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Covered all other kinds besides `ExprKind::Lit`. Added check for replacing `break` with `return`.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,131 @@ | ||
| // 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::{intravisit::FnKind, Body, ExprKind, FnDecl}; | ||
| use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; | ||
| use crate::rustc::{declare_tool_lint, lint_array}; | ||
| use crate::rustc_errors::Applicability; | ||
| use crate::syntax::{ast::NodeId, source_map::Span}; | ||
| use crate::utils::{snippet_opt, span_lint_and_then}; | ||
|
|
||
| /// **What it does:** Checks for missing return statements at the end of a block. | ||
| /// | ||
| /// **Why is this bad?** Actually omitting the return keyword is idiomatic Rust code. Programmers | ||
| /// coming from other languages might prefer the expressiveness of `return`. | ||
| /// | ||
| /// **Known problems:** None. | ||
| /// | ||
| /// **Example:** | ||
| /// ```rust | ||
| /// fn foo(x: usize) { | ||
| /// x | ||
| /// } | ||
| /// ``` | ||
| /// add return | ||
| /// ```rust | ||
| /// fn foo(x: usize) { | ||
| /// return x; | ||
| /// } | ||
| /// ``` | ||
| declare_clippy_lint! { | ||
| pub IMPLICIT_RETURN, | ||
| restriction, | ||
| "use a return statement like `return expr` instead of an expression" | ||
| } | ||
|
|
||
| pub struct Pass; | ||
|
|
||
| impl Pass { | ||
| fn expr_match(cx: &LateContext<'_, '_>, expr: &rustc::hir::Expr) { | ||
| match &expr.node { | ||
| ExprKind::Block(block, ..) => { | ||
| if let Some(expr) = &block.expr { | ||
| Self::expr_match(cx, expr); | ||
| } | ||
| // only needed in the case of `break` with `;` at the end | ||
| else if let Some(stmt) = block.stmts.last() { | ||
| if let rustc::hir::StmtKind::Semi(expr, ..) = &stmt.node { | ||
| Self::expr_match(cx, expr); | ||
| } | ||
| } | ||
| }, | ||
| // use `return` instead of `break` | ||
| ExprKind::Break(.., break_expr) => { | ||
| if let Some(break_expr) = break_expr { | ||
| span_lint_and_then(cx, IMPLICIT_RETURN, expr.span, "missing return statement", |db| { | ||
| if let Some(snippet) = snippet_opt(cx, break_expr.span) { | ||
| db.span_suggestion_with_applicability( | ||
| expr.span, | ||
| "change `break` to `return` as shown", | ||
| format!("return {}", snippet), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| } | ||
| }); | ||
| } | ||
| }, | ||
| ExprKind::If(.., if_expr, else_expr) => { | ||
| Self::expr_match(cx, if_expr); | ||
|
|
||
| if let Some(else_expr) = else_expr { | ||
| Self::expr_match(cx, else_expr); | ||
| } | ||
| }, | ||
| ExprKind::Match(_, arms, ..) => { | ||
| for arm in arms { | ||
| Self::expr_match(cx, &arm.body); | ||
| } | ||
| }, | ||
| // loops could be using `break` instead of `return` | ||
| ExprKind::Loop(block, ..) => { | ||
| if let Some(expr) = &block.expr { | ||
| Self::expr_match(cx, expr); | ||
| } | ||
| }, | ||
| // skip if it already has a return statement | ||
| ExprKind::Ret(..) => (), | ||
| // everything else is missing `return` | ||
| _ => span_lint_and_then(cx, IMPLICIT_RETURN, expr.span, "missing return statement", |db| { | ||
| if let Some(snippet) = snippet_opt(cx, expr.span) { | ||
| db.span_suggestion_with_applicability( | ||
| expr.span, | ||
| "add `return` as shown", | ||
| format!("return {}", snippet), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| } | ||
| }), | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl LintPass for Pass { | ||
| fn get_lints(&self) -> LintArray { | ||
| lint_array!(IMPLICIT_RETURN) | ||
| } | ||
| } | ||
|
|
||
| impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass { | ||
| fn check_fn( | ||
| &mut self, | ||
| cx: &LateContext<'a, 'tcx>, | ||
| _: FnKind<'tcx>, | ||
| _: &'tcx FnDecl, | ||
| body: &'tcx Body, | ||
| _: Span, | ||
| _: NodeId, | ||
| ) { | ||
| let def_id = cx.tcx.hir.body_owner_def_id(body.id()); | ||
| let mir = cx.tcx.optimized_mir(def_id); | ||
|
|
||
| if !mir.return_ty().is_unit() { | ||
| Self::expr_match(cx, &body.value); | ||
| } | ||
| } | ||
| } |
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20 changes: 10 additions & 10 deletions
20
tests/ui/missing_returns.stderr → tests/ui/implicit_return.stderr
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