+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::{position_before_rarrow, snippet_opt};
use if_chain::if_chain;
use rustc_ast::ast;
use rustc_ast::visit::FnKind;
use rustc_errors::Applicability;
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::BytePos;
-use crate::utils::{position_before_rarrow, span_lint_and_sugg};
-
declare_clippy_lint! {
- /// **What it does:** Checks for unit (`()`) expressions that can be removed.
+ /// ### What it does
+ /// Checks for unit (`()`) expressions that can be removed.
///
- /// **Why is this bad?** Such expressions add no value, but can make the code
+ /// ### Why is this bad?
+ /// Such expressions add no value, but can make the code
/// less readable. Depending on formatting they can make a `break` or `return`
/// statement look like a function call.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// fn return_unit() -> () {
/// ()
/// }
/// ```
+ /// is equivalent to
+ /// ```rust
+ /// fn return_unit() {}
+ /// ```
+ #[clippy::version = "1.31.0"]
pub UNUSED_UNIT,
style,
"needless unit expression"
fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
if_chain! {
- if let Some(ref stmt) = block.stmts.last();
+ if let Some(stmt) = block.stmts.last();
if let ast::StmtKind::Expr(ref expr) = stmt.kind;
- if is_unit_expr(expr) && !stmt.span.from_expansion();
+ if is_unit_expr(expr);
+ let ctxt = block.span.ctxt();
+ if stmt.span.ctxt() == ctxt && expr.span.ctxt() == ctxt;
then {
let sp = expr.span;
span_lint_and_sugg(
if_chain! {
if segments.len() == 1;
- if ["Fn", "FnMut", "FnOnce"].contains(&&*segments[0].ident.name.as_str());
+ if ["Fn", "FnMut", "FnOnce"].contains(&segments[0].ident.name.as_str());
if let Some(args) = &segments[0].args;
if let ast::GenericArgs::Parenthesized(generic_args) = &**args;
if let ast::FnRetTy::Ty(ty) = &generic_args.output;
}
fn lint_unneeded_unit_return(cx: &EarlyContext<'_>, ty: &ast::Ty, span: Span) {
- let (ret_span, appl) = if let Ok(fn_source) = cx.sess().source_map().span_to_snippet(span.with_hi(ty.span.hi())) {
- position_before_rarrow(&fn_source).map_or((ty.span, Applicability::MaybeIncorrect), |rpos| {
- (
- #[allow(clippy::cast_possible_truncation)]
- ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
- Applicability::MachineApplicable,
- )
- })
- } else {
- (ty.span, Applicability::MaybeIncorrect)
- };
+ let (ret_span, appl) =
+ snippet_opt(cx, span.with_hi(ty.span.hi())).map_or((ty.span, Applicability::MaybeIncorrect), |fn_source| {
+ position_before_rarrow(&fn_source).map_or((ty.span, Applicability::MaybeIncorrect), |rpos| {
+ (
+ #[allow(clippy::cast_possible_truncation)]
+ ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
+ Applicability::MachineApplicable,
+ )
+ })
+ });
span_lint_and_sugg(
cx,
UNUSED_UNIT,