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Auto merge of #6937 - Jarcho:map_entry_suggestion, r=giraffate

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Improve `map_entry` suggestion

fixes: #5176
fixes: #4674
fixes: #4664
fixes: #1450

Still need to handle the value returned by `insert` correctly.

changelog: Improve `map_entry` suggestion. Will now suggest `or_insert`, `insert_with` or `match _.entry(_)` as appopriate.
changelog: Fix `map_entry` false positives where the entry api can't be used. e.g. when the map is used for multiple things.
This commit is contained in:
bors 2021-04-16 13:23:23 +00:00
commit 1e0a3ff55c
19 changed files with 1531 additions and 384 deletions
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723
clippy_lints/src/entry.rs
View file

@ -1,17 +1,19 @@
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::source::{snippet, snippet_opt, snippet_with_applicability};
use clippy_utils::ty::{is_type_diagnostic_item, match_type};
use clippy_utils::SpanlessEq;
use clippy_utils::{get_item_name, paths};
use if_chain::if_chain;
use clippy_utils::{
can_move_expr_to_closure_no_visit,
diagnostics::span_lint_and_sugg,
is_expr_final_block_expr, is_expr_used_or_unified, match_def_path, paths, peel_hir_expr_while,
source::{reindent_multiline, snippet_indent, snippet_with_applicability, snippet_with_context},
SpanlessEq,
};
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{BorrowKind, Expr, ExprKind, UnOp};
use rustc_hir::{
intravisit::{walk_expr, ErasedMap, NestedVisitorMap, Visitor},
Block, Expr, ExprKind, Guard, HirId, Local, Stmt, StmtKind, UnOp,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::map::Map;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::sym;
use rustc_span::{Span, SyntaxContext, DUMMY_SP};
use std::fmt::Write;
declare_clippy_lint! {
/// **What it does:** Checks for uses of `contains_key` + `insert` on `HashMap`
@ -19,15 +21,14 @@ declare_clippy_lint! {
///
/// **Why is this bad?** Using `entry` is more efficient.
///
/// **Known problems:** Some false negatives, eg.:
/// **Known problems:** The suggestion may have type inference errors in some cases. e.g.
/// ```rust
/// # use std::collections::HashMap;
/// # let mut map = HashMap::new();
/// # let v = 1;
/// # let k = 1;
/// if !map.contains_key(&k) {
/// map.insert(k.clone(), v);
/// }
/// let mut map = std::collections::HashMap::new();
/// let _ = if !map.contains_key(&0) {
/// map.insert(0, 0)
/// } else {
/// None
/// };
/// ```
///
/// **Example:**
@ -56,132 +57,584 @@ declare_clippy_lint! {
declare_lint_pass!(HashMapPass => [MAP_ENTRY]);
impl<'tcx> LateLintPass<'tcx> for HashMapPass {
#[allow(clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::If(check, then_block, ref else_block) = expr.kind {
if let ExprKind::Unary(UnOp::Not, check) = check.kind {
if let Some((ty, map, key)) = check_cond(cx, check) {
// in case of `if !m.contains_key(&k) { m.insert(k, v); }`
// we can give a better error message
let sole_expr = {
else_block.is_none()
&& if let ExprKind::Block(then_block, _) = then_block.kind {
(then_block.expr.is_some() as usize) + then_block.stmts.len() == 1
} else {
true
}
// XXXManishearth we can also check for if/else blocks containing `None`.
