Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 1141 insertions, 0 deletions

diff --git a/tests/ui/transmutability/primitives/bool.rs b/tests/ui/transmutability/primitives/bool.rs
new file mode 100644
index 000000000..eebb74fff
--- /dev/null
+++ b/tests/ui/transmutability/primitives/bool.rs
@@ -0,0 +1,25 @@
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code)]
+#![allow(incomplete_features)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+    pub struct Context;
+
+    pub fn is_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, { Assume::SAFETY }>
+    {}
+
+    pub fn is_maybe_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, { Assume::SAFETY.and(Assume::VALIDITY) }>
+    {}
+}
+
+fn contrast_with_u8() {
+    assert::is_transmutable::<u8, bool>(); //~ ERROR cannot be safely transmuted
+    assert::is_maybe_transmutable::<u8, bool>();
+    assert::is_transmutable::<bool, u8>();
+}
diff --git a/tests/ui/transmutability/primitives/bool.stderr b/tests/ui/transmutability/primitives/bool.stderr
new file mode 100644
index 000000000..214b5e150
--- /dev/null
+++ b/tests/ui/transmutability/primitives/bool.stderr
@@ -0,0 +1,19 @@
+error[E0277]: `u8` cannot be safely transmuted into `bool` in the defining scope of `assert::Context`.
+  --> $DIR/bool.rs:22:35
+   |
+LL |     assert::is_transmutable::<u8, bool>();
+   |                                   ^^^^ `u8` cannot be safely transmuted into `bool` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: true, validity: false }>` is not implemented for `bool`
+note: required by a bound in `is_transmutable`
+  --> $DIR/bool.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context, { Assume::SAFETY }>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/transmutability/primitives/numbers.rs b/tests/ui/transmutability/primitives/numbers.rs
new file mode 100644
index 000000000..0df43d204
--- /dev/null
+++ b/tests/ui/transmutability/primitives/numbers.rs
@@ -0,0 +1,128 @@
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code)]
+#![allow(incomplete_features)]
+
+mod assert {
+    use std::mem::BikeshedIntrinsicFrom;
+    struct Context;
+
+    pub fn is_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context>
+    {}
+}
+
+fn should_accept_identity() {
+    assert::is_transmutable::<   i8,    i8>();
+    assert::is_transmutable::<   u8,    u8>();
+    assert::is_transmutable::<  i16,   i16>();
+    assert::is_transmutable::<  u16,   u16>();
+    assert::is_transmutable::<  i32,   i32>();
+    assert::is_transmutable::<  f32,   f32>();
+    assert::is_transmutable::<  u32,   u32>();
+    assert::is_transmutable::<  i64,   i64>();
+    assert::is_transmutable::<  f64,   f64>();
+    assert::is_transmutable::<  u64,   u64>();
+    assert::is_transmutable::< i128,  i128>();
+    assert::is_transmutable::< u128,  u128>();
+    assert::is_transmutable::<isize, isize>();
+    assert::is_transmutable::<usize, usize>();
+}
+
+fn should_be_bitransmutable() {
+    assert::is_transmutable::<   i8,    u8>();
+    assert::is_transmutable::<   u8,    i8>();
+
+    assert::is_transmutable::<  i16,   u16>();
+    assert::is_transmutable::<  u16,   i16>();
+
+    assert::is_transmutable::<  i32,   f32>();
+    assert::is_transmutable::<  i32,   u32>();
+    assert::is_transmutable::<  f32,   i32>();
+    assert::is_transmutable::<  f32,   u32>();
+    assert::is_transmutable::<  u32,   i32>();
+    assert::is_transmutable::<  u32,   f32>();
+
+    assert::is_transmutable::<  u64,   i64>();
+    assert::is_transmutable::<  u64,   f64>();
+    assert::is_transmutable::<  i64,   u64>();
+    assert::is_transmutable::<  i64,   f64>();
+    assert::is_transmutable::<  f64,   u64>();
+    assert::is_transmutable::<  f64,   i64>();
+
+    assert::is_transmutable::< u128,  i128>();
+    assert::is_transmutable::< i128,  u128>();
+
+    assert::is_transmutable::<isize, usize>();
+    assert::is_transmutable::<usize, isize>();
+}
+
+fn should_reject_extension() {
+    assert::is_transmutable::<   i8,   i16>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,   u16>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,   i32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,   f32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,   u32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,   u64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,   i64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,   f64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   i8,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<   u8,   i16>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,   u16>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,   i32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,   f32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,   u32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,   u64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,   i64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,   f64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<   u8,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  i16,   i32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i16,   f32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i16,   u32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i16,   u64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i16,   i64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i16,   f64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i16,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i16,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  u16,   i32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u16,   