1 //! This module contains functions that retrieve specific elements.
3 #![deny(clippy::missing_docs_in_private_items)]
5 use crate::ty::is_type_diagnostic_item;
6 use crate::{is_expn_of, match_def_path, paths};
7 use if_chain::if_chain;
8 use rustc_ast::ast::{self, LitKind};
10 use rustc_hir::{Arm, Block, Expr, ExprKind, HirId, LoopSource, MatchSource, Node, Pat, QPath};
11 use rustc_lint::LateContext;
12 use rustc_span::{sym, symbol, Span};
14 /// The essential nodes of a desugared for loop as well as the entire span:
15 /// `for pat in arg { body }` becomes `(pat, arg, body)`. Return `(pat, arg, body, span)`.
16 pub struct ForLoop<'tcx> {
18 pub pat: &'tcx hir::Pat<'tcx>,
19 /// `IntoIterator` argument
20 pub arg: &'tcx hir::Expr<'tcx>,
22 pub body: &'tcx hir::Expr<'tcx>,
23 /// Compare this against `hir::Destination.target`
25 /// entire `for` loop span
29 impl<'tcx> ForLoop<'tcx> {
30 /// Parses a desugared `for` loop
31 pub fn hir(expr: &Expr<'tcx>) -> Option<Self> {
33 if let hir::ExprKind::DropTemps(e) = expr.kind;
34 if let hir::ExprKind::Match(iterexpr, [arm], hir::MatchSource::ForLoopDesugar) = e.kind;
35 if let hir::ExprKind::Call(_, [arg]) = iterexpr.kind;
36 if let hir::ExprKind::Loop(block, ..) = arm.body.kind;
37 if let [stmt] = &*block.stmts;
38 if let hir::StmtKind::Expr(e) = stmt.kind;
39 if let hir::ExprKind::Match(_, [_, some_arm], _) = e.kind;
40 if let hir::PatKind::Struct(_, [field], _) = some_arm.pat.kind;
46 loop_id: arm.body.hir_id,
47 span: expr.span.ctxt().outer_expn_data().call_site,
55 /// An `if` expression without `DropTemps`
58 pub cond: &'hir Expr<'hir>,
59 /// `if` then expression
60 pub then: &'hir Expr<'hir>,
62 pub r#else: Option<&'hir Expr<'hir>>,
67 /// Parses an `if` expression
68 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
71 kind: ExprKind::DropTemps(cond),
78 Some(Self { cond, then, r#else })
85 /// An `if let` expression
86 pub struct IfLet<'hir> {
88 pub let_pat: &'hir Pat<'hir>,
89 /// `if let` scrutinee
90 pub let_expr: &'hir Expr<'hir>,
91 /// `if let` then expression
92 pub if_then: &'hir Expr<'hir>,
93 /// `if let` else expression
94 pub if_else: Option<&'hir Expr<'hir>>,
97 impl<'hir> IfLet<'hir> {
98 /// Parses an `if let` expression
99 pub fn hir(cx: &LateContext<'_>, expr: &Expr<'hir>) -> Option<Self> {
103 ExprKind::Let(hir::Let {
114 let mut iter = cx.tcx.hir().parent_iter(expr.hir_id);
115 if let Some((_, Node::Block(Block { stmts: [], .. }))) = iter.next() {
119 kind: ExprKind::Loop(_, _, LoopSource::While, _),
124 // while loop desugar
139 /// An `if let` or `match` expression. Useful for lints that trigger on one or the other.
140 pub enum IfLetOrMatch<'hir> {
141 /// Any `match` expression
142 Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource),
143 /// scrutinee, pattern, then block, else block
148 Option<&'hir Expr<'hir>>,
152 impl<'hir> IfLetOrMatch<'hir> {
153 /// Parses an `if let` or `match` expression
154 pub fn parse(cx: &LateContext<'_>, expr: &Expr<'hir>) -> Option<Self> {
156 ExprKind::Match(expr, arms, source) => Some(Self::Match(expr, arms, source)),
157 _ => IfLet::hir(cx, expr).map(
163 }| { Self::IfLet(let_expr, let_pat, if_then, if_else) },
169 /// An `if` or `if let` expression
170 pub struct IfOrIfLet<'hir> {
171 /// `if` condition that is maybe a `let` expression
172 pub cond: &'hir Expr<'hir>,
173 /// `if` then expression
174 pub then: &'hir Expr<'hir>,
175 /// `else` expression
176 pub r#else: Option<&'hir Expr<'hir>>,
179 impl<'hir> IfOrIfLet<'hir> {
181 /// Parses an `if` or `if let` expression
182 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
183 if let ExprKind::If(cond, then, r#else) = expr.kind {
184 if let ExprKind::DropTemps(new_cond) = cond.kind {
191 if let ExprKind::Let(..) = cond.kind {
192 return Some(Self { cond, then, r#else });
199 /// Represent a range akin to `ast::ExprKind::Range`.
