Merge rust-lang#3427

3427: Fix wrong suggestion for `redundant_closure_call` r=oli-obk a=mikerite Fixes rust-lang#1684 Co-authored-by: Michael Wright <mikerite@lavabit.com>

Author: bors[bot]

clippy_lints/src/misc_early.rs

@@ -15,7 +15,7 @@ use if_chain::if_chain;
 use std::char;
 use crate::syntax::ast::*;
 use crate::syntax::source_map::Span;
-use crate::syntax::visit::FnKind;
+use crate::syntax::visit::{FnKind, Visitor, walk_expr};
 use crate::utils::{constants, snippet, snippet_opt, span_help_and_lint, span_lint, span_lint_and_then};
 use crate::rustc_errors::Applicability;
 
@@ -199,6 +199,31 @@ impl LintPass for MiscEarly {
  }
 }
 
+// Used to find `return` statements or equivalents e.g. `?`
+struct ReturnVisitor {
+ found_return: bool,
+}
+
+impl ReturnVisitor {
+ fn new() -> Self {
+ Self {
+ found_return: false,
+ }
+ }
+}
+
+impl<'ast> Visitor<'ast> for ReturnVisitor {
+ fn visit_expr(&mut self, ex: &'ast Expr) {
+ if let ExprKind::Ret(_) = ex.node {
+ self.found_return = true;
+ } else if let ExprKind::Try(_) = ex.node {
+ self.found_return = true;
+ }
+
+ walk_expr(self, ex)
+ }
+}
+
 impl EarlyLintPass for MiscEarly {
  fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
  for param in &gen.params {
@@ -311,21 +336,25 @@ impl EarlyLintPass for MiscEarly {
  match expr.node {
  ExprKind::Call(ref paren, _) => if let ExprKind::Paren(ref closure) = paren.node {
  if let ExprKind::Closure(_, _, _, ref decl, ref block, _) = closure.node {
- span_lint_and_then(
- cx,
- REDUNDANT_CLOSURE_CALL,
- expr.span,
- "Try not to call a closure in the expression where it is declared.",
- |db| if decl.inputs.is_empty() {
- let hint = snippet(cx, block.span, "..").into_owned();
- db.span_suggestion_with_applicability(
- expr.span,
- "Try doing something like: ",
- hint,
- Applicability::MachineApplicable, // snippet
- );
- },
- );
+ let mut visitor = ReturnVisitor::new();
+ visitor.visit_expr(block);
+ if !visitor.found_return {
+ span_lint_and_then(
+ cx,
+ REDUNDANT_CLOSURE_CALL,
+ expr.span,
+ "Try not to call a closure in the expression where it is declared.",
+ |db| if decl.inputs.is_empty() {
+ let hint = snippet(cx, block.span, "..").into_owned();
+ db.span_suggestion_with_applicability(
+ expr.span,
+ "Try doing something like: ",
+ hint,
+ Applicability::MachineApplicable, // snippet
+ );
+ },
+ );
+ }
  }
  },
  ExprKind::Unary(UnOp::Neg, ref inner) => if let ExprKind::Unary(UnOp::Neg, _) = inner.node {

tests/ui/redundant_closure_call.rs

@@ -28,4 +28,9 @@ fn main() {
 i = closure(3);
 
 i = closure(4);
+
+ #[allow(clippy::needless_return)]
+ (|| return 2)();
+ (|| -> Option<i32> { None? })();
+ (|| -> Result<i32, i32> { r#try!(Err(2)) })();
 }