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Auto merge of #88598 - estebank:type-ascription-can-die-in-a-fire, r=wesleywiser

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Detect bare blocks with type ascription that were meant to be a `struct` literal

Address part of #34255.

Potential improvement: silence the other knock down errors in `issue-34255-1.rs`.
This commit is contained in:
bors 2021-09-04 01:40:36 +00:00
commit b4e8596e3e
13 changed files with 67 additions and 5 deletions
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16
compiler/rustc_resolve/src/late.rs
View file

@ -383,6 +383,11 @@ struct DiagnosticMetadata<'ast> {
/// Only used for better errors on `fn(): fn()`.
current_type_ascription: Vec<Span>,
/// Only used for better errors on `let x = { foo: bar };`.
/// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
/// needed for cases where this parses as a correct type ascription.
current_block_could_be_bare_struct_literal: Option<Span>,
/// Only used for better errors on `let <pat>: <expr, not type>;`.
current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
@ -1871,6 +1876,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
let instead = res.is_some();
let suggestion =
if res.is_none() { this.report_missing_type_error(path) } else { None };
// get_from_node_id
this.r.use_injections.push(UseError {
err,
@ -2254,6 +2260,15 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
self.ribs[ValueNS].push(Rib::new(NormalRibKind));
}
let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
(block.could_be_bare_literal, &block.stmts[..])
{
if let ExprKind::Type(..) = expr.kind {
self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
Some(block.span);
}
}
// Descend into the block.
for stmt in &block.stmts {
if let StmtKind::Item(ref item) = stmt.kind {
@ -2267,6 +2282,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
self.visit_stmt(stmt);
}
self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
// Move back up.
self.parent_scope.module = orig_module;

10
compiler/rustc_resolve/src/late/diagnostics.rs
View file

@ -207,6 +207,16 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
let code = source.error_code(res.is_some());
let mut err = self.r.session.struct_span_err_with_code(base_span, &base_msg, code);
if let Some(span) = self.diagnostic_metadata.current_block_could_be_bare_struct_literal {
err.multipart_suggestion(
"you might have meant to write a `struct` literal",
vec![
(span.shrink_to_lo(), "{ SomeStruct ".to_string()),
(span.shrink_to_hi(), "}".to_string()),
],
Applicability::HasPlaceholders,
);
}
match (source, self.diagnostic_metadata.in_if_condition) {
(PathSource::Expr(_), Some(Expr { span, kind: ExprKind::Assign(..), .. })) => {
err.span_suggestion_verbose(