};
let (cond_expr, then_expr, else_expr) = match expr.kind {
ExprKind::If(c, t, e) => (c, t, e),
_ => return,
};
let (map_ty, contains_expr) = match try_parse_contains(cx, cond_expr) {
Some(x) => x,
None => return,
};
let mut visitor = InsertVisitor {
cx,
span: expr.span,
ty,
map,
key,
sole_expr,
};
let then_search = match find_insert_calls(cx, &contains_expr, then_expr) {
Some(x) => x,
None => return,
};
walk_expr(&mut visitor, then_block);
}
} else if let Some(else_block) = *else_block {
if let Some((ty, map, key)) = check_cond(cx, check) {
let mut visitor = InsertVisitor {
cx,
span: expr.span,
ty,
map,
key,
sole_expr: false,
};
walk_expr(&mut visitor, else_block);
}
}
}
}
}
fn check_cond<'a>(cx: &LateContext<'_>, check: &'a Expr<'a>) -> Option<(&'static str, &'a Expr<'a>, &'a Expr<'a>)> {
if_chain! {
if let ExprKind::MethodCall(path, _, params, _) = check.kind;
if params.len() >= 2;
if path.ident.name == sym!(contains_key);
if let ExprKind::AddrOf(BorrowKind::Ref, _, key) = params[1].kind;
then {
let map = &params[0];
let obj_ty = cx.typeck_results().expr_ty(map).peel_refs();
return if match_type(cx, obj_ty, &paths::BTREEMAP) {
Some(("BTreeMap", map, key))
}
else if is_type_diagnostic_item(cx, obj_ty, sym::hashmap_type) {
Some(("HashMap", map, key))
}
else {
None
let mut app = Applicability::MachineApplicable;
let map_str = snippet_with_context(cx, contains_expr.map.span, contains_expr.call_ctxt, "..", &mut app).0;
let key_str = snippet_with_context(cx, contains_expr.key.span, contains_expr.call_ctxt, "..", &mut app).0;
let sugg = if let Some(else_expr) = else_expr {
let else_search = match find_insert_calls(cx, &contains_expr, else_expr) {
Some(search) => search,
None => return,
};
}
}
None
}
struct InsertVisitor<'a, 'tcx, 'b> {
cx: &'a LateContext<'tcx>,
span: Span,
ty: &'static str,
map: &'b Expr<'b>,
key: &'b Expr<'b>,
sole_expr: bool,
}
impl<'a, 'tcx, 'b> Visitor<'tcx> for InsertVisitor<'a, 'tcx, 'b> {
type Map = Map<'tcx>;
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::MethodCall(path, _, params, _) = expr.kind;
if params.len() == 3;
if path.ident.name == sym!(insert);
if get_item_name(self.cx, self.map) == get_item_name(self.cx, &params[0]);
if SpanlessEq::new(self.cx).eq_expr(self.key, &params[1]);
if snippet_opt(self.cx, self.map.span) == snippet_opt(self.cx, params[0].span);
then {
span_lint_and_then(self.cx, MAP_ENTRY, self.span,
&format!("usage of `contains_key` followed by `insert` on a `{}`", self.ty), |diag| {
if self.sole_expr {
let mut app = Applicability::MachineApplicable;
let help = format!("{}.entry({}).or_insert({});",
snippet_with_applicability(self.cx, self.map.span, "map", &mut app),
snippet_with_applicability(self.cx, params[1].span, "..", &mut app),
snippet_with_applicability(self.cx, params[2].span, "..", &mut app));
diag.span_suggestion(
self.span,
"consider using",
help,
Applicability::MachineApplicable, // snippet
);
}
else {
let help = format!("consider using `{}.entry({})`",
snippet(self.cx, self.map.span, "map"),
snippet(self.cx, params[1].span, ".."));
diag.span_label(
self.span,
&help,
);
}
});
if then_search.edits.is_empty() && else_search.edits.is_empty() {
// No insertions
return;
} else if then_search.edits.is_empty() || else_search.edits.is_empty() {
// if .. { insert } else { .. } or if .. { .. } else { insert }
let ((then_str, entry_kind), else_str) = match (else_search.edits.is_empty(), contains_expr.negated) {
(true, true) => (
then_search.snippet_vacant(cx, then_expr.span, &mut app),
snippet_with_applicability(cx, else_expr.span, "{ .. }", &mut app),
),
(true, false) => (
then_search.snippet_occupied(cx, then_expr.span, &mut app),
