256 lines
8.9 KiB
Rust
256 lines
8.9 KiB
Rust
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! This module contains functions for retrieve the original AST from lowered
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//! `hir`.
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#![deny(clippy::missing_docs_in_private_items)]
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use if_chain::if_chain;
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use crate::rustc::{hir, ty};
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use crate::rustc::lint::LateContext;
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use crate::syntax::ast;
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use crate::utils::{is_expn_of, match_def_path, match_qpath, opt_def_id, paths, resolve_node};
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/// Convert a hir binary operator to the corresponding `ast` type.
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pub fn binop(op: hir::BinOpKind) -> ast::BinOpKind {
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match op {
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hir::BinOpKind::Eq => ast::BinOpKind::Eq,
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hir::BinOpKind::Ge => ast::BinOpKind::Ge,
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hir::BinOpKind::Gt => ast::BinOpKind::Gt,
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hir::BinOpKind::Le => ast::BinOpKind::Le,
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hir::BinOpKind::Lt => ast::BinOpKind::Lt,
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hir::BinOpKind::Ne => ast::BinOpKind::Ne,
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hir::BinOpKind::Or => ast::BinOpKind::Or,
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hir::BinOpKind::Add => ast::BinOpKind::Add,
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hir::BinOpKind::And => ast::BinOpKind::And,
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hir::BinOpKind::BitAnd => ast::BinOpKind::BitAnd,
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hir::BinOpKind::BitOr => ast::BinOpKind::BitOr,
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hir::BinOpKind::BitXor => ast::BinOpKind::BitXor,
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hir::BinOpKind::Div => ast::BinOpKind::Div,
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hir::BinOpKind::Mul => ast::BinOpKind::Mul,
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hir::BinOpKind::Rem => ast::BinOpKind::Rem,
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hir::BinOpKind::Shl => ast::BinOpKind::Shl,
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hir::BinOpKind::Shr => ast::BinOpKind::Shr,
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hir::BinOpKind::Sub => ast::BinOpKind::Sub,
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}
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}
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/// Represent a range akin to `ast::ExprKind::Range`.
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#[derive(Debug, Copy, Clone)]
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pub struct Range<'a> {
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/// The lower bound of the range, or `None` for ranges such as `..X`.
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pub start: Option<&'a hir::Expr>,
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/// The upper bound of the range, or `None` for ranges such as `X..`.
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pub end: Option<&'a hir::Expr>,
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/// Whether the interval is open or closed.
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pub limits: ast::RangeLimits,
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}
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/// Higher a `hir` range to something similar to `ast::ExprKind::Range`.
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pub fn range<'a, 'b, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'b hir::Expr) -> Option<Range<'b>> {
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let def_path = match cx.tables.expr_ty(expr).sty {
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ty::Adt(def, _) => cx.tcx.def_path(def.did),
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_ => return None,
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};
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// sanity checks for std::ops::RangeXXXX
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if def_path.data.len() != 3 {
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return None;
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}
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if def_path.data.get(0)?.data.as_interned_str() != "ops" {
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return None;
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}
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if def_path.data.get(1)?.data.as_interned_str() != "range" {
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return None;
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}
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let type_name = def_path.data.get(2)?.data.as_interned_str();
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let range_types = [
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"RangeFrom",
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"RangeFull",
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"RangeInclusive",
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"Range",
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"RangeTo",
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"RangeToInclusive",
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];
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if !range_types.contains(&&*type_name.as_str()) {
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return None;
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}
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/// Find the field named `name` in the field. Always return `Some` for
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/// convenience.
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fn get_field<'a>(name: &str, fields: &'a [hir::Field]) -> Option<&'a hir::Expr> {
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let expr = &fields.iter().find(|field| field.ident.name == name)?.expr;
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Some(expr)
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}
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// The range syntax is expanded to literal paths starting with `core` or `std`
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// depending on
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// `#[no_std]`. Testing both instead of resolving the paths.
