Bug#1128289: musl-tools: musl-gcc wrapper incorrectly references x86_64 compiler on arm64

Package: musl-tools
User: [email protected]
Usertags: arm64
X-Debbugs-Cc: [email protected]
Version: 1.2.5-3
Severity: normal

Dear Maintainer,

On arm64 hosts, the musl-gcc wrapper script incorrectly references the
x86_64 compiler instead of the arm64 compiler.

Environment:
- Docker image: public.ecr.aws/docker/library/rust:slim (arm64)
- Building Rust project with target aarch64-unknown-linux-musl
- RUSTFLAGS="-C linker=musl-gcc" CC="musl-gcc"

Steps to reproduce:
1. Run arm64 rust:slim container on native arm64 host
2. Install musl-tools: apt-get install musl-tools
3. Check /usr/bin/musl-gcc contents

Actual result:
The wrapper contains:
  exec "${REALGCC:-x86_64-linux-gnu-gcc}" "$@" -specs "/usr/lib/x86_64-linux-musl/musl-gcc.specs"

Expected result:
On arm64, it should contain:
  exec "${REALGCC:-aarch64-linux-gnu-gcc}" "$@" -specs "/usr/lib/aarch64-linux-musl/musl-gcc.specs"

This causes compilation failures with architecture-specific flags:
  cc1: error: bad value 'armv8.4-a+sha3' for '-march=' switch
  cc1: note: valid arguments are: nocona core2 ... x86-64 ...

Suggested fix:
The package should detect host architecture and create the appropriate
wrapper pointing to the correct compiler and specs file.

Workaround:
Manually recreate the wrapper after installation:
  echo '#!/bin/sh' > /usr/bin/musl-gcc
  echo 'exec "${REALGCC:-aarch64-linux-gnu-gcc}" "$@" -specs "/usr/lib/aarch64-linux-musl/musl-gcc.specs"' >> /usr/bin/musl-gcc <https://aka.ms/GetOutlookForMac>

-- System Information:
Debian Release: 13.3
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.247-247.992.amzn2int.x86_64 (SMP w/16 CPU threads)
Locale: LANG=C, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: unable to detect

Versions of packages musl-tools depends on:
ii  musl-dev  1.2.5-3

musl-tools recommends no packages.

musl-tools suggests no packages.

-- no debconf information