snippet_with_applicability(cx, else_expr.span, "{ .. }", &mut app),
),
(false, true) => (
else_search.snippet_occupied(cx, else_expr.span, &mut app),
snippet_with_applicability(cx, then_expr.span, "{ .. }", &mut app),
),
(false, false) => (
else_search.snippet_vacant(cx, else_expr.span, &mut app),
snippet_with_applicability(cx, then_expr.span, "{ .. }", &mut app),
),
};
format!(
"if let {}::{} = {}.entry({}) {} else {}",
map_ty.entry_path(),
entry_kind,
map_str,
key_str,
then_str,
else_str,
)
} else {
// if .. { insert } else { insert }
let ((then_str, then_entry), (else_str, else_entry)) = if contains_expr.negated {
(
then_search.snippet_vacant(cx, then_expr.span, &mut app),
else_search.snippet_occupied(cx, else_expr.span, &mut app),
)
} else {
(
then_search.snippet_occupied(cx, then_expr.span, &mut app),
else_search.snippet_vacant(cx, else_expr.span, &mut app),
)
};
let indent_str = snippet_indent(cx, expr.span);
let indent_str = indent_str.as_deref().unwrap_or("");
format!(
"match {}.entry({}) {{\n{indent} {entry}::{} => {}\n\
{indent} {entry}::{} => {}\n{indent}}}",
map_str,
key_str,
then_entry,
reindent_multiline(then_str.into(), true, Some(4 + indent_str.len())),
else_entry,
reindent_multiline(else_str.into(), true, Some(4 + indent_str.len())),
entry = map_ty.entry_path(),
indent = indent_str,
)
}
} else {
if then_search.edits.is_empty() {
// no insertions
return;
}
}
if !self.sole_expr {
walk_expr(self, expr);
// if .. { insert }
if !then_search.allow_insert_closure {
let (body_str, entry_kind) = if contains_expr.negated {
then_search.snippet_vacant(cx, then_expr.span, &mut app)
} else {
then_search.snippet_occupied(cx, then_expr.span, &mut app)
};
format!(
"if let {}::{} = {}.entry({}) {}",
map_ty.entry_path(),
entry_kind,
map_str,
key_str,
body_str,
)
} else if let Some(insertion) = then_search.as_single_insertion() {
let value_str = snippet_with_context(cx, insertion.value.span, then_expr.span.ctxt(), "..", &mut app).0;
if contains_expr.negated {
if insertion.value.can_have_side_effects() {
format!("{}.entry({}).or_insert_with(|| {});", map_str, key_str, value_str)
} else {
format!("{}.entry({}).or_insert({});", map_str, key_str, value_str)
}
} else {
// TODO: suggest using `if let Some(v) = map.get_mut(k) { .. }` here.
// This would need to be a different lint.
return;
}
} else {
let block_str = then_search.snippet_closure(cx, then_expr.span, &mut app);
if contains_expr.negated {
format!("{}.entry({}).or_insert_with(|| {});", map_str, key_str, block_str)
} else {
// TODO: suggest using `if let Some(v) = map.get_mut(k) { .. }` here.
// This would need to be a different lint.
return;
}
}
};
span_lint_and_sugg(
cx,
MAP_ENTRY,
expr.span,
&format!("usage of `contains_key` followed by `insert` on a `{}`", map_ty.name()),
"try this",
sugg,
app,
);
}
}
#[derive(Clone, Copy)]
enum MapType {
Hash,
BTree,
}
impl MapType {
fn name(self) -> &'static str {
match self {
Self::Hash => "HashMap",
Self::BTree => "BTreeMap",
}
}
fn entry_path(self) -> &'static str {
match self {
Self::Hash => "std::collections::hash_map::Entry",
Self::BTree => "std::collections::btree_map::Entry",
}
}
}
struct ContainsExpr<'tcx> {
negated: bool,
map: &'tcx Expr<'tcx>,
key: &'tcx Expr<'tcx>,
call_ctxt: SyntaxContext,
}
fn try_parse_contains(cx: &LateContext<'_>, expr: &'tcx Expr<'_>) -> Option<(MapType, ContainsExpr<'tcx>)> {
let mut negated = false;
let expr = peel_hir_expr_while(expr, |e| match e.kind {
ExprKind::Unary(UnOp::Not, e) => {
negated = !negated;
Some(e)
},
_ => None,
});
match expr.kind {
ExprKind::MethodCall(
_,
_,
[map, Expr {
kind: ExprKind::AddrOf(_, _, key),
span: key_span,
..