200 #[derive(Debug, Copy, Clone)]
201 pub struct Range<'a> {
202 /// The lower bound of the range, or `None` for ranges such as `..X`.
203 pub start: Option<&'a hir::Expr<'a>>,
204 /// The upper bound of the range, or `None` for ranges such as `X..`.
205 pub end: Option<&'a hir::Expr<'a>>,
206 /// Whether the interval is open or closed.
207 pub limits: ast::RangeLimits,
211 /// Higher a `hir` range to something similar to `ast::ExprKind::Range`.
212 pub fn hir(expr: &'a hir::Expr<'_>) -> Option<Range<'a>> {
213 /// Finds the field named `name` in the field. Always return `Some` for
215 fn get_field<'c>(name: &str, fields: &'c [hir::ExprField<'_>]) -> Option<&'c hir::Expr<'c>> {
216 let expr = &fields.iter().find(|field| field.ident.name.as_str() == name)?.expr;
221 hir::ExprKind::Call(path, args)
224 hir::ExprKind::Path(hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, ..))
228 start: Some(&args[0]),
230 limits: ast::RangeLimits::Closed,
233 hir::ExprKind::Struct(path, fields, None) => match &path {
234 hir::QPath::LangItem(hir::LangItem::RangeFull, ..) => Some(Range {
237 limits: ast::RangeLimits::HalfOpen,
239 hir::QPath::LangItem(hir::LangItem::RangeFrom, ..) => Some(Range {
240 start: Some(get_field("start", fields)?),
242 limits: ast::RangeLimits::HalfOpen,
244 hir::QPath::LangItem(hir::LangItem::Range, ..) => Some(Range {
245 start: Some(get_field("start", fields)?),
246 end: Some(get_field("end", fields)?),
247 limits: ast::RangeLimits::HalfOpen,
249 hir::QPath::LangItem(hir::LangItem::RangeToInclusive, ..) => Some(Range {
251 end: Some(get_field("end", fields)?),
252 limits: ast::RangeLimits::Closed,
254 hir::QPath::LangItem(hir::LangItem::RangeTo, ..) => Some(Range {
256 end: Some(get_field("end", fields)?),
257 limits: ast::RangeLimits::HalfOpen,
266 /// Represent the pre-expansion arguments of a `vec!` invocation.
267 pub enum VecArgs<'a> {
268 /// `vec![elem; len]`
269 Repeat(&'a hir::Expr<'a>, &'a hir::Expr<'a>),
271 Vec(&'a [hir::Expr<'a>]),
274 impl<'a> VecArgs<'a> {
275 /// Returns the arguments of the `vec!` macro if this expression was expanded
277 pub fn hir(cx: &LateContext<'_>, expr: &'a hir::Expr<'_>) -> Option<VecArgs<'a>> {
279 if let hir::ExprKind::Call(fun, args) = expr.kind;
280 if let hir::ExprKind::Path(ref qpath) = fun.kind;
281 if is_expn_of(fun.span, "vec").is_some();
282 if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
284 return if match_def_path(cx, fun_def_id, &paths::VEC_FROM_ELEM) && args.len() == 2 {
285 // `vec![elem; size]` case
286 Some(VecArgs::Repeat(&args[0], &args[1]))
287 } else if match_def_path(cx, fun_def_id, &paths::SLICE_INTO_VEC) && args.len() == 1 {
288 // `vec![a, b, c]` case
290 if let hir::ExprKind::Box(boxed) = args[0].kind;
291 if let hir::ExprKind::Array(args) = boxed.kind;
293 return Some(VecArgs::Vec(args));
298 } else if match_def_path(cx, fun_def_id, &paths::VEC_NEW) && args.is_empty() {
299 Some(VecArgs::Vec(&[]))
310 /// A desugared `while` loop
311 pub struct While<'hir> {
312 /// `while` loop condition
313 pub condition: &'hir Expr<'hir>,
314 /// `while` loop body
315 pub body: &'hir Expr<'hir>,
318 impl<'hir> While<'hir> {
320 /// Parses a desugared `while` loop
321 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
322 if let ExprKind::Loop(
329 kind: ExprKind::DropTemps(condition),
344 return Some(Self { condition, body });
350 /// A desugared `while let` loop
351 pub struct WhileLet<'hir> {
352 /// `while let` loop item pattern
353 pub let_pat: &'hir Pat<'hir>,
354 /// `while let` loop scrutinee
355 pub let_expr: &'hir Expr<'hir>,
356 /// `while let` loop body
357 pub if_then: &'hir Expr<'hir>,
360 impl<'hir> WhileLet<'hir> {
362 /// Parses a desugared `while let` loop
363 pub const fn hir(expr: &Expr<'hir>) -> Option<Self> {
364 if let ExprKind::Loop(
372 ExprKind::Let(hir::Let {
401 /// Converts a hir binary operator to the corresponding `ast` type.
