Rollup merge of rust-lang#76636 - RalfJung:miri-size-assert, r=oli-obk

RalfJung · web-flow · commit 8a7cb1eac176 · 2020-09-19T11:47:49.000+02:00
assert ScalarMaybeUninit size I noticed most low-level Miri types have such an assert but `ScalarMaybeUninit` does not, so let's add that. Good t see that the `Option`-like optimization kicks in and this is no bigger than `Scalar`. :) r? @oli-obk
diff --git a/compiler/rustc_middle/src/mir/interpret/value.rs b/compiler/rustc_middle/src/mir/interpret/value.rs
@@ -578,6 +578,9 @@ pub enum ScalarMaybeUninit<Tag = ()> {
     Uninit,
 }
 
+#[cfg(target_arch = "x86_64")]
+static_assert_size!(ScalarMaybeUninit, 24);
+
 impl<Tag> From<Scalar<Tag>> for ScalarMaybeUninit<Tag> {
     #[inline(always)]
     fn from(s: Scalar<Tag>) -> Self {

Original file line number	Diff line number	Diff line change
`@@ -578,6 +578,9 @@ pub enum ScalarMaybeUninit<Tag = ()> {`
`578`	`578`	`Uninit,`
`579`	`579`	`}`
`580`	`580`
	`581`	`+#[cfg(target_arch = "x86_64")]`
	`582`	`+static_assert_size!(ScalarMaybeUninit, 24);`
	`583`	`+`
`581`	`584`	`impl<Tag> From<Scalar<Tag>> for ScalarMaybeUninit<Tag> {`
`582`	`585`	`#[inline(always)]`
`583`	`586`	`fn from(s: Scalar<Tag>) -> Self {`