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matthiaskrgrmatthiaskrgr
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Rollup merge of #112995 - strottos:ref-clone-suggestions, r=fee1-dead
Check for `<&NotClone as Clone>::clone()` calls and suggest to add Clone trait appropriately Added recursive checking back up the HIR to see if a `Clone` suggestion would be helpful. Addresses #112857 Largely based on: #112977
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‎compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs‎

Lines changed: 84 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1523,9 +1523,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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found_ty: Ty<'tcx>,
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expr: &hir::Expr<'_>,
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) {
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// When `expr` is `x` in something like `let x = foo.clone(); x`, need to recurse up to get
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// `foo` and `clone`.
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let expr = self.note_type_is_not_clone_inner_expr(expr);
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// If we've recursed to an `expr` of `foo.clone()`, get `foo` and `clone`.
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let hir::ExprKind::MethodCall(segment, callee_expr, &[], _) = expr.kind else {
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return;
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};
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let Some(clone_trait_did) = self.tcx.lang_items().clone_trait() else {
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return;
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};
@@ -1578,6 +1584,84 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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}
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}
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/// Given a type mismatch error caused by `&T` being cloned instead of `T`, and
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/// the `expr` as the source of this type mismatch, try to find the method call
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/// as the source of this error and return that instead. Otherwise, return the
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/// original expression.
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fn note_type_is_not_clone_inner_expr<'b>(
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&'b self,
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expr: &'b hir::Expr<'b>,
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) -> &'b hir::Expr<'b> {
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match expr.peel_blocks().kind {
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hir::ExprKind::Path(hir::QPath::Resolved(
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None,
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hir::Path { segments: [_], res: crate::Res::Local(binding), .. },
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)) => {
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let Some(hir::Node::Pat(hir::Pat { hir_id, .. })) = self.tcx.hir().find(*binding)
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else {
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return expr;
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};
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let Some(parent) = self.tcx.hir().find(self.tcx.hir().parent_id(*hir_id)) else {
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return expr;
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};
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match parent {
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// foo.clone()
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hir::Node::Local(hir::Local { init: Some(init), .. }) => {
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self.note_type_is_not_clone_inner_expr(init)
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}
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// When `expr` is more complex like a tuple
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hir::Node::Pat(hir::Pat {
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hir_id: pat_hir_id,
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kind: hir::PatKind::Tuple(pats, ..),
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..
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}) => {
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let Some(hir::Node::Local(hir::Local { init: Some(init), .. })) =
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self.tcx.hir().find(self.tcx.hir().parent_id(*pat_hir_id)) else {
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return expr;
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};
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match init.peel_blocks().kind {
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ExprKind::Tup(init_tup) => {
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if let Some(init) = pats
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.iter()
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.enumerate()
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.filter(|x| x.1.hir_id == *hir_id)
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.map(|(i, _)| init_tup.get(i).unwrap())
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.next()
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{
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self.note_type_is_not_clone_inner_expr(init)
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} else {
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expr
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}
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}
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_ => expr,
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}
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}
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_ => expr,
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}
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}
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// If we're calling into a closure that may not be typed recurse into that call. no need
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// to worry if it's a call to a typed function or closure as this would ne handled
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// previously.
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hir::ExprKind::Call(Expr { kind: call_expr_kind, .. }, _) => {
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if let hir::ExprKind::Path(hir::QPath::Resolved(None, call_expr_path)) = call_expr_kind
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&& let hir::Path { segments: [_], res: crate::Res::Local(binding), .. } = call_expr_path
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&& let Some(hir::Node::Pat(hir::Pat { hir_id, .. })) = self.tcx.hir().find(*binding)
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&& let Some(closure) = self.tcx.hir().find(self.tcx.hir().parent_id(*hir_id))
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&& let hir::Node::Local(hir::Local { init: Some(init), .. }) = closure
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&& let Expr { kind: hir::ExprKind::Closure(hir::Closure { body: body_id, .. }), ..} = init
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{
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let hir::Body { value: body_expr, .. } = self.tcx.hir().body(*body_id);
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self.note_type_is_not_clone_inner_expr(body_expr)
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} else {
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expr
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}
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}
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_ => expr,
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}
1663+
}
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/// A common error is to add an extra semicolon:
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///
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/// ```compile_fail,E0308

‎tests/ui/typeck/explain_clone_autoref.rs‎

Lines changed: 116 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11,3 +11,119 @@ fn clone_thing(nc: &NotClone) -> NotClone {
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//~| NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
1212
//~| NOTE expected `NotClone`, found `&NotClone`
1313
}
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fn clone_thing2(nc: &NotClone) -> NotClone {
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let nc: NotClone = nc.clone();
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//~^ ERROR mismatched type
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//~| NOTE expected due to this
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//~| NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
20+
//~| NOTE expected `NotClone`, found `&NotClone`
21+
nc
22+
}
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fn clone_thing3(nc: &NotClone) -> NotClone {
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//~^ NOTE expected `NotClone` because of return type
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let nc = nc.clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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nc
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//~^ ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
31+
}
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fn clone_thing4(nc: &NotClone) -> NotClone {
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//~^ NOTE expected `NotClone` because of return type
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let nc = nc.clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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let nc2 = nc;
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nc2
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//~^ ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
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}
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impl NotClone {
44+
fn other_fn(&self) {}
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fn get_ref_notclone(&self) -> &Self {
46+
self
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}
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}
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fn clone_thing5(nc: &NotClone) -> NotClone {
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//~^ NOTE expected `NotClone` because of return type
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let nc = nc.clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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let nc2 = nc;
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nc2.other_fn();
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let nc3 = nc2;
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nc3
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//~^ ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
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}
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fn clone_thing6(nc: &NotClone) -> NotClone {
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//~^ NOTE expected `NotClone` because of return type
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let (ret, _) = (nc.clone(), 1);
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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let _ = nc.clone();
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ret
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//~^ ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
70+
}
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fn clone_thing7(nc: Vec<&NotClone>) -> NotClone {
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//~^ NOTE expected `NotClone` because of return type
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let ret = nc[0].clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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ret
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//~^ ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
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}
80+
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fn clone_thing8(nc: &NotClone) -> NotClone {
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//~^ NOTE expected `NotClone` because of return type
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let ret = {
84+
let a = nc.clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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a
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};
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ret
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//~^ ERROR mismatched type
90+
//~| NOTE expected `NotClone`, found `&NotClone`
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}
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93+
fn clone_thing9(nc: &NotClone) -> NotClone {
94+
//~^ NOTE expected `NotClone` because of return type
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let cl = || nc.clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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let ret = cl();
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ret
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//~^ ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
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}
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fn clone_thing10(nc: &NotClone) -> (NotClone, NotClone) {
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let (a, b) = {
105+
let a = nc.clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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(a, nc.clone())
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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};
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(a, b)
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//~^ ERROR mismatched type
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//~| ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
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//~| NOTE expected `NotClone`, found `&NotClone`
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}
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fn clone_thing11(nc: &NotClone) -> NotClone {
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//~^ NOTE expected `NotClone` because of return type
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let a = {
120+
let nothing = nc.clone();
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let a = nc.clone();
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//~^ NOTE `NotClone` does not implement `Clone`, so `&NotClone` was cloned instead
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let nothing = nc.clone();
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a
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};
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a
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//~^ ERROR mismatched type
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//~| NOTE expected `NotClone`, found `&NotClone`
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}

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