1 //! This module contains functions that retrieve specific elements.
3 #![deny(clippy::missing_docs_in_private_items)]
5 use crate::consts::{constant_simple, Constant};
6 use crate::ty::is_type_diagnostic_item;
7 use crate::{is_expn_of, match_def_path, paths};
8 use if_chain::if_chain;
11 use rustc_hir::{Arm, Block, Expr, ExprKind, HirId, LoopSource, MatchSource, Node, Pat, QPath};
12 use rustc_lint::LateContext;
13 use rustc_span::{sym, symbol, Span};
15 /// The essential nodes of a desugared for loop as well as the entire span:
16 /// `for pat in arg { body }` becomes `(pat, arg, body)`. Return `(pat, arg, body, span)`.
17 pub struct ForLoop<'tcx> {
19 pub pat: &'tcx hir::Pat<'tcx>,
20 /// `IntoIterator` argument
21 pub arg: &'tcx hir::Expr<'tcx>,
23 pub body: &'tcx hir::Expr<'tcx>,
24 /// Compare this against `hir::Destination.target`
26 /// entire `for` loop span
30 impl<'tcx> ForLoop<'tcx> {
31 /// Parses a desugared `for` loop
32 pub fn hir(expr: &Expr<'tcx>) -> Option<Self> {
34 if let hir::ExprKind::DropTemps(e) = expr.kind;
35 if let hir::ExprKind::Match(iterexpr, [arm], hir::MatchSource::ForLoopDesugar) = e.kind;
36 if let hir::ExprKind::Call(_, [arg]) = iterexpr.kind;
37 if let hir::ExprKind::Loop(block, ..) = arm.body.kind;
38 if let [stmt] = block.stmts;
39 if let hir::StmtKind::Expr(e) = stmt.kind;
40 if let hir::ExprKind::Match(_, [_, some_arm], _) = e.kind;
41 if let hir::PatKind::Struct(_, [field], _) = some_arm.pat.kind;
47 loop_id: arm.body.hir_id,
48 span: expr.span.ctxt().outer_expn_data().call_site,
56 /// An `if` expression without `DropTemps`
59 pub cond: &'hir Expr<'hir>,
60 /// `if` then expression
61 pub then: &'hir Expr<'hir>,
63 pub r#else: Option<&'hir Expr<'hir>>,
68 /// Parses an `if` expression
69 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
72 kind: ExprKind::DropTemps(cond),
79 Some(Self { cond, then, r#else })
86 /// An `if let` expression
87 pub struct IfLet<'hir> {
89 pub let_pat: &'hir Pat<'hir>,
90 /// `if let` scrutinee
91 pub let_expr: &'hir Expr<'hir>,
92 /// `if let` then expression
93 pub if_then: &'hir Expr<'hir>,
94 /// `if let` else expression
95 pub if_else: Option<&'hir Expr<'hir>>,
98 impl<'hir> IfLet<'hir> {
99 /// Parses an `if let` expression
100 pub fn hir(cx: &LateContext<'_>, expr: &Expr<'hir>) -> Option<Self> {
104 ExprKind::Let(hir::Let {
115 let mut iter = cx.tcx.hir().parent_iter(expr.hir_id);
116 if let Some((_, Node::Block(Block { stmts: [], .. }))) = iter.next() {
120 kind: ExprKind::Loop(_, _, LoopSource::While, _),
125 // while loop desugar
140 /// An `if let` or `match` expression. Useful for lints that trigger on one or the other.
141 pub enum IfLetOrMatch<'hir> {
142 /// Any `match` expression
143 Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource),
144 /// scrutinee, pattern, then block, else block
149 Option<&'hir Expr<'hir>>,
153 impl<'hir> IfLetOrMatch<'hir> {
154 /// Parses an `if let` or `match` expression
155 pub fn parse(cx: &LateContext<'_>, expr: &Expr<'hir>) -> Option<Self> {
157 ExprKind::Match(expr, arms, source) => Some(Self::Match(expr, arms, source)),
158 _ => IfLet::hir(cx, expr).map(
164 }| { Self::IfLet(let_expr, let_pat, if_then, if_else) },
170 /// An `if` or `if let` expression
171 pub struct IfOrIfLet<'hir> {
172 /// `if` condition that is maybe a `let` expression
173 pub cond: &'hir Expr<'hir>,
174 /// `if` then expression
175 pub then: &'hir Expr<'hir>,
176 /// `else` expression
177 pub r#else: Option<&'hir Expr<'hir>>,
180 impl<'hir> IfOrIfLet<'hir> {
182 /// Parses an `if` or `if let` expression
183 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
184 if let ExprKind::If(cond, then, r#else) = expr.kind {
185 if let ExprKind::DropTemps(new_cond) = cond.kind {
192 if let ExprKind::Let(..) = cond.kind {
193 return Some(Self { cond, then, r#else });
200 /// Represent a range akin to `ast::ExprKind::Range`.
