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fix: map_unwrap_or suggests wrongly for empty slice

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This commit is contained in:
yanglsh 2025-09-24 08:53:48 +08:00 • committed by Linshu Yang
parent 9565b28598
commit 0db25dbd9d
8 changed files with 211 additions and 177 deletions
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2
clippy_lints/src/derivable_impls.rs
View file

@ -105,7 +105,7 @@ fn check_struct<'tcx>(
if let TyKind::Path(QPath::Resolved(_, p)) = self_ty.kind
&& let Some(PathSegment { args, .. }) = p.segments.last()
{
let args = args.map(|a| a.args).unwrap_or(&[]);
let args = args.map(|a| a.args).unwrap_or_default();
// ty_args contains the generic parameters of the type declaration, while args contains the
// arguments used at instantiation time. If both len are not equal, it means that some

231
clippy_lints/src/methods/map_unwrap_or.rs
View file

@ -1,13 +1,13 @@
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::msrvs::{self, Msrv};
use clippy_utils::res::MaybeDef;
use clippy_utils::res::{MaybeDef as _, MaybeResPath as _};
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::is_copy;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::Applicability;
use rustc_hir::def::Res;
use rustc_hir::intravisit::{Visitor, walk_path};
use rustc_hir::{ExprKind, HirId, Node, PatKind, Path, QPath};
use rustc_hir::intravisit::{Visitor, walk_expr, walk_path};
use rustc_hir::{ExprKind, HirId, LangItem, Node, PatKind, Path, QPath};
use rustc_lint::LateContext;
use rustc_middle::hir::nested_filter;
use rustc_span::{Span, sym};
@ -28,116 +28,131 @@ pub(super) fn check<'tcx>(
msrv: Msrv,
) {
let recv_ty = cx.typeck_results().expr_ty(recv).peel_refs();
let is_option = recv_ty.is_diag_item(cx, sym::Option);
let is_result = recv_ty.is_diag_item(cx, sym::Result);
let recv_ty_kind = match recv_ty.opt_diag_name(cx) {
Some(sym::Option) => sym::Option,
Some(sym::Result) if msrv.meets(cx, msrvs::RESULT_MAP_OR) => sym::Result,
_ => return,
};
if is_result && !msrv.meets(cx, msrvs::RESULT_MAP_OR) {
let unwrap_arg_ty = cx.typeck_results().expr_ty(unwrap_arg);
if !is_copy(cx, unwrap_arg_ty) {
// Replacing `.map(<f>).unwrap_or(<a>)` with `.map_or(<a>, <f>)` can sometimes lead to
// borrowck errors, see #10579 for one such instance.
// In particular, if `a` causes a move and `f` references that moved binding, then we cannot lint:
// ```
// let x = vec![1, 2];
// x.get(0..1).map(|s| s.to_vec()).unwrap_or(x);
// ```
// This compiles, but changing it to `map_or` will produce a compile error:
// ```
// let x = vec![1, 2];
// x.get(0..1).map_or(x, |s| s.to_vec())
// ^ moving `x` here
// ^^^^^^^^^^^ while it is borrowed here (and later used in the closure)
// ```
// So, we have to check that `a` is not referenced anywhere (even outside of the `.map` closure!)
// before the call to `unwrap_or`.
let mut unwrap_visitor = UnwrapVisitor {
cx,
