Rollup merge of #49194 - Zoxc:unsafe-generator, r=cramertj

Make resuming generators unsafe instead of the creation of immovable generators

cc @withoutboats

Fixes #47787

25 files changed, 70 insertions, 94 deletions

diff --git a/src/test/run-pass/dynamic-drop.rs b/src/test/run-pass/dynamic-drop.rs
index 1f543f7be0e..765fb06e5f3 100644
--- a/src/test/run-pass/dynamic-drop.rs
+++ b/src/test/run-pass/dynamic-drop.rs
@@ -179,7 +179,7 @@ fn generator(a: &Allocator, run_count: usize) {
          );
     };
     for _ in 0..run_count {
-        gen.resume();
+        unsafe { gen.resume(); }
     }
 }
 
diff --git a/src/test/run-pass/generator/conditional-drop.rs b/src/test/run-pass/generator/conditional-drop.rs
index 8329684e1a3..3d39c46186b 100644
--- a/src/test/run-pass/generator/conditional-drop.rs
+++ b/src/test/run-pass/generator/conditional-drop.rs
@@ -42,9 +42,9 @@ fn t1() {
     };
 
     let n = A.load(Ordering::SeqCst);
-    a.resume();
+    unsafe { a.resume() };
     assert_eq!(A.load(Ordering::SeqCst), n + 1);
-    a.resume();
+    unsafe { a.resume() };
     assert_eq!(A.load(Ordering::SeqCst), n + 1);
 }
 
@@ -58,8 +58,8 @@ fn t2() {
     };
 
     let n = A.load(Ordering::SeqCst);
-    a.resume();
+    unsafe { a.resume() };
     assert_eq!(A.load(Ordering::SeqCst), n);
-    a.resume();
+    unsafe { a.resume() };
     assert_eq!(A.load(Ordering::SeqCst), n + 1);
 }
diff --git a/src/test/run-pass/generator/control-flow.rs b/src/test/run-pass/generator/control-flow.rs
index 60a00b4e467..09971410e55 100644
--- a/src/test/run-pass/generator/control-flow.rs
+++ b/src/test/run-pass/generator/control-flow.rs
@@ -16,7 +16,7 @@ fn finish<T>(mut amt: usize, mut t: T) -> T::Return
     where T: Generator<Yield = ()>
 {
     loop {
-        match t.resume() {
+        match unsafe { t.resume() } {
             GeneratorState::Yielded(()) => amt = amt.checked_sub(1).unwrap(),
             GeneratorState::Complete(ret) => {
                 assert_eq!(amt, 0);
diff --git a/src/test/run-pass/generator/drop-env.rs b/src/test/run-pass/generator/drop-env.rs
index ac42a25899d..ef4dc24472e 100644
--- a/src/test/run-pass/generator/drop-env.rs
+++ b/src/test/run-pass/generator/drop-env.rs
@@ -37,7 +37,7 @@ fn t1() {
     };
 
     let n = A.load(Ordering::SeqCst);
-    drop(foo.resume());
+    drop(unsafe { foo.resume() });
     assert_eq!(A.load(Ordering::SeqCst), n);
     drop(foo);
     assert_eq!(A.load(Ordering::SeqCst), n + 1);
@@ -50,7 +50,7 @@ fn t2() {
     };
 
     let n = A.load(Ordering::SeqCst);
-    drop(foo.resume());
+    drop(unsafe { foo.resume() });
     assert_eq!(A.load(Ordering::SeqCst), n + 1);
     drop(foo);
     assert_eq!(A.load(Ordering::SeqCst), n + 1);
diff --git a/src/test/run-pass/generator/issue-44197.rs b/src/test/run-pass/generator/issue-44197.rs
index 7cb80ea8b21..8ce4fc6affa 100644
--- a/src/test/run-pass/generator/issue-44197.rs
+++ b/src/test/run-pass/generator/issue-44197.rs
@@ -35,6 +35,8 @@ fn bar2(baz: String) -> impl Generator<Yield = String, Return = ()> {
 }
 
 fn main() {
-    assert_eq!(bar(String::new()).resume(), GeneratorState::Yielded(String::new()));
-    assert_eq!(bar2(String::new()).resume(), GeneratorState::Complete(()));
+    unsafe {
+        assert_eq!(bar(String::new()).resume(), GeneratorState::Yielded(String::new()));
+        assert_eq!(bar2(String::new()).resume(), GeneratorState::Complete(()));
+    }
 }
diff --git a/src/test/run-pass/generator/iterator-count.rs b/src/test/run-pass/generator/iterator-count.rs
index 9afe95f9e86..654b18928c0 100644
--- a/src/test/run-pass/generator/iterator-count.rs
+++ b/src/test/run-pass/generator/iterator-count.rs
@@ -14,11 +14,13 @@ use std::ops::{GeneratorState, Generator};
 
 struct W<T>(T);
 
