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Fix unit struct/enum variant in destructuring assignment

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This commit is contained in:
Michael Goulet 2022-04-01 20:24:32 -07:00
parent 8f36334ca9
commit 17f5c4d255
4 changed files with 80 additions and 7 deletions
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37
compiler/rustc_ast_lowering/src/expr.rs
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@ -1020,6 +1020,28 @@ impl<'hir> LoweringContext<'_, 'hir> {
None
}
/// If the given expression is a path to a unit struct, returns that path.
/// It is not a complete check, but just tries to reject most paths early
/// if they are not unit structs.
/// Type checking will take care of the full validation later.
fn extract_unit_struct_path<'a>(
&mut self,
expr: &'a Expr,
) -> Option<(&'a Option<QSelf>, &'a Path)> {
if let ExprKind::Path(qself, path) = &expr.kind {
// Does the path resolve to something disallowed in a unit struct/variant pattern?
if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
if partial_res.unresolved_segments() == 0
&& !partial_res.base_res().expected_in_unit_struct_pat()
{
return None;
}
}
return Some((qself, path));
}
None
}
/// Convert the LHS of a destructuring assignment to a pattern.
/// Each sub-assignment is recorded in `assignments`.
fn destructure_assign(
@ -1080,6 +1102,21 @@ impl<'hir> LoweringContext<'_, 'hir> {
return self.pat_without_dbm(lhs.span, tuple_struct_pat);
}
}
// Unit structs and enum variants.
ExprKind::Path(..) => {
if let Some((qself, path)) = self.extract_unit_struct_path(lhs) {
let qpath = self.lower_qpath(
lhs.id,
qself,
path,
ParamMode::Optional,
ImplTraitContext::Disallowed(ImplTraitPosition::Path),
);
// Destructure like a unit struct.
let unit_struct_pat = hir::PatKind::Path(qpath);
return self.pat_without_dbm(lhs.span, unit_struct_pat);
}
}
// Structs.
ExprKind::Struct(se) => {
let field_pats = self.arena.alloc_from_iter(se.fields.iter().map(|f| {