identifiers: FxHashSet::default(),
};
unwrap_visitor.visit_expr(unwrap_arg);
let mut reference_visitor = ReferenceVisitor {
cx,
identifiers: unwrap_visitor.identifiers,
unwrap_or_span: unwrap_arg.span,
};
let body = cx.tcx.hir_body_owned_by(cx.tcx.hir_enclosing_body_owner(expr.hir_id));
// Visit the body, and return if we've found a reference
if reference_visitor.visit_body(body).is_break() {
return;
}
}
if !unwrap_arg.span.eq_ctxt(map_span) {
return;
}
// lint if the caller of `map()` is an `Option`
if is_option || is_result {
if !is_copy(cx, cx.typeck_results().expr_ty(unwrap_arg)) {
// Replacing `.map(<f>).unwrap_or(<a>)` with `.map_or(<a>, <f>)` can sometimes lead to
// borrowck errors, see #10579 for one such instance.
// In particular, if `a` causes a move and `f` references that moved binding, then we cannot lint:
// ```
// let x = vec![1, 2];
// x.get(0..1).map(|s| s.to_vec()).unwrap_or(x);
// ```
// This compiles, but changing it to `map_or` will produce a compile error:
// ```
// let x = vec![1, 2];
// x.get(0..1).map_or(x, |s| s.to_vec())
// ^ moving `x` here
// ^^^^^^^^^^^ while it is borrowed here (and later used in the closure)
// ```
// So, we have to check that `a` is not referenced anywhere (even outside of the `.map` closure!)
// before the call to `unwrap_or`.
let mut applicability = Applicability::MachineApplicable;
// get snippet for unwrap_or()
let unwrap_snippet = snippet_with_applicability(cx, unwrap_arg.span, "..", &mut applicability);
// lint message
let mut unwrap_visitor = UnwrapVisitor {
cx,
identifiers: FxHashSet::default(),
};
unwrap_visitor.visit_expr(unwrap_arg);
let mut reference_visitor = ReferenceVisitor {
cx,
identifiers: unwrap_visitor.identifiers,
unwrap_or_span: unwrap_arg.span,
};
let body = cx.tcx.hir_body_owned_by(cx.tcx.hir_enclosing_body_owner(expr.hir_id));
// Visit the body, and return if we've found a reference
if reference_visitor.visit_body(body).is_break() {
return;
}
}
if !unwrap_arg.span.eq_ctxt(map_span) {
return;
}
// is_some_and is stabilised && `unwrap_or` argument is false; suggest `is_some_and` instead
let suggest_is_some_and = matches!(&unwrap_arg.kind, ExprKind::Lit(lit)
if matches!(lit.node, rustc_ast::LitKind::Bool(false)))
&& msrv.meets(cx, msrvs::OPTION_RESULT_IS_VARIANT_AND);
let mut applicability = Applicability::MachineApplicable;
// get snippet for unwrap_or()
let unwrap_snippet = snippet_with_applicability(cx, unwrap_arg.span, "..", &mut applicability);
// lint message
// comparing the snippet from source to raw text ("None") below is safe
// because we already have checked the type.
let unwrap_snippet_none = is_option && unwrap_snippet == "None";
let arg = if unwrap_snippet_none {
"None"
} else if suggest_is_some_and {
"false"
} else {
"<a>"
};
let suggest = if unwrap_snippet_none {
"and_then(<f>)"
} else if suggest_is_some_and {
if is_result {
"is_ok_and(<f>)"
} else {
"is_some_and(<f>)"
}
} else {
"map_or(<a>, <f>)"