+// This impl isn't safe in general, but the generator used in this test is movable
+// so it won't cause problems.
 impl<T: Generator<Return = ()>> Iterator for W<T> {
     type Item = T::Yield;
 
     fn next(&mut self) -> Option<Self::Item> {
-        match self.0.resume() {
+        match unsafe { self.0.resume() } {
             GeneratorState::Complete(..) => None,
             GeneratorState::Yielded(v) => Some(v),
         }
diff --git a/src/test/run-pass/generator/live-upvar-across-yield.rs b/src/test/run-pass/generator/live-upvar-across-yield.rs
index e34b0b3100c..28e7da232ce 100644
--- a/src/test/run-pass/generator/live-upvar-across-yield.rs
+++ b/src/test/run-pass/generator/live-upvar-across-yield.rs
@@ -17,5 +17,5 @@ fn main() {
     let mut a = || {
         b(yield);
     };
-    a.resume();
+    unsafe { a.resume() };
 }
diff --git a/src/test/run-pass/generator/nested_generators.rs b/src/test/run-pass/generator/nested_generators.rs
index f70d4144a3c..29808da85a7 100644
--- a/src/test/run-pass/generator/nested_generators.rs
+++ b/src/test/run-pass/generator/nested_generators.rs
@@ -20,7 +20,7 @@ fn main() {
             yield 2;
         };
 
-        match sub_generator.resume() {
+        match unsafe { sub_generator.resume() } {
             GeneratorState::Yielded(x) => {
                 yield x;
             }
diff --git a/src/test/run-pass/generator/panic-drops.rs b/src/test/run-pass/generator/panic-drops.rs
index 36e401a54bc..3d7b60ab6b9 100644
--- a/src/test/run-pass/generator/panic-drops.rs
+++ b/src/test/run-pass/generator/panic-drops.rs
@@ -42,7 +42,7 @@ fn main() {
 
     assert_eq!(A.load(Ordering::SeqCst), 0);
     let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-        foo.resume()
+        unsafe { foo.resume() }
     }));
     assert!(res.is_err());
     assert_eq!(A.load(Ordering::SeqCst), 1);
@@ -57,7 +57,7 @@ fn main() {
 
     assert_eq!(A.load(Ordering::SeqCst), 1);
     let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-        foo.resume()
+        unsafe { foo.resume() }
     }));
     assert!(res.is_err());
     assert_eq!(A.load(Ordering::SeqCst), 1);
diff --git a/src/test/run-pass/generator/panic-safe.rs b/src/test/run-pass/generator/panic-safe.rs
index 0d5bae7876b..ace5cdde51d 100644
--- a/src/test/run-pass/generator/panic-safe.rs
+++ b/src/test/run-pass/generator/panic-safe.rs
@@ -24,13 +24,13 @@ fn main() {
     };
 
     let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-        foo.resume()
+        unsafe { foo.resume() }
     }));
     assert!(res.is_err());
 
     for _ in 0..10 {
         let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
-            foo.resume()
+            unsafe { foo.resume() }
         }));
         assert!(res.is_err());
     }
diff --git a/src/test/run-pass/generator/resume-after-return.rs b/src/test/run-pass/generator/resume-after-return.rs
index 56511dcd53a..06e7615d261 100644
--- a/src/test/run-pass/generator/resume-after-return.rs
+++ b/src/test/run-pass/generator/resume-after-return.rs
@@ -23,12 +23,12 @@ fn main() {
         yield;
     };
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(()) => {}
         s => panic!("bad state: {:?}", s),
     }
 
