62 lines
1.8 KiB
Rust
62 lines
1.8 KiB
Rust
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
|
|
// file at the top-level directory of this distribution.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
|
|
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
|
|
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
|
|
// option. This file may not be copied, modified, or distributed
|
|
// except according to those terms.
|
|
|
|
|
|
use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
|
|
use crate::rustc::{declare_tool_lint, lint_array};
|
|
use crate::rustc::hir::{Expr, ExprKind};
|
|
use crate::utils::is_adjusted;
|
|
use crate::utils::span_lint;
|
|
|
|
/// **What it does:** Checks for construction of a structure or tuple just to
|
|
/// assign a value in it.
|
|
///
|
|
/// **Why is this bad?** Readability. If the structure is only created to be
|
|
/// updated, why not write the structure you want in the first place?
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// (0, 0).0 = 1
|
|
/// ```
|
|
declare_clippy_lint! {
|
|
pub TEMPORARY_ASSIGNMENT,
|
|
complexity,
|
|
"assignments to temporaries"
|
|
}
|
|
|
|
fn is_temporary(expr: &Expr) -> bool {
|
|
match expr.node {
|
|
ExprKind::Struct(..) | ExprKind::Tup(..) => true,
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
#[derive(Copy, Clone)]
|
|
pub struct Pass;
|
|
|
|
impl LintPass for Pass {
|
|
fn get_lints(&self) -> LintArray {
|
|
lint_array!(TEMPORARY_ASSIGNMENT)
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
|
|
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
|
|
if let ExprKind::Assign(ref target, _) = expr.node {
|
|
if let ExprKind::Field(ref base, _) = target.node {
|
|
if is_temporary(base) && !is_adjusted(cx, base) {
|
|
span_lint(cx, TEMPORARY_ASSIGNMENT, expr.span, "assignment to temporary");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|