};
let msg = format!(
"called `map(<f>).unwrap_or({arg})` on an `{}` value",
if is_option { "Option" } else { "Result" }
);
span_lint_and_then(cx, MAP_UNWRAP_OR, expr.span, msg, |diag| {
let map_arg_span = map_arg.span;
let mut suggestion = vec![
(
map_span,
String::from(if unwrap_snippet_none {
"and_then"
} else if suggest_is_some_and {
if is_result { "is_ok_and" } else { "is_some_and" }
} else {
"map_or"
}),
),
(expr.span.with_lo(unwrap_recv.span.hi()), String::new()),
];
if !unwrap_snippet_none && !suggest_is_some_and {
suggestion.push((map_arg_span.with_hi(map_arg_span.lo()), format!("{unwrap_snippet}, ")));
}
diag.multipart_suggestion(format!("use `{suggest}` instead"), suggestion, applicability);
});
let suggest_kind = if recv_ty_kind == sym::Option
&& unwrap_arg
.basic_res()
.ctor_parent(cx)
.is_lang_item(cx, LangItem::OptionNone)
{
SuggestedKind::AndThen
}
// is_some_and is stabilised && `unwrap_or` argument is false; suggest `is_some_and` instead
else if matches!(&unwrap_arg.kind, ExprKind::Lit(lit)
if matches!(lit.node, rustc_ast::LitKind::Bool(false)))
&& msrv.meets(cx, msrvs::OPTION_RESULT_IS_VARIANT_AND)
{
SuggestedKind::IsVariantAnd
} else {
SuggestedKind::Other
};
let arg = match suggest_kind {
SuggestedKind::AndThen => "None",
SuggestedKind::IsVariantAnd => "false",
SuggestedKind::Other => "<a>",
};
let suggest = match (suggest_kind, recv_ty_kind) {
(SuggestedKind::AndThen, _) => "and_then(<f>)",
(SuggestedKind::IsVariantAnd, sym::Result) => "is_ok_and(<f>)",
(SuggestedKind::IsVariantAnd, sym::Option) => "is_some_and(<f>)",
_ => "map_or(<a>, <f>)",
};
let msg = format!(
"called `map(<f>).unwrap_or({arg})` on {} `{recv_ty_kind}` value",
if recv_ty_kind == sym::Option { "an" } else { "a" }
);
span_lint_and_then(cx, MAP_UNWRAP_OR, expr.span, msg, |diag| {
let map_arg_span = map_arg.span;
let mut suggestion = vec![
(
map_span,
String::from(match (suggest_kind, recv_ty_kind) {
(SuggestedKind::AndThen, _) => "and_then",
(SuggestedKind::IsVariantAnd, sym::Result) => "is_ok_and",
(SuggestedKind::IsVariantAnd, sym::Option) => "is_some_and",
(SuggestedKind::Other, _)
if unwrap_arg_ty.peel_refs().is_array()
&& cx.typeck_results().expr_ty_adjusted(unwrap_arg).peel_refs().is_slice() =>
{
return;
},
_ => "map_or",
}),
),
(expr.span.with_lo(unwrap_recv.span.hi()), String::new()),
];
if matches!(suggest_kind, SuggestedKind::Other) {
suggestion.push((map_arg_span.with_hi(map_arg_span.lo()), format!("{unwrap_snippet}, ")));
}
diag.multipart_suggestion(format!("use `{suggest}` instead"), suggestion, applicability);
});
}
#[derive(Clone, Copy, PartialEq, Eq)]
enum SuggestedKind {
AndThen,
IsVariantAnd,
Other,
}
struct UnwrapVisitor<'a, 'tcx> {
@ -186,7 +201,7 @@ impl<'tcx> Visitor<'tcx> for ReferenceVisitor<'_, 'tcx> {
{
return ControlFlow::Break(());
}
rustc_hir::intravisit::walk_expr(self, expr)
walk_expr(self, expr)
}
fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {

81
clippy_lints/src/methods/map_unwrap_or_else.rs
View file

@ -1,18 +1,18 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::msrvs::{self, Msrv};
use clippy_utils::res::MaybeDef;
use clippy_utils::res::MaybeDef as _;
use clippy_utils::source::snippet;
use clippy_utils::sym;
use clippy_utils::usage::mutated_variables;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_span::symbol::sym;
use super::MAP_UNWRAP_OR;
/// lint use of `map().unwrap_or_else()` for `Option`s and `Result`s
///
/// Returns true if the lint was emitted
/// Is part of the `map_unwrap_or` lint, split into separate files for readability.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx hir::Expr<'_>,
@ -22,49 +22,46 @@ pub(super) fn check<'tcx>(
msrv: Msrv,
) -> bool {
let recv_ty = cx.typeck_results().expr_ty(recv).peel_refs();
let is_option = recv_ty.is_diag_item(cx, sym::Option);
let is_result = recv_ty.is_diag_item(cx, sym::Result);
let recv_ty_kind = match recv_ty.opt_diag_name(cx) {
Some(sym::Option) => sym::Option,
Some(sym::Result) if msrv.meets(cx, msrvs::RESULT_MAP_OR_ELSE) => sym::Result,
_ => return false,
};
if is_result && !msrv.meets(cx, msrvs::RESULT_MAP_OR_ELSE) {
// Don't make a suggestion that may fail to compile due to mutably borrowing
// the same variable twice.
let Some(map_mutated_vars) = mutated_variables(recv, cx) else {
return false;
};
let Some(unwrap_mutated_vars) = mutated_variables(unwrap_arg, cx) else {
return false;
};
if map_mutated_vars.intersection(&unwrap_mutated_vars).next().is_some() {
return false;
}
if is_option || is_result {
// Don't make a suggestion that may fail to compile due to mutably borrowing
// the same variable twice.
let map_mutated_vars = mutated_variables(recv, cx);
let unwrap_mutated_vars = mutated_variables(unwrap_arg, cx);
if let (Some(map_mutated_vars), Some(unwrap_mutated_vars)) = (map_mutated_vars, unwrap_mutated_vars) {
if map_mutated_vars.intersection(&unwrap_mutated_vars).next().is_some() {
return false;
}
} else {
return false;
}
// lint message
let msg = if is_option {
"called `map(<f>).unwrap_or_else(<g>)` on an `Option` value"
} else {
"called `map(<f>).unwrap_or_else(<g>)` on a `Result` value"
};
// get snippets for args to map() and unwrap_or_else()
let map_snippet = snippet(cx, map_arg.span, "..");
let unwrap_snippet = snippet(cx, unwrap_arg.span, "..");
// lint, with note if both map() and unwrap_or_else() have the same span
if map_arg.span.eq_ctxt(unwrap_arg.span) {
let var_snippet = snippet(cx, recv.span, "..");
span_lint_and_sugg(
cx,
MAP_UNWRAP_OR,
expr.span,
msg,
"try",
format!("{var_snippet}.map_or_else({unwrap_snippet}, {map_snippet})"),
Applicability::MachineApplicable,
);
return true;
}
// lint message
let msg = if recv_ty_kind == sym::Option {
"called `map(<f>).unwrap_or_else(<g>)` on an `Option` value"
} else {
"called `map(<f>).unwrap_or_else(<g>)` on a `Result` value"
};
// get snippets for args to map() and unwrap_or_else()
let map_snippet = snippet(cx, map_arg.span, "..");
let unwrap_snippet = snippet(cx, unwrap_arg.span, "..");
// lint, with note if both map() and unwrap_or_else() have the same span
if map_arg.span.eq_ctxt(unwrap_arg.span) {
let var_snippet = snippet(cx, recv.span, "..");
span_lint_and_sugg(
cx,
MAP_UNWRAP_OR,
expr.span,
msg,
"try",
format!("{var_snippet}.map_or_else({unwrap_snippet}, {map_snippet})"),
Applicability::MachineApplicable,
);
return true;
}
false

8
tests/ui/map_unwrap_or.rs
View file

@ -156,3 +156,11 @@ mod issue_10579 {
println!("{y:?}");
}
}
fn issue15752() {
struct Foo<'a>(&'a [u32]);
let x = Some(Foo(&[1, 2, 3]));
x.map(|y| y.0).unwrap_or(&[]);
//~^ map_unwrap_or
}

8
tests/ui/map_unwrap_or.stderr
View file

@ -232,5 +232,11 @@ LL - let _ = opt.map(|x| x > 5).unwrap_or(false);
LL + let _ = opt.is_some_and(|x| x > 5);
|
error: aborting due to 15 previous errors
error: called `map(<f>).unwrap_or(<a>)` on an `Option` value
--> tests/ui/map_unwrap_or.rs:164:5
|
LL | x.map(|y| y.0).unwrap_or(&[]);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 16 previous errors

6
tests/ui/map_unwrap_or_fixable.fixed
View file

@ -1,7 +1,11 @@
//@aux-build:option_helpers.rs
#![warn(clippy::map_unwrap_or)]
#![allow(clippy::unnecessary_lazy_evaluations)]
#![allow(
clippy::unnecessary_lazy_evaluations,
clippy::manual_is_variant_and,
clippy::unnecessary_map_or
)]
#[macro_use]
extern crate option_helpers;

6
tests/ui/map_unwrap_or_fixable.rs
View file

@ -1,7 +1,11 @@
//@aux-build:option_helpers.rs
#![warn(clippy::map_unwrap_or)]
#![allow(clippy::unnecessary_lazy_evaluations)]
#![allow(
clippy::unnecessary_lazy_evaluations,
clippy::manual_is_variant_and,
clippy::unnecessary_map_or
)]
#[macro_use]
extern crate option_helpers;