-    match panic::catch_unwind(move || foo.resume()) {
+    match panic::catch_unwind(move || unsafe { foo.resume() }) {
         Ok(_) => panic!("generator successfully resumed"),
         Err(_) => {}
     }
diff --git a/src/test/run-pass/generator/smoke.rs b/src/test/run-pass/generator/smoke.rs
index 8693964665d..7395c8484c1 100644
--- a/src/test/run-pass/generator/smoke.rs
+++ b/src/test/run-pass/generator/smoke.rs
@@ -24,7 +24,7 @@ fn simple() {
         }
     };
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(()) => {}
         s => panic!("bad state: {:?}", s),
     }
@@ -40,7 +40,7 @@ fn return_capture() {
         a
     };
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(ref s) if *s == "foo" => {}
         s => panic!("bad state: {:?}", s),
     }
@@ -52,11 +52,11 @@ fn simple_yield() {
         yield;
     };
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Yielded(()) => {}
         s => panic!("bad state: {:?}", s),
     }
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(()) => {}
         s => panic!("bad state: {:?}", s),
     }
@@ -69,11 +69,11 @@ fn yield_capture() {
         yield b;
     };
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Yielded(ref s) if *s == "foo" => {}
         s => panic!("bad state: {:?}", s),
     }
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(()) => {}
         s => panic!("bad state: {:?}", s),
     }
@@ -86,11 +86,11 @@ fn simple_yield_value() {
         return String::from("foo")
     };
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Yielded(ref s) if *s == "bar" => {}
         s => panic!("bad state: {:?}", s),
     }
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(ref s) if *s == "foo" => {}
         s => panic!("bad state: {:?}", s),
     }
@@ -104,11 +104,11 @@ fn return_after_yield() {
         return a
     };
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Yielded(()) => {}
         s => panic!("bad state: {:?}", s),
     }
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(ref s) if *s == "foo" => {}
         s => panic!("bad state: {:?}", s),
     }
@@ -156,11 +156,11 @@ fn send_and_sync() {
 fn send_over_threads() {
     let mut foo = || { yield };
     thread::spawn(move || {
-        match foo.resume() {
+        match unsafe { foo.resume() } {
             GeneratorState::Yielded(()) => {}
             s => panic!("bad state: {:?}", s),
         }
-        match foo.resume() {
+        match unsafe { foo.resume() } {
             GeneratorState::Complete(()) => {}
             s => panic!("bad state: {:?}", s),
         }
@@ -169,11 +169,11 @@ fn send_over_threads() {
     let a = String::from("a");
     let mut foo = || { yield a };
     thread::spawn(move || {
-        match foo.resume() {
+        match unsafe { foo.resume() } {
             GeneratorState::Yielded(ref s) if *s == "a" => {}
             s => panic!("bad state: {:?}", s),
         }
-        match foo.resume() {
+        match unsafe { foo.resume() } {
             GeneratorState::Complete(()) => {}
             s => panic!("bad state: {:?}", s),
         }
diff --git a/src/test/run-pass/generator/static-generators.rs b/src/test/run-pass/generator/static-generators.rs
index 9504414d8b6..ebc070eee09 100644
--- a/src/test/run-pass/generator/static-generators.rs
+++ b/src/test/run-pass/generator/static-generators.rs
@@ -13,14 +13,14 @@
 use std::ops::{Generator, GeneratorState};
 
 fn main() {
-    let mut generator = unsafe {
-        static || {
-            let a = true;
-            let b = &a;
-            yield;
-            assert_eq!(b as *const _, &a as *const _);
-        }
+    let mut generator = static || {
+        let a = true;
+        let b = &a;
+        yield;
+        assert_eq!(b as *const _, &a as *const _);
     };
-    assert_eq!(generator.resume(), GeneratorState::Yielded(()));
-    assert_eq!(generator.resume(), GeneratorState::Complete(()));
+    unsafe {
+        assert_eq!(generator.resume(), GeneratorState::Yielded(()));
+        assert_eq!(generator.resume(), GeneratorState::Complete(()));
+    }
 }
diff --git a/src/test/run-pass/generator/xcrate-reachable.rs b/src/test/run-pass/generator/xcrate-reachable.rs
index dff5e08b9c2..8eeb0133144 100644
--- a/src/test/run-pass/generator/xcrate-reachable.rs
+++ b/src/test/run-pass/generator/xcrate-reachable.rs
@@ -17,5 +17,5 @@ extern crate xcrate_reachable as foo;
 use std::ops::Generator;
 
 fn main() {
-    foo::foo().resume();
+    unsafe { foo::foo().resume(); }
 }
diff --git a/src/test/run-pass/generator/xcrate.rs b/src/test/run-pass/generator/xcrate.rs
index dc7a6fdef9c..04791d51356 100644
--- a/src/test/run-pass/generator/xcrate.rs
+++ b/src/test/run-pass/generator/xcrate.rs
@@ -19,18 +19,18 @@ use std::ops::{GeneratorState, Generator};
 fn main() {
     let mut foo = xcrate::foo();
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(()) => {}
         s => panic!("bad state: {:?}", s),
     }
 
     let mut foo = xcrate::bar(3);
 
