Crashes on Apple Silicon M1 when installed through homebrew

[0xADD1E]

Problem
Cargo/libgit2 crashes on Apple Silicon M1 when installed through homebrew

This is definitely a weird one - I've been unable to reproduce this outside of homebrew's environment, but it's happening rather consistently when attempting to take actions in homebrew's cargo root.

The most obvious symptom of this is the rather oddly phrased error message seen below

    Updating crates.io index
warning: spurious network error (2 tries remaining): failed to lock file '$CARGO_HOME/registry/index/git.luolix.top-1ecc6299db9ec823/.git/refs/remotes/origin/master.lock' for writing: ; class=Os (2)
warning: spurious network error (1 tries remaining): failed to lock file '$CARGO_HOME/registry/index/git.luolix.top-1ecc6299db9ec823/.git/refs/remotes/origin/master.lock' for writing: ; class=Os (2)
error: failed to fetch `https://github.com/rust-lang/crates.io-index`

Caused by:
  failed to lock file '$CARGO_HOME/registry/index/git.luolix.top-1ecc6299db9ec823/.git/refs/remotes/origin/master.lock' for writing: ; class=Os (2)

($CARGO_HOME being homebrew's own cargo root - $HOME/Library/Caches/Homebrew/cargo_cache)

The error message naturally just means "lock file already exists", though this wasn't incredibly obvious at first glance...

Upon further investigation, on the first run without the lock file in place, cargo actually crashes in the middle of a libgit2 call (crash dump available below).

At this point I realized that I could simply ask cargo to use the git cli instead of libgit2, and after putting more time than I care to admit hitting my head against this, I was more than happy to take that option. Hopefully this information will help someone else to have less frustrations, or hopefully even fully diagnose and fix the issue at play.

Steps

1. Edit homebrew formula to use aarch64 compiler for bootstrapping (see notes)
2. Install the lightly customized rust formula, building from source, using the HEAD release (brew install -s --HEAD rust)
3. Attempt to install another brew formula that uses rust's build environment (brew install -s --HEAD tree-sitter, for instance, though others also fail)
4. Observe the failure described above

Possible Solution(s) / Workaround
Change cargo config to use the git cli for interactions.
(printf '[net]\ngit-fetch-with-cli = true' >> ~/Library/Caches/Homebrew/cargo_cache/config, in this case)

Notes

Output of cargo version: cargo 1.50.0

Diff to rust formula

diff --git a/Formula/rust.rb b/Formula/rust.rb
index 64d42a594e..68b1926dd1 100644
--- a/Formula/rust.rb
+++ b/Formula/rust.rb
@@ -42,8 +42,13 @@ class Rust < Formula
   resource "cargobootstrap" do
     on_macos do
       # From https://github.com/rust-lang/rust/blob/#{version}/src/stage0.txt
-      url "https://static.rust-lang.org/dist/2020-11-19/cargo-1.48.0-x86_64-apple-darwin.tar.gz"
-      sha256 "ce00d796cf5a9ac8d88d9df94c408e5d7ccd3541932a829eae833cc8e57efb15"
+      if Hardware::CPU.arch == :arm64
+        url "https://static.rust-lang.org/dist/2020-12-20/cargo-nightly-aarch64-apple-darwin.tar.gz"
+        sha256 "740d16056af3061fd22e9b5bc900483779a4a603f5e63750593d465ee58e019b"
+      else
+        url "https://static.rust-lang.org/dist/2020-11-19/cargo-1.48.0-x86_64-apple-darwin.tar.gz"
+        sha256 "ce00d796cf5a9ac8d88d9df94c408e5d7ccd3541932a829eae833cc8e57efb15"
+      end
     end

     on_linux do
@@ -78,17 +83,9 @@ class Rust < Formula
     else
       args << "--release-channel=stable"
     end
-    # Cross-compile arm64 with x86_64 bootstrap compiler.
-    if Hardware::CPU.arch == :arm64
-      args << "--build=x86_64-apple-darwin"
-      args << "--host=aarch64-apple-darwin"
-      args << "--target=aarch64-apple-darwin"
-      system "./configure", *args
-      system "arch", "-x86_64", "make"
-    else
-      system "./configure", *args
-      system "make"
-    end
+
+    system "./configure", *args
+    system "make"
     system "make", "install"

     resource("cargobootstrap").stage do

macOS Crash Dump

Process:               cargo [5638]
Path:                  /opt/homebrew/*/cargo
Identifier:            cargo
Version:               0
Code Type:             ARM-64 (Native)
Parent Process:        zsh [2671]
Responsible:           iTerm2 [2661]
User ID:               501

Date/Time:             2020-12-21 19:52:03.839 -0600
OS Version:            macOS 11.1 (20C69)
Report Version:        12
Anonymous UUID:        0CCE72DD-EE13-823A-089C-2C884E109E6E


Time Awake Since Boot: 4600 seconds

System Integrity Protection: enabled

Crashed Thread:        0  Dispatch queue: com.apple.main-thread

Exception Type:        EXC_BAD_ACCESS (SIGBUS)
Exception Codes:       EXC_ARM_DA_ALIGN at 0x000000013bf35ebc
Exception Note:        EXC_CORPSE_NOTIFY

Termination Signal:    Bus error: 10
Termination Reason:    Namespace SIGNAL, Code 0xa
Terminating Process:   exc handler [5638]

