From b1931e48a01b418b4b1ba6c747f2c99a5b10d96f Mon Sep 17 00:00:00 2001
From: Huon Wilson <dbau.pp+github@gmail.com>
Date: Mon, 29 Jun 2015 14:51:56 -0700
Subject: [PATCH] lint: only consider actual calls as unconditional recursion.

Specifically, just mentioning the function name as a value is fine, as
long as it isn't called, e.g. `fn main() { let _ = main; }`.

Closes #21705.
---
 src/librustc_lint/builtin.rs                          | 9 +++++++--
 src/test/compile-fail/lint-unconditional-recursion.rs | 4 ++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/librustc_lint/builtin.rs b/src/librustc_lint/builtin.rs
index db48608823d..3d5eb422b63 100644
--- a/src/librustc_lint/builtin.rs
+++ b/src/librustc_lint/builtin.rs
@@ -1973,8 +1973,13 @@ impl LintPass for UnconditionalRecursion {
                                       fn_id: ast::NodeId,
                                       _: ast::Ident,
                                       id: ast::NodeId) -> bool {
-            tcx.def_map.borrow().get(&id)
-               .map_or(false, |def| def.def_id() == local_def(fn_id))
+            match tcx.map.get(id) {
+                ast_map::NodeExpr(&ast::Expr { node: ast::ExprCall(ref callee, _), .. }) => {
+                    tcx.def_map.borrow().get(&callee.id)
+                        .map_or(false, |def| def.def_id() == local_def(fn_id))
+                }
+                _ => false
+            }
         }
 
         // check if the method call `id` refers to method `method_id`
diff --git a/src/test/compile-fail/lint-unconditional-recursion.rs b/src/test/compile-fail/lint-unconditional-recursion.rs
index 0c3d1c6adea..0cd71aebd63 100644
--- a/src/test/compile-fail/lint-unconditional-recursion.rs
+++ b/src/test/compile-fail/lint-unconditional-recursion.rs
@@ -63,4 +63,8 @@ impl Baz {
     }
 }
 
+fn all_fine() {
+    let _f = all_fine;
+}
+
 fn main() {}