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match expr.node {
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hir::ExprKind::Path(ref path) => {
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if match_qpath(path, &paths::RANGE_FULL_STD) || match_qpath(path, &paths::RANGE_FULL) {
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Some(Range {
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start: None,
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end: None,
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limits: ast::RangeLimits::HalfOpen,
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})
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} else {
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None
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}
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},
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hir::ExprKind::Call(ref path, ref args) => if let hir::ExprKind::Path(ref path) = path.node {
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if match_qpath(path, &paths::RANGE_INCLUSIVE_STD_NEW) || match_qpath(path, &paths::RANGE_INCLUSIVE_NEW) {
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Some(Range {
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start: Some(&args[0]),
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end: Some(&args[1]),
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limits: ast::RangeLimits::Closed,
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})
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} else {
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None
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}
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} else {
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None
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},
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hir::ExprKind::Struct(ref path, ref fields, None) => if match_qpath(path, &paths::RANGE_FROM_STD)
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|| match_qpath(path, &paths::RANGE_FROM)
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{
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Some(Range {
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start: Some(get_field("start", fields)?),
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end: None,
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limits: ast::RangeLimits::HalfOpen,
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})
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} else if match_qpath(path, &paths::RANGE_STD) || match_qpath(path, &paths::RANGE) {
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Some(Range {
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start: Some(get_field("start", fields)?),
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end: Some(get_field("end", fields)?),
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limits: ast::RangeLimits::HalfOpen,
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})
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} else if match_qpath(path, &paths::RANGE_TO_INCLUSIVE_STD) || match_qpath(path, &paths::RANGE_TO_INCLUSIVE) {
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Some(Range {
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start: None,
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end: Some(get_field("end", fields)?),
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limits: ast::RangeLimits::Closed,
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})
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} else if match_qpath(path, &paths::RANGE_TO_STD) || match_qpath(path, &paths::RANGE_TO) {
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Some(Range {
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start: None,
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end: Some(get_field("end", fields)?),
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limits: ast::RangeLimits::HalfOpen,
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})
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} else {
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None
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},
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_ => None,
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}
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}
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/// Checks if a `let` decl is from a `for` loop desugaring.
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pub fn is_from_for_desugar(decl: &hir::Decl) -> bool {
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// This will detect plain for-loops without an actual variable binding:
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//
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// ```
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// for x in some_vec {
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// // do stuff
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// }
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// ```
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if_chain! {
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if let hir::DeclKind::Local(ref loc) = decl.node;
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if let Some(ref expr) = loc.init;
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if let hir::ExprKind::Match(_, _, hir::MatchSource::ForLoopDesugar) = expr.node;
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then {
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return true;
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}
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}
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// This detects a variable binding in for loop to avoid `let_unit_value`
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// lint (see issue #1964).
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//
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// ```
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// for _ in vec![()] {
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// // anything
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// }
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// ```
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if_chain! {
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if let hir::DeclKind::Local(ref loc) = decl.node;
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if let hir::LocalSource::ForLoopDesugar = loc.source;
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then {
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return true;
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}
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}
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false
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}
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/// Recover the essential nodes of a desugared for loop:
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/// `for pat in arg { body }` becomes `(pat, arg, body)`.
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pub fn for_loop(expr: &hir::Expr) -> Option<(&hir::Pat, &hir::Expr, &hir::Expr)> {
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if_chain! {
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if let hir::ExprKind::Match(ref iterexpr, ref arms, hir::MatchSource::ForLoopDesugar) = expr.node;
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if let hir::ExprKind::Call(_, ref iterargs) = iterexpr.node;
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if iterargs.len() == 1 && arms.len() == 1 && arms[0].guard.is_none();
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if let hir::ExprKind::Loop(ref block, _, _) = arms[0].body.node;
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if block.expr.is_none();
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if let [ _, _, ref let_stmt, ref body ] = *block.stmts;
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if let hir::StmtKind::Decl(ref decl, _) = let_stmt.node;
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if let hir::DeclKind::Local(ref decl) = decl.node;
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if let hir::StmtKind::Expr(ref expr, _) = body.node;
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then {
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return Some((&*decl.pat, &iterargs[0], expr));
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}
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}
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None
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}
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/// Represent the pre-expansion arguments of a `vec!` invocation.
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pub enum VecArgs<'a> {
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/// `vec![elem; len]`
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Repeat(&'a hir::Expr, &'a hir::Expr),
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/// `vec![a, b, c]`
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Vec(&'a [hir::Expr]),
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}
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/// Returns the arguments of the `vec!` macro if this expression was expanded
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/// from `vec!`.
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pub fn vec_macro<'e>(cx: &LateContext<'_, '_>, expr: &'e hir::Expr) -> Option<VecArgs<'e>> {
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if_chain! {
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if let hir::ExprKind::Call(ref fun, ref args) = expr.node;
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if let hir::ExprKind::Path(ref path) = fun.node;
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if is_expn_of(fun.span, "vec").is_some();
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if let Some(fun_def_id) = opt_def_id(resolve_node(cx, path, fun.hir_id));
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then {
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return if match_def_path(cx.tcx, fun_def_id, &paths::VEC_FROM_ELEM) && args.len() == 2 {
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// `vec![elem; size]` case
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Some(VecArgs::Repeat(&args[0], &args[1]))
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}
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else if match_def_path(cx.tcx, fun_def_id, &paths::SLICE_INTO_VEC) && args.len() == 1 {
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// `vec![a, b, c]` case
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if_chain! {
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if let hir::ExprKind::Box(ref boxed) = args[0].node;
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if let hir::ExprKind::Array(ref args) = boxed.node;
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then {
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return Some(VecArgs::Vec(&*args));
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}
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}
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None
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}
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else {
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None
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};
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}
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}
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None
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}
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