From 087f1c23a70f889ea157c68b9db36c524e95ba8f Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <edy.burt@gmail.com>
Date: Mon, 18 Dec 2017 15:06:34 +0200
Subject: [PATCH] rustc: ensure optimized enums have a properly aligned size.
---
src/librustc/ty/layout.rs | 3 ++-
src/test/run-pass/packed-struct-optimized-enum.rs | 13 ++++++++++---
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs
index 42987e3dd782a..a2692fb8f5a1e 100644
--- a/src/librustc/ty/layout.rs
+++ b/src/librustc/ty/layout.rs
@@ -1492,7 +1492,7 @@ impl<'a, 'tcx> LayoutDetails {
}).collect::<Result<Vec<_>, _>>()?;
let offset = st[i].fields.offset(field_index) + offset;
- let LayoutDetails { size, mut align, .. } = st[i];
+ let LayoutDetails { mut size, mut align, .. } = st[i];
let mut niche_align = niche.value.align(dl);
let abi = if offset.bytes() == 0 && niche.value.size(dl) == size {
@@ -1504,6 +1504,7 @@ impl<'a, 'tcx> LayoutDetails {
Abi::Aggregate { sized: true }
};
align = align.max(niche_align);
+ size = size.abi_align(align);
return Ok(tcx.intern_layout(LayoutDetails {
variants: Variants::NicheFilling {
diff --git a/src/test/run-pass/packed-struct-optimized-enum.rs b/src/test/run-pass/packed-struct-optimized-enum.rs
index 876b74a042f8e..b8a1e6f2f5400 100644
--- a/src/test/run-pass/packed-struct-optimized-enum.rs
+++ b/src/test/run-pass/packed-struct-optimized-enum.rs
@@ -16,14 +16,21 @@ impl<T: Copy> Clone for Packed<T> {
fn clone(&self) -> Self { *self }
}
-fn main() {
- let one = (Some(Packed((&(), 0))), true);
+fn sanity_check_size<T: Copy>(one: T) {
let two = [one, one];
let stride = (&two[1] as *const _ as usize) - (&two[0] as *const _ as usize);
+ assert_eq!(stride, std::mem::size_of_val(&one));
+}
+fn main() {
// This can fail if rustc and LLVM disagree on the size of a type.
// In this case, `Option<Packed<(&(), u32)>>` was erronously not
// marked as packed despite needing alignment `1` and containing
// its `&()` discriminant, which has alignment larger than `1`.
- assert_eq!(stride, std::mem::size_of_val(&one));
+ sanity_check_size((Some(Packed((&(), 0))), true));
+
+ // In #46769, `Option<(Packed<&()>, bool)>` was found to have
+ // pointer alignment, without actually being aligned in size.
+ // E.g. on 64-bit platforms, it had alignment `8` but size `9`.
+ sanity_check_size(Some((Packed(&()), true)));
}