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Fix manual_match with let-expressions

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This commit is contained in:
Cameron Steffen 2021-08-26 10:05:33 -05:00 committed by flip1995
parent 61bb96738c
commit 5722a7dacd
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GPG Key ID: 1CA0DF2AF59D68A5
4 changed files with 195 additions and 215 deletions
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32
clippy_lints/src/collapsible_match.rs
View File

@ -1,9 +1,10 @@
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::higher::IfLetOrMatch;
use clippy_utils::visitors::is_local_used;
use clippy_utils::{higher, is_lang_ctor, is_unit_expr, path_to_local, peel_ref_operators, SpanlessEq};
use clippy_utils::{is_lang_ctor, is_unit_expr, path_to_local, peel_ref_operators, SpanlessEq};
use if_chain::if_chain;
use rustc_hir::LangItem::OptionNone;
use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, MatchSource, Pat, PatKind, StmtKind};
use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::{MultiSpan, Span};
@ -149,33 +150,6 @@ fn strip_singleton_blocks<'hir>(mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir>
expr
}
enum IfLetOrMatch<'hir> {
Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource),
/// scrutinee, pattern, then block, else block
IfLet(
&'hir Expr<'hir>,
&'hir Pat<'hir>,
&'hir Expr<'hir>,
Option<&'hir Expr<'hir>>,
),
}
impl<'hir> IfLetOrMatch<'hir> {
fn parse(cx: &LateContext<'_>, expr: &Expr<'hir>) -> Option<Self> {
match expr.kind {
ExprKind::Match(expr, arms, source) => Some(Self::Match(expr, arms, source)),
_ => higher::IfLet::hir(cx, expr).map(
|higher::IfLet {
let_expr,
let_pat,
if_then,
if_else,
}| { Self::IfLet(let_expr, let_pat, if_then, if_else) },
),
}
}
}
/// A "wild-like" arm has a wild (`_`) or `None` pattern and no guard. Such arms can be "collapsed"
/// into a single wild arm without any significant loss in semantics or readability.
fn arm_is_wild_like(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {

342
clippy_lints/src/manual_map.rs
View File

@ -1,6 +1,6 @@
use crate::{map_unit_fn::OPTION_MAP_UNIT_FN, matches::MATCH_AS_REF};
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::higher;
use clippy_utils::higher::IfLetOrMatch;
use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
use clippy_utils::ty::{is_type_diagnostic_item, peel_mid_ty_refs_is_mutable};
use clippy_utils::{
@ -46,190 +46,169 @@
impl LateLintPass<'_> for ManualMap {
#[allow(clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let Some(higher::IfLet {
let_pat,
let_expr,
if_then,
if_else: Some(if_else),
}) = higher::IfLet::hir(cx, expr)
{
manage_lint(cx, expr, (&let_pat.kind, if_then), (&PatKind::Wild, if_else), let_expr);
}
if let ExprKind::Match(scrutinee, [then @ Arm { guard: None, .. }, r#else @ Arm { guard: None, .. }], _) =
expr.kind
{
manage_lint(
cx,
expr,
(&then.pat.kind, then.body),
(&r#else.pat.kind, r#else.body),
let (scrutinee, then_pat, then_body, else_pat, else_body) = match IfLetOrMatch::parse(cx, expr) {
Some(IfLetOrMatch::IfLet(scrutinee, pat, body, Some(r#else))) => (scrutinee, pat, body, None, r#else),
Some(IfLetOrMatch::Match(
scrutinee,
);
[arm1 @ Arm { guard: None, .. }, arm2 @ Arm { guard: None, .. }],
_,
)) => (scrutinee, arm1.pat, arm1.body, Some(arm2.pat), arm2.body),
_ => return,
};
if in_external_macro(cx.sess(), expr.span) || in_constant(cx, expr.hir_id) {
return;
}
}
}
fn manage_lint<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
then: (&'tcx PatKind<'_>, &'tcx Expr<'_>),
r#else: (&'tcx PatKind<'_>, &'tcx Expr<'_>),
scrut: &'tcx Expr<'_>,
) {
if in_external_macro(cx.sess(), expr.span) || in_constant(cx, expr.hir_id) {
return;
}
let (scrutinee_ty, ty_ref_count, ty_mutability) =
peel_mid_ty_refs_is_mutable(cx.typeck_results().expr_ty(scrutinee));
if !(is_type_diagnostic_item(cx, scrutinee_ty, sym::option_type)
&& is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::option_type))
{
return;
}
let (scrutinee_ty, ty_ref_count, ty_mutability) = peel_mid_ty_refs_is_mutable(cx.typeck_results().expr_ty(scrut));
if !(is_type_diagnostic_item(cx, scrutinee_ty, sym::option_type)
&& is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::option_type))
{
return;
}
let expr_ctxt = expr.span.ctxt();
let (some_expr, some_pat, pat_ref_count, is_wild_none) = match (
try_parse_pattern(cx, then_pat, expr_ctxt),
else_pat.map_or(Some(OptionPat::Wild), |p| try_parse_pattern(cx, p, expr_ctxt)),
) {
(Some(OptionPat::Wild), Some(OptionPat::Some { pattern, ref_count })) if is_none_expr(cx, then_body) => {
(else_body, pattern, ref_count, true)
},
(Some(OptionPat::None), Some(OptionPat::Some { pattern, ref_count })) if is_none_expr(cx, then_body) => {
(else_body, pattern, ref_count, false)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::Wild)) if is_none_expr(cx, else_body) => {
(then_body, pattern, ref_count, true)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::None)) if is_none_expr(cx, else_body) => {
(then_body, pattern, ref_count, false)
},
_ => return,
};
let (then_pat, then_expr) = then;
let (else_pat, else_expr) = r#else;
// Top level or patterns aren't allowed in closures.
if matches!(some_pat.kind, PatKind::Or(_)) {
return;
}
let expr_ctxt = expr.span.ctxt();
let (some_expr, some_pat, pat_ref_count, is_wild_none) = match (
try_parse_pattern(cx, then_pat, expr_ctxt),
try_parse_pattern(cx, else_pat, expr_ctxt),
) {
(Some(OptionPat::Wild), Some(OptionPat::Some { pattern, ref_count })) if is_none_expr(cx, then_expr) => {
(else_expr, pattern, ref_count, true)
},
(Some(OptionPat::None), Some(OptionPat::Some { pattern, ref_count })) if is_none_expr(cx, then_expr) => {
(else_expr, pattern, ref_count, false)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::Wild)) if is_none_expr(cx, else_expr) => {
(then_expr, pattern, ref_count, true)
},
(Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::None)) if is_none_expr(cx, else_expr) => {
(then_expr, pattern, ref_count, false)
},
_ => return,
};
let some_expr = match get_some_expr(cx, some_expr, expr_ctxt) {
Some(expr) => expr,
None => return,
};
// Top level or patterns aren't allowed in closures.
if matches!(some_pat.kind, PatKind::Or(_)) {
return;
}
// These two lints will go back and forth with each other.
if cx.typeck_results().expr_ty(some_expr) == cx.tcx.types.unit
&& !is_lint_allowed(cx, OPTION_MAP_UNIT_FN, expr.hir_id)
{
return;
}
let some_expr = match get_some_expr(cx, some_expr, expr_ctxt) {
Some(expr) => expr,
None => return,
};
// `map` won't perform any adjustments.
if !cx.typeck_results().expr_adjustments(some_expr).is_empty() {
return;
}
if cx.typeck_results().expr_ty(some_expr) == cx.tcx.types.unit
&& !is_lint_allowed(cx, OPTION_MAP_UNIT_FN, expr.hir_id)
{
return;
}
// Determine which binding mode to use.
let explicit_ref = some_pat.contains_explicit_ref_binding();
let binding_ref = explicit_ref.or_else(|| (ty_ref_count != pat_ref_count).then(|| ty_mutability));
// `map` won't perform any adjustments.
if !cx.typeck_results().expr_adjustments(some_expr).is_empty() {
return;
}
let as_ref_str = match binding_ref {
Some(Mutability::Mut) => ".as_mut()",
Some(Mutability::Not) => ".as_ref()",
None => "",
};
// Determine which binding mode to use.
let explicit_ref = some_pat.contains_explicit_ref_binding();
let binding_ref = explicit_ref.or_else(|| (ty_ref_count != pat_ref_count).then(|| ty_mutability));
let as_ref_str = match binding_ref {
Some(Mutability::Mut) => ".as_mut()",
Some(Mutability::Not) => ".as_ref()",
None => "",
};
match can_move_expr_to_closure(cx, some_expr) {
Some(captures) => {
// 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.
if let Some(binding_ref_mutability) = binding_ref {
let e = peel_hir_expr_while(scrut, |e| match e.kind {
ExprKind::Field(e, _) | ExprKind::AddrOf(_, _, e) => Some(e),
_ => None,
});
if let ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(l), .. })) = e.kind {
match captures.get(l) {
Some(CaptureKind::Value | CaptureKind::Ref(Mutability::Mut)) => return,
