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allow check for match in lint [option_if_let_else]

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and add test case for `Result`
This commit is contained in:
J-ZhengLi 2022-04-16 16:57:06 +08:00 committed by Philipp Krones
parent 41309df8ef
commit 5d403c0b85
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GPG Key ID: 1CA0DF2AF59D68A5
4 changed files with 183 additions and 45 deletions
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170
clippy_lints/src/option_if_let_else.rs
View File

@ -7,15 +7,18 @@
};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::LangItem::OptionSome;
use rustc_hir::{def::Res, BindingAnnotation, Expr, ExprKind, Mutability, PatKind, Path, QPath, UnOp};
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{
def::Res, Arm, BindingAnnotation, Expr, ExprKind, MatchSource, Mutability, Pat, PatKind, Path, QPath, UnOp,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
declare_clippy_lint! {
/// ### What it does
/// Lints usage of `if let Some(v) = ... { y } else { x }` which is more
/// Lints usage of `if let Some(v) = ... { y } else { x }` and
/// `match .. { Some(v) => y, None/_ => x }` which are more
/// idiomatically done with `Option::map_or` (if the else bit is a pure
/// expression) or `Option::map_or_else` (if the else bit is an impure
/// expression).
@ -39,6 +42,10 @@
/// } else {
/// 5
/// };
/// let _ = match optional {
/// Some(val) => val + 1,
/// None => 5
/// };
/// let _ = if let Some(foo) = optional {
/// foo
/// } else {
@ -53,6 +60,7 @@
/// # let optional: Option<u32> = Some(0);
/// # fn do_complicated_function() -> u32 { 5 };
/// let _ = optional.map_or(5, |foo| foo);
/// let _ = optional.map_or(5, |val| val + 1);
/// let _ = optional.map_or_else(||{
/// let y = do_complicated_function();
/// y*y
@ -76,9 +84,21 @@ fn is_result_ok(cx: &LateContext<'_>, expr: &'_ Expr<'_>) -> bool {
}
}
/// A struct containing information about occurrences of the
/// `if let Some(..) = .. else` construct that this lint detects.
struct OptionIfLetElseOccurrence {
/// A struct containing information about occurrences of construct that this lint detects
///
/// Such as:
///
/// ```ignore
/// if let Some(..) = {..} else {..}
/// ```
/// or
/// ```ignore
/// match x {
/// Some(..) => {..},
/// None/_ => {..}
/// }
/// ```
struct OptionOccurence {
option: String,
method_sugg: String,
some_expr: String,
@ -99,43 +119,39 @@ fn format_option_in_sugg(cx: &LateContext<'_>, cond_expr: &Expr<'_>, as_ref: boo
)
}
/// If this expression is the option if let/else construct we're detecting, then
/// this function returns an `OptionIfLetElseOccurrence` struct with details if
/// this construct is found, or None if this construct is not found.
fn detect_option_if_let_else<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> Option<OptionIfLetElseOccurrence> {
fn try_get_option_occurence<'tcx>(
cx: &LateContext<'tcx>,
pat: &Pat<'tcx>,
expr: &Expr<'_>,
if_then: &'tcx Expr<'_>,
if_else: &'tcx Expr<'_>,
) -> Option<OptionOccurence> {
let cond_expr = match expr.kind {
ExprKind::Unary(UnOp::Deref, inner_expr) | ExprKind::AddrOf(_, _, inner_expr) => inner_expr,
_ => expr,
};
if_chain! {
if !expr.span.from_expansion(); // Don't lint macros, because it behaves weirdly
if !in_constant(cx, expr.hir_id);
if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else: Some(if_else) })
= higher::IfLet::hir(cx, expr);
if !is_else_clause(cx.tcx, expr);
if !is_result_ok(cx, let_expr); // Don't lint on Result::ok because a different lint does it already
if let PatKind::TupleStruct(struct_qpath, [inner_pat], _) = &let_pat.kind;
if is_lang_ctor(cx, struct_qpath, OptionSome);
if let PatKind::Binding(bind_annotation, _, id, None) = &inner_pat.kind;
if !is_result_ok(cx, cond_expr); // Don't lint on Result::ok because a different lint does it already
let inner_pat = try_get_inner_pat(cx, pat)?;
if let PatKind::Binding(bind_annotation, _, id, None) = inner_pat.kind;
if let Some(some_captures) = can_move_expr_to_closure(cx, if_then);
if let Some(none_captures) = can_move_expr_to_closure(cx, if_else);
if some_captures
.iter()
.filter_map(|(id, &c)| none_captures.get(id).map(|&c2| (c, c2)))
.all(|(x, y)| x.is_imm_ref() && y.is_imm_ref());
then {
let capture_mut = if bind_annotation == &BindingAnnotation::Mutable { "mut " } else { "" };
