1 //! This module contains functions for retrieve the original AST from lowered
4 #![deny(missing_docs_in_private_items)]
6 use if_chain::if_chain;
8 use rustc::lint::LateContext;
10 use crate::utils::{is_expn_of, match_def_path, match_qpath, opt_def_id, paths, resolve_node};
12 /// Convert a hir binary operator to the corresponding `ast` type.
13 pub fn binop(op: hir::BinOpKind) -> ast::BinOpKind {
15 hir::BinOpKind::Eq => ast::BinOpKind::Eq,
16 hir::BinOpKind::Ge => ast::BinOpKind::Ge,
17 hir::BinOpKind::Gt => ast::BinOpKind::Gt,
18 hir::BinOpKind::Le => ast::BinOpKind::Le,
19 hir::BinOpKind::Lt => ast::BinOpKind::Lt,
20 hir::BinOpKind::Ne => ast::BinOpKind::Ne,
21 hir::BinOpKind::Or => ast::BinOpKind::Or,
22 hir::BinOpKind::Add => ast::BinOpKind::Add,
23 hir::BinOpKind::And => ast::BinOpKind::And,
24 hir::BinOpKind::BitAnd => ast::BinOpKind::BitAnd,
25 hir::BinOpKind::BitOr => ast::BinOpKind::BitOr,
26 hir::BinOpKind::BitXor => ast::BinOpKind::BitXor,
27 hir::BinOpKind::Div => ast::BinOpKind::Div,
28 hir::BinOpKind::Mul => ast::BinOpKind::Mul,
29 hir::BinOpKind::Rem => ast::BinOpKind::Rem,
30 hir::BinOpKind::Shl => ast::BinOpKind::Shl,
31 hir::BinOpKind::Shr => ast::BinOpKind::Shr,
32 hir::BinOpKind::Sub => ast::BinOpKind::Sub,
36 /// Represent a range akin to `ast::ExprKind::Range`.
37 #[derive(Debug, Copy, Clone)]
38 pub struct Range<'a> {
39 /// The lower bound of the range, or `None` for ranges such as `..X`.
40 pub start: Option<&'a hir::Expr>,
41 /// The upper bound of the range, or `None` for ranges such as `X..`.
42 pub end: Option<&'a hir::Expr>,
43 /// Whether the interval is open or closed.
44 pub limits: ast::RangeLimits,
47 /// Higher a `hir` range to something similar to `ast::ExprKind::Range`.
48 pub fn range<'a, 'b, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'b hir::Expr) -> Option<Range<'b>> {
50 let def_path = match cx.tables.expr_ty(expr).sty {
51 ty::TyAdt(def, _) => cx.tcx.def_path(def.did),
55 // sanity checks for std::ops::RangeXXXX
56 if def_path.data.len() != 3 {
59 if def_path.data.get(0)?.data.as_interned_str() != "ops" {
62 if def_path.data.get(1)?.data.as_interned_str() != "range" {
65 let type_name = def_path.data.get(2)?.data.as_interned_str();
74 if !range_types.contains(&&*type_name.as_str()) {
78 /// Find the field named `name` in the field. Always return `Some` for
80 fn get_field<'a>(name: &str, fields: &'a [hir::Field]) -> Option<&'a hir::Expr> {
81 let expr = &fields.iter().find(|field| field.ident.name == name)?.expr;
86 // The range syntax is expanded to literal paths starting with `core` or `std`
88 // `#[no_std]`. Testing both instead of resolving the paths.
