mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-23 03:23:33 +00:00
218 lines
8 KiB
Rust
218 lines
8 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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use crate::rustc::hir::*;
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use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use crate::rustc::{declare_tool_lint, lint_array};
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use crate::rustc_errors::Applicability;
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use crate::syntax::source_map::Spanned;
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use crate::utils::SpanlessEq;
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use crate::utils::{get_parent_expr, is_allowed, match_type, paths, span_lint, span_lint_and_sugg, walk_ptrs_ty};
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/// **What it does:** Checks for string appends of the form `x = x + y` (without
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/// `let`!).
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///
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/// **Why is this bad?** It's not really bad, but some people think that the
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/// `.push_str(_)` method is more readable.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// let mut x = "Hello".to_owned();
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/// x = x + ", World";
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/// ```
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declare_clippy_lint! {
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pub STRING_ADD_ASSIGN,
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pedantic,
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"using `x = x + ..` where x is a `String` instead of `push_str()`"
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}
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/// **What it does:** Checks for all instances of `x + _` where `x` is of type
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/// `String`, but only if [`string_add_assign`](#string_add_assign) does *not*
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/// match.
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///
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/// **Why is this bad?** It's not bad in and of itself. However, this particular
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/// `Add` implementation is asymmetric (the other operand need not be `String`,
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/// but `x` does), while addition as mathematically defined is symmetric, also
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/// the `String::push_str(_)` function is a perfectly good replacement.
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/// Therefore some dislike it and wish not to have it in their code.
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///
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/// That said, other people think that string addition, having a long tradition
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/// in other languages is actually fine, which is why we decided to make this
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/// particular lint `allow` by default.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// let x = "Hello".to_owned();
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/// x + ", World"
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/// ```
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declare_clippy_lint! {
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pub STRING_ADD,
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restriction,
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"using `x + ..` where x is a `String` instead of `push_str()`"
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}
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/// **What it does:** Checks for the `as_bytes` method called on string literals
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/// that contain only ASCII characters.
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///
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/// **Why is this bad?** Byte string literals (e.g. `b"foo"`) can be used
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/// instead. They are shorter but less discoverable than `as_bytes()`.
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///
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/// **Known Problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// let bs = "a byte string".as_bytes();
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/// ```
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declare_clippy_lint! {
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pub STRING_LIT_AS_BYTES,
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style,
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"calling `as_bytes` on a string literal instead of using a byte string literal"
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}
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#[derive(Copy, Clone)]
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pub struct StringAdd;
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impl LintPass for StringAdd {
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fn get_lints(&self) -> LintArray {
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lint_array!(STRING_ADD, STRING_ADD_ASSIGN)
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StringAdd {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
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if let ExprKind::Binary(
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Spanned {
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node: BinOpKind::Add, ..
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},
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ref left,
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_,
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) = e.node
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{
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if is_string(cx, left) {
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if !is_allowed(cx, STRING_ADD_ASSIGN, e.id) {
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let parent = get_parent_expr(cx, e);
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if let Some(p) = parent {
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if let ExprKind::Assign(ref target, _) = p.node {
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// avoid duplicate matches
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if SpanlessEq::new(cx).eq_expr(target, left) {
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return;
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}
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}
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}
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}
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span_lint(
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cx,
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STRING_ADD,
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e.span,
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"you added something to a string. Consider using `String::push_str()` instead",
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);
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}
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} else if let ExprKind::Assign(ref target, ref src) = e.node {
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if is_string(cx, target) && is_add(cx, src, target) {
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span_lint(
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cx,
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STRING_ADD_ASSIGN,
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e.span,
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"you assigned the result of adding something to this string. Consider using \
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`String::push_str()` instead",
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);
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}
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}
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}
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}
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fn is_string(cx: &LateContext<'_, '_>, e: &Expr) -> bool {
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match_type(cx, walk_ptrs_ty(cx.tables.expr_ty(e)), &paths::STRING)
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}
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fn is_add(cx: &LateContext<'_, '_>, src: &Expr, target: &Expr) -> bool {
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match src.node {
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ExprKind::Binary(
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Spanned {
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node: BinOpKind::Add, ..
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},
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ref left,
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_,
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) => SpanlessEq::new(cx).eq_expr(target, left),
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ExprKind::Block(ref block, _) => {
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block.stmts.is_empty() && block.expr.as_ref().map_or(false, |expr| is_add(cx, expr, target))
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},
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_ => false,
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}
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}
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#[derive(Copy, Clone)]
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pub struct StringLitAsBytes;
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impl LintPass for StringLitAsBytes {
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fn get_lints(&self) -> LintArray {
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lint_array!(STRING_LIT_AS_BYTES)
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StringLitAsBytes {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
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use crate::syntax::ast::{LitKind, StrStyle};
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use crate::utils::{in_macro, snippet, snippet_with_applicability};
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if let ExprKind::MethodCall(ref path, _, ref args) = e.node {
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if path.ident.name == "as_bytes" {
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if let ExprKind::Lit(ref lit) = args[0].node {
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if let LitKind::Str(ref lit_content, style) = lit.node {
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let callsite = snippet(cx, args[0].span.source_callsite(), r#""foo""#);
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let expanded = if let StrStyle::Raw(n) = style {
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let term = (0..n).map(|_| '#').collect::<String>();
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format!("r{0}\"{1}\"{0}", term, lit_content.as_str())
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} else {
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format!("\"{}\"", lit_content.as_str())
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};
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let mut applicability = Applicability::MachineApplicable;
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if callsite.starts_with("include_str!") {
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span_lint_and_sugg(
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cx,
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STRING_LIT_AS_BYTES,
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e.span,
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"calling `as_bytes()` on `include_str!(..)`",
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"consider using `include_bytes!(..)` instead",
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snippet_with_applicability(cx, args[0].span, r#""foo""#, &mut applicability).replacen(
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"include_str",
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"include_bytes",
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1,
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),
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applicability,
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);
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} else if callsite == expanded
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&& lit_content.as_str().chars().all(|c| c.is_ascii())
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&& !in_macro(args[0].span)
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{
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span_lint_and_sugg(
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cx,
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STRING_LIT_AS_BYTES,
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e.span,
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"calling `as_bytes()` on a string literal",
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"consider using a byte string literal instead",
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format!(
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"b{}",
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snippet_with_applicability(cx, args[0].span, r#""foo""#, &mut applicability)
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),
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applicability,
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);
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}
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}
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}
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}
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}
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}
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}
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