1 files changed, 259 insertions, 0 deletions

diff --git a/src/test/ui/issues/issue-23611-enum-swap-in-drop.rs b/src/test/ui/issues/issue-23611-enum-swap-in-drop.rs
new file mode 100644
index 000000000..403cf970b
--- /dev/null
+++ b/src/test/ui/issues/issue-23611-enum-swap-in-drop.rs
@@ -0,0 +1,259 @@
+// run-pass
+#![allow(non_upper_case_globals)]
+
+// Issue 23611: this test is ensuring that, for an instance `X` of the
+// enum `E`, if you swap in a different variant during the execution
+// of the `<E as Drop>::drop`, then the appropriate substructure will
+// be torn down after the `<E as Drop>::drop` method returns.
+
+use std::cell::RefCell;
+use std::mem;
+
+use self::d::D;
+
+pub fn main() {
+    let log = RefCell::new(vec![]);
+    d::println("created empty log");
+    test(&log);
+
+    // println!("log: {:?}", &log.borrow()[..]);
+    assert_eq!(
+        &log.borrow()[..],
+        [
+            //                                         created empty log
+            // +-- Make D(test_1, 10000000)
+            // | +-- Make D(g_b_5, 50000001)
+            // | |                                     in g_B(b2b0) from E::drop, b=b4b0
+            // | +-- Drop D(g_b_5, 50000001)
+            50000001,
+            // |
+            // | +-- Make D(drop_6, 60000002)
+            // | | +-- Make D(g_b_5, 50000003)
+            // | | |                                   in g_B(b2b0) from E::drop, b=b4b1
+            // | | +-- Drop D(g_b_5, 50000003)
+            50000003,
+            // | |
+            // | | +-- Make D(GaspB::drop_3, 30000004)
+            // | | | +-- Make D(g_b_5, 50000005)
+            // | | | |                                 in g_B(b4b2) from GaspB::drop
+            // | | | +-- Drop D(g_b_5, 50000005)
+            50000005,
+            // | | |
+            // | | +-- Drop D(GaspB::drop_3, 30000004)
+            30000004,
+            // | |
+            // +-- Drop D(test_1, 10000000)
+            10000000,
+            //   |
+            // +-- Make D(GaspA::drop_2, 20000006)
+            // | | +-- Make D(f_a_4, 40000007)
+            // | | |                                   in f_A(a3a0) from GaspA::drop
+            // | | +-- Drop D(f_a_4, 40000007)
+            40000007,
+            // | |
+            // +-- Drop D(GaspA::drop_2, 20000006)
+            20000006,
+            //   |
+            //   +-- Drop D(drop_6, 60000002)
+            60000002
+            //
+                ]);
+
+    // For reference purposes, the old (incorrect) behavior would produce the following
+    // output, which you can compare to the above:
+    //
+    //                                             created empty log
+    // +-- Make D(test_1, 10000000)
+    // | +-- Make D(g_b_5, 50000001)
+    // | |                                     in g_B(b2b0) from E::drop, b=b4b0
+    // | +-- Drop D(g_b_5, 50000001)
+    // |
+    // | +-- Make D(drop_6, 60000002)
+    // | | +-- Make D(g_b_5, 50000003)
+    // | | |                                   in g_B(b2b0) from E::drop, b=b4b1
+    // | | +-- Drop D(g_b_5, 50000003)
+    // | |
+    // | | +-- Make D(GaspB::drop_3, 30000004)
+    // | | | +-- Make D(g_b_5, 50000005)
+    // | | | |                                 in g_B(b4b2) from GaspB::drop
+    // | | | +-- Drop D(g_b_5, 50000005)
+    // | | |
+    // | | +-- Drop D(GaspB::drop_3, 30000004)
+    // | |
+    // +-- Drop D(test_1, 10000000)
+    //   |
+    // +-- Make D(GaspB::drop_3, 30000006)
+    // | | +-- Make D(f_a_4, 40000007)
+    // | | |                                   in f_A(a3a0) from GaspB::drop
+    // | | +-- Drop D(f_a_4, 40000007)
+    // | |
+    // +-- Drop D(GaspB::drop_3, 30000006)
+    //   |
+    //   +-- Drop D(drop_6, 60000002)
+
+    // Note that this calls f_A from GaspB::drop (and thus creates a D
+    // with a uid incorporating the origin of GaspB's drop that
+    // surrounds the f_A invocation), but the code as written only
+    // ever hands f_A off to instances of GaspA, and thus one should
+    // be able to prove the invariant that f_A is *only* invoked from
+    // from an instance of GaspA (either via the GaspA drop
+    // implementation or the E drop implementaton). Yet the old (bad)
+    // behavior allowed a call to f_A to leak in while we are tearing
+    // down a value of type GaspB.
