Write {ui,} tests for pin_macro and pin!

Author: danielhenrymantilla

library/core/tests/lib.rs

@@ -45,6 +45,7 @@
 #![feature(inline_const)]
 #![feature(is_sorted)]
 #![feature(pattern)]
+#![feature(pin_macro)]
 #![feature(sort_internals)]
 #![feature(slice_take)]
 #![feature(maybe_uninit_uninit_array)]
@@ -122,6 +123,7 @@ mod ops;
 mod option;
 mod pattern;
 mod pin;
+mod pin_macro;
 mod ptr;
 mod result;
 mod simd;

library/core/tests/pin_macro.rs

@@ -0,0 +1,33 @@
+// edition:2021
+use core::{
+    marker::PhantomPinned,
+    mem::{drop as stuff, transmute},
+    pin::{pin, Pin},
+};
+
+#[test]
+fn basic() {
+    let it: Pin<&mut PhantomPinned> = pin!(PhantomPinned);
+    stuff(it);
+}
+
+#[test]
+fn extension_works_through_block() {
+    let it: Pin<&mut PhantomPinned> = { pin!(PhantomPinned) };
+    stuff(it);
+}
+
+#[test]
+fn extension_works_through_unsafe_block() {
+    // "retro-type-inference" works as well.
+    let it: Pin<&mut PhantomPinned> = unsafe { pin!(transmute(())) };
+    stuff(it);
+}
+
+#[test]
+fn unsize_coercion() {
+    let slice: Pin<&mut [PhantomPinned]> = pin!([PhantomPinned; 2]);
+    stuff(slice);
+    let dyn_obj: Pin<&mut dyn Send> = pin!([PhantomPinned; 2]);
+    stuff(dyn_obj);
+}

src/test/ui/pin-macro/cant_access_internals.rs

@@ -0,0 +1,13 @@
+// edition:2018
+#![feature(pin_macro)]
+
+use core::{
+    marker::PhantomPinned,
+    mem,
+    pin::{pin, Pin},
+};
+
+fn main() {
+    let mut phantom_pinned = pin!(PhantomPinned);
+    mem::take(phantom_pinned.pointer); //~ ERROR use of unstable library feature 'unsafe_pin_internals'
+}

src/test/ui/pin-macro/cant_access_internals.stderr

@@ -0,0 +1,11 @@
+error[E0658]: use of unstable library feature 'unsafe_pin_internals'
+  --> $DIR/cant_access_internals.rs:12:15
+   |
+LL |     mem::take(phantom_pinned.pointer);
+   |               ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(unsafe_pin_internals)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/pin-macro/lifetime_errors_on_promotion_misusage.rs

@@ -0,0 +1,29 @@
+// edition:2018
+#![feature(pin_macro)]
+
+use core::{
+    convert::identity,
+    marker::PhantomPinned,
+    mem::drop as stuff,
+    pin::pin,
+};
+
+fn function_call_stops_borrow_extension() {
+    let phantom_pinned = identity(pin!(PhantomPinned));
+    //~^ ERROR temporary value dropped while borrowed
+    stuff(phantom_pinned)
+}
+
+fn promotion_only_works_for_the_innermost_block() {
+    let phantom_pinned = {
+        let phantom_pinned = pin!(PhantomPinned);
+        //~^ ERROR temporary value dropped while borrowed
+        phantom_pinned
+    };
+    stuff(phantom_pinned)
+}
+
+fn main() {
+    function_call_stops_borrow_extension();
+    promotion_only_works_for_the_innermost_block();
+}

src/test/ui/pin-macro/lifetime_errors_on_promotion_misusage.stderr

@@ -0,0 +1,31 @@
+error[E0716]: temporary value dropped while borrowed
+  --> $DIR/lifetime_errors_on_promotion_misusage.rs:12:35
+   |
+LL |     let phantom_pinned = identity(pin!(PhantomPinned));
+   |                                   ^^^^^^^^^^^^^^^^^^^ - temporary value is freed at the end of this statement
+   |                                   |
+   |                                   creates a temporary which is freed while still in use
+LL |
+LL |     stuff(phantom_pinned)
+   |           -------------- borrow later used here
+   |
+   = note: consider using a `let` binding to create a longer lived value
+   = note: this error originates in the macro `pin` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0716]: temporary value dropped while borrowed
+  --> $DIR/lifetime_errors_on_promotion_misusage.rs:19:30
+   |
+LL |     let phantom_pinned = {
+   |         -------------- borrow later stored here
+LL |         let phantom_pinned = pin!(PhantomPinned);
+   |                              ^^^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use
+...
+LL |     };
+   |     - temporary value is freed at the end of this statement
+   |
+   = note: consider using a `let` binding to create a longer lived value
+   = note: this error originates in the macro `pin` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0716`.