let capture_mut = if bind_annotation == BindingAnnotation::Mutable { "mut " } else { "" };
let some_body = peel_blocks(if_then);
let none_body = peel_blocks(if_else);
let method_sugg = if eager_or_lazy::switch_to_eager_eval(cx, none_body) { "map_or" } else { "map_or_else" };
let capture_name = id.name.to_ident_string();
let (as_ref, as_mut) = match &let_expr.kind {
let (as_ref, as_mut) = match &expr.kind {
ExprKind::AddrOf(_, Mutability::Not, _) => (true, false),
ExprKind::AddrOf(_, Mutability::Mut, _) => (false, true),
_ => (bind_annotation == &BindingAnnotation::Ref, bind_annotation == &BindingAnnotation::RefMut),
};
let cond_expr = match let_expr.kind {
// Pointer dereferencing happens automatically, so we can omit it in the suggestion
ExprKind::Unary(UnOp::Deref, expr) | ExprKind::AddrOf(_, _, expr) => expr,
_ => let_expr,
_ => (bind_annotation == BindingAnnotation::Ref, bind_annotation == BindingAnnotation::RefMut),
};
// Check if captures the closure will need conflict with borrows made in the scrutinee.
// TODO: check all the references made in the scrutinee expression. This will require interacting
// with the borrow checker. Currently only `<local>[.<field>]*` is checked for.
@ -154,33 +170,99 @@ fn detect_option_if_let_else<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) ->
}
}
}
Some(OptionIfLetElseOccurrence {
return Some(OptionOccurence {
option: format_option_in_sugg(cx, cond_expr, as_ref, as_mut),
method_sugg: method_sugg.to_string(),
some_expr: format!("|{}{}| {}", capture_mut, capture_name, Sugg::hir_with_macro_callsite(cx, some_body, "..")),
none_expr: format!("{}{}", if method_sugg == "map_or" { "" } else { "|| " }, Sugg::hir_with_macro_callsite(cx, none_body, "..")),
})
});
}
}
None
}
fn try_get_inner_pat<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'tcx>) -> Option<&'tcx Pat<'tcx>> {
if let PatKind::TupleStruct(ref qpath, [inner_pat], ..) = pat.kind {
if is_lang_ctor(cx, qpath, OptionSome) {
return Some(inner_pat);
}
}
None
}
/// If this expression is the option if let/else construct we're detecting, then
/// this function returns an `OptionOccurence` struct with details if
/// this construct is found, or None if this construct is not found.
fn detect_option_if_let_else<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> Option<OptionOccurence> {
if let Some(higher::IfLet {
let_pat,
let_expr,
if_then,
if_else: Some(if_else),
}) = higher::IfLet::hir(cx, expr)
{
if !is_else_clause(cx.tcx, expr) {
return try_get_option_occurence(cx, let_pat, let_expr, if_then, if_else);
}
}
None
}
fn detect_option_match<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> Option<OptionOccurence> {
if let ExprKind::Match(ex, arms, MatchSource::Normal) = expr.kind {
if let Some((let_pat, if_then, if_else)) = try_convert_match(cx, arms) {
return try_get_option_occurence(cx, let_pat, ex, if_then, if_else);
}
}
None
}
fn try_convert_match<'tcx>(
cx: &LateContext<'tcx>,
arms: &[Arm<'tcx>],
) -> Option<(&'tcx Pat<'tcx>, &'tcx Expr<'tcx>, &'tcx Expr<'tcx>)> {
if arms.len() == 2 {
return if is_none_arm(cx, &arms[1]) {
Some((arms[0].pat, arms[0].body, arms[1].body))
} else if is_none_arm(cx, &arms[0]) {
Some((arms[1].pat, arms[1].body, arms[0].body))
} else {
None
}
};
}
None
}
fn is_none_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
match arm.pat.kind {
PatKind::Path(ref qpath) => is_lang_ctor(cx, qpath, OptionNone),
PatKind::Wild => true,
_ => false,
}
}
impl<'tcx> LateLintPass<'tcx> for OptionIfLetElse {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
if let Some(detection) = detect_option_if_let_else(cx, expr) {
span_lint_and_sugg(
cx,
OPTION_IF_LET_ELSE,
expr.span,
format!("use Option::{} instead of an if let/else", detection.method_sugg).as_str(),
"try",
format!(
"{}.{}({}, {})",
detection.option, detection.method_sugg, detection.none_expr, detection.some_expr,
),
Applicability::MaybeIncorrect,
);
// Don't lint macros, because it behaves weirdly
// and don't lint constant as well
if !expr.span.from_expansion() && !in_constant(cx, expr.hir_id) {
let detection = detect_option_if_let_else(cx, expr).or_else(|| detect_option_match(cx, expr));
if let Some(det) = detection {
span_lint_and_sugg(
cx,
OPTION_IF_LET_ELSE,
expr.span,
format!("use Option::{} instead of an if let/else", det.method_sugg).as_str(),
"try",
format!(
"{}.{}({}, {})",
det.option, det.method_sugg, det.none_expr, det.some_expr
),
Applicability::MaybeIncorrect,
);
}
}
}
}

