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Change pattern borrowing suggestions to be verbose

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Synthesize a more accurate span and use verbose suggestion output to
make the message clearer.
This commit is contained in:
Esteban Küber 2022-12-08 09:02:54 -08:00
parent ed620cf969
commit e46416eed6
41 changed files with 1309 additions and 766 deletions
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64
compiler/rustc_borrowck/src/diagnostics/move_errors.rs
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@ -4,7 +4,7 @@ use rustc_middle::ty;
use rustc_mir_dataflow::move_paths::{
IllegalMoveOrigin, IllegalMoveOriginKind, LookupResult, MoveError, MovePathIndex,
};
use rustc_span::Span;
use rustc_span::{BytePos, Span};
use crate::diagnostics::{DescribePlaceOpt, UseSpans};
use crate::prefixes::PrefixSet;
@ -148,7 +148,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
match_span: Span,
statement_span: Span,
) {
debug!("append_binding_error(match_place={:?}, match_span={:?})", match_place, match_span);
debug!(?match_place, ?match_span, "append_binding_error");
let from_simple_let = match_place.is_none();
let match_place = match_place.unwrap_or(move_from);
@ -160,7 +160,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
if let GroupedMoveError::MovesFromPlace { span, binds_to, .. } = ge
&& match_span == *span
{
debug!("appending local({:?}) to list", bind_to);
debug!("appending local({bind_to:?}) to list");
if !binds_to.is_empty() {
binds_to.push(bind_to);
}
@ -198,7 +198,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
} = ge
{
if match_span == *span && mpi == *other_mpi {
debug!("appending local({:?}) to list", bind_to);
debug!("appending local({bind_to:?}) to list");
binds_to.push(bind_to);
return;
}
@ -410,14 +410,12 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
fn add_move_hints(&self, error: GroupedMoveError<'tcx>, err: &mut Diagnostic, span: Span) {
match error {
GroupedMoveError::MovesFromPlace { mut binds_to, move_from, .. } => {
if let Ok(snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(span) {
err.span_suggestion(
span,
"consider borrowing here",
format!("&{snippet}"),
Applicability::Unspecified,
);
}
err.span_suggestion_verbose(
span.shrink_to_lo(),
"consider borrowing here",
"&".to_string(),
Applicability::Unspecified,
);
if binds_to.is_empty() {
let place_ty = move_from.ty(self.body, self.infcx.tcx).ty;
@ -469,28 +467,36 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
VarBindingForm { pat_span, .. },
)))) = bind_to.local_info
{
if let Ok(pat_snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(pat_span)
let Ok(pat_snippet) =
self.infcx.tcx.sess.source_map().span_to_snippet(pat_span) else { continue; };
let Some(stripped) = pat_snippet.strip_prefix('&') else { continue; };
let inner_pat_snippet = stripped.trim_start();
let (pat_span, suggestion, to_remove) = if inner_pat_snippet.starts_with("mut")
&& inner_pat_snippet["mut".len()..].starts_with(rustc_lexer::is_whitespace)
{
if let Some(stripped) = pat_snippet.strip_prefix('&') {
let pat_snippet = stripped.trim_start();
let (suggestion, to_remove) = if pat_snippet.starts_with("mut")
&& pat_snippet["mut".len()..].starts_with(rustc_lexer::is_whitespace)
{
(pat_snippet["mut".len()..].trim_start(), "&mut")
} else {
(pat_snippet, "&")
};
suggestions.push((pat_span, to_remove, suggestion.to_owned()));
}
}
let pat_span = pat_span.with_hi(
pat_span.lo()
+ BytePos((pat_snippet.len() - inner_pat_snippet.len()) as u32),
);
(pat_span, String::new(), "mutable borrow")
} else {
let pat_span = pat_span.with_hi(
pat_span.lo()
+ BytePos(
(pat_snippet.len() - inner_pat_snippet.trim_start().len()) as u32,
),
);
(pat_span, String::new(), "borrow")
};
suggestions.push((pat_span, to_remove, suggestion.to_owned()));
}
}
suggestions.sort_unstable_by_key(|&(span, _, _)| span);
suggestions.dedup_by_key(|&mut (span, _, _)| span);
for (span, to_remove, suggestion) in suggestions {
err.span_suggestion(
err.span_suggestion_verbose(
span,
&format!("consider removing the `{to_remove}`"),
&format!("consider removing the {to_remove}"),
suggestion,
Applicability::MachineApplicable,
);
@ -521,8 +527,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
if binds_to.len() > 1 {
err.note(
"move occurs because these variables have types that \
don't implement the `Copy` trait",
"move occurs because these variables have types that don't implement the `Copy` \
trait",
);
}
}