mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-22 19:13:29 +00:00
60 lines
1.8 KiB
Rust
60 lines
1.8 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::{Expr, ExprKind};
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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::utils::is_adjusted;
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use crate::utils::span_lint;
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/// **What it does:** Checks for construction of a structure or tuple just to
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/// assign a value in it.
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///
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/// **Why is this bad?** Readability. If the structure is only created to be
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/// updated, why not write the structure you want in the first place?
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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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/// (0, 0).0 = 1
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/// ```
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declare_clippy_lint! {
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pub TEMPORARY_ASSIGNMENT,
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complexity,
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"assignments to temporaries"
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}
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fn is_temporary(expr: &Expr) -> bool {
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match expr.node {
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ExprKind::Struct(..) | ExprKind::Tup(..) => true,
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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 Pass;
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impl LintPass for Pass {
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fn get_lints(&self) -> LintArray {
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lint_array!(TEMPORARY_ASSIGNMENT)
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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if let ExprKind::Assign(ref target, _) = expr.node {
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if let ExprKind::Field(ref base, _) = target.node {
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if is_temporary(base) && !is_adjusted(cx, base) {
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span_lint(cx, TEMPORARY_ASSIGNMENT, expr.span, "assignment to temporary");
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}
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}
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}
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}
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}
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