Re: [PATCH 1/1] Fix detection of pwritev support for OSX.

James Hilliard <james(dot)hilliard1(at)gmail(dot)com> writes:
> On Wed, Jan 20, 2021 at 4:07 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I'm not sure that the case of not having the "command line tools"
>> installed is interesting for our purposes. AFAIK you have to have
>> that in order to have access to required tools like bison and gmake.
>> (That reminds me, I was intending to add something to our docs
>> about how-to-build-from-source to say that you need to install those.)

> Yeah, not 100% sure but I was able to build just fine after deleting my
> command line tools.

Hm. I've never been totally clear on what's included in the "command line
tools", although it's now apparent that one thing that gets installed is
an SDK matching the host OS version. However, Apple's description at [1]
says

Command Line Tools

Download the macOS SDK, headers, and build tools such as the Apple
LLVM compiler and Make. These tools make it easy to install open
source software or develop on UNIX within Terminal. macOS can
automatically download these tools the first time you try to build
software, and they are available on the downloads page.

which certainly strongly implies that gmake is not there otherwise.
At this point I lack any "bare" macOS system to check it on. I wonder
whether you have a copy of make available from MacPorts or Homebrew.
Or maybe uninstalling the command line tools doesn't really remove
everything?

> It would be pretty annoying to have to install an outdated SDK just to
> build postgres for no other reason than the autoconf feature detection
> being broken.

It's only as "outdated" as your host system ;-). Besides, it doesn't
look like Apple's really giving you a choice not to.

The long and short of this is that I'm unwilling to buy into maintaining
our own substitutes for standard autoconf probes in order to make it
possible to use the wrong SDK version. The preadv/pwritev case is already
messy enough, and I fear that trying to support such scenarios is going to
lead to more and more pain in the future.

regards, tom lane

[1] https://developer.apple.com/xcode/features/