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Rollup merge of #101908 - chenyukang:fix-101880, r=estebank

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Suggest let for assignment, and some code refactor

Fixes #101880
This commit is contained in:
Dylan DPC 2022-10-23 15:20:16 +05:30 • committed by GitHub
commit 518d5ebc81
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6 changed files with 165 additions and 53 deletions
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8
compiler/rustc_resolve/src/late.rs
View file

@ -524,6 +524,9 @@ struct DiagnosticMetadata<'ast> {
/// Used to detect possible `if let` written without `let` and to provide structured suggestion.
in_if_condition: Option<&'ast Expr>,
/// Used to detect possible new binding written without `let` and to provide structured suggestion.
in_assignment: Option<&'ast Expr>,
/// If we are currently in a trait object definition. Used to point at the bounds when
/// encountering a struct or enum.
current_trait_object: Option<&'ast [ast::GenericBound]>,
@ -3905,6 +3908,11 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
self.resolve_expr(elem, Some(expr));
self.visit_expr(idx);
}
ExprKind::Assign(..) => {
let old = self.diagnostic_metadata.in_assignment.replace(expr);
visit::walk_expr(self, expr);
self.diagnostic_metadata.in_assignment = old;
}
_ => {
visit::walk_expr(self, expr);
}

96
compiler/rustc_resolve/src/late/diagnostics.rs
View file

@ -708,7 +708,9 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
// If the trait has a single item (which wasn't matched by Levenshtein), suggest it
let suggestion = self.get_single_associated_item(&path, &source, is_expected);
self.r.add_typo_suggestion(err, suggestion, ident_span);
if !self.r.add_typo_suggestion(err, suggestion, ident_span) {
fallback = !self.let_binding_suggestion(err, ident_span);
}
}
fallback
}
@ -1105,41 +1107,14 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
// where a brace being opened means a block is being started. Look
// ahead for the next text to see if `span` is followed by a `{`.
let sm = self.r.session.source_map();
let mut sp = span;
loop {
sp = sm.next_point(sp);
match sm.span_to_snippet(sp) {
Ok(ref snippet) => {
if snippet.chars().any(|c| !c.is_whitespace()) {
break;
}
}
_ => break,
}
}
let sp = sm.span_look_ahead(span, None, Some(50));
let followed_by_brace = matches!(sm.span_to_snippet(sp), Ok(ref snippet) if snippet == "{");
// In case this could be a struct literal that needs to be surrounded
// by parentheses, find the appropriate span.
let mut i = 0;
let mut closing_brace = None;
loop {
sp = sm.next_point(sp);
match sm.span_to_snippet(sp) {
Ok(ref snippet) => {
if snippet == "}" {
closing_brace = Some(span.to(sp));
break;
}
}
_ => break,
}
i += 1;
// The bigger the span, the more likely we're incorrect --
// bound it to 100 chars long.
if i > 100 {
break;
}
}
let closing_span = sm.span_look_ahead(span, Some("}"), Some(50));
let closing_brace: Option<Span> = sm
.span_to_snippet(closing_span)
.map_or(None, |s| if s == "}" { Some(span.to(closing_span)) } else { None });
(followed_by_brace, closing_brace)
}
@ -1779,26 +1754,16 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
}
}
if let Ok(base_snippet) = base_snippet {
let mut sp = after_colon_sp;
for _ in 0..100 {
// Try to find an assignment
sp = sm.next_point(sp);
let snippet = sm.span_to_snippet(sp);
match snippet {
Ok(ref x) if x.as_str() == "=" => {
err.span_suggestion(
base_span,
"maybe you meant to write an assignment here",
format!("let {}", base_snippet),
Applicability::MaybeIncorrect,
);
show_label = false;
break;
}
Ok(ref x) if x.as_str() == "\n" => break,
Err(_) => break,
Ok(_) => {}
}
// Try to find an assignment
let eq_span = sm.span_look_ahead(after_colon_sp, Some("="), Some(50));
if let Ok(ref snippet) = sm.span_to_snippet(eq_span) && snippet == "=" {
err.span_suggestion(
base_span,
"maybe you meant to write an assignment here",
format!("let {}", base_snippet),
Applicability::MaybeIncorrect,
);
show_label = false;
}
}
}
@ -1815,6 +1780,31 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
false
}
fn let_binding_suggestion(&self, err: &mut Diagnostic, ident_span: Span) -> bool {
// try to give a suggestion for this pattern: `name = 1`, which is common in other languages
let mut added_suggestion = false;
if let Some(Expr { kind: ExprKind::Assign(lhs, _rhs, _), .. }) = self.diagnostic_metadata.in_assignment &&
let ast::ExprKind::Path(None, _) = lhs.kind {
let sm = self.r.session.source_map();
let line_span = sm.span_extend_to_line(ident_span);
let ident_name = sm.span_to_snippet(ident_span).unwrap();
// HACK(chenyukang): make sure ident_name is at the starting of the line to protect against macros
if sm
.span_to_snippet(line_span)
.map_or(false, |s| s.trim().starts_with(&ident_name))
{
err.span_suggestion_verbose(
ident_span.shrink_to_lo(),
"you might have meant to introduce a new binding",
"let ".to_string(),
Applicability::MaybeIncorrect,
);
added_suggestion = true;
}
}
added_suggestion
}
fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> {
let mut result = None;
let mut seen_modules = FxHashSet::default();