From 418dd641dc41e3e9edc832f9083a669836110d15 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 7 Feb 2020 14:02:36 +0100
Subject: [PATCH] test more generator resume things

---
 tests/run-pass/generator.rs     | 155 ++++++++++++++++++++++++++++----
 tests/run-pass/generator.stderr |   1 +
 2 files changed, 138 insertions(+), 18 deletions(-)
 create mode 100644 tests/run-pass/generator.stderr

diff --git a/tests/run-pass/generator.rs b/tests/run-pass/generator.rs
index 7f95f374ac7d..a7c72ed3530c 100644
--- a/tests/run-pass/generator.rs
+++ b/tests/run-pass/generator.rs
@@ -1,30 +1,33 @@
 #![feature(generators, generator_trait, never_type)]
 
-use std::ops::{GeneratorState, Generator};
+use std::panic::{catch_unwind, AssertUnwindSafe};
+use std::ops::{GeneratorState::{self, *}, Generator};
 use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::fmt::Debug;
 
-fn finish<T>(mut amt: usize, mut t: T) -> T::Return
-    where T: Generator<Yield = usize>
-{
-    // We are not moving the `t` around until it gets dropped, so this is okay.
-    let mut t = unsafe { Pin::new_unchecked(&mut t) };
-    loop {
-        match t.as_mut().resume(()) {
-            GeneratorState::Yielded(y) => amt -= y,
-            GeneratorState::Complete(ret) => {
-                assert_eq!(amt, 0);
-                return ret
+fn basic() {
+    fn finish<T>(mut amt: usize, mut t: T) -> T::Return
+        where T: Generator<Yield = usize>
+    {
+        // We are not moving the `t` around until it gets dropped, so this is okay.
+        let mut t = unsafe { Pin::new_unchecked(&mut t) };
+        loop {
+            match t.as_mut().resume(()) {
+                GeneratorState::Yielded(y) => amt -= y,
+                GeneratorState::Complete(ret) => {
+                    assert_eq!(amt, 0);
+                    return ret
+                }
             }
         }
     }
-}
 
-enum Never {}
-fn never() -> Never {
-    panic!()
-}
+    enum Never {}
+    fn never() -> Never {
+        panic!()
+    }
 
-fn main() {
     finish(1, || yield 1);
 
     finish(3, || {
@@ -94,3 +97,119 @@ fn main() {
         let _x: (String, !) = (String::new(), { yield 2; return });
     });
 }
+
+fn smoke_resume_arg() {
+    fn drain<G: Generator<R, Yield = Y> + Unpin, R, Y>(
+        gen: &mut G,
+        inout: Vec<(R, GeneratorState<Y, G::Return>)>,
+    ) where
+        Y: Debug + PartialEq,
+        G::Return: Debug + PartialEq,
+    {
+        let mut gen = Pin::new(gen);
+
+        for (input, out) in inout {
+            assert_eq!(gen.as_mut().resume(input), out);
+        }
+    }
+
+    static DROPS: AtomicUsize = AtomicUsize::new(0);
+
+    #[derive(Debug, PartialEq)]
+    struct DropMe;
+
+    impl Drop for DropMe {
+        fn drop(&mut self) {
+            DROPS.fetch_add(1, Ordering::SeqCst);
+        }
+    }
+
+    fn expect_drops<T>(expected_drops: usize, f: impl FnOnce() -> T) -> T {
+        DROPS.store(0, Ordering::SeqCst);
+
+        let res = f();
+
+        let actual_drops = DROPS.load(Ordering::SeqCst);
+        assert_eq!(actual_drops, expected_drops);
+        res
+    }
+
+    drain(
+        &mut |mut b| {
+            while b != 0 {
+                b = yield (b + 1);
+            }
+            -1
+        },
+        vec![(1, Yielded(2)), (-45, Yielded(-44)), (500, Yielded(501)), (0, Complete(-1))],
+    );
+
+    expect_drops(2, || drain(&mut |a| yield a, vec![(DropMe, Yielded(DropMe))]));
+
+    expect_drops(6, || {
+        drain(
+            &mut |a| yield yield a,
+            vec![(DropMe, Yielded(DropMe)), (DropMe, Yielded(DropMe)), (DropMe, Complete(DropMe))],
+        )
+    });
+
+    #[allow(unreachable_code)]
+    expect_drops(2, || drain(&mut |a| yield return a, vec![(DropMe, Complete(DropMe))]));
+
+    expect_drops(2, || {
+        drain(
+            &mut |a: DropMe| {
+                if false { yield () } else { a }
+            },
+            vec![(DropMe, Complete(DropMe))],
+        )
+    });
+
+    expect_drops(4, || {
+        drain(
+            #[allow(unused_assignments, unused_variables)]
+            &mut |mut a: DropMe| {
+                a = yield;
+                a = yield;
+                a = yield;
+            },
+            vec![
+                (DropMe, Yielded(())),
+                (DropMe, Yielded(())),
+                (DropMe, Yielded(())),
+                (DropMe, Complete(())),
+            ],
+        )
+    });
+}
+
+fn panic_drop_resume() {
+    static DROP: AtomicUsize = AtomicUsize::new(0);
+
+    struct Dropper {}
+
+    impl Drop for Dropper {
+        fn drop(&mut self) {
+            DROP.fetch_add(1, Ordering::SeqCst);
+        }
+    }
+
+    let mut gen = |_arg| {
+        if true {
+            panic!();
+        }
+        yield ();
+    };
+    let mut gen = Pin::new(&mut gen);
+
+    assert_eq!(DROP.load(Ordering::Acquire), 0);
+    let res = catch_unwind(AssertUnwindSafe(|| gen.as_mut().resume(Dropper {})));
+    assert!(res.is_err());
+    assert_eq!(DROP.load(Ordering::Acquire), 1);
+}
+
+fn main() {
+    basic();
+    smoke_resume_arg();
+    panic_drop_resume();
+}
diff --git a/tests/run-pass/generator.stderr b/tests/run-pass/generator.stderr
new file mode 100644
index 000000000000..17f385d4d695
--- /dev/null
+++ b/tests/run-pass/generator.stderr
@@ -0,0 +1 @@
+thread 'main' panicked at 'explicit panic', $DIR/generator.rs:199:13