From cf5bd26329eb8dcff4c1e619b655ede662eda0d9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomasz=20Mi=C4=85sko?= <tomasz.miasko@gmail.com>
Date: Thu, 10 Dec 2020 00:00:00 +0000
Subject: [PATCH] Describe why `size_align` have not been inlined so far

---
 library/core/src/alloc/layout.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/library/core/src/alloc/layout.rs b/library/core/src/alloc/layout.rs
index 57c6624b64f9e..c572c66ce328b 100644
--- a/library/core/src/alloc/layout.rs
+++ b/library/core/src/alloc/layout.rs
@@ -4,6 +4,12 @@ use crate::mem;
 use crate::num::NonZeroUsize;
 use crate::ptr::NonNull;
 
+// While this function is used in one place and its implementation
+// could be inlined, the previous attempts to do so made rustc
+// slower:
+//
+// * https://github.com/rust-lang/rust/pull/72189
+// * https://github.com/rust-lang/rust/pull/79827
 const fn size_align<T>() -> (usize, usize) {
     (mem::size_of::<T>(), mem::align_of::<T>())
 }