f32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u16,   u32>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u16,   u64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u16,   i64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u16,   f64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u16,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u16,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  i32,   u64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i32,   i64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i32,   f64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i32,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i32,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  f32,   u64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  f32,   i64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  f32,   f64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  f32,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  f32,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  u32,   u64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u32,   i64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u32,   f64>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u32,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u32,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  u64,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  u64,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  i64,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  i64,  i128>(); //~ ERROR cannot be safely transmuted
+
+    assert::is_transmutable::<  f64,  u128>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<  f64,  i128>(); //~ ERROR cannot be safely transmuted
+}
diff --git a/tests/ui/transmutability/primitives/numbers.stderr b/tests/ui/transmutability/primitives/numbers.stderr
new file mode 100644
index 000000000..7cb7ca8e6
--- /dev/null
+++ b/tests/ui/transmutability/primitives/numbers.stderr
@@ -0,0 +1,915 @@
+error[E0277]: `i8` cannot be safely transmuted into `i16` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:62:40
+   |
+LL |     assert::is_transmutable::<   i8,   i16>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `i16` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i16`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `u16` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:63:40
+   |
+LL |     assert::is_transmutable::<   i8,   u16>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `u16` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u16`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:64:40
+   |
+LL |     assert::is_transmutable::<   i8,   i32>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:65:40
+   |
+LL |     assert::is_transmutable::<   i8,   f32>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:66:40
+   |
+LL |     assert::is_transmutable::<   i8,   u32>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:67:40
+   |
+LL |     assert::is_transmutable::<   i8,   u64>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:68:40
+   |
+LL |     assert::is_transmutable::<   i8,   i64>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:69:40
+   |
+LL |     assert::is_transmutable::<   i8,   f64>();
+   |                                        ^^^ `i8` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:70:39
+   |
+LL |     assert::is_transmutable::<   i8,  u128>();
+   |                                       ^^^^ `i8` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i8` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:71:39
+   |
+LL |     assert::is_transmutable::<   i8,  i128>();
+   |                                       ^^^^ `i8` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `i16` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:73:40
+   |
+LL |     assert::is_transmutable::<   u8,   i16>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `i16` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i16`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `u16` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:74:40
+   |
+LL |     assert::is_transmutable::<   u8,   u16>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `u16` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u16`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:75:40
+   |
+LL |     assert::is_transmutable::<   u8,   i32>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:76:40
+   |
+LL |     assert::is_transmutable::<   u8,   f32>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:77:40
+   |
+LL |     assert::is_transmutable::<   u8,   u32>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:78:40
+   |
+LL |     assert::is_transmutable::<   u8,   u64>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:79:40
+   |
+LL |     assert::is_transmutable::<   u8,   i64>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:80:40
+   |
+LL |     assert::is_transmutable::<   u8,   f64>();
+   |                                        ^^^ `u8` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:81:39
+   |
+LL |     assert::is_transmutable::<   u8,  u128>();
+   |                                       ^^^^ `u8` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u8` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:82:39
+   |
+LL |     assert::is_transmutable::<   u8,  i128>();
+   |                                       ^^^^ `u8` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u8, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:84:40
+   |
+LL |     assert::is_transmutable::<  i16,   i32>();
+   |                                        ^^^ `i16` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:85:40
