From a5e1d4f3f8781c91d9fdfe198f27290b544c1808 Mon Sep 17 00:00:00 2001
From: Prakash Rudraraju <1471544+prakashrj@users.noreply.github.com>
Date: Sun, 30 Aug 2026 11:14:15 -0700
Subject: [PATCH] build: let the environment override MACOS_TARGET
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`MACOS_TARGET := 15.0` is a simply-expanded assignment, so an environment
variable does not override it. `MACOS_TARGET=14.0 make c-archive` builds 15.0
and reports success — you set the floor, make agrees, and you get the old one.
Only `make MACOS_TARGET=14.0 c-archive` works.

Measured with `make -n` against this Makefile, GOOS=darwin:

                    before      after
  env override      15.0        14.0
  command-line      14.0        14.0
  default           15.0        15.0

`?=` fixes the environment case and changes nothing else: a command-line
override still wins, and the default is untouched for anyone not setting it.

Found while lowering the macOS floor of a TailscaleKit.xcframework built from
this repo. The failure is quiet in a way that matters here — nothing warns, the
build succeeds, and the resulting binary is stamped with a floor its Go objects
do not actually support. On macOS the only signal is an `ld: warning: object
file ... was built for newer 'macOS' version`, which is easy to lose in build
output.

This is the same knob #60's "Aside" points at: if the project lowers its own
deployment targets, whoever does it is likely to reach for the environment
variable first.

Not touched here: the comment above the line still says the wrapper requires
macOS 15.0 features. That is a separate question and depends on #60, which
measures macOS 14.0 as buildable once the listener API is gated.
---
 Makefile | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index cbbb224..2dcd938 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,13 @@ export CGO_ENABLED=1
 # This should match the minimum target in the xCode project
 # The wrapper lib currently requires features available in
 # MacOS 15.0 (Sequoia)
-MACOS_TARGET := 15.0
+#
+# `?=` rather than `:=` so the environment can override it. With `:=`,
+# `MACOS_TARGET=14.0 make c-archive` is silently ignored — make reports success
+# and builds 15.0 anyway, because an environment variable does not override a
+# makefile assignment. Only `make MACOS_TARGET=14.0 c-archive` worked, which is
+# easy to get wrong and gives no signal when you do.
+MACOS_TARGET ?= 15.0
 
 # Set macOS-specific flags for darwin builds
 ifeq ($(GOOS),darwin)