use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
use clippy_utils::source::snippet_opt;
-use clippy_utils::{fn_def_id, in_macro, path_to_local_id};
+use clippy_utils::{fn_def_id, path_to_local_id};
use if_chain::if_chain;
use rustc_ast::ast::Attribute;
use rustc_errors::Applicability;
-use rustc_hir::intravisit::{walk_expr, FnKind, NestedVisitorMap, Visitor};
+use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
use rustc_hir::{Block, Body, Expr, ExprKind, FnDecl, HirId, MatchSource, PatKind, StmtKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_middle::hir::map::Map;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_session::{declare_lint_pass, declare_tool_lint};
/// String::new()
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub LET_AND_RETURN,
style,
"creating a let-binding and then immediately returning it like `let x = expr; x` at the end of a block"
/// x
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub NEEDLESS_RETURN,
style,
"using a return statement like `return expr;` where an expression would suffice"
enum RetReplacement {
Empty,
Block,
+ Unit,
}
declare_lint_pass!(Return => [LET_AND_RETURN, NEEDLESS_RETURN]);
if !last_statement_borrows(cx, initexpr);
if !in_external_macro(cx.sess(), initexpr.span);
if !in_external_macro(cx.sess(), retexpr.span);
- if !in_external_macro(cx.sess(), local.span);
- if !in_macro(local.span);
+ if !local.span.from_expansion();
then {
span_lint_and_then(
cx,
// (except for unit type functions) so we don't match it
ExprKind::Match(_, arms, MatchSource::Normal) => {
for arm in arms.iter() {
- check_final_expr(cx, arm.body, Some(arm.body.span), RetReplacement::Block);
+ check_final_expr(cx, arm.body, Some(arm.body.span), RetReplacement::Unit);
}
},
ExprKind::DropTemps(expr) => check_final_expr(cx, expr, None, RetReplacement::Empty),
Applicability::MachineApplicable,
);
},
+ RetReplacement::Unit => {
+ span_lint_and_sugg(
+ cx,
+ NEEDLESS_RETURN,
+ ret_span,
+ "unneeded `return` statement",
+ "replace `return` with a unit value",
+ "()".to_string(),
+ Applicability::MachineApplicable,
+ );
+ },
},
}
}
}
impl<'tcx> Visitor<'tcx> for BorrowVisitor<'_, 'tcx> {
- type Map = Map<'tcx>;
-
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
if self.borrows {
return;
.fn_sig(def_id)
.output()
.skip_binder()
- .walk(self.cx.tcx)
+ .walk()
.any(|arg| matches!(arg.unpack(), GenericArgKind::Lifetime(_)));
}
walk_expr(self, expr);
}
-
- fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
- NestedVisitorMap::None
- }
}