Ensuring correct lint message is output for Option and Result type

Author: Donald Robertson

clippy_lints/src/methods.rs

@@ -998,13 +998,20 @@ fn lint_expect_fun_call(cx: &LateContext, expr: &hir::Expr, method_span: Span, n
         cx: &LateContext,
         name: &str,
         method_span: Span,
+        self_expr: &hir::Expr,
         arg: &hir::Expr,
         span: Span,
     ) {
         if name != "expect" {
             return;
         }
 
+        let self_ty = cx.tables.expr_ty(self_expr);
+        let closure = match match_type(cx, self_ty, &paths::OPTION) {
+            true => "||",
+            false => "|_|",
+        };
+
         // don't lint for constant values
         let owner_def = cx.tcx.hir.get_parent_did(arg.id);
         let promotable = cx.tcx.rvalue_promotable_map(owner_def).contains(&arg.hir_id.local_id);
@@ -1021,14 +1028,14 @@ fn lint_expect_fun_call(cx: &LateContext, expr: &hir::Expr, method_span: Span, n
             span_replace_word,
             &format!("use of `{}` followed by a function call", name),
             "try this",
-            format!("unwrap_or_else(|_| panic!({}))", sugg),
+            format!("unwrap_or_else({} panic!({}))", closure, sugg),
         );
     }
 
     if args.len() == 2 {
         match args[1].node {
             hir::ExprLit(_) => {},
-            _ => check_general_case(cx, name, method_span, &args[1], expr.span),
+            _ => check_general_case(cx, name, method_span, &args[0], &args[1], expr.span),
         }
     }
 }

tests/ui/methods.stderr

@@ -427,15 +427,15 @@ error: use of `expect` followed by a function call
    --> $DIR/methods.rs:355:26
     |
 355 |     with_none_and_format.expect(&format!("Error {}: fake error", error_code));
-    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| panic!(&format!("Error {}: fake error", error_code)))`
+    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| panic!(&format!("Error {}: fake error", error_code)))`
     |
     = note: `-D expect-fun-call` implied by `-D warnings`
 
 error: use of `expect` followed by a function call
    --> $DIR/methods.rs:358:26
     |
 358 |     with_none_and_as_str.expect(format!("Error {}: fake error", error_code).as_str());
-    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| panic!(format!("Error {}: fake error", error_code).as_str()))`
+    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| panic!(format!("Error {}: fake error", error_code).as_str()))`
 
 error: use of `expect` followed by a function call
    --> $DIR/methods.rs:368:25