46
tests/ui/map_unwrap_or_fixable.stderr
View file

@ -1,5 +1,5 @@
error: called `map(<f>).unwrap_or_else(<g>)` on an `Option` value
--> tests/ui/map_unwrap_or_fixable.rs:17:13
--> tests/ui/map_unwrap_or_fixable.rs:21:13
|
LL | let _ = opt.map(|x| x + 1)
| _____________^
@ -11,7 +11,7 @@ LL | | .unwrap_or_else(|| 0);
= help: to override `-D warnings` add `#[allow(clippy::map_unwrap_or)]`
error: called `map(<f>).unwrap_or_else(<g>)` on a `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:48:13
--> tests/ui/map_unwrap_or_fixable.rs:52:13
|
LL | let _ = res.map(|x| x + 1)
| _____________^
@ -20,7 +20,7 @@ LL | | .unwrap_or_else(|_e| 0);
| |_______________________________^ help: try: `res.map_or_else(|_e| 0, |x| x + 1)`
error: called `map(<f>).unwrap_or(<a>)` on an `Option` value
--> tests/ui/map_unwrap_or_fixable.rs:65:20
--> tests/ui/map_unwrap_or_fixable.rs:69:20
|
LL | println!("{}", o.map(|y| y + 1).unwrap_or(3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -32,13 +32,13 @@ LL + println!("{}", o.map_or(3, |y| y + 1));
|
error: called `map(<f>).unwrap_or_else(<g>)` on an `Option` value
--> tests/ui/map_unwrap_or_fixable.rs:67:20
--> tests/ui/map_unwrap_or_fixable.rs:71:20
|
LL | println!("{}", o.map(|y| y + 1).unwrap_or_else(|| 3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `o.map_or_else(|| 3, |y| y + 1)`
error: called `map(<f>).unwrap_or(<a>)` on an `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:69:20
error: called `map(<f>).unwrap_or(<a>)` on a `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:73:20
|
LL | println!("{}", r.map(|y| y + 1).unwrap_or(3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -50,13 +50,13 @@ LL + println!("{}", r.map_or(3, |y| y + 1));
|
error: called `map(<f>).unwrap_or_else(<g>)` on a `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:71:20
--> tests/ui/map_unwrap_or_fixable.rs:75:20
|
LL | println!("{}", r.map(|y| y + 1).unwrap_or_else(|()| 3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `r.map_or_else(|()| 3, |y| y + 1)`
error: called `map(<f>).unwrap_or(false)` on an `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:74:20
error: called `map(<f>).unwrap_or(false)` on a `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:78:20
|
LL | println!("{}", r.map(|y| y == 1).unwrap_or(false));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -68,18 +68,6 @@ LL + println!("{}", r.is_ok_and(|y| y == 1));
|
error: called `map(<f>).unwrap_or(<a>)` on an `Option` value
--> tests/ui/map_unwrap_or_fixable.rs:80:20
|
LL | println!("{}", x.map(|y| y + 1).unwrap_or(3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: use `map_or(<a>, <f>)` instead
|
LL - println!("{}", x.map(|y| y + 1).unwrap_or(3));
LL + println!("{}", x.map_or(3, |y| y + 1));
|
error: called `map(<f>).unwrap_or(<a>)` on an `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:84:20
|
LL | println!("{}", x.map(|y| y + 1).unwrap_or(3));
@ -91,14 +79,26 @@ LL - println!("{}", x.map(|y| y + 1).unwrap_or(3));
LL + println!("{}", x.map_or(3, |y| y + 1));
|
error: called `map(<f>).unwrap_or_else(<g>)` on an `Option` value
error: called `map(<f>).unwrap_or(<a>)` on a `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:88:20
|
LL | println!("{}", x.map(|y| y + 1).unwrap_or(3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: use `map_or(<a>, <f>)` instead
|
LL - println!("{}", x.map(|y| y + 1).unwrap_or(3));
LL + println!("{}", x.map_or(3, |y| y + 1));
|
error: called `map(<f>).unwrap_or_else(<g>)` on an `Option` value
--> tests/ui/map_unwrap_or_fixable.rs:92:20
|
LL | println!("{}", x.map(|y| y + 1).unwrap_or_else(|| 3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `x.map_or_else(|| 3, |y| y + 1)`
error: called `map(<f>).unwrap_or_else(<g>)` on a `Result` value
--> tests/ui/map_unwrap_or_fixable.rs:92:20
--> tests/ui/map_unwrap_or_fixable.rs:96:20
|
LL | println!("{}", x.map(|y| y + 1).unwrap_or_else(|_| 3));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `x.map_or_else(|_| 3, |y| y + 1)`