Currently, late lint checking uses two HIR visitors: LateContext and
IdVisitor. IdVisitor only overrides visit_id, and for each node searches
for builtin lints previously added to the session; LateContext overrides
a number of methods, and runs late lints. When LateContext encounters an
item, it first has IdVisitor walk everything in it except nested items
(OnlyBodies), then recurses into it itself - i.e. there are two separate
walks.
Aside from apparently being unnecessary, this separation prevents lint
attributes (allow/deny/warn) on non-item HIR nodes from working
properly. Test case:
// generates warning without this change
fn main() { #[allow(unreachable_code)] loop { break; break; } }
LateContext contains logic to merge attributes seen into the current lint
settings while walking (with_lint_attrs), but IdVisitor does not. So
such attributes will affect late lints (because they are called from
LateContext), and if the node contains any items within it, they will
affect builtin lints within those items (because that IdVisitor is run
while LateContext is within the attributed node), but otherwise the
attributes will be ignored for builtin lints.
This change simply removes IdVisitor and moves its visit_id into
LateContext itself. Hopefully this doesn't break anything...
Also added walk calls to visit_lifetime and visit_lifetime_def
respectively, so visit_lifetime_def will recurse into the lifetime and
visit_lifetime will recurse into the name. In principle this could
confuse lint plugins. This is "necessary" because walk_lifetime calls
visit_id on the lifetime; of course, an alternative would be directly
calling visit_id (which would require manually iterating over the
lifetimes in visit_lifetime_def), but that seems less clean.
This allows you to enable *all* nested visits in a future-compatible
sort of way. Moreover, if you choose to override the `visit_nested`
methods yourself, you can "future-proof" against omissions by overriding
`nested_visit_map` to panic.
Group unused import warnings per import list
Given a file
``` rust
use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
fn main() {}
```
Show a single warning, instead of three for each unused import:
``` nocode
warning: unused imports, #[warn(unused_imports)] on by default
--> file2.rs:1:24
|
1 | use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
| ^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^
```
Include support for lints pointing at `MultilineSpan`s, instead of just
`Span`s.
Fixes#16132.
Given a file
```rust
use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
fn main() {}
```
Show a single warning, instead of three for each unused import:
```nocode
warning: unused imports, #[warn(unused_imports)] on by default
--> foo.rs:1:24
|
1 | use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
| ^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^
```
Include support for lints pointing at `MultilineSpan`s, instead of just
`Span`s.
Most of the Rust community agrees that the vec! macro is clearer when
called using square brackets [] instead of regular brackets (). Most of
these ocurrences are from before macros allowed using different types of
brackets.
There is one left unchanged in a pretty-print test, as the pretty
printer still wants it to have regular brackets.
Some lint-level attributes (like `bad-style`, or, more dramatically,
`warnings`) can affect more than one lint; it seems fairer to point out
the attribute once for each distinct lint affected. Also, a UI test is
added. This remains in the matter of #24690.
We introduce a new `one_time_diagnostics` field on
`rustc::session::Session` to hold a hashset of diagnostic messages we've
set once but don't want to see again (as uniquified by span and message
text), "lint level defined here" being the motivating example dealt with
here.
This is in the matter of #24690.
When we emit E0453 (lint level attribute overruled by outer `forbid`
lint level), it could be helpful to note where the `forbid` level was
set, for the convenience of users who, e.g., believe that the correct
fix is to weaken the `forbid` to `deny`.
This is a spiritual succesor to #34268/8531d581, in which we replaced a
number of matches of None to the unit value with `if let` conditionals
where it was judged that this made for clearer/simpler code (as would be
recommended by Manishearth/rust-clippy's `single_match` lint). The same
rationale applies to matches of None to the empty block.
