build: let the environment override MACOS_TARGET - #61
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barnstar merged 1 commit intoAug 31, 2026
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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 tailscale#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 tailscale#60, which
measures macOS 14.0 as buildable once the listener API is gated.
barnstar
approved these changes
Aug 31, 2026
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MACOS_TARGET := 15.0is a simply-expanded assignment, so an environment variable does not override it.MACOS_TARGET=14.0 make c-archivebuilds 15.0 and reports success — you set the floor, make agrees, and you get the old one. Onlymake MACOS_TARGET=14.0 c-archiveworks.Measured
make -n,GOOS=darwin, against this Makefile:MACOS_TARGET=14.0 make …(env)make MACOS_TARGET=14.0 …(command line)?=fixes the environment case and changes nothing else: a command-line override still wins, and the default is untouched for anyone not setting it.Why it's worth fixing
The failure is quiet in a way that matters for this particular variable. Nothing warns, the build succeeds, and the resulting binary is stamped with a floor its Go objects don't 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 — andotoolwon't catch it either, since it reports the number the binary claims.Found while lowering the macOS floor of a
TailscaleKit.xcframeworkbuilt from this repo.It's also the same knob #60's "Aside" points at: if the project lowers its own deployment targets, whoever does that 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's a separate question and depends on #60, which measures macOS 14.0 as buildable once the listener API is gated — happy to follow up there if that lands.