Rollup merge of rust-lang#39834 - cseale:feature-gate-static-recursio…

…n, r=est31

static recursion test added to compile-fail test suite

Issue rust-lang#39059
r? @est31

src/test/compile-fail/feature-gate-static_recursion.rs

@@ -0,0 +1,49 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+static mut S: *const u8 = unsafe { &S as *const *const u8 as *const u8 };
+//~^ ERROR recursive static (see issue #29719)
+
+struct StaticDoubleLinked {
+    prev: &'static StaticDoubleLinked,
+    next: &'static StaticDoubleLinked,
+    data: i32,
+    head: bool,
+}
+
+static L1: StaticDoubleLinked = StaticDoubleLinked{prev: &L3, next: &L2, data: 1, head: true};
+//~^ ERROR recursive static (see issue #29719)
+//~^^ ERROR recursive static (see issue #29719)
+//~^^^ ERROR recursive static (see issue #29719)
+static L2: StaticDoubleLinked = StaticDoubleLinked{prev: &L1, next: &L3, data: 2, head: false};
+static L3: StaticDoubleLinked = StaticDoubleLinked{prev: &L2, next: &L1, data: 3, head: false};
+
+
+pub fn main() {
+    unsafe { assert_eq!(S, *(S as *const *const u8)); }
+
+    let mut test_vec = Vec::new();
+    let mut cur = &L1;
+    loop {
+        test_vec.push(cur.data);
+        cur = cur.next;
+        if cur.head { break }
+    }
+    assert_eq!(&test_vec, &[1,2,3]);
+
+    let mut test_vec = Vec::new();
+    let mut cur = &L1;
+    loop {
+        cur = cur.prev;
+        test_vec.push(cur.data);
+        if cur.head { break }
+    }
+    assert_eq!(&test_vec, &[3,2,1]);
+}

src/tools/tidy/src/features.rs

@@ -166,7 +166,7 @@ pub fn check(path: &Path, bad: &mut bool) {
 
     // FIXME get this whitelist empty.
     let whitelist = vec![
-        "abi_ptx", "simd", "static_recursion",
+        "abi_ptx", "simd",
         "cfg_target_has_atomic",
         "unboxed_closures", "stmt_expr_attributes",
         "cfg_target_thread_local", "unwind_attributes",