}],
_,
) if key_span.ctxt() == expr.span.ctxt() => {
let id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
let expr = ContainsExpr {
negated,
map,
key,
call_ctxt: expr.span.ctxt(),
};
if match_def_path(cx, id, &paths::BTREEMAP_CONTAINS_KEY) {
Some((MapType::BTree, expr))
} else if match_def_path(cx, id, &paths::HASHMAP_CONTAINS_KEY) {
Some((MapType::Hash, expr))
} else {
None
}
},
_ => None,
}
}
struct InsertExpr<'tcx> {
map: &'tcx Expr<'tcx>,
key: &'tcx Expr<'tcx>,
value: &'tcx Expr<'tcx>,
}
fn try_parse_insert(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<InsertExpr<'tcx>> {
if let ExprKind::MethodCall(_, _, [map, key, value], _) = expr.kind {
let id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
if match_def_path(cx, id, &paths::BTREEMAP_INSERT) || match_def_path(cx, id, &paths::HASHMAP_INSERT) {
Some(InsertExpr { map, key, value })
} else {
None
}
} else {
None
}
}
/// An edit that will need to be made to move the expression to use the entry api
#[derive(Clone, Copy)]
enum Edit<'tcx> {
/// A semicolon that needs to be removed. Used to create a closure for `insert_with`.
RemoveSemi(Span),
/// An insertion into the map.
Insertion(Insertion<'tcx>),
}
impl Edit<'tcx> {
fn as_insertion(self) -> Option<Insertion<'tcx>> {
if let Self::Insertion(i) = self { Some(i) } else { None }
}
}
#[derive(Clone, Copy)]
struct Insertion<'tcx> {
call: &'tcx Expr<'tcx>,
value: &'tcx Expr<'tcx>,
}
/// This visitor needs to do a multiple things:
/// * Find all usages of the map. An insertion can only be made before any other usages of the map.
/// * Determine if there's an insertion using the same key. There's no need for the entry api
/// otherwise.
/// * Determine if the final statement executed is an insertion. This is needed to use
/// `or_insert_with`.
/// * Determine if there's any sub-expression that can't be placed in a closure.
/// * Determine if there's only a single insert statement. `or_insert` can be used in this case.
#[allow(clippy::struct_excessive_bools)]
struct InsertSearcher<'cx, 'tcx> {
cx: &'cx LateContext<'tcx>,
/// The map expression used in the contains call.
map: &'tcx Expr<'tcx>,
/// The key expression used in the contains call.
key: &'tcx Expr<'tcx>,
/// The context of the top level block. All insert calls must be in the same context.
ctxt: SyntaxContext,
/// Whether this expression can be safely moved into a closure.
allow_insert_closure: bool,
/// Whether this expression can use the entry api.
can_use_entry: bool,
/// Whether this expression is the final expression in this code path. This may be a statement.
in_tail_pos: bool,
// Is this expression a single insert. A slightly better suggestion can be made in this case.
is_single_insert: bool,
/// If the visitor has seen the map being used.
is_map_used: bool,
/// The locations where changes need to be made for the suggestion.
edits: Vec<Edit<'tcx>>,
/// A stack of loops the visitor is currently in.
loops: Vec<HirId>,
}
impl<'tcx> InsertSearcher<'_, 'tcx> {
/// Visit the expression as a branch in control flow. Multiple insert calls can be used, but
/// only if they are on separate code paths. This will return whether the map was used in the
/// given expression.
fn visit_cond_arm(&mut self, e: &'tcx Expr<'_>) -> bool {
let is_map_used = self.is_map_used;
let in_tail_pos = self.in_tail_pos;
self.visit_expr(e);
let res = self.is_map_used;
self.is_map_used = is_map_used;
self.in_tail_pos = in_tail_pos;
res
}
/// Visits an expression which is not itself in a tail position, but other sibling expressions
/// may be. e.g. if conditions
fn visit_non_tail_expr(&mut self, e: &'tcx Expr<'_>) {
let in_tail_pos = self.in_tail_pos;
self.in_tail_pos = false;
self.visit_expr(e);
self.in_tail_pos = in_tail_pos;
}
}
impl<'tcx> Visitor<'tcx> for InsertSearcher<'_, 'tcx> {
type Map = ErasedMap<'tcx>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) {
match stmt.kind {
StmtKind::Semi(e) => {
self.visit_expr(e);
if self.in_tail_pos && self.allow_insert_closure {
// The spans are used to slice the top level expression into multiple parts. This requires that
// they all come from the same part of the source code.
if stmt.span.ctxt() == self.ctxt && e.span.ctxt() == self.ctxt {
self.edits
.push(Edit::RemoveSemi(stmt.span.trim_start(e.span).unwrap_or(DUMMY_SP)));
} else {
self.allow_insert_closure = false;
}
}
},
StmtKind::Expr(e) => self.visit_expr(e),
StmtKind::Local(Local { init: Some(e), .. }) => {
self.allow_insert_closure &= !self.in_tail_pos;
self.in_tail_pos = false;
self.is_single_insert = false;
self.visit_expr(e);
},
_ => {
self.allow_insert_closure &= !self.in_tail_pos;
self.is_single_insert = false;
},
}
}
fn visit_block(&mut self, block: &'tcx Block<'_>) {
// If the block is in a tail position, then the last expression (possibly a statement) is in the
// tail position. The rest, however, are not.
match (block.stmts, block.expr) {
([], None) => {
self.allow_insert_closure &= !self.in_tail_pos;
},
([], Some(expr)) => self.visit_expr(expr),
(stmts, Some(expr)) => {
let in_tail_pos = self.in_tail_pos;
self.in_tail_pos = false;
for stmt in stmts {
self.visit_stmt(stmt);
}
self.in_tail_pos = in_tail_pos;
self.visit_expr(expr);
},
([stmts @ .., stmt], None) => {
let in_tail_pos = self.in_tail_pos;
self.in_tail_pos = false;
for stmt in stmts {
self.visit_stmt(stmt);
}
self.in_tail_pos = in_tail_pos;
self.visit_stmt(stmt);
},
}
}
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if !self.can_use_entry {
return;
}
match try_parse_insert(self.cx, expr) {
Some(insert_expr) if SpanlessEq::new(self.cx).eq_expr(self.map, insert_expr.map) => {
// Multiple inserts, inserts with a different key, and inserts from a macro can't use the entry api.
if self.is_map_used
|| !SpanlessEq::new(self.cx).eq_expr(self.key, insert_expr.key)
|| expr.span.ctxt() != self.ctxt
{
self.can_use_entry = false;
return;
}
self.edits.push(Edit::Insertion(Insertion {
call: expr,
value: insert_expr.value,
}));
self.is_map_used = true;
self.allow_insert_closure &= self.in_tail_pos;
// The value doesn't affect whether there is only a single insert expression.
let is_single_insert = self.is_single_insert;
self.visit_non_tail_expr(insert_expr.value);
self.is_single_insert = is_single_insert;
},
_ if SpanlessEq::new(self.cx).eq_expr(self.map, expr) => {
self.is_map_used = true;
},
_ => match expr.kind {
ExprKind::If(cond_expr, then_expr, Some(else_expr)) => {
self.is_single_insert = false;
self.visit_non_tail_expr(cond_expr);
// Each branch may contain it's own insert expression.
let mut is_map_used = self.visit_cond_arm(then_expr);
is_map_used |= self.visit_cond_arm(else_expr);
self.is_map_used = is_map_used;
},
ExprKind::Match(scrutinee_expr, arms, _) => {
self.is_single_insert = false;
self.visit_non_tail_expr(scrutinee_expr);
// Each branch may contain it's own insert expression.
let mut is_map_used = self.is_map_used;
for arm in arms {
if let Some(Guard::If(guard) | Guard::IfLet(_, guard)) = arm.guard {
self.visit_non_tail_expr(guard)
}
is_map_used |= self.visit_cond_arm(arm.body);
}
self.is_map_used = is_map_used;
},
ExprKind::Loop(block, ..) => {
self.loops.push(expr.hir_id);
self.is_single_insert = false;
self.allow_insert_closure &= !self.in_tail_pos;
// Don't allow insertions inside of a loop.
let edit_len = self.edits.len();
self.visit_block(block);
if self.edits.len() != edit_len {
self.can_use_entry = false;
}
self.loops.pop();
},
ExprKind::Block(block, _) => self.visit_block(block),
ExprKind::InlineAsm(_) | ExprKind::LlvmInlineAsm(_) => {
self.can_use_entry = false;
},
_ => {
self.allow_insert_closure &= !self.in_tail_pos;
self.allow_insert_closure &= can_move_expr_to_closure_no_visit(self.cx, expr, &self.loops);
// Sub expressions are no longer in the tail position.
self.is_single_insert = false;
self.in_tail_pos = false;
walk_expr(self, expr);
},
},
}
}
}
struct InsertSearchResults<'tcx> {
edits: Vec<Edit<'tcx>>,
allow_insert_closure: bool,
is_single_insert: bool,
}
impl InsertSearchResults<'tcx> {
fn as_single_insertion(&self) -> Option<Insertion<'tcx>> {
self.is_single_insert.then(|| self.edits[0].as_insertion().unwrap())
}
fn snippet(
&self,
cx: &LateContext<'_>,
mut span: Span,
app: &mut Applicability,
write_wrapped: impl Fn(&mut String, Insertion<'_>, SyntaxContext, &mut Applicability),
) -> String {
let ctxt = span.ctxt();
let mut res = String::new();
for insertion in self.edits.iter().filter_map(|e| e.as_insertion()) {
res.push_str(&snippet_with_applicability(
cx,
span.until(insertion.call.span),
"..",
app,
));
if is_expr_used_or_unified(cx.tcx, insertion.call) {
write_wrapped(&mut res, insertion, ctxt, app);
} else {
let _ = write!(
res,
"e.insert({})",
snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0
);
}
span = span.trim_start(insertion.call.span).unwrap_or(DUMMY_SP);
}
res.push_str(&snippet_with_applicability(cx, span, "..", app));
res
}
fn snippet_occupied(&self, cx: &LateContext<'_>, span: Span, app: &mut Applicability) -> (String, &'static str) {
(
self.snippet(cx, span, app, |res, insertion, ctxt, app| {
// Insertion into a map would return `Some(&mut value)`, but the entry returns `&mut value`
let _ = write!(
res,
"Some(e.insert({}))",
snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0
);
}),
"Occupied(mut e)",
)
}
fn snippet_vacant(&self, cx: &LateContext<'_>, span: Span, app: &mut Applicability) -> (String, &'static str) {
(
self.snippet(cx, span, app, |res, insertion, ctxt, app| {
// Insertion into a map would return `None`, but the entry returns a mutable reference.
let _ = if is_expr_final_block_expr(cx.tcx, insertion.call) {
write!(
res,
"e.insert({});\n{}None",
snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0,
snippet_indent(cx, insertion.call.span).as_deref().unwrap_or(""),
)
} else {
write!(
res,
"{{ e.insert({}); None }}",
snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0,
)
};
}),
"Vacant(e)",
)
}
fn snippet_closure(&self, cx: &LateContext<'_>, mut span: Span, app: &mut Applicability) -> String {
let ctxt = span.ctxt();
let mut res = String::new();
for edit in &self.edits {
match *edit {
Edit::Insertion(insertion) => {
// Cut out the value from `map.insert(key, value)`
res.push_str(&snippet_with_applicability(
cx,
span.until(insertion.call.span),
"..",
app,
));
res.push_str(&snippet_with_context(cx, insertion.value.span, ctxt, "..", app).0);
span = span.trim_start(insertion.call.span).unwrap_or(DUMMY_SP);
},
Edit::RemoveSemi(semi_span) => {
// Cut out the semicolon. This allows the value to be returned from the closure.
