mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-22 19:13:29 +00:00
179 lines
6 KiB
Rust
179 lines
6 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::hir::def::Def;
|
|
use crate::rustc::hir::*;
|
|
use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
|
|
use crate::rustc::{declare_tool_lint, lint_array};
|
|
use crate::syntax::ptr::P;
|
|
use crate::utils::sugg::Sugg;
|
|
use if_chain::if_chain;
|
|
|
|
use crate::rustc_errors::Applicability;
|
|
use crate::utils::paths::*;
|
|
use crate::utils::{match_def_path, match_type, span_lint_and_then, SpanlessEq};
|
|
|
|
/// **What it does:** Checks for expressions that could be replaced by the question mark operator
|
|
///
|
|
/// **Why is this bad?** Question mark usage is more idiomatic
|
|
///
|
|
/// **Known problems:** None
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// if option.is_none() {
|
|
/// return None;
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// Could be written:
|
|
///
|
|
/// ```rust
|
|
/// option?;
|
|
/// ```
|
|
declare_clippy_lint! {
|
|
pub QUESTION_MARK,
|
|
style,
|
|
"checks for expressions that could be replaced by the question mark operator"
|
|
}
|
|
|
|
#[derive(Copy, Clone)]
|
|
pub struct Pass;
|
|
|
|
impl LintPass for Pass {
|
|
fn get_lints(&self) -> LintArray {
|
|
lint_array!(QUESTION_MARK)
|
|
}
|
|
}
|
|
|
|
impl Pass {
|
|
/// Check if the given expression on the given context matches the following structure:
|
|
///
|
|
/// ```ignore
|
|
/// if option.is_none() {
|
|
/// return None;
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// If it matches, it will suggest to use the question mark operator instead
|
|
fn check_is_none_and_early_return_none(cx: &LateContext<'_, '_>, expr: &Expr) {
|
|
if_chain! {
|
|
if let ExprKind::If(if_expr, body, else_) = &expr.node;
|
|
if let ExprKind::MethodCall(segment, _, args) = &if_expr.node;
|
|
if segment.ident.name == "is_none";
|
|
if Self::expression_returns_none(cx, body);
|
|
if let Some(subject) = args.get(0);
|
|
if Self::is_option(cx, subject);
|
|
|
|
then {
|
|
if let Some(else_) = else_ {
|
|
if_chain! {
|
|
if let ExprKind::Block(block, None) = &else_.node;
|
|
if block.stmts.len() == 0;
|
|
if let Some(block_expr) = &block.expr;
|
|
if SpanlessEq::new(cx).ignore_fn().eq_expr(subject, block_expr);
|
|
then {
|
|
span_lint_and_then(
|
|
cx,
|
|
QUESTION_MARK,
|
|
expr.span,
|
|
"this block may be rewritten with the `?` operator",
|
|
|db| {
|
|
db.span_suggestion_with_applicability(
|
|
expr.span,
|
|
"replace_it_with",
|
|
format!("Some({}?)", Sugg::hir(cx, subject, "..")),
|
|
Applicability::MaybeIncorrect, // snippet
|
|
);
|
|
}
|
|
)
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
|
|
span_lint_and_then(
|
|
cx,
|
|
QUESTION_MARK,
|
|
expr.span,
|
|
"this block may be rewritten with the `?` operator",
|
|
|db| {
|
|
let receiver_str = &Sugg::hir(cx, subject, "..");
|
|
|
|
db.span_suggestion_with_applicability(
|
|
expr.span,
|
|
"replace_it_with",
|
|
format!("{}?;", receiver_str),
|
|
Applicability::MaybeIncorrect, // snippet
|
|
);
|
|
}
|
|
)
|
|
}
|
|
}
|
|
}
|
|
|
|
fn is_option(cx: &LateContext<'_, '_>, expression: &Expr) -> bool {
|
|
let expr_ty = cx.tables.expr_ty(expression);
|
|
|
|
match_type(cx, expr_ty, &OPTION)
|
|
}
|
|
|
|
fn expression_returns_none(cx: &LateContext<'_, '_>, expression: &Expr) -> bool {
|
|
match expression.node {
|
|
ExprKind::Block(ref block, _) => {
|
|
if let Some(return_expression) = Self::return_expression(block) {
|
|
return Self::expression_returns_none(cx, &return_expression);
|
|
}
|
|
|
|
false
|
|
},
|
|
ExprKind::Ret(Some(ref expr)) => Self::expression_returns_none(cx, expr),
|
|
ExprKind::Path(ref qp) => {
|
|
if let Def::VariantCtor(def_id, _) = cx.tables.qpath_def(qp, expression.hir_id) {
|
|
return match_def_path(cx.tcx, def_id, &OPTION_NONE);
|
|
}
|
|
|
|
false
|
|
},
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn return_expression(block: &Block) -> Option<P<Expr>> {
|
|
// Check if last expression is a return statement. Then, return the expression
|
|
if_chain! {
|
|
if block.stmts.len() == 1;
|
|
if let Some(expr) = block.stmts.iter().last();
|
|
if let StmtKind::Semi(ref expr, _) = expr.node;
|
|
if let ExprKind::Ret(ref ret_expr) = expr.node;
|
|
if let &Some(ref ret_expr) = ret_expr;
|
|
|
|
then {
|
|
return Some(ret_expr.clone());
|
|
}
|
|
}
|
|
|
|
// Check for `return` without a semicolon.
|
|
if_chain! {
|
|
if block.stmts.len() == 0;
|
|
if let Some(ExprKind::Ret(Some(ret_expr))) = block.expr.as_ref().map(|e| &e.node);
|
|
then {
|
|
return Some(ret_expr.clone());
|
|
}
|
|
}
|
|
|
|
None
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
|
|
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
|
|
Self::check_is_none_and_early_return_none(cx, expr);
|
|
}
|
|
}
|