The `try_coerce` method coerces from a source to a target
type, possibly inserting adjustments. It should guarantee
that the post-adjustment type is a subtype of the target type
(or else that some side-constraint has been registered which will lead
to an error). However, it used to return the (possibly adjusted) source
as the type of the expression rather than the target. This led to
less good downstream errors.
To work around this, the code around blocks -- and particular tail
expressions in blocks -- had some special case manipulation. However,
since that code is now using the more general `CoerceMany` construct (to
account for breaks), it can no longer take advantage of that. This lead
to some regressions in compile-fail tests were errors were reported at
"less good" locations than before.
This change modifies coercions to return the target type when successful
rather the source type. This extends the behavior from blocks to all
coercions. Typically this has limited effect but on a few tests yielded
better errors results (and avoided regressions, of course).
This change also restores the hint about removing semicolons which went
missing (by giving 'force-unit' coercions a chance to add notes etc).
For the most part, the current code performs similarly, although it
differs in some particulars. I'll be nice to have these tests for
judging future changes, as well.
First, we keep a `CoerceMany` now to find the LUB of all the break
expressions. Second, this `CoerceMany` is actually an
`Option<CoerceMany>`, and we store `None` for loops where "break with an
expression" is disallowed. This avoids silly duplicate errors about a
type mismatch, since the loops pass already reports an error that the
break cannot have an expression. Finally, since we now detect an invalid
break target during HIR lowering, refactor `find_loop` to be infallible.
Adjust tests as needed:
- some spans from breaks are slightly different
- break up a single loop into multiple since `CoerceMany` silences
redundant and derived errors
- add a ui test that we only give on error for loop-break-value
Instead, wait until coercion time. This has some small effects on a few
tests (one less temporary, generally better errors when trying to call
methods or otherwise "force" the type).
`match { }` now (correctly?) indicates divergence, which results in more
unreachable warnings. We also avoid fallback to `!` if there is just one
arm (see new test: `match-unresolved-one-arm.rs`).
The new strategy is as follows. First, the `!` type is assigned
in two cases:
- a block with a diverging statement and no tail expression (e.g.,
`{return;}`);
- any expression with the type `!` is considered diverging.
Second, we track when we are in a diverging state, and we permit a value
of any type to be coerced **into** `!` if the expression that produced
it is diverging. This means that `fn foo() -> ! { panic!(); 22 }`
type-checks, even though the block has a type of `usize`.
Finally, coercions **from** the `!` type to any other are always
permitted.
Fixes#39808.
macros: improve `Span`'s expansion information
This PR improves `Span`'s expansion information. More specifically:
- It refactors AST node span construction to preserve expansion information.
- Today, we only use the underlying tokens' `BytePos`s, throwing away the `ExpnId`s.
- This improves the accuracy of AST nodes' expansion information, fixing #30506.
- It refactors `span.expn_id: ExpnId` to `span.ctxt: SyntaxContext` and removes `ExpnId`.
- This gives all tokens as much hygiene information as `Ident`s.
- This is groundwork for procedural macros 2.0 `TokenStream` API.
- This is also groundwork for declarative macros 2.0, which will need this hygiene information for some non-`Ident` tokens.
- It simplifies processing of spans' expansion information throughout the compiler.
- It fixes#40649.
- It fixes#39450 and fixes part of #23480.
r? @nrc
Clarify suggetion for field used as method
Instead of
```rust
error: no method named `src_addr` found for type `&wire::ipv4::Repr` in the current scope
--> src/wire/ipv4.rs:409:34
|
409 | packet.set_src_addr(self.src_addr());
| ^^^^^^^^
|
note: did you mean to write `self.src_addr`?
--> src/wire/ipv4.rs:409:34
|
409 | packet.set_src_addr(self.src_addr());
| ^^^^^^^^
```
present
```rust
error: no method named `src_addr` found for type `&wire::ipv4::Repr` in the current scope
--> src/wire/ipv4.rs:409:34
|
409 | packet.set_src_addr(self.src_addr());
| ^^^^^^^^ field, not a method
|
= help: did you mean to write `self.src_addr` instead of `self.src_addr(...)`?
```
Fix#38321.