+   |
+LL |     assert::is_transmutable::<  i16,   f32>();
+   |                                        ^^^ `i16` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:86:40
+   |
+LL |     assert::is_transmutable::<  i16,   u32>();
+   |                                        ^^^ `i16` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:87:40
+   |
+LL |     assert::is_transmutable::<  i16,   u64>();
+   |                                        ^^^ `i16` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:88:40
+   |
+LL |     assert::is_transmutable::<  i16,   i64>();
+   |                                        ^^^ `i16` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:89:40
+   |
+LL |     assert::is_transmutable::<  i16,   f64>();
+   |                                        ^^^ `i16` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:90:39
+   |
+LL |     assert::is_transmutable::<  i16,  u128>();
+   |                                       ^^^^ `i16` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i16` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:91:39
+   |
+LL |     assert::is_transmutable::<  i16,  i128>();
+   |                                       ^^^^ `i16` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:93:40
+   |
+LL |     assert::is_transmutable::<  u16,   i32>();
+   |                                        ^^^ `u16` cannot be safely transmuted into `i32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:94:40
+   |
+LL |     assert::is_transmutable::<  u16,   f32>();
+   |                                        ^^^ `u16` cannot be safely transmuted into `f32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:95:40
+   |
+LL |     assert::is_transmutable::<  u16,   u32>();
+   |                                        ^^^ `u16` cannot be safely transmuted into `u32` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u32`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:96:40
+   |
+LL |     assert::is_transmutable::<  u16,   u64>();
+   |                                        ^^^ `u16` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:97:40
+   |
+LL |     assert::is_transmutable::<  u16,   i64>();
+   |                                        ^^^ `u16` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:98:40
+   |
+LL |     assert::is_transmutable::<  u16,   f64>();
+   |                                        ^^^ `u16` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:99:39
+   |
+LL |     assert::is_transmutable::<  u16,  u128>();
+   |                                       ^^^^ `u16` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u16` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:100:39
+   |
+LL |     assert::is_transmutable::<  u16,  i128>();
+   |                                       ^^^^ `u16` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u16, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i32` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:102:40
+   |
+LL |     assert::is_transmutable::<  i32,   u64>();
+   |                                        ^^^ `i32` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i32` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:103:40
+   |
+LL |     assert::is_transmutable::<  i32,   i64>();
+   |                                        ^^^ `i32` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i32` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:104:40
+   |
+LL |     assert::is_transmutable::<  i32,   f64>();
+   |                                        ^^^ `i32` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i32` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:105:39
+   |
+LL |     assert::is_transmutable::<  i32,  u128>();
+   |                                       ^^^^ `i32` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i32` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:106:39
+   |
+LL |     assert::is_transmutable::<  i32,  i128>();
+   |                                       ^^^^ `i32` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `f32` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:108:40
+   |
+LL |     assert::is_transmutable::<  f32,   u64>();
+   |                                        ^^^ `f32` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<f32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `f32` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:109:40
+   |
+LL |     assert::is_transmutable::<  f32,   i64>();
+   |                                        ^^^ `f32` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<f32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `f32` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:110:40
+   |
+LL |     assert::is_transmutable::<  f32,   f64>();
+   |                                        ^^^ `f32` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<f32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `f32` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:111:39
+   |
+LL |     assert::is_transmutable::<  f32,  u128>();
+   |                                       ^^^^ `f32` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<f32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `f32` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:112:39
+   |
+LL |     assert::is_transmutable::<  f32,  i128>();
+   |                                       ^^^^ `f32` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<f32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u32` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:114:40
+   |
+LL |     assert::is_transmutable::<  u32,   u64>();
