From 087f1c23a70f889ea157c68b9db36c524e95ba8f Mon Sep 17 00:00:00 2001 From: Eduard-Mihai Burtescu 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 42987e3dd78..a2692fb8f5a 100644 --- a/src/librustc/ty/layout.rs +++ b/src/librustc/ty/layout.rs @@ -1492,7 +1492,7 @@ impl<'a, 'tcx> LayoutDetails { }).collect::, _>>()?; 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 876b74a042f..b8a1e6f2f54 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 Clone for Packed { fn clone(&self) -> Self { *self } } -fn main() { - let one = (Some(Packed((&(), 0))), true); +fn sanity_check_size(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>` 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))); }