res.push_str(&snippet_with_applicability(cx, span.until(semi_span), "..", app));
span = span.trim_start(semi_span).unwrap_or(DUMMY_SP);
},
}
}
res.push_str(&snippet_with_applicability(cx, span, "..", app));
res
}
}
fn find_insert_calls(
cx: &LateContext<'tcx>,
contains_expr: &ContainsExpr<'tcx>,
expr: &'tcx Expr<'_>,
) -> Option<InsertSearchResults<'tcx>> {
let mut s = InsertSearcher {
cx,
map: contains_expr.map,
key: contains_expr.key,
ctxt: expr.span.ctxt(),
edits: Vec::new(),
is_map_used: false,
allow_insert_closure: true,
can_use_entry: true,
in_tail_pos: true,
is_single_insert: true,
loops: Vec::new(),
};
s.visit_expr(expr);
let allow_insert_closure = s.allow_insert_closure;
let is_single_insert = s.is_single_insert;
let edits = s.edits;
s.can_use_entry.then(|| InsertSearchResults {
edits,
allow_insert_closure,
is_single_insert,
})
}

57
clippy_lints/src/manual_map.rs
View file

@ -1,16 +1,14 @@
use crate::{map_unit_fn::OPTION_MAP_UNIT_FN, matches::MATCH_AS_REF};
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
use clippy_utils::ty::{can_partially_move_ty, is_type_diagnostic_item, peel_mid_ty_refs_is_mutable};
use clippy_utils::{in_constant, is_allowed, is_else_clause, is_lang_ctor, match_var, peel_hir_expr_refs};
use clippy_utils::ty::{is_type_diagnostic_item, peel_mid_ty_refs_is_mutable};
use clippy_utils::{
can_move_expr_to_closure, in_constant, is_allowed, is_else_clause, is_lang_ctor, match_var, peel_hir_expr_refs,
};
use rustc_ast::util::parser::PREC_POSTFIX;
use rustc_errors::Applicability;
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{
def::Res,
intravisit::{walk_expr, ErasedMap, NestedVisitorMap, Visitor},
Arm, BindingAnnotation, Block, Expr, ExprKind, MatchSource, Mutability, Pat, PatKind, Path, QPath,
};
use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, MatchSource, Mutability, Pat, PatKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_session::{declare_lint_pass, declare_tool_lint};
@ -199,51 +197,6 @@ impl LateLintPass<'_> for ManualMap {
}
}
// Checks if the expression can be moved into a closure as is.
fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
struct V<'cx, 'tcx> {
cx: &'cx LateContext<'tcx>,
make_closure: bool,
}
impl Visitor<'tcx> for V<'_, 'tcx> {
type Map = ErasedMap<'tcx>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
match e.kind {
ExprKind::Break(..)
| ExprKind::Continue(_)
| ExprKind::Ret(_)
| ExprKind::Yield(..)
| ExprKind::InlineAsm(_)
| ExprKind::LlvmInlineAsm(_) => {
self.make_closure = false;
},
// Accessing a field of a local value can only be done if the type isn't
// partially moved.
ExprKind::Field(base_expr, _)
if matches!(
base_expr.kind,
ExprKind::Path(QPath::Resolved(_, Path { res: Res::Local(_), .. }))
) && can_partially_move_ty(self.cx, self.cx.typeck_results().expr_ty(base_expr)) =>
{
// TODO: check if the local has been partially moved. Assume it has for now.
self.make_closure = false;
return;
}
_ => (),
};
walk_expr(self, e);
}
}
let mut v = V { cx, make_closure: true };
v.visit_expr(expr);
v.make_closure
}
// Checks whether the expression could be passed as a function, or whether a closure is needed.
// Returns the function to be passed to `map` if it exists.
fn can_pass_as_func(cx: &LateContext<'tcx>, binding: Ident, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {