Fix single binding closure

clippy_lints/src/matches.rs

@@ -3,9 +3,10 @@ use crate::utils::paths;
 use crate::utils::sugg::Sugg;
 use crate::utils::usage::is_unused;
 use crate::utils::{
- expr_block, get_arg_name, in_macro, indent_of, is_allowed, is_expn_of, is_refutable, is_wild, match_qpath,
- match_type, match_var, multispan_sugg, remove_blocks, snippet, snippet_block, snippet_with_applicability,
- span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then, walk_ptrs_ty,
+ expr_block, get_arg_name, get_parent_expr, in_macro, indent_of, is_allowed, is_expn_of, is_refutable, is_wild,
+ match_qpath, match_type, match_var, multispan_sugg, remove_blocks, snippet, snippet_block,
+ snippet_with_applicability, span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then,
+ walk_ptrs_ty,
 };
 use if_chain::if_chain;
 use rustc::lint::in_external_macro;
@@ -928,14 +929,27 @@ fn check_match_single_binding<'a>(cx: &LateContext<'_, 'a>, ex: &Expr<'a>, arms:
  ),
  )
  } else {
+ // If we are in closure, we need curly braces around suggestion
+ let mut indent = " ".repeat(indent_of(cx, ex.span).unwrap_or(0));
+ let (mut cbrace_start, mut cbrace_end) = ("".to_string(), "".to_string());
+ if let Some(parent_expr) = get_parent_expr(cx, expr) {
+ if let ExprKind::Closure(..) = parent_expr.kind {
+ cbrace_end = format!("\n{}}}", indent);
+ // Fix body indent due to the closure
+ indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
+ cbrace_start = format!("{{\n{}", indent);
+ }
+ };
  (
  expr.span,
  format!(
- "let {} = {};\n{}{}",
+ "{}let {} = {};\n{}{}{}",
+ cbrace_start,
  snippet_with_applicability(cx, bind_names, "..", &mut applicability),
  snippet_with_applicability(cx, matched_vars, "..", &mut applicability),
- " ".repeat(indent_of(cx, expr.span).unwrap_or(0)),
- snippet_body
+ indent,
+ snippet_body,
+ cbrace_end
  ),
  )
  };

tests/ui/match_single_binding.fixed

@@ -67,4 +67,14 @@ fn main() {
  // Lint
  let Point { x, y } = coords();
  let product = x * y;
+ // Lint
+ let v = vec![Some(1), Some(2), Some(3), Some(4)];
+ #[allow(clippy::let_and_return)]
+ let _ = v
+ .iter()
+ .map(|i| {
+ let unwrapped = i.unwrap();
+ unwrapped
+ })
+ .collect::<Vec<u8>>();
 }

tests/ui/match_single_binding.rs

@@ -80,4 +80,13 @@ fn main() {
  let product = match coords() {
  Point { x, y } => x * y,
  };
+ // Lint
+ let v = vec![Some(1), Some(2), Some(3), Some(4)];
+ #[allow(clippy::let_and_return)]
+ let _ = v
+ .iter()
+ .map(|i| match i.unwrap() {
+ unwrapped => unwrapped,
+ })
+ .collect::<Vec<u8>>();
 }

tests/ui/match_single_binding.stderr

@@ -150,5 +150,22 @@ LL | let Point { x, y } = coords();
 LL | let product = x * y;
  |
 
-error: aborting due to 10 previous errors
+error: this match could be written as a `let` statement
+ --> $DIR/match_single_binding.rs:88:18
+ |
+LL | .map(|i| match i.unwrap() {
+ | __________________^
+LL | | unwrapped => unwrapped,
+LL | | })
+ | |_________^
+ |
+help: consider using `let` statement
+ |
+LL | .map(|i| {
+LL | let unwrapped = i.unwrap();
+LL | unwrapped
+LL | })
+ |
+
+error: aborting due to 11 previous errors