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Auto merge of #10813 - y21:issue10755, r=xFrednet

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[`default_constructed_unit_structs`]: do not lint on type alias paths

Fixes #10755.

Type aliases cannot be used as a constructor, so this lint should not trigger in those cases.
I also changed `clippy_utils::is_ty_alias` to also consider associated types since [they kinda are type aliases too](48ec50ae39/compiler/rustc_resolve/src/late/diagnostics.rs (L1520)).

changelog: [`default_constructed_unit_structs`]: do not lint on type alias paths
This commit is contained in:
bors 2023-05-26 15:20:21 +00:00
commit f1fd4673bc
5 changed files with 62 additions and 7 deletions
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15
clippy_lints/src/default_constructed_unit_structs.rs
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@ -1,4 +1,4 @@
use clippy_utils::{diagnostics::span_lint_and_sugg, match_def_path, paths};
use clippy_utils::{diagnostics::span_lint_and_sugg, is_ty_alias, match_def_path, paths};
use hir::{def::Res, ExprKind};
use rustc_errors::Applicability;
use rustc_hir as hir;
@ -43,12 +43,23 @@ declare_clippy_lint! {
}
declare_lint_pass!(DefaultConstructedUnitStructs => [DEFAULT_CONSTRUCTED_UNIT_STRUCTS]);
fn is_alias(ty: hir::Ty<'_>) -> bool {
if let hir::TyKind::Path(ref qpath) = ty.kind {
is_ty_alias(qpath)
} else {
false
}
}
impl LateLintPass<'_> for DefaultConstructedUnitStructs {
fn check_expr<'tcx>(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
if_chain!(
// make sure we have a call to `Default::default`
if let hir::ExprKind::Call(fn_expr, &[]) = expr.kind;
if let ExprKind::Path(ref qpath@ hir::QPath::TypeRelative(_,_)) = fn_expr.kind;
if let ExprKind::Path(ref qpath @ hir::QPath::TypeRelative(base, _)) = fn_expr.kind;
// make sure this isn't a type alias:
// `<Foo as Bar>::Assoc` cannot be used as a constructor
if !is_alias(*base);
if let Res::Def(_, def_id) = cx.qpath_res(qpath, fn_expr.hir_id);
if match_def_path(cx, def_id, &paths::DEFAULT_TRAIT_METHOD);
// make sure we have a struct with no fields (unit struct)