+}
+
+fn test<'a>(log: d::Log<'a>) {
+    let _e = E::B(GaspB(g_b, 0xB4B0, log, D::new("test", 1, log)), true);
+}
+
+struct GaspA<'a>(for <'b> fn(u32, &'b str, d::Log<'a>), u32, d::Log<'a>, d::D<'a>);
+struct GaspB<'a>(for <'b> fn(u32, &'b str, d::Log<'a>), u32, d::Log<'a>, d::D<'a>);
+
+impl<'a> Drop for GaspA<'a> {
+    fn drop(&mut self) {
+        let _d = d::D::new("GaspA::drop", 2, self.2);
+        (self.0)(self.1, "GaspA::drop", self.2);
+    }
+}
+
+impl<'a> Drop for GaspB<'a> {
+    fn drop(&mut self) {
+        let _d = d::D::new("GaspB::drop", 3, self.2);
+        (self.0)(self.1, "GaspB::drop", self.2);
+    }
+}
+
+enum E<'a> {
+    A(GaspA<'a>, bool), B(GaspB<'a>, bool),
+}
+
+fn f_a(x: u32, ctxt: &str, log: d::Log) {
+    let _d = d::D::new("f_a", 4, log);
+    d::println(&format!("in f_A({:x}) from {}", x, ctxt));
+}
+fn g_b(y: u32, ctxt: &str, log: d::Log) {
+    let _d = d::D::new("g_b", 5, log);
+    d::println(&format!("in g_B({:x}) from {}", y, ctxt));
+}
+
+impl<'a> Drop for E<'a> {
+    fn drop(&mut self) {
+        let (do_drop, log) = match *self {
+            E::A(GaspA(ref f, ref mut val_a, log, ref _d_a), ref mut do_drop) => {
+                f(0xA1A0, &format!("E::drop, a={:x}", val_a), log);
+                *val_a += 1;
+                // swap in do_drop := false to avoid infinite dtor regress
+                (mem::replace(do_drop, false), log)
+            }
+            E::B(GaspB(ref g, ref mut val_b, log, ref _d_b), ref mut do_drop) => {
+                g(0xB2B0, &format!("E::drop, b={:x}", val_b), log);
+                *val_b += 1;
+                // swap in do_drop := false to avoid infinite dtor regress
+                (mem::replace(do_drop, false), log)
+            }
+        };
+
+        #[allow(unused_must_use)]
+        if do_drop {
+            mem::replace(self, E::A(GaspA(f_a, 0xA3A0, log, D::new("drop", 6, log)), true));
+        }
+    }
+}
+
+// This module provides simultaneous printouts of the dynamic extents
+// of all of the D values, in addition to logging the order that each
+// is dropped.
+//
+// This code is similar to a support code module embedded within
+// test/run-pass/issue-123338-ensure-param-drop-order.rs; however,
+// that (slightly simpler) code only identifies objects in the log via
+// (creation) time-stamps; this incorporates both timestamping and the
+// point of origin within the source code into the unique ID (uid).
+
+const PREF_INDENT: u32 = 20;
+
+pub mod d {
+    #![allow(unused_parens)]
+    use std::fmt;
+    use std::mem;
+    use std::cell::RefCell;
+
+    static mut counter: u16 = 0;
+    static mut trails: u64 = 0;
+
+    pub type Log<'a> = &'a RefCell<Vec<u32>>;
+
+    pub fn current_width() -> u32 {
+        unsafe { max_width() - trails.leading_zeros() }
+    }
+
+    pub fn max_width() -> u32 {
+        unsafe {
+            (mem::size_of_val(&trails)*8) as u32
+        }
+    }
+
+    pub fn indent_println(my_trails: u32, s: &str) {
+        let mut indent: String = String::new();
+        for i in 0..my_trails {
+            unsafe {
+                if trails & (1 << i) != 0 {
+                    indent = indent + "| ";
+                } else {
+                    indent = indent + "  ";
+                }
+            }
+        }
+        println!("{}{}", indent, s);
+    }
+
+    pub fn println(s: &str) {
+        indent_println(super::PREF_INDENT, s);
+    }
+
+    fn first_avail() -> u32 {
+        unsafe {
+            for i in 0..64 {
+                if trails & (1 << i) == 0 {
+                    return i;
+                }
+            }
+        }
+        panic!("exhausted trails");
+    }
+
+    pub struct D<'a> {
+        name: &'static str, i: u8, uid: u32, trail: u32, log: Log<'a>
+    }
+
+    impl<'a> fmt::Display for D<'a> {
+        fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
+            write!(w, "D({}_{}, {})", self.name, self.i, self.uid)
+        }
+    }
+
+    impl<'a> D<'a> {
+        pub fn new(name: &'static str, i: u8, log: Log<'a>) -> D<'a> {
+            unsafe {
+                let trail = first_avail();
+                let ctr = ((i as u32) * 10_000_000) + (counter as u32);
+                counter += 1;
+                trails |= (1 << trail);
+                let ret = D {
+                    name: name, i: i, log: log, uid: ctr, trail: trail
+                };
+                indent_println(trail, &format!("+-- Make {}", ret));
+                ret
+            }
+        }
+    }
+
+    impl<'a> Drop for D<'a> {
+        fn drop(&mut self) {
+            unsafe { trails &= !(1 << self.trail); };
+            self.log.borrow_mut().push(self.uid);
+            indent_println(self.trail, &format!("+-- Drop {}", self));
+            indent_println(::PREF_INDENT, "");
+        }
+    }
+}