rustc_trans: do not treat byval as using up registers.
Perhaps not that well-documented, `byval` pointer arguments *are not* the same as pointer arguments used by pass-by-ref, but rather the pointer is only used by LLVM to pass the *contents* on the stack.
Fixes#41375.
Fix ICE building gluon_vm
The problem was due to various places we were failing to propagate obligations. I think I got them mostly correct, but I didn't get around to writing test cases for each case.
r? @eddyb or @arielb1
Add a way to get shorter spans until `char` for pointing at defs
```rust
error[E0072]: recursive type `X` has infinite size
--> file.rs:10:1
|
10 | struct X {
| ^^^^^^^^ recursive type has infinite size
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `X` representable
```
vs
```rust
error[E0072]: recursive type `X` has infinite size
--> file.rs:10:1
|
10 | struct X {
| _^ starting here...
11 | | x: X,
12 | | }
| |_^ ...ending here: recursive type has infinite size
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `X` representable
```
Re: #35965, #38246. Follow up to #38328.
r? @jonathandturner
Ban registering obligations during InferCtxt snapshots.
Back in #33852, a flag was added to `InferCtxt` to prevent rolling back a snapshot if obligations were added to some `FulfillmentContext` during the snapshot, to prevent leaking fresh inference variables (created during that snapshot, so their indices would get reused) in obligations, which could ICE or worse.
But that isn't enough in the long run, as type-checking ends up relying on success implying that eager side-effects are fine, and while stray obligations *do* get caught nowadays, those errors prevent, e.g. the speculative coercions from #37658, which *have to* be rolled back *even* if they succeed.
We can't just allow those obligations to stay around though, because we end up, again, in ICEs or worse.
Instead, this PR modifies `lookup_method_in_trait_adjusted` to return `InferOk` containing the obligations that `Autoderef::finalize_as_infer_ok` can propagate to deref coercions.
As there shouldn't be *anything* left that registers obligations during snapshots, it's completely banned.
r? @nikomatsakis @arielb1
Move E0101 and E0102 logic into new E0282 mechanism #40013
Hello there!
## What's this?
Previously, me and @nikomatsakis worked on error messages of uninferred locals. (#38812)
This aims to build up on that by moving certain type checks from `writeback`.
With this, `E0101` and `E0102` errors are getting obsoleted and no longer thrown.
They're replaced with customized versions of `E0282`s instead.
## Sample Error Messages
#### `E0101` is getting converted into:
```rust
error[E0282]: type annotations needed
--> test.rs:2:14
|
2 | let x = |_| {};
| ^ consider giving this closure parameter a type
error: aborting due to previous error
```
#### `E0102` is getting converted into:
```rust
error[E0282]: type annotations needed
--> test.rs:2:9
|
2 | let x = [];
| ^
| |
| consider giving `x` a type
| cannot infer type for `[_; 0]`
error: aborting due to previous error
```
## Annoyances
- I think we need to change our way of type name resolving in relevant places, because that `[_; 0]` looks horrible IMHO.
- I'm not terribly happy with the note ordering of errors. So please do point to code that might help me accomplish this.
## Tests
Tests of `E0101` and `E0102` are getting converted from `compile-fail` to `ui` tests.
## Documentation
Please help me with documentation update. There are some confusing places that needed an update but I'm not sure if I did the right ones.
Please do comment on messages, layouts and other details.
## Appreciation
Huge thanks goes to @nikomatsakis for being a patient and humble mentor along this long journey. 🍻
lower `move_val_init` during MIR construction
Because of its "magic" order-of-evaluation semantics, `move_val_init` must be lowered during MIR construction in order to work without needing a temporary.
r? @eddyb
[on-demand] Turn monomorphic_const_eval into a proper query, not just a cache.
The error definitions and reporting logic, alongside with `eval_length` were moved to `librustc`.
Both local and cross-crate constant evaluation is on-demand now, but the latter is only used for `enum` discriminants, to replace the manual insertion into the cache which was done when decoding variants.
r? @nikomatsakis
:vis matcher for macro_rules
Resurrection of @DanielKeep's implementation posted with [RFC 1575](https://github.com/rust-lang/rfcs/pull/1575).
@jseyfried was of the opinion that this doesn't need an RFC.
Needed before merge:
- [x] sign-off from @DanielKeep since I stole his code
- [x] feature gate
- [x] docs
Specialize Vec::from_elem to use calloc
Fixes#38723. This specializes the implementation for `u8` only, but it could be extended to other zeroable types if desired.
I haven't tested this extensively, but I did verify that it gives the expected performance boost for large `vec![0; n]` allocations with both alloc_system and jemalloc, on Linux. (I have not tested or even built the Windows code.)