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Yielded(3) => {}
         s => panic!("bad state: {:?}", s),
     }
-    match foo.resume() {
+    match unsafe { foo.resume() } {
         GeneratorState::Complete(()) => {}
         s => panic!("bad state: {:?}", s),
     }
diff --git a/src/test/ui/generator/borrowing.rs b/src/test/ui/generator/borrowing.rs
index de10bdef4ae..e56927d8182 100644
--- a/src/test/ui/generator/borrowing.rs
+++ b/src/test/ui/generator/borrowing.rs
@@ -15,7 +15,7 @@ use std::ops::Generator;
 fn main() {
     let _b = {
         let a = 3;
-        (|| yield &a).resume()
+        unsafe { (|| yield &a).resume() }
         //~^ ERROR: `a` does not live long enough
     };
 
diff --git a/src/test/ui/generator/borrowing.stderr b/src/test/ui/generator/borrowing.stderr
index 2a5de3790ad..45d950b5aef 100644
--- a/src/test/ui/generator/borrowing.stderr
+++ b/src/test/ui/generator/borrowing.stderr
@@ -1,10 +1,10 @@
 error[E0597]: `a` does not live long enough
-  --> $DIR/borrowing.rs:18:20
+  --> $DIR/borrowing.rs:18:29
    |
-LL |         (|| yield &a).resume()
-   |          --        ^ borrowed value does not live long enough
-   |          |
-   |          capture occurs here
+LL |         unsafe { (|| yield &a).resume() }
+   |                   --        ^ borrowed value does not live long enough
+   |                   |
+   |                   capture occurs here
 LL |         //~^ ERROR: `a` does not live long enough
 LL |     };
    |     - borrowed value only lives until here
diff --git a/src/test/ui/generator/dropck.rs b/src/test/ui/generator/dropck.rs
index 0b143d7f514..b2240fb225f 100644
--- a/src/test/ui/generator/dropck.rs
+++ b/src/test/ui/generator/dropck.rs
@@ -23,6 +23,6 @@ fn main() {
         let _d = ref_.take(); //~ ERROR `ref_` does not live long enough
         yield;
     };
-    gen.resume();
+    unsafe { gen.resume(); }
     // drops the RefCell and then the Ref, leading to use-after-free
 }
diff --git a/src/test/ui/generator/sized-yield.rs b/src/test/ui/generator/sized-yield.rs
index f38ebf8b946..a1c8ca77e41 100644
--- a/src/test/ui/generator/sized-yield.rs
+++ b/src/test/ui/generator/sized-yield.rs
@@ -17,5 +17,5 @@ fn main() {
    let mut gen = move || { //~ ERROR the trait bound `str: std::marker::Sized` is not satisfied
        yield s[..];
    };
-   gen.resume(); //~ ERROR the trait bound `str: std::marker::Sized` is not satisfied
+   unsafe { gen.resume(); } //~ ERROR the trait bound `str: std::marker::Sized` is not satisfied
 }
diff --git a/src/test/ui/generator/sized-yield.stderr b/src/test/ui/generator/sized-yield.stderr
index fc99c7e3bd7..957fac172c2 100644
--- a/src/test/ui/generator/sized-yield.stderr
+++ b/src/test/ui/generator/sized-yield.stderr
@@ -11,10 +11,10 @@ LL | |    };
    = note: the yield type of a generator must have a statically known size
 
 error[E0277]: the trait bound `str: std::marker::Sized` is not satisfied
-  --> $DIR/sized-yield.rs:20:8
+  --> $DIR/sized-yield.rs:20:17
    |
-LL |    gen.resume(); //~ ERROR the trait bound `str: std::marker::Sized` is not satisfied
-   |        ^^^^^^ `str` does not have a constant size known at compile-time
+LL |    unsafe { gen.resume(); } //~ ERROR the trait bound `str: std::marker::Sized` is not satisfied
+   |                 ^^^^^^ `str` does not have a constant size known at compile-time
    |
    = help: the trait `std::marker::Sized` is not implemented for `str`
 
