bjoernager/rust
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Provide structured suggestion for dropped temp value

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This commit is contained in:
Esteban Küber 2022-07-14 17:12:01 -07:00
parent 0fe5390a88
commit 20b5aaf111
20 changed files with 205 additions and 35 deletions
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33
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
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@ -1500,7 +1500,38 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
| BorrowExplanation::UsedLaterInLoop(..)
| BorrowExplanation::UsedLaterWhenDropped { .. } => {
// Only give this note and suggestion if it could be relevant.
err.note("consider using a `let` binding to create a longer lived value");
let sm = self.infcx.tcx.sess.source_map();
let mut suggested = false;
let msg = "consider using a `let` binding to create a longer lived value";
if let Some(scope) =
self.body.source_scopes.get(self.body.source_info(location).scope)
&& let ClearCrossCrate::Set(scope_data) = &scope.local_data
&& let Some(node) = self.infcx.tcx.hir().find(scope_data.lint_root)
&& let Some(id) = node.body_id()
&& let hir::ExprKind::Block(block, _) = self.infcx.tcx.hir().body(id).value.kind
{
for stmt in block.stmts {
if stmt.span.contains(proper_span)
&& let Some(p) = sm.span_to_margin(stmt.span)
&& let Ok(s) = sm.span_to_snippet(proper_span)
{
let addition = format!("let binding = {};\n{}", s, " ".repeat(p));
err.multipart_suggestion_verbose(
msg,
vec![
(stmt.span.shrink_to_lo(), addition),
(proper_span, "binding".to_string()),
],
Applicability::MaybeIncorrect,
);
suggested = true;
break;
}
}
}
if !suggested {
err.note(msg);
}
}
_ => {}
}