Rustdoc: memoize `pub use`-reexported macros so they don't appear twice in docs
Closes#39436
Preserves existing behavior for `#[macro_reexport]`. `pub use`'d macros are shown as reexports unless inlined, and also correctly obey `#[doc(hidden)]`.
r? @jseyfried
cc @SergioBenitez
borrowck: consolidate `mut` suggestions
This converts all of borrowck's `mut` suggestions to a new
`mc::ImmutabilityBlame` API instead of the current mix of various hacks.
Fixes#35937.
Fixes#40823.
Fixes#40859.
cc @estebank
r? @pnkfelix
store a copy of the Issue32230 info within TypeError
The data can't be looked up from the region variable directly, because
the region variable might have been destroyed at the end of a snapshot.
Fixes#40000.
Fixes#40743.
beta-nominating because regression.
r? @nikomatsakis
std: Don't cache stdio handles on Windows
This alters the stdio code on Windows to always call `GetStdHandle` whenever the
stdio read/write functions are called as this allows us to track changes to the
value over time (such as if a process calls `SetStdHandle` while it's running).
Closes#40490
keep the AST node-id when lowering ExprKind::Range
When the Range expression is the root of a constant, its node-id is
used for the def-id of the body, so it has to be preserved in the AST ->
HIR lowering.
Fixes#40749.
r? @eddyb
beta-nominating because regression
This converts all of borrowck's `mut` suggestions to a new
`mc::ImmutabilityBlame` API instead of the current mix of various hacks.
Fixes#35937.
Fixes#40823.
Allow `use` macro imports to shadow global macros
Terminology:
- global scope: builtin macros, macros from the prelude, `#[macro_use]`, or `#![plugin(..)]`.
- legacy scope: crate-local `macro_rules!`.
- modern scope: `use` macro imports, `macro` (once implemented).
Today, the legacy scope can shadow the global scope (modulo RFC 1560 expanded shadowing restrictions). However, the modern scope cannot shadow or be shadowed by either the global or legacy scopes, leading to ambiguity errors.
This PR allows the modern scope to shadow the global scope (subject to some restrictions).
More specifically, a name in the global scope is as shadowable as a glob import in the module `self`. In other words, we imagine a special, implicit glob import in each module item:
```rust
mod foo {
#[lexical_only] // Not accessible via `foo::<name>`, like pre-RFC 1560 `use` imports.
#[shadowable_by_legacy_scope] // for back-compat
use <global_macros>::*;
}
```
r? @nrc
The data can't be looked up from the region variable directly, because
the region variable might have been destroyed at the end of a snapshot.
Fixes#40000.
Fixes#40743.
Remove internal liblog
This commit deletes the internal liblog in favor of the implementation that
lives on crates.io. Similarly it's also setting a convention for adding crates
to the compiler. The main restriction right now is that we want compiler
implementation details to be unreachable from normal Rust code (e.g. requires a
feature), and by default everything in the sysroot is reachable via `extern
crate`.
The proposal here is to require that crates pulled in have these lines in their
`src/lib.rs`:
#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
This'll mean that by default they're not using these attributes but when
compiled as part of the compiler they do a few things:
* Mark themselves as entirely unstable via the `staged_api` feature and the
`#![unstable]` attribute.
* Allow usage of other unstable crates via `feature(rustc_private)` which is
required if the crate relies on any other crates to compile (other than std).
Instead of
```
error: no method named `src_addr` found for type `&wire::ipv4::Repr` in the current scope
--> src/wire/ipv4.rs:409:34
|
409 | packet.set_src_addr(self.src_addr());
| ^^^^^^^^
|
note: did you mean to write `self.src_addr`?
--> src/wire/ipv4.rs:409:34
|
409 | packet.set_src_addr(self.src_addr());
| ^^^^^^^^
```
present
```
error: no method named `src_addr` found for type `&wire::ipv4::Repr` in the current scope
--> src/wire/ipv4.rs:409:34
|
409 | packet.set_src_addr(self.src_addr());
| ^^^^^^^^ `src_addr` is a field, not a method
|
= help: did you mean to write `self.src_addr` instead of `self.src_addr(...)`?
```