+   |                                        ^^^ `u32` cannot be safely transmuted into `u64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u32` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:115:40
+   |
+LL |     assert::is_transmutable::<  u32,   i64>();
+   |                                        ^^^ `u32` cannot be safely transmuted into `i64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u32` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:116:40
+   |
+LL |     assert::is_transmutable::<  u32,   f64>();
+   |                                        ^^^ `u32` cannot be safely transmuted into `f64` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `f64`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u32` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:117:39
+   |
+LL |     assert::is_transmutable::<  u32,  u128>();
+   |                                       ^^^^ `u32` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u32` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:118:39
+   |
+LL |     assert::is_transmutable::<  u32,  i128>();
+   |                                       ^^^^ `u32` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u32, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u64` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:120:39
+   |
+LL |     assert::is_transmutable::<  u64,  u128>();
+   |                                       ^^^^ `u64` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u64, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `u64` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:121:39
+   |
+LL |     assert::is_transmutable::<  u64,  i128>();
+   |                                       ^^^^ `u64` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u64, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i64` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:123:39
+   |
+LL |     assert::is_transmutable::<  i64,  u128>();
+   |                                       ^^^^ `i64` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i64, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `i64` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:124:39
+   |
+LL |     assert::is_transmutable::<  i64,  i128>();
+   |                                       ^^^^ `i64` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<i64, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `f64` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:126:39
+   |
+LL |     assert::is_transmutable::<  f64,  u128>();
+   |                                       ^^^^ `f64` cannot be safely transmuted into `u128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<f64, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `u128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error[E0277]: `f64` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+  --> $DIR/numbers.rs:127:39
+   |
+LL |     assert::is_transmutable::<  f64,  i128>();
+   |                                       ^^^^ `f64` cannot be safely transmuted into `i128` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<f64, assert::Context, Assume { alignment: false, lifetimes: false, safety: false, validity: false }>` is not implemented for `i128`
+note: required by a bound in `is_transmutable`
+  --> $DIR/numbers.rs:12:14
+   |
+LL |     pub fn is_transmutable<Src, Dst>()
+   |            --------------- required by a bound in this
+LL |     where
+LL |         Dst: BikeshedIntrinsicFrom<Src, Context>
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
+
+error: aborting due to 57 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/transmutability/primitives/unit.rs b/tests/ui/transmutability/primitives/unit.rs
new file mode 100644
index 000000000..1975a61de
--- /dev/null
+++ b/tests/ui/transmutability/primitives/unit.rs
@@ -0,0 +1,29 @@
+//! The unit type, `()`, should be one byte.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+
+    pub fn is_transmutable<Src, Dst, Context>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, {
+            Assume::ALIGNMENT
+                .and(Assume::LIFETIMES)
+                .and(Assume::SAFETY)
+                .and(Assume::VALIDITY)
+        }>
+    {}
+}
+
+#[repr(C)]
+struct Zst;
+
+fn should_have_correct_size() {
+    struct Context;
+    assert::is_transmutable::<(), Zst, Context>();
+    assert::is_transmutable::<Zst, (), Context>();
+    assert::is_transmutable::<(), u8, Context>(); //~ ERROR cannot be safely transmuted
+}
diff --git a/tests/ui/transmutability/primitives/unit.stderr b/tests/ui/transmutability/primitives/unit.stderr
new file mode 100644
index 000000000..8cabe44a0
--- /dev/null
+++ b/tests/ui/transmutability/primitives/unit.stderr
@@ -0,0 +1,25 @@
+error[E0277]: `()` cannot be safely transmuted into `u8` in the defining scope of `should_have_correct_size::Context`.
+  --> $DIR/unit.rs:28:35
+   |
+LL |     assert::is_transmutable::<(), u8, Context>();
+   |                                   ^^ `()` cannot be safely transmuted into `u8` in the defining scope of `should_have_correct_size::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<(), should_have_correct_size::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `u8`
+note: required by a bound in `is_transmutable`
+  --> $DIR/unit.rs:12:14
+   |
+LL |       pub fn is_transmutable<Src, Dst, Context>()
+   |              --------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume::ALIGNMENT
+LL | |                 .and(Assume::LIFETIMES)
+LL | |                 .and(Assume::SAFETY)
+LL | |                 .and(Assume::VALIDITY)
+LL | |         }>
+   | |__________^ required by this bound in `is_transmutable`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.