Some(CaptureKind::Ref(Mutability::Not)) if binding_ref_mutability == Mutability::Mut => {
return;
},
Some(CaptureKind::Ref(Mutability::Not)) | None => (),
match can_move_expr_to_closure(cx, some_expr) {
Some(captures) => {
// 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.
if let Some(binding_ref_mutability) = binding_ref {
let e = peel_hir_expr_while(scrutinee, |e| match e.kind {
ExprKind::Field(e, _) | ExprKind::AddrOf(_, _, e) => Some(e),
_ => None,
});
if let ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(l), .. })) = e.kind {
match captures.get(l) {
Some(CaptureKind::Value | CaptureKind::Ref(Mutability::Mut)) => return,
Some(CaptureKind::Ref(Mutability::Not)) if binding_ref_mutability == Mutability::Mut => {
return;
},
Some(CaptureKind::Ref(Mutability::Not)) | None => (),
}
}
}
},
None => return,
};
let mut app = Applicability::MachineApplicable;
// Remove address-of expressions from the scrutinee. Either `as_ref` will be called, or
// it's being passed by value.
let scrutinee = peel_hir_expr_refs(scrutinee).0;
let (scrutinee_str, _) = snippet_with_context(cx, scrutinee.span, expr_ctxt, "..", &mut app);
let scrutinee_str =
if scrutinee.span.ctxt() == expr.span.ctxt() && scrutinee.precedence().order() < PREC_POSTFIX {
format!("({})", scrutinee_str)
} else {
scrutinee_str.into()
};
let body_str = if let PatKind::Binding(annotation, id, some_binding, None) = some_pat.kind {
match can_pass_as_func(cx, id, some_expr) {
Some(func) if func.span.ctxt() == some_expr.span.ctxt() => {
snippet_with_applicability(cx, func.span, "..", &mut app).into_owned()
},
_ => {
if path_to_local_id(some_expr, id)
&& !is_lint_allowed(cx, MATCH_AS_REF, expr.hir_id)
&& binding_ref.is_some()
{
return;
}
// `ref` and `ref mut` annotations were handled earlier.
let annotation = if matches!(annotation, BindingAnnotation::Mutable) {
"mut "
} else {
""
};
format!(
"|{}{}| {}",
annotation,
some_binding,
snippet_with_context(cx, some_expr.span, expr_ctxt, "..", &mut app).0
)
},
}
},
None => return,
};
let mut app = Applicability::MachineApplicable;
// Remove address-of expressions from the scrutinee. Either `as_ref` will be called, or
// it's being passed by value.
let scrutinee = peel_hir_expr_refs(scrut).0;
let (scrutinee_str, _) = snippet_with_context(cx, scrutinee.span, expr_ctxt, "..", &mut app);
let scrutinee_str = if scrutinee.span.ctxt() == expr.span.ctxt() && scrutinee.precedence().order() < PREC_POSTFIX {
format!("({})", scrutinee_str)
} else {
scrutinee_str.into()
};
let body_str = if let PatKind::Binding(annotation, id, some_binding, None) = some_pat.kind {
match can_pass_as_func(cx, id, some_expr) {
Some(func) if func.span.ctxt() == some_expr.span.ctxt() => {
snippet_with_applicability(cx, func.span, "..", &mut app).into_owned()
},
_ => {
if path_to_local_id(some_expr, id)
&& !is_lint_allowed(cx, MATCH_AS_REF, expr.hir_id)
&& binding_ref.is_some()
{
return;
}
// `ref` and `ref mut` annotations were handled earlier.
let annotation = if matches!(annotation, BindingAnnotation::Mutable) {
"mut "
} else {
""
};
format!(
"|{}{}| {}",
annotation,
some_binding,
snippet_with_context(cx, some_expr.span, expr_ctxt, "..", &mut app).0
)
},
}
} else if !is_wild_none && explicit_ref.is_none() {
// TODO: handle explicit reference annotations.
format!(
"|{}| {}",
snippet_with_context(cx, some_pat.span, expr_ctxt, "..", &mut app).0,
snippet_with_context(cx, some_expr.span, expr_ctxt, "..", &mut app).0
)
} else {
// Refutable bindings and mixed reference annotations can't be handled by `map`.
return;
};
span_lint_and_sugg(
cx,
MANUAL_MAP,
expr.span,
"manual implementation of `Option::map`",
"try this",
if is_else_clause(cx.tcx, expr) {
format!("{{ {}{}.map({}) }}", scrutinee_str, as_ref_str, body_str)
} else if !is_wild_none && explicit_ref.is_none() {
// TODO: handle explicit reference annotations.
format!(
"|{}| {}",
snippet_with_context(cx, some_pat.span, expr_ctxt, "..", &mut app).0,
snippet_with_context(cx, some_expr.span, expr_ctxt, "..", &mut app).0
)
} else {
format!("{}{}.map({})", scrutinee_str, as_ref_str, body_str)
},
app,
);
// Refutable bindings and mixed reference annotations can't be handled by `map`.
return;
};
span_lint_and_sugg(
cx,
MANUAL_MAP,
expr.span,
"manual implementation of `Option::map`",
"try this",
if else_pat.is_none() && is_else_clause(cx.tcx, expr) {
format!("{{ {}{}.map({}) }}", scrutinee_str, as_ref_str, body_str)
} else {
format!("{}{}.map({})", scrutinee_str, as_ref_str, body_str)
},
app,
);
}
}
// Checks whether the expression could be passed as a function, or whether a closure is needed.
@ -259,28 +238,21 @@ enum OptionPat<'a> {
// Try to parse into a recognized `Option` pattern.
// i.e. `_`, `None`, `Some(..)`, or a reference to any of those.
fn try_parse_pattern(
cx: &LateContext<'tcx>,
pat_kind: &'tcx PatKind<'_>,
ctxt: SyntaxContext,
) -> Option<OptionPat<'tcx>> {
fn f(
cx: &LateContext<'tcx>,
pat_kind: &'tcx PatKind<'_>,
ref_count: usize,
ctxt: SyntaxContext,
) -> Option<OptionPat<'tcx>> {
match pat_kind {
fn try_parse_pattern(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, ctxt: SyntaxContext) -> Option<OptionPat<'tcx>> {
fn f(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, ref_count: usize, ctxt: SyntaxContext) -> Option<OptionPat<'tcx>> {
match pat.kind {
PatKind::Wild => Some(OptionPat::Wild),
PatKind::Ref(ref_pat, _) => f(cx, &ref_pat.kind, ref_count + 1, ctxt),
PatKind::Ref(pat, _) => f(cx, pat, ref_count + 1, ctxt),
PatKind::Path(ref qpath) if is_lang_ctor(cx, qpath, OptionNone) => Some(OptionPat::None),
PatKind::TupleStruct(ref qpath, [pattern], _) if is_lang_ctor(cx, qpath, OptionSome) => {
PatKind::TupleStruct(ref qpath, [pattern], _)
if is_lang_ctor(cx, qpath, OptionSome) && pat.span.ctxt() == ctxt =>
{
Some(OptionPat::Some { pattern, ref_count })
},
_ => None,
}
}
f(cx, pat_kind, 0, ctxt)
f(cx, pat, 0, ctxt)
}
// Checks for an expression wrapped by the `Some` constructor. Returns the contained expression.