201 #[derive(Debug, Copy, Clone)]
202 pub struct Range<'a> {
203 /// The lower bound of the range, or `None` for ranges such as `..X`.
204 pub start: Option<&'a hir::Expr<'a>>,
205 /// The upper bound of the range, or `None` for ranges such as `X..`.
206 pub end: Option<&'a hir::Expr<'a>>,
207 /// Whether the interval is open or closed.
208 pub limits: ast::RangeLimits,
212 /// Higher a `hir` range to something similar to `ast::ExprKind::Range`.
213 pub fn hir(expr: &'a hir::Expr<'_>) -> Option<Range<'a>> {
214 /// Finds the field named `name` in the field. Always return `Some` for
216 fn get_field<'c>(name: &str, fields: &'c [hir::ExprField<'_>]) -> Option<&'c hir::Expr<'c>> {
217 let expr = &fields.iter().find(|field| field.ident.name.as_str() == name)?.expr;
222 hir::ExprKind::Call(path, args)
225 hir::ExprKind::Path(hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, ..))
229 start: Some(&args[0]),
231 limits: ast::RangeLimits::Closed,
234 hir::ExprKind::Struct(path, fields, None) => match &path {
235 hir::QPath::LangItem(hir::LangItem::RangeFull, ..) => Some(Range {
238 limits: ast::RangeLimits::HalfOpen,
240 hir::QPath::LangItem(hir::LangItem::RangeFrom, ..) => Some(Range {
241 start: Some(get_field("start", fields)?),
243 limits: ast::RangeLimits::HalfOpen,
245 hir::QPath::LangItem(hir::LangItem::Range, ..) => Some(Range {
246 start: Some(get_field("start", fields)?),
247 end: Some(get_field("end", fields)?),
248 limits: ast::RangeLimits::HalfOpen,
250 hir::QPath::LangItem(hir::LangItem::RangeToInclusive, ..) => Some(Range {
252 end: Some(get_field("end", fields)?),
253 limits: ast::RangeLimits::Closed,
255 hir::QPath::LangItem(hir::LangItem::RangeTo, ..) => Some(Range {
257 end: Some(get_field("end", fields)?),
258 limits: ast::RangeLimits::HalfOpen,
267 /// Represent the pre-expansion arguments of a `vec!` invocation.
268 pub enum VecArgs<'a> {
269 /// `vec![elem; len]`
270 Repeat(&'a hir::Expr<'a>, &'a hir::Expr<'a>),
272 Vec(&'a [hir::Expr<'a>]),
275 impl<'a> VecArgs<'a> {
276 /// Returns the arguments of the `vec!` macro if this expression was expanded
278 pub fn hir(cx: &LateContext<'_>, expr: &'a hir::Expr<'_>) -> Option<VecArgs<'a>> {
280 if let hir::ExprKind::Call(fun, args) = expr.kind;
281 if let hir::ExprKind::Path(ref qpath) = fun.kind;
282 if is_expn_of(fun.span, "vec").is_some();
283 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
285 return if match_def_path(cx, fun_def_id, &paths::VEC_FROM_ELEM) && args.len() == 2 {
286 // `vec![elem; size]` case
287 Some(VecArgs::Repeat(&args[0], &args[1]))
288 } else if match_def_path(cx, fun_def_id, &paths::SLICE_INTO_VEC) && args.len() == 1 {
289 // `vec![a, b, c]` case
291 if let hir::ExprKind::Box(boxed) = args[0].kind;
292 if let hir::ExprKind::Array(args) = boxed.kind;
294 return Some(VecArgs::Vec(args));
299 } else if match_def_path(cx, fun_def_id, &paths::VEC_NEW) && args.is_empty() {
300 Some(VecArgs::Vec(&[]))
311 /// A desugared `while` loop
312 pub struct While<'hir> {
313 /// `while` loop condition
314 pub condition: &'hir Expr<'hir>,
315 /// `while` loop body
316 pub body: &'hir Expr<'hir>,
319 impl<'hir> While<'hir> {
321 /// Parses a desugared `while` loop
322 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
323 if let ExprKind::Loop(
330 kind: ExprKind::DropTemps(condition),
345 return Some(Self { condition, body });
351 /// A desugared `while let` loop
352 pub struct WhileLet<'hir> {
353 /// `while let` loop item pattern
354 pub let_pat: &'hir Pat<'hir>,
355 /// `while let` loop scrutinee
356 pub let_expr: &'hir Expr<'hir>,
357 /// `while let` loop body
358 pub if_then: &'hir Expr<'hir>,
361 impl<'hir> WhileLet<'hir> {
363 /// Parses a desugared `while let` loop
364 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
365 if let ExprKind::Loop(
373 ExprKind::Let(hir::Let {
402 /// Converts a hir binary operator to the corresponding `ast` type.