403 pub fn binop(op: hir::BinOpKind) -> ast::BinOpKind {
405 hir::BinOpKind::Eq => ast::BinOpKind::Eq,
406 hir::BinOpKind::Ge => ast::BinOpKind::Ge,
407 hir::BinOpKind::Gt => ast::BinOpKind::Gt,
408 hir::BinOpKind::Le => ast::BinOpKind::Le,
409 hir::BinOpKind::Lt => ast::BinOpKind::Lt,
410 hir::BinOpKind::Ne => ast::BinOpKind::Ne,
411 hir::BinOpKind::Or => ast::BinOpKind::Or,
412 hir::BinOpKind::Add => ast::BinOpKind::Add,
413 hir::BinOpKind::And => ast::BinOpKind::And,
414 hir::BinOpKind::BitAnd => ast::BinOpKind::BitAnd,
415 hir::BinOpKind::BitOr => ast::BinOpKind::BitOr,
416 hir::BinOpKind::BitXor => ast::BinOpKind::BitXor,
417 hir::BinOpKind::Div => ast::BinOpKind::Div,
418 hir::BinOpKind::Mul => ast::BinOpKind::Mul,
419 hir::BinOpKind::Rem => ast::BinOpKind::Rem,
420 hir::BinOpKind::Shl => ast::BinOpKind::Shl,
421 hir::BinOpKind::Shr => ast::BinOpKind::Shr,
422 hir::BinOpKind::Sub => ast::BinOpKind::Sub,
426 /// A parsed `Vec` initialization expression
427 #[derive(Clone, Copy)]
428 pub enum VecInitKind {
431 /// `Vec::default()` or `Default::default()`
433 /// `Vec::with_capacity(123)`
434 WithLiteralCapacity(u64),
435 /// `Vec::with_capacity(slice.len())`
436 WithExprCapacity(HirId),
439 /// Checks if given expression is an initialization of `Vec` and returns its kind.
440 pub fn get_vec_init_kind<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Option<VecInitKind> {
441 if let ExprKind::Call(func, args) = expr.kind {
443 ExprKind::Path(QPath::TypeRelative(ty, name))
444 if is_type_diagnostic_item(cx, cx.typeck_results().node_type(ty.hir_id), sym::Vec) =>
446 if name.ident.name == sym::new {
447 return Some(VecInitKind::New);
448 } else if name.ident.name == symbol::kw::Default {
449 return Some(VecInitKind::Default);
450 } else if name.ident.name.as_str() == "with_capacity" {
451 let arg = args.get(0)?;
453 if let ExprKind::Lit(lit) = &arg.kind;
454 if let LitKind::Int(num, _) = lit.node;
456 return Some(VecInitKind::WithLiteralCapacity(num.try_into().ok()?));
459 return Some(VecInitKind::WithExprCapacity(arg.hir_id));
462 ExprKind::Path(QPath::Resolved(_, path))
463 if match_def_path(cx, path.res.opt_def_id()?, &paths::DEFAULT_TRAIT_METHOD)
464 && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::Vec) =>
466 return Some(VecInitKind::Default);