VM Regions Near 0x13bf35ebc:
    MALLOC_TINY                 13be00000-13bf00000    [ 1024K] rw-/rwx SM=PRV  
--> MALLOC_TINY                 13bf00000-13c000000    [ 1024K] rw-/rwx SM=PRV  
    MALLOC_SMALL                13c000000-13c800000    [ 8192K] rw-/rwx SM=PRV  

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   cargo                         	0x0000000101277eb4 git_repository__configmap_lookup + 32
1   cargo                         	0x00000001012ae014 git_refdb_should_write_reflog + 48
2   cargo                         	0x00000001012ae014 git_refdb_should_write_reflog + 48
3   cargo                         	0x00000001012b0a58 refdb_fs_backend__write_tail + 248
4   cargo                         	0x00000001012aecf0 refdb_fs_backend__write + 176
5   cargo                         	0x00000001012b2cf8 reference__create + 544
6   cargo                         	0x00000001012b2a74 git_reference_create_matching + 176
7   cargo                         	0x00000001012b7c38 update_tips_for_spec + 672
8   cargo                         	0x00000001012b7288 git_remote_update_tips + 448
9   cargo                         	0x00000001012b7078 git_remote_fetch + 384
10  cargo                         	0x000000010102f440 git2::remote::Remote::fetch::h64b7a377f0447347 + 412

Thread 1:
0   libsystem_pthread.dylib       	0x000000018d1e7d8c start_wqthread + 0

Thread 2:
0   libsystem_pthread.dylib       	0x000000018d1e7d8c start_wqthread + 0

Thread 0 crashed with ARM Thread State (64-bit):
    x0: 0x000000016f0e121c   x1: 0x000000013bf35d30   x2: 0x000000000000000a   x3: 0x0000000000000003
    x4: 0x000000010be05b30   x5: 0x0000000000000003   x6: 0x0000000000000000   x7: 0x000000010be05940
    x8: 0x000000013bf35d58   x9: 0x0000000000000303  x10: 0x00000000000bcfa0  x11: 0x0000000000003f2a
   x12: 0x000000010be00000  x13: 0x00000000203b1f66  x14: 0x00000000203b1e68  x15: 0x000000000000fe26
   x16: 0x000000000000fe26  x17: 0x0000000000004828  x18: 0x0000000000000000  x19: 0x000000016f0e1264
   x20: 0x000000013bf36b00  x21: 0x000000010be05ad0  x22: 0x000000013bf35ebc  x23: 0x000000013bf36b20
   x24: 0x000000010be05b0c  x25: 0x0000000000000000  x26: 0x0000000000000001  x27: 0x000000010be05ab0
   x28: 0x0000000000000002   fp: 0x000000016f0e1200   lr: 0x00000001012ae014
    sp: 0x000000016f0e11b0   pc: 0x0000000101277eb4 cpsr: 0x60000000
   far: 0x000000013bf35ebc  esr: 0x92000021


Binary Images:
[Excluded to keep this an almost-reasonable length, but can be attached if necessary]

External Modification Summary:
  Calls made by other processes targeting this process:
    task_for_pid: 0
    thread_create: 0
    thread_set_state: 0
  Calls made by this process:
    task_for_pid: 0
    thread_create: 0
    thread_set_state: 0
  Calls made by all processes on this machine:
    task_for_pid: 3399
    thread_create: 0
    thread_set_state: 0

VM Region Summary:
ReadOnly portion of Libraries: Total=573.1M resident=0K(0%) swapped_out_or_unallocated=573.1M(100%)
Writable regions: Total=657.8M written=0K(0%) resident=0K(0%) swapped_out=0K(0%) unallocated=657.8M(100%)
 
                                VIRTUAL   REGION 
REGION TYPE                        SIZE    COUNT (non-coalesced) 
===========                     =======  ======= 
Activity Tracing                   256K        1 
Dispatch continuations            64.0M        1 
Kernel Alloc Once                   32K        1 
MALLOC                           104.1M       26 
MALLOC guard page                   96K        5 
MALLOC_MEDIUM (reserved)         480.0M        4         reserved VM address space (unallocated)
STACK GUARD                         32K        2 
Stack                             9248K        3 
Stack Guard                       56.0M        1 
VM_ALLOCATE                        160K        3 
__AUTH                             271K       62 
__AUTH_CONST                      3497K      151 
__DATA                            1328K      145 
__DATA_CONST                      4806K      151 
__DATA_DIRTY                       302K       62 
__LINKEDIT                       482.6M        6 
__OBJC_CONST                       433K       41 
__OBJC_RO                         64.5M        1 
__OBJC_RW                         2544K        1 
__TEXT                            90.5M      163 
__UNICODE                          588K        1 
mapped file                       1888K        4 
shared memory                       80K        5 
===========                     =======  ======= 
TOTAL                              1.3G      840 
TOTAL, minus reserved VM space   886.7M      840

[ehuss]

I believe this has been fixed via #9009 (via rust-lang/git2-rs#646, via libgit2/libgit2#5746). The fix landed in Rust 1.50 (rust-lang/rust#80322) on Dec 24. It looks like the nightly snapshot in your diff is just before that landed, so I'm guessing that nightly is too old. It looks like people are working on updating 1.49 (Homebrew/homebrew-core#68089), and it looks like they have a more recently nightly, so I think things should be working there.

I'm going to close this for now, but if you continue to have problems with the updated versions, feel free to leave a comment.