Can't build latest mozilla-central version of third_party/rust/autocfg using either rustc 1.68.0 or rustc 1.69.0-beta.1

[mac198442]

I tried this code:

<code>

I expected to see this happen: explanation

Instead, this happened: explanation

Meta

rustc --version --verbose:

<version>

Backtrace

<backtrace>

[mac198442]

I can not build mozilla-central/third_party/rust/autocfg using rustc version 1.68.0 or rustc 1.69.0-beta.1 under windows with older AMD CPUs both result in this error:

Compiling autocfg v1.1.0 (C:\Users\mac\mozilla\firefox\mozilla\third_party\rust\autocfg)
error: could not compile autocfg

Caused by:
process didn't exit successfully: rustc --crate-name autocfg 'src\lib.rs' --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=79 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C metadata=b77804a677fb1e0d -C extra-filename=-b77804a677fb1e0d --out-dir 'c:\Users\mac\mozilla\firefox\mozilla\third_party\rust\autocfg\target\debug\deps' -C 'incremental=c:\Users\mac\mozilla\firefox\mozilla\third_party\rust\autocfg\target\debug\incremental' -L 'dependency=c:\Users\mac\mozilla\firefox\mozilla\third_party\rust\autocfg\target\debug\deps' (exit code: 0xc000001d, STATUS_ILLEGAL_INSTRUCTION)

this compiles successfully using either rustc 1.67.1 or rustc 1.70.0-nightly.

So, it would seem the issue is known and has been fixed but the fix really needs to be backported to a 1.68.1 and a newer 1.69.0 beta. It is embarrassing for a compiler to abort compiling legitimate code. This is embarrassing both to the rust project and Mozilla.

[mac198442]

Oh I meant to add the results from various AMD CPUs that i had access to to test this:

FAILS AMD Phenom(tm) II X3 710 Processor 2.60 GHz
FAILS AMD A6-3420M with Radeon(tm) HD Grpahics 1,50 GHz
WORKS AMD A6-4400M APU with Radeon(tm) HD Graphics 2.70 GHz
WORKS AMD Ryzen 7 3700U with Radeon Vega Mobile Gfx 2.30 GHz

[albertlarsan68]

This issue exists as #108978, please report your results there.