From c4acd2a47eb53a56758d55117e84e18608460bbe Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 19 Feb 2026 18:02:52 +0000
Subject: [PATCH] Fix macOS cross-compilation from ARM64 to x86_64 in
 mk_unix_dist.py and mk_util.py

When macos-latest changed to ARM64 runners, the mac-build-x64 job started
producing arm64 libz3.dylib inside x86_64-tagged wheels, causing import
failures on macOS x86_64.

Root cause: mk_make.py subprocess detects the ARM64 host at module level
(IS_ARCH_ARM64=True), and without --arm64=false override it adds -arch arm64
to SLIBEXTRAFLAGS, overriding the -arch x86_64 set via environment variables.

Fix 1 (mk_unix_dist.py): Pass --arm64=false to mk_make.py subprocess when
building x64 on an ARM64 host, preventing the arm64 flag inheritance.

Fix 2 (mk_util.py): When IS_ARCH_ARM64=False on an ARM64 macOS host, add
-arch x86_64 to SLIBEXTRAFLAGS so the shared library linker also targets
x86_64 (LDFLAGS already receives this flag from the env var).

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>
---
 scripts/mk_unix_dist.py | 4 ++++
 scripts/mk_util.py      | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/scripts/mk_unix_dist.py b/scripts/mk_unix_dist.py
index 4df68d4c7..4ec98db05 100644
--- a/scripts/mk_unix_dist.py
+++ b/scripts/mk_unix_dist.py
@@ -140,6 +140,10 @@ def mk_build_dir(path):
             opts.append('--python')
         if mk_util.IS_ARCH_ARM64:
             opts.append('--arm64=true')
+        elif HOST_IS_ARM64:
+            # Explicitly disable arm64 when cross-compiling from ARM64 host to x64;
+            # without this, mk_make.py detects the ARM64 host and adds -arch arm64 flags
+            opts.append('--arm64=false')
         if mk_util.IS_ARCH_ARM64 and LINUX_X64:
             # we are on x64 machine but build for arm64
             # so we have to do cross compiling on Linux
diff --git a/scripts/mk_util.py b/scripts/mk_util.py
index 1af384242..4ec3d5dbd 100644
--- a/scripts/mk_util.py
+++ b/scripts/mk_util.py
@@ -2756,6 +2756,11 @@ def mk_config():
             CXXFLAGS = '%s -arch arm64' % CXXFLAGS
             LDFLAGS = '%s -arch arm64' % LDFLAGS
             SLIBEXTRAFLAGS = '%s -arch arm64' % SLIBEXTRAFLAGS
+        elif IS_OSX and os.uname()[4] == 'arm64':
+            # Cross-compiling from ARM64 host to x86_64: ensure the shared library
+            # linker also targets x86_64 (LDFLAGS already contains -arch x86_64
+            # from the environment, but SLIBEXTRAFLAGS is independent)
+            SLIBEXTRAFLAGS = '%s -arch x86_64' % SLIBEXTRAFLAGS
         if IS_OSX:
             SLIBFLAGS += ' -Wl,-headerpad_max_install_names'