diff --git a/src/test/ui/generator/unsafe-immovable.rs b/src/test/ui/generator/unsafe-immovable.rs
deleted file mode 100644
index 45acbf50931..00000000000
--- a/src/test/ui/generator/unsafe-immovable.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2017 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.
-
-#![feature(generators)]
-
-fn main() {
-    static || { //~ ERROR: construction of immovable generator requires unsafe
-        yield;
-    };
-}
diff --git a/src/test/ui/generator/unsafe-immovable.stderr b/src/test/ui/generator/unsafe-immovable.stderr
deleted file mode 100644
index b2add55613d..00000000000
--- a/src/test/ui/generator/unsafe-immovable.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-error[E0133]: construction of immovable generator requires unsafe function or block
-  --> $DIR/unsafe-immovable.rs:14:5
-   |
-LL | /     static || { //~ ERROR: construction of immovable generator requires unsafe
-LL | |         yield;
-LL | |     };
-   | |_____^ construction of immovable generator
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0133`.
diff --git a/src/test/ui/generator/yield-while-iterating.rs b/src/test/ui/generator/yield-while-iterating.rs
index bc53448cb08..b8a67a0e7b6 100644
--- a/src/test/ui/generator/yield-while-iterating.rs
+++ b/src/test/ui/generator/yield-while-iterating.rs
@@ -43,7 +43,7 @@ fn yield_during_iter_borrowed_slice_2() {
     println!("{:?}", x);
 }
 
-fn yield_during_iter_borrowed_slice_3() {
+unsafe fn yield_during_iter_borrowed_slice_3() {
     // OK to take a mutable ref to `x` and yield
     // up pointers from it:
     let mut x = vec![22_i32];
@@ -55,7 +55,7 @@ fn yield_during_iter_borrowed_slice_3() {
     b.resume();
 }
 
-fn yield_during_iter_borrowed_slice_4() {
+unsafe fn yield_during_iter_borrowed_slice_4() {
     // ...but not OK to do that while reading
     // from `x` too
     let mut x = vec![22_i32];
@@ -68,7 +68,7 @@ fn yield_during_iter_borrowed_slice_4() {
     b.resume();
 }
 
-fn yield_during_range_iter() {
+unsafe fn yield_during_range_iter() {
     // Should be OK.
     let mut b = || {
         let v = vec![1,2,3];
diff --git a/src/test/ui/generator/yield-while-local-borrowed.rs b/src/test/ui/generator/yield-while-local-borrowed.rs
index 11bd4ed05ca..3dc2650a2ec 100644
--- a/src/test/ui/generator/yield-while-local-borrowed.rs
+++ b/src/test/ui/generator/yield-while-local-borrowed.rs
@@ -15,7 +15,7 @@
 use std::ops::{GeneratorState, Generator};
 use std::cell::Cell;
 
-fn borrow_local_inline() {
+unsafe fn borrow_local_inline() {
     // Not OK to yield with a borrow of a temporary.
     //
     // (This error occurs because the region shows up in the type of
@@ -30,7 +30,7 @@ fn borrow_local_inline() {
     b.resume();
 }
 
-fn borrow_local_inline_done() {
+unsafe fn borrow_local_inline_done() {
     // No error here -- `a` is not in scope at the point of `yield`.
     let mut b = move || {
         {
@@ -41,7 +41,7 @@ fn borrow_local_inline_done() {
     b.resume();
 }
 
-fn borrow_local() {
+unsafe fn borrow_local() {
     // Not OK to yield with a borrow of a temporary.
     //
     // (This error occurs because the region shows up in the type of
diff --git a/src/test/ui/generator/yield-while-ref-reborrowed.rs b/src/test/ui/generator/yield-while-ref-reborrowed.rs
index b9c963ae740..573dd4377bb 100644
--- a/src/test/ui/generator/yield-while-ref-reborrowed.rs
+++ b/src/test/ui/generator/yield-while-ref-reborrowed.rs
@@ -13,7 +13,7 @@
 use std::ops::{GeneratorState, Generator};
 use std::cell::Cell;
 
-fn reborrow_shared_ref(x: &i32) {
+unsafe fn reborrow_shared_ref(x: &i32) {
     // This is OK -- we have a borrow live over the yield, but it's of
     // data that outlives the generator.
     let mut b = move || {
@@ -24,7 +24,7 @@ fn reborrow_shared_ref(x: &i32) {
     b.resume();
 }
 
-fn reborrow_mutable_ref(x: &mut i32) {
+unsafe fn reborrow_mutable_ref(x: &mut i32) {
     // This is OK -- we have a borrow live over the yield, but it's of
     // data that outlives the generator.
     let mut b = move || {
@@ -35,7 +35,7 @@ fn reborrow_mutable_ref(x: &mut i32) {
     b.resume();
 }
 
-fn reborrow_mutable_ref_2(x: &mut i32) {
+unsafe fn reborrow_mutable_ref_2(x: &mut i32) {
     // ...but not OK to go on using `x`.
     let mut b = || {
         let a = &mut *x;