15
tests/ui/option_if_let_else.fixed
View File

@ -179,4 +179,19 @@ fn main() {
let _ = pattern_to_vec("hello world");
let _ = complex_subpat();
// issue #8492
let _ = s.map_or(1, |string| string.len());
let _ = Some(10).map_or(5, |a| a + 1);
let res: Result<i32, i32> = Ok(5);
let _ = match res {
Ok(a) => a + 1,
_ => 1,
};
let _ = match res {
Err(_) => 1,
Ok(a) => a + 1,
};
let _ = if let Ok(a) = res { a + 1 } else { 5 };
}

21
tests/ui/option_if_let_else.rs
View File

@ -208,4 +208,25 @@ async fn _f2() {
let _ = pattern_to_vec("hello world");
let _ = complex_subpat();
// issue #8492
let _ = match s {
Some(string) => string.len(),
None => 1,
};
let _ = match Some(10) {
Some(a) => a + 1,
None => 5,
};
let res: Result<i32, i32> = Ok(5);
let _ = match res {
Ok(a) => a + 1,
_ => 1,
};
let _ = match res {
Err(_) => 1,
Ok(a) => a + 1,
};
let _ = if let Ok(a) = res { a + 1 } else { 5 };
}

22
tests/ui/option_if_let_else.stderr
View File

@ -206,5 +206,25 @@ LL + s.len() + x
LL ~ });
|
error: aborting due to 15 previous errors
error: use Option::map_or instead of an if let/else
--> $DIR/option_if_let_else.rs:212:13
|
LL | let _ = match s {
| _____________^
LL | | Some(string) => string.len(),
LL | | None => 1,
LL | | };
| |_____^ help: try: `s.map_or(1, |string| string.len())`
error: use Option::map_or instead of an if let/else
--> $DIR/option_if_let_else.rs:216:13
|
LL | let _ = match Some(10) {
| _____________^
LL | | Some(a) => a + 1,
LL | | None => 5,
LL | | };
| |_____^ help: try: `Some(10).map_or(5, |a| a + 1)`
error: aborting due to 17 previous errors