29
clippy_utils/src/higher.rs
View File

@ -6,7 +6,7 @@
use if_chain::if_chain;
use rustc_ast::ast::{self, LitKind};
use rustc_hir as hir;
use rustc_hir::{Block, BorrowKind, Expr, ExprKind, LoopSource, Node, Pat, StmtKind, UnOp};
use rustc_hir::{Arm, Block, BorrowKind, Expr, ExprKind, LoopSource, MatchSource, Node, Pat, StmtKind, UnOp};
use rustc_lint::LateContext;
use rustc_span::{sym, ExpnKind, Span, Symbol};
@ -115,6 +115,33 @@ pub fn hir(cx: &LateContext<'_>, expr: &Expr<'hir>) -> Option<Self> {
}
}
pub enum IfLetOrMatch<'hir> {
Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource),
/// scrutinee, pattern, then block, else block
IfLet(
&'hir Expr<'hir>,
&'hir Pat<'hir>,
&'hir Expr<'hir>,
Option<&'hir Expr<'hir>>,
),
}
impl<'hir> IfLetOrMatch<'hir> {
pub fn parse(cx: &LateContext<'_>, expr: &Expr<'hir>) -> Option<Self> {
match expr.kind {
ExprKind::Match(expr, arms, source) => Some(Self::Match(expr, arms, source)),
_ => IfLet::hir(cx, expr).map(
|IfLet {
let_expr,
let_pat,
if_then,
if_else,
}| { Self::IfLet(let_expr, let_pat, if_then, if_else) },
),
}
}
}
pub struct IfOrIfLet<'hir> {
pub cond: &'hir Expr<'hir>,
pub r#else: Option<&'hir Expr<'hir>>,

7
clippy_utils/src/lib.rs
View File

@ -808,6 +808,13 @@ fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
capture_expr_ty = e;
}
},
ExprKind::Let(pat, ..) => {
let mutability = match pat_capture_kind(cx, pat) {
CaptureKind::Value => Mutability::Not,
CaptureKind::Ref(m) => m,
};
return CaptureKind::Ref(mutability);
},
ExprKind::Match(_, arms, _) => {
let mut mutability = Mutability::Not;
for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {