Date: Sun, 22 May 2022 18:26:06 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>,
	Andrew Dunstan <andrew@dunslane.net>, pgsql-hackers@postgresql.org,
	Thomas Munro <thomas.munro@gmail.com>,
	Melanie Plageman <melanieplageman@gmail.com>,
	Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
	Daniel Gustafsson <daniel@yesql.se>
Subject: ccache, MSVC, and meson
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An update.

ccache 4.6.1 was released which allows compiling postgres
I submitted a request to update the package in chocolatey.

But with the existing build system, it's no faster anyway, I guess due to poor
use of parallelism.
https://cirrus-ci.com/task/5972008205811712

Currently, meson doesn't (automatically) use ccache with MSVC - see
mesonbuild/environment.py.

And CC=ccache gives an error - I suppose it should not try to pop ccache off the
compiler list if the list has only one element.

|[21:44:49.791]   File "C:\python\lib\site-packages\mesonbuild\compilers\detect.py", line 375, in _detect_c_or_cpp_compiler
|[21:44:49.791]     compiler_name = os.path.basename(compiler[0])
|[21:44:49.791] IndexError: list index out of range
|...
|[21:44:49.791] meson.build:1:0: ERROR: Unhandled python exception
|[21:44:49.791] 
|[21:44:49.791]     This is a Meson bug and should be reported!

But it can be convinced to use ccache by renaming the executable to "pgccache".
Which builds in 46sec: https://cirrus-ci.com/task/4862234995195904
This requires ccache 4.6, released in Feburary and already in choco.
Note that ccache supports neither /Zi debugging nor precompiled headers.
I'm not sure, but -Dc_args=/Z7 may do what's wanted here.