code lint
isn't special-casing that or anything).
Resolves#19140.
r? @pnkfelix
impl Trait Lifetime Handling
This PR implements the updated strategy for handling `impl Trait` lifetimes, as described in [RFC 1951](https://github.com/rust-lang/rfcs/blob/master/text/1951-expand-impl-trait.md) (cc #42183).
With this PR, the `impl Trait` desugaring works as follows:
```rust
fn foo<T, 'a, 'b, 'c>(...) -> impl Foo<'a, 'b> { ... }
// desugars to
exists type MyFoo<ParentT, 'parent_a, 'parent_b, 'parent_c, 'a, 'b>: Foo<'a, 'b>;
fn foo<T, 'a, 'b, 'c>(...) -> MyFoo<T, 'static, 'static, 'static, 'a, 'b> { ... }
```
All of the in-scope (parent) generics are listed as parent generics of the anonymous type, with parent regions being replaced by `'static`. Parent regions referenced in the `impl Trait` return type are duplicated into the anonymous type's generics and mapped appropriately.
One case came up that wasn't specified in the RFC: it's possible to write a return type that contains multiple regions, neither of which outlives the other. In that case, it's not clear what the required lifetime of the output type should be, so we generate an error.
There's one remaining FIXME in one of the tests: `-> impl Foo<'a, 'b> + 'c` should be able to outlive both `'a` and `'b`, but not `'c`. Currently, it can't outlive any of them. @nikomatsakis and I have discussed this, and there are some complex interactions here if we ever allow `impl<'a, 'b> SomeTrait for AnonType<'a, 'b> { ... }`, so the plan is to hold off on this until we've got a better idea of what the interactions are here.
cc #34511.
Fixes#44727.
show macro backtrace with -Z flag
Fixes#39413 by adding a facility to restore the "old school" macro expansion backtraces (previously removed in 61865384b8).
The restored functionality is accessed through the flag `-Z external-macro-backtrace`. Errors showing the truncated backtraces will suggest this flag.
### Example
Code: <details>
`a/src/lib.rs`
```rust
#[macro_export]
macro_rules! a {
() => { a!(@) };
(@) => { a!(@@) };
(@@) => {
syntax error;
}
}
```
`b/src/main.rs`
```rust
#[macro_use] extern crate a;
macro_rules! b {
() => { b!(@) };
(@) => { b!(@@) };
(@@) => {
syntax error;
}
}
fn main() {
a!();
b!();
}
```
</details>
<br/><br/>
Running without env var (note: first error is from remote macro, second from local macro):
<details>
```
$ cargo +custom run
Compiling b v0.1.0
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:12:5
|
12 | a!();
| ^^^^^
| |
| expected one of 8 possible tokens here
| unexpected token
|
= note: this error originates in a macro outside of the current crate (run with RUST_MACRO_BACKTRACE=1 for more info)
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:7:16
|
7 | syntax error;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
...
13 | b!();
| ----- in this macro invocation
error: aborting due to 2 previous errors
error: Could not compile `b`.
To learn more, run the command again with --verbose.
```
</details>
The output is the same as today, except for an addition to the note which aids discoverability of the new environment variable.
<br/><br/>
Running _with_ env var:
<details>
```
$ RUST_MACRO_BACKTRACE=1 cargo +custom run
Compiling b v0.1.0
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> <a macros>:1:72
|
1 | ( ) => { a ! ( @ ) } ; ( @ ) => { a ! ( @ @ ) } ; ( @ @ ) => { syntax error ;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
src/main.rs:12:5: 12:10 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:11: 1:20 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:36: 1:47 note: in this expansion of a! (defined in <a macros>)
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:7:16
|
7 | syntax error;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
src/main.rs:12:5: 12:10 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:11: 1:20 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:36: 1:47 note: in this expansion of a! (defined in <a macros>)
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:7:16
|
7 | syntax error;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
src/main.rs:13:5: 13:10 note: in this expansion of b! (defined in src/main.rs)
src/main.rs:4:13: 4:18 note: in this expansion of b! (defined in src/main.rs)
src/main.rs:5:14: 5:20 note: in this expansion of b! (defined in src/main.rs)
error: aborting due to 2 previous errors
error: Could not compile `b`.
To learn more, run the command again with --verbose.
```
</details>
The output is hard to read, but better than nothing (and it's exactly what we used to have before the infamous `fix_multispans_in_std_macros`).
<br/><br/>
Wishlist:
- Save the actual source of macros in crate metadata, not just AST, so the output can be improved
- Hopefully this would allow line numbers in the trace as well
- Show the actual macro invocations in the traces
r? @nrc
