| use clippy_utils::diagnostics::span_lint_and_sugg; |
| use clippy_utils::source::{snippet_opt, trim_span}; |
| use rustc_ast::ast::{Expr, ExprKind}; |
| use rustc_errors::Applicability; |
| use rustc_lint::{EarlyContext, EarlyLintPass, LintContext}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for empty `else` branches. |
| /// |
| /// ### Why is this bad? |
| /// An empty else branch does nothing and can be removed. |
| /// |
| /// ### Example |
| /// ```no_run |
| ///# fn check() -> bool { true } |
| /// if check() { |
| /// println!("Check successful!"); |
| /// } else { |
| /// } |
| /// ``` |
| /// Use instead: |
| /// ```no_run |
| ///# fn check() -> bool { true } |
| /// if check() { |
| /// println!("Check successful!"); |
| /// } |
| /// ``` |
| #[clippy::version = "1.72.0"] |
| pub NEEDLESS_ELSE, |
| style, |
| "empty else branch" |
| } |
| declare_lint_pass!(NeedlessElse => [NEEDLESS_ELSE]); |
| |
| impl EarlyLintPass for NeedlessElse { |
| fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) { |
| if let ExprKind::If(_, then_block, Some(else_clause)) = &expr.kind |
| && let ExprKind::Block(block, _) = &else_clause.kind |
| && !expr.span.from_expansion() |
| && !else_clause.span.from_expansion() |
| && block.stmts.is_empty() |
| && let Some(trimmed) = expr.span.trim_start(then_block.span) |
| && let span = trim_span(cx.sess().source_map(), trimmed) |
| && let Some(else_snippet) = snippet_opt(cx, span) |
| // Ignore else blocks that contain comments or #[cfg]s |
| && !else_snippet.contains(['/', '#']) |
| { |
| span_lint_and_sugg( |
| cx, |
| NEEDLESS_ELSE, |
| span, |
| "this `else` branch is empty", |
| "you can remove it", |
| String::new(), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |