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Rollup merge of #87958 - m-ou-se:closure-migration-multispan-suggestions, r=estebank

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Closure migration multispan suggestions

This changes the `rust_2021_incompatible_closure_captures` lint to only suggest inserting the parts that need to be inserted, instead of suggesting to replace the entire closure by an almost identical closure with one statement added.

Before:
```
[...]
help: add a dummy let to cause `a` to be fully captured
   |
5  ~     let _ = || {
6  +         let _ = &a;
7  +         dbg!(a.0);
8  +         println!("1");
9  +         println!("2");
10 +         println!("3");
 ...
   |

[...]
help: add a dummy let to cause `b` to be fully captured
   |
14 |     let _ = || { let _ = &b; dbg!(b.0); };
   |                ~~~~~~~~~~~~~~~~~~~~~~~~~~

[...]
help: add a dummy let to cause `c` to be fully captured
   |
16 |     let _ = || { let _ = &c; dbg!(c.0) };
   |                ~~~~~~~~~~~~~~~~~~~~~~~~~
```

After:
```
[...]
help: add a dummy let to cause `a` to be fully captured
   |
5  ~     let _ = || {
6  +         let _ = &a;
   |

[...]
help: add a dummy let to cause `b` to be fully captured
   |
14 |     let _ = || { let _ = &b; dbg!(b.0); };
   |                  +++++++++++

[...]
help: add a dummy let to cause `c` to be fully captured
   |
16 |     let _ = || { let _ = &c; dbg!(c.0) };
   |                +++++++++++++           +
```
This commit is contained in:
Mara Bos 2021-08-16 23:37:27 +02:00 • committed by GitHub
commit d7df1b13da
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10 changed files with 96 additions and 188 deletions
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88
compiler/rustc_typeck/src/check/upvar.rs
View file

@ -47,7 +47,7 @@ use rustc_middle::ty::{
};
use rustc_session::lint;
use rustc_span::sym;
use rustc_span::{MultiSpan, Span, Symbol, DUMMY_SP};
use rustc_span::{BytePos, MultiSpan, Pos, Span, Symbol, DUMMY_SP};
use rustc_trait_selection::infer::InferCtxtExt;
use rustc_data_structures::stable_map::FxHashMap;
@ -645,6 +645,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
diagnostics_builder.note("for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>");
let diagnostic_msg = format!(
"add a dummy let to cause {} to be fully captured",
migrated_variables_concat
);
let mut closure_body_span = self.tcx.hir().span(body_id.hir_id);
// If the body was entirely expanded from a macro
@ -655,43 +660,54 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
closure_body_span = closure_body_span.parent().unwrap_or(DUMMY_SP);
}
let (span, sugg, app) =
match self.tcx.sess.source_map().span_to_snippet(closure_body_span) {
Ok(s) => {
let trimmed = s.trim_start();
let mut lines = trimmed.lines();
let line1 = lines.next().unwrap_or_default();
if let Ok(s) = self.tcx.sess.source_map().span_to_snippet(closure_body_span) {
let mut lines = s.lines();
let line1 = lines.next().unwrap_or_default();
// If the closure contains a block then replace the opening brace
// with "{ let _ = (..); "
let sugg = if line1.trim_end() == "{" {
// This is a multi-line closure with just a `{` on the first line,
// so we put the `let` on its own line.
// We take the indentation from the next non-empty line.
let line2 = lines.filter(|line| !line.is_empty()).next().unwrap_or_default();
let indent = line2.split_once(|c: char| !c.is_whitespace()).unwrap_or_default().0;
format!("{{\n{}{};{}", indent, migration_string, &trimmed[line1.len()..])
} else if line1.starts_with('{') {
format!("{{ {}; {}", migration_string, &trimmed[1..].trim_start())
} else {
format!("{{ {}; {} }}", migration_string, s)
};
(closure_body_span, sugg, Applicability::MachineApplicable)
}
Err(_) => (closure_span, migration_string.clone(), Applicability::HasPlaceholders),
};
if line1.trim_end() == "{" {
// This is a multi-line closure with just a `{` on the first line,
// so we put the `let` on its own line.
// We take the indentation from the next non-empty line.
let line2 = lines.filter(|line| !line.is_empty()).next().unwrap_or_default();
let indent = line2.split_once(|c: char| !c.is_whitespace()).unwrap_or_default().0;
diagnostics_builder.span_suggestion(
closure_body_span.with_lo(closure_body_span.lo() + BytePos::from_usize(line1.len())).shrink_to_lo(),
&diagnostic_msg,
format!("\n{}{};", indent, migration_string),
Applicability::MachineApplicable,
);
} else if line1.starts_with('{') {
// This is a closure with its body wrapped in
// braces, but with more than just the opening
// brace on the first line. We put the `let`
// directly after the `{`.
diagnostics_builder.span_suggestion(
closure_body_span.with_lo(closure_body_span.lo() + BytePos(1)).shrink_to_lo(),
&diagnostic_msg,
format!(" {};", migration_string),
Applicability::MachineApplicable,
);
} else {
// This is a closure without braces around the body.
// We add braces to add the `let` before the body.
diagnostics_builder.multipart_suggestion(
&diagnostic_msg,
vec![
(closure_body_span.shrink_to_lo(), format!("{{ {}; ", migration_string)),
(closure_body_span.shrink_to_hi(), " }".to_string()),
],
Applicability::MachineApplicable
);
}
} else {
diagnostics_builder.span_suggestion(
closure_span,
&diagnostic_msg,
migration_string,
Applicability::HasPlaceholders
);
}
let diagnostic_msg = format!(
"add a dummy let to cause {} to be fully captured",
migrated_variables_concat
);
diagnostics_builder.span_suggestion(
span,
&diagnostic_msg,
sugg,
app,
);
diagnostics_builder.emit();
},
);