From 944187beedc044698d32cdfa8c86ced7e73ff0f5 Mon Sep 17 00:00:00 2001
From: Prakash Rudraraju <1471544+prakashrj@users.noreply.github.com>
Date: Wed, 26 Aug 2026 16:05:35 -0700
Subject: [PATCH] build: produce a universal (arm64 + x86_64) macOS slice

The macOS build is Apple-Silicon-only by construction, so an app embedding
TailscaleKit cannot produce a universal macOS release build:

  TailscaleKit.xcframework is missing architecture(s) required by this target
  (x86_64), but may still be link-compatible

Two places pin it. The root Makefile's `c-archive` builds libtailscale.a for
the host arch, because no GOARCH is set. And swift/Makefile's `macos` target
passes -destination 'platform=macOS,arch=arm64', so the framework is built for
one arch even if the archive were fat.

The iOS Simulator target already solves exactly this: separate GOARCH=arm64 and
GOARCH=amd64 c-archives joined with lipo, each built through a clangwrap script
that pins the SDK and arch. This mirrors that pattern for macOS rather than
inventing a second approach:

  - clangwrap-macos-arm.sh / clangwrap-macos-x86.sh, matching the existing
    ios-sim wrappers and pinning -mmacos-version-min to MACOS_TARGET (15.0)
  - libtailscale_macos_arm64.a and libtailscale_macos_x86_64.a
  - c-archive-macos-universal, which lipos them into libtailscale.a
  - swift/Makefile's macos target now uses c-archive-macos-universal and builds
    with -destination 'generic/platform=macOS' ARCHS="arm64 x86_64"

`make c-archive` is untouched, so anything building for the host only keeps its
current behaviour.

Verified on an Apple Silicon host:

  lipo -info libtailscale.a
    -> Architectures in the fat file: x86_64 arm64

  make -C swift macos
  lipo -info swift/build/Build/Products/Release/TailscaleKit.framework/Versions/A/TailscaleKit
    -> Architectures in the fat file: x86_64 arm64

Updates tailscale/tailscale#20992
---
 Makefile                            | 10 ++++++++++
 swift/Makefile                      |  5 +++--
 swift/script/clangwrap-macos-arm.sh | 11 +++++++++++
 swift/script/clangwrap-macos-x86.sh | 11 +++++++++++
 4 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100755 swift/script/clangwrap-macos-arm.sh
 create mode 100755 swift/script/clangwrap-macos-x86.sh

diff --git a/Makefile b/Makefile
index cbbb224..5af89fd 100644
--- a/Makefile
+++ b/Makefile
@@ -37,6 +37,16 @@ libtailscale_ios_sim_arm64.a:
 libtailscale_ios_sim_x86_64.a:
 	GOOS=ios GOARCH=amd64 CC=$(PWD)/swift/script/clangwrap-ios-sim-x86.sh go build -v -ldflags -w -tags ios -o $@ -buildmode=c-archive
 
+libtailscale_macos_arm64.a:
+	GOOS=darwin GOARCH=arm64 CC=$(PWD)/swift/script/clangwrap-macos-arm.sh $(DARWIN_DEPLOYMENT_TARGET) go build -v -ldflags -w -o $@ -buildmode=c-archive
+
+libtailscale_macos_x86_64.a:
+	GOOS=darwin GOARCH=amd64 CC=$(PWD)/swift/script/clangwrap-macos-x86.sh $(DARWIN_DEPLOYMENT_TARGET) go build -v -ldflags -w -o $@ -buildmode=c-archive
+
+.PHONY: c-archive-macos-universal
+c-archive-macos-universal: libtailscale_macos_arm64.a libtailscale_macos_x86_64.a ## Builds a universal (arm64 + x86_64) libtailscale.a for macOS
+	lipo -create -output libtailscale.a libtailscale_macos_arm64.a libtailscale_macos_x86_64.a
+
 .PHONY: c-archive-ios
 c-archive-ios: libtailscale_ios.a  ## Builds libtailscale_ios.a for iOS (iOS SDK required)
 
diff --git a/swift/Makefile b/swift/Makefile
index 4071ff0..63a08c1 100644
--- a/swift/Makefile
+++ b/swift/Makefile
@@ -17,12 +17,13 @@ all: test ios macos ios-fat  ## Runs the tests and builds all library targets
 macos:  ## Builds TailscaleKit for macos to swift/build/Build/Products/Release (unsigned)
 	@echo
 	@echo "::: Building TailscaleKit.framework for macOS :::"
-	cd .. && make c-archive
+	cd .. && make c-archive-macos-universal
 	mkdir -p build
 	xcodebuild build -scheme "TailscaleKit (macOS)" \
 	 -derivedDataPath build \
 	 -configuration Release \
-	 -destination 'platform=macOS,arch=arm64' \
+	 -destination 'generic/platform=macOS' \
+	 ARCHS="arm64 x86_64" ONLY_ACTIVE_ARCH=NO \
 	 CODE_SIGNING_ALLOWED=NO | $(XCPRETTIFIER)
 
 .PHONY: ios
diff --git a/swift/script/clangwrap-macos-arm.sh b/swift/script/clangwrap-macos-arm.sh
new file mode 100755
index 0000000..fa88630
--- /dev/null
+++ b/swift/script/clangwrap-macos-arm.sh
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+SDK=macosx
+CLANGARCH=arm64
+
+SDK_PATH=`xcrun --sdk $SDK --show-sdk-path`
+
+# cmd/cgo doesn't support llvm-gcc-4.2, so we have to use clang.
+CLANG=`xcrun --sdk $SDK --find clang`
+
+exec "$CLANG" -arch $CLANGARCH -isysroot "$SDK_PATH" -mmacos-version-min=15.0 "$@"
diff --git a/swift/script/clangwrap-macos-x86.sh b/swift/script/clangwrap-macos-x86.sh
new file mode 100755
index 0000000..5849ade
--- /dev/null
+++ b/swift/script/clangwrap-macos-x86.sh
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+SDK=macosx
+CLANGARCH=x86_64
+
+SDK_PATH=`xcrun --sdk $SDK --show-sdk-path`
+
+# cmd/cgo doesn't support llvm-gcc-4.2, so we have to use clang.
+CLANG=`xcrun --sdk $SDK --find clang`
+
+exec "$CLANG" -arch $CLANGARCH -isysroot "$SDK_PATH" -mmacos-version-min=15.0 "$@"