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

Make resuming generators unsafe instead of the creation of immovable generators

cc @withoutboats

Fixes #47787

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
     };
 

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

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
 }

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
 }

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`
 

src/test/ui/generator/unsafe-immovable.rs

@@ -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;
-    };
-}

src/test/ui/generator/unsafe-immovable.stderr

@@ -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`.

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];

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

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;