91 hir::ExprKind::Path(ref path) => {
92 if match_qpath(path, &paths::RANGE_FULL_STD) || match_qpath(path, &paths::RANGE_FULL) {
96 limits: ast::RangeLimits::HalfOpen,
102 hir::ExprKind::Call(ref path, ref args) => if let hir::ExprKind::Path(ref path) = path.node {
103 if match_qpath(path, &paths::RANGE_INCLUSIVE_STD_NEW) || match_qpath(path, &paths::RANGE_INCLUSIVE_NEW) {
105 start: Some(&args[0]),
107 limits: ast::RangeLimits::Closed,
115 hir::ExprKind::Struct(ref path, ref fields, None) => if match_qpath(path, &paths::RANGE_FROM_STD)
116 || match_qpath(path, &paths::RANGE_FROM)
119 start: Some(get_field("start", fields)?),
121 limits: ast::RangeLimits::HalfOpen,
123 } else if match_qpath(path, &paths::RANGE_STD) || match_qpath(path, &paths::RANGE) {
125 start: Some(get_field("start", fields)?),
126 end: Some(get_field("end", fields)?),
127 limits: ast::RangeLimits::HalfOpen,
129 } else if match_qpath(path, &paths::RANGE_TO_INCLUSIVE_STD) || match_qpath(path, &paths::RANGE_TO_INCLUSIVE) {
132 end: Some(get_field("end", fields)?),
133 limits: ast::RangeLimits::Closed,
135 } else if match_qpath(path, &paths::RANGE_TO_STD) || match_qpath(path, &paths::RANGE_TO) {
138 end: Some(get_field("end", fields)?),
139 limits: ast::RangeLimits::HalfOpen,
148 /// Checks if a `let` decl is from a `for` loop desugaring.
149 pub fn is_from_for_desugar(decl: &hir::Decl) -> bool {
150 // This will detect plain for-loops without an actual variable binding:
153 // for x in some_vec {
158 if let hir::DeclKind::Local(ref loc) = decl.node;
159 if let Some(ref expr) = loc.init;
160 if let hir::ExprKind::Match(_, _, hir::MatchSource::ForLoopDesugar) = expr.node;
166 // This detects a variable binding in for loop to avoid `let_unit_value`
167 // lint (see issue #1964).
170 // for _ in vec![()] {
175 if let hir::DeclKind::Local(ref loc) = decl.node;
176 if let hir::LocalSource::ForLoopDesugar = loc.source;
185 /// Recover the essential nodes of a desugared for loop:
186 /// `for pat in arg { body }` becomes `(pat, arg, body)`.
187 pub fn for_loop(expr: &hir::Expr) -> Option<(&hir::Pat, &hir::Expr, &hir::Expr)> {
189 if let hir::ExprKind::Match(ref iterexpr, ref arms, hir::MatchSource::ForLoopDesugar) = expr.node;
190 if let hir::ExprKind::Call(_, ref iterargs) = iterexpr.node;
191 if iterargs.len() == 1 && arms.len() == 1 && arms[0].guard.is_none();
192 if let hir::ExprKind::Loop(ref block, _, _) = arms[0].body.node;
193 if block.expr.is_none();
194 if let [ _, _, ref let_stmt, ref body ] = *block.stmts;
195 if let hir::StmtKind::Decl(ref decl, _) = let_stmt.node;
196 if let hir::DeclKind::Local(ref decl) = decl.node;
197 if let hir::StmtKind::Expr(ref expr, _) = body.node;
199 return Some((&*decl.pat, &iterargs[0], expr));
205 /// Represent the pre-expansion arguments of a `vec!` invocation.
206 pub enum VecArgs<'a> {
207 /// `vec![elem; len]`
208 Repeat(&'a hir::Expr, &'a hir::Expr),
210 Vec(&'a [hir::Expr]),
213 /// Returns the arguments of the `vec!` macro if this expression was expanded
215 pub fn vec_macro<'e>(cx: &LateContext<'_, '_>, expr: &'e hir::Expr) -> Option<VecArgs<'e>> {
217 if let hir::ExprKind::Call(ref fun, ref args) = expr.node;
218 if let hir::ExprKind::Path(ref path) = fun.node;
219 if is_expn_of(fun.span, "vec").is_some();
220 if let Some(fun_def_id) = opt_def_id(resolve_node(cx, path, fun.hir_id));
222 return if match_def_path(cx.tcx, fun_def_id, &paths::VEC_FROM_ELEM) && args.len() == 2 {
223 // `vec![elem; size]` case
224 Some(VecArgs::Repeat(&args[0], &args[1]))
226 else if match_def_path(cx.tcx, fun_def_id, &paths::SLICE_INTO_VEC) && args.len() == 1 {
227 // `vec![a, b, c]` case
229 if let hir::ExprKind::Box(ref boxed) = args[0].node;
230 if let hir::ExprKind::Array(ref args) = boxed.node;
232 return Some(VecArgs::Vec(&*args));