404 pub fn binop(op: hir::BinOpKind) -> ast::BinOpKind {
406 hir::BinOpKind::Eq => ast::BinOpKind::Eq,
407 hir::BinOpKind::Ge => ast::BinOpKind::Ge,
408 hir::BinOpKind::Gt => ast::BinOpKind::Gt,
409 hir::BinOpKind::Le => ast::BinOpKind::Le,
410 hir::BinOpKind::Lt => ast::BinOpKind::Lt,
411 hir::BinOpKind::Ne => ast::BinOpKind::Ne,
412 hir::BinOpKind::Or => ast::BinOpKind::Or,
413 hir::BinOpKind::Add => ast::BinOpKind::Add,
414 hir::BinOpKind::And => ast::BinOpKind::And,
415 hir::BinOpKind::BitAnd => ast::BinOpKind::BitAnd,
416 hir::BinOpKind::BitOr => ast::BinOpKind::BitOr,
417 hir::BinOpKind::BitXor => ast::BinOpKind::BitXor,
418 hir::BinOpKind::Div => ast::BinOpKind::Div,
419 hir::BinOpKind::Mul => ast::BinOpKind::Mul,
420 hir::BinOpKind::Rem => ast::BinOpKind::Rem,
421 hir::BinOpKind::Shl => ast::BinOpKind::Shl,
422 hir::BinOpKind::Shr => ast::BinOpKind::Shr,
423 hir::BinOpKind::Sub => ast::BinOpKind::Sub,
427 /// A parsed `Vec` initialization expression
428 #[derive(Clone, Copy)]
429 pub enum VecInitKind {
432 /// `Vec::default()` or `Default::default()`
434 /// `Vec::with_capacity(123)`
435 WithConstCapacity(u128),
436 /// `Vec::with_capacity(slice.len())`
437 WithExprCapacity(HirId),
440 /// Checks if given expression is an initialization of `Vec` and returns its kind.
441 pub fn get_vec_init_kind<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Option<VecInitKind> {
442 if let ExprKind::Call(func, args) = expr.kind {
444 ExprKind::Path(QPath::TypeRelative(ty, name))
445 if is_type_diagnostic_item(cx, cx.typeck_results().node_type(ty.hir_id), sym::Vec) =>
447 if name.ident.name == sym::new {
448 return Some(VecInitKind::New);
449 } else if name.ident.name == symbol::kw::Default {
450 return Some(VecInitKind::Default);
451 } else if name.ident.name.as_str() == "with_capacity" {
452 let arg = args.get(0)?;
453 return match constant_simple(cx, cx.typeck_results(), arg) {
454 Some(Constant::Int(num)) => Some(VecInitKind::WithConstCapacity(num)),
455 _ => Some(VecInitKind::WithExprCapacity(arg.hir_id)),
459 ExprKind::Path(QPath::Resolved(_, path))
460 if match_def_path(cx, path.res.opt_def_id()?, &paths::DEFAULT_TRAIT_METHOD)
461 && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::Vec) =>
463 return Some(VecInitKind::Default);