[Pkg-rust-maintainers] Bug#905795: rustc: Please include workaround for regression on sparc64

[John Paul Adrian Glaubitz]

Source: rustc
Version: 1.28.0+dfsg1-2
Severity: normal
Tags: patch
User: debian-sparc at lists.debian.org
Usertags: sparc64

Hello!

With version 1.28, the Rust compiler has regressed in the sense that
it generates code with unaligned access [1].

This problem existed in the past and was supposed to be fixed [2],
however it just recently came back.

The attached patch contains a workaround for sparc64 such that
rustc will at least build again. Please include it in the next
upload.

Thanks,
Adrian

> [1] https://github.com/rust-lang/rust/issues/53181
> [2] https://github.com/rust-lang/rust/pull/45679

--
  .''`.  John Paul Adrian Glaubitz
 : :' :  Debian Developer - glaubitz at debian.org
 `. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
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Description: <short summary of the patch>
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 .
 rustc (1.28.0+dfsg1-2) unstable; urgency=medium
 .
   * Switch on verbose-tests to restore the old pre-1.28 behaviour, and restore
     old failure-counting logic.
   * Allow 50 test failures on s390x, restored failure-counting logic avoids
     more double-counts.
Author: Ximin Luo <infinity0 at debian.org>

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--- rustc-1.28.0+dfsg1.orig/src/libsyntax_pos/span_encoding.rs
+++ rustc-1.28.0+dfsg1/src/libsyntax_pos/span_encoding.rs
@@ -26,7 +26,9 @@ use std::hash::{Hash, Hasher};
 /// The primary goal of `Span` is to be as small as possible and fit into other structures
 /// (that's why it uses `packed` as well). Decoding speed is the second priority.
 /// See `SpanData` for the info on span fields in decoded representation.
-#[repr(packed)]
+
+/// Workaround for compiler bug: https://github.com/rust-lang/rust/issues/53181
+#[cfg_attr(not(any(target_arch = "sparc64", target_arch = "sparcv9")), repr(packed))]
 pub struct Span(u32);
 
 impl Copy for Span {}