bjoernager/rust
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Avoid incorrect suggestion

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We check that there's a single level of block nesting to ensure always
correct suggestions. If we don't, then we only provide a free-form
message to avoid misleading users in cases like
`src/test/ui/nll/borrowed-temporary-error.rs`.

We could expand the analysis to suggest hoising all of the relevant
parts of the users' code to make the code compile, but that could be
too much.
This commit is contained in:
Esteban Küber 2022-07-14 18:41:12 -07:00
parent 20b5aaf111
commit 635c38187b
4 changed files with 42 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

40
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
View file

@ -1503,15 +1503,49 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
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)
use rustc_hir::intravisit::Visitor;
/// We check that there's a single level of block nesting to ensure always correct
/// suggestions. If we don't, then we only provide a free-form message to avoid
/// misleading users in cases like `src/test/ui/nll/borrowed-temporary-error.rs`.
/// We could expand the analysis to suggest hoising all of the relevant parts of
/// the users' code to make the code compile, but that could be too much.
struct NestedStatementVisitor {
span: Span,
current: usize,
found: usize,
}
impl<'tcx> Visitor<'tcx> for NestedStatementVisitor {
fn visit_block(&mut self, block: &hir::Block<'tcx>) {
self.current += 1;
rustc_hir::intravisit::walk_block(self, block);
self.current -= 1;
}
fn visit_expr(&mut self, expr: &hir::Expr<'tcx>) {
if self.span == expr.span {
self.found = self.current;
}
rustc_hir::intravisit::walk_expr(self, expr);
}
}
let source_info = self.body.source_info(location);
if let Some(scope) = self.body.source_scopes.get(source_info.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 mut visitor = NestedStatementVisitor {
span: proper_span,
current: 0,
found: 0,
};
visitor.visit_stmt(stmt);
if visitor.found == 0
&& stmt.span.contains(proper_span)
&& let Some(p) = sm.span_to_margin(stmt.span)
&& let Ok(s) = sm.span_to_snippet(proper_span)
{