Do not desugar if-let-else to match arm guards
Fixes#41272
Changed the desugaring code
**Before**
```rust
match <sub_expr> {
<pat> => <body>,
[_ if <else_opt_if_cond> => <else_opt_if_body>,]
_ => [<else_opt> | ()]
}
```
**After**
```rust
match <sub_expr> {
<pat> => <body>,
_ => [<else_opt> | ()]
}
```
With this fix, it doesn't cause E0301
I've added some explicit tests that negative impls are allowed to
overlap, and also to make sure that the feature doesn't interfere with
specialization. I've not added an explicit test for positive overlapping
with negative, as that's already tested elsewhere.
This patch allows overlap to occur between any two impls of a trait for
traits which have no associated items.
Several compile-fail tests around coherence had to be changed to add at
least one item to the trait they test against.
Ref #29864
Fix rustdoc infinitely recursing when an external crate reexports itself
Previously, rustdoc's LibEmbargoVisitor unconditionally visited the
child modules of an external crate. If a module re-exported its parent
via `pub use super::*`, rustdoc would re-walk the parent, leading to
infinite recursion.
This commit makes LibEmbargoVisitor store already visited modules in an
FxHashSet, ensuring that each module is only walked once.
Fixes#40936
Implement global_asm!() (RFC 1548)
This is a first attempt. ~~One (potential) problem I haven't solved is how to handle multiple usages of `global_asm!` in a module/crate. It looks like `LLVMSetModuleInlineAsm` overwrites module asm, and `LLVMAppendModuleInlineAsm` is not provided in LLVM C headers 😦~~
I can provide more detail as needed, but honestly, there's not a lot going on here.
r? @eddyb
CC @Amanieu @jackpot51
Tracking issue: #35119
rustc_typeck: consolidate adjustment composition
Instead of having `write_adjustment` overwrite the previous adjustment, have `apply_adjustment` compose a new adjustment on top of the previous one. This is important because `NeverToAny` adjustments can be present on expressions during coercion.
Fixes#41213.
r? @nikomatsakis
Fix invalid 128-bit division on 32-bit target (#41228)
The bug of #41228 is a typo, this line: 1dca19ae3f/src/libcompiler_builtins/lib.rs (L183)
```rust
// 1 <= sr <= u64::bits() - 1
q = n.wrapping_shl(64u32.wrapping_sub(sr));
```
The **64** should be **128**.
(Compare with 280d19f112/src/int/udiv.rs (L213-L214):
```rust
// 1 <= sr <= <hty!($ty)>::bits() - 1
q = n << (<$ty>::bits() - sr);
```
Or compare with the C implementation https://github.com/llvm-mirror/compiler-rt/blob/master/lib/builtins/udivmodti4.c#L113-L116
```c
/* 1 <= sr <= n_udword_bits - 1 */
/* q.all = n.all << (n_utword_bits - sr); */
q.s.low = 0;
q.s.high = n.s.low << (n_udword_bits - sr);
```
)
Added a bunch of randomly generated division test cases to try to cover every described branch of `udivmodti4`.
Improve the LLVM IR we generate for trivial functions, especially #[naked] ones.
These two small changes fixedef1c/libfringe#68:
* Don't emit ZST allocas, such as when returning `()`
* Don't emit a branch from LLVM's entry block to MIR's `START_BLOCK` unless needed
* That is, if a loop branches back to it, although I'm not sure that's even valid MIR
Windows builder croaked. This change tries to fix that by actually
calling the global_asm-defined function so the symbol doesn't get
optimized away, if that is in fact what was happening.
Additionally, we provide an empty main() for non-x86 arches.
Handle subtyping in inference through obligations
We currently store subtyping relations in the `TypeVariables` structure as a kind of special case. This branch uses normal obligations to propagate subtyping, thus converting our inference variables into normal fallback. It also does a few other things:
- Removes the (unstable, outdated) support for custom type inference fallback.
- It's not clear how we want this to work, but we know that we don't want it to work the way it currently does.
- The existing support was also just getting in my way.
- Fixes#30225, which was caused by the trait caching code pretending type variables were normal unification variables, when indeed they were not (but now are).
There is one fishy part of these changes: when computing the LUB/GLB of a "bivariant" type parameter, I currently return the `a` value. Bivariant type parameters are only allowed in a very particular situation, where the type parameter is only used as an associated type output, like this:
```rust
pub struct Foo<A, B>
where A: Fn() -> B
{
data: A
}
```
In principle, if one had `T=Foo<A, &'a u32>` and `U=Foo<A, &'b u32>` and (e.g.) `A: for<'a> Fn() -> &'a u32`, then I think that computing the LUB of `T` and `U` might do the wrong thing. Probably the right behavior is just to create a fresh type variable. However, that particular example would not compile (because the where-clause is illegal; `'a` does not appear in any input type). I was not able to make an example that *would* compile and demonstrate this shortcoming, and handling the LUB/GLB was mildly inconvenient, so I left it as is. I am considering whether to revisit this or what.
I have started a crater run to test the impact of these changes.
