Re: meson: Specify -Wformat as a common warning flag for extensions

Hi Andres,

Thanks for reviewing this!

In <20240407232635.fq4kc5556lahaoej@awork3.anarazel.de>
  "Re: meson: Specify -Wformat as a common warning flag for extensions" on Sun, 7 Apr 2024 16:26:35 -0700,
  Andres Freund <andres@anarazel.de> wrote:

> This seems like a fair amount of extra configure tests. Particularly because
> /W* isn't ever interesting for Makefile.global - they're msvc flags - because
> you can't use that with msvc.
> 
> I'm also doubtful that it's worth supporting warning_level=3/everything, you
> end up with a completely flood of warnings that way.

OK. I've removed "/W*" flags and warning_level==3/everything
cases.

How about the attached v5 patch?


Thanks,
-- 
kou
From 205ef88c66cf1050eedfc1e72d951de93a02e53a Mon Sep 17 00:00:00 2001
From: Sutou Kouhei <kou@clear-code.com>
Date: Fri, 15 Mar 2024 18:27:30 +0900
Subject: [PATCH v5] meson: Restore implicit warning/debug/optimize flags for
 extensions

Meson specifies warning/debug/optimize flags such as "-Wall", "-g" and
"-O2" automatically based on "--warnlevel" and "--buildtype"
options. And we use "--warning_level=1" and
"--buildtype=debugoptimized" by default.

We don't specify warning/debug/optimize flags explicitly to build
PostgreSQL with Meson. Because Meson does it automatically as we said.
But Meson doesn't care about flags in Makefile.global and
pg_config. So we need to care about them manually.

This changes do it. They detect warning/debug/optimize flags based on
warning_level/debug/optimization option values because Meson doesn't
tell us flags Meson guessed.
---
 meson.build             | 41 +++++++++++++++++++++++++++++++++++++++++
 src/include/meson.build |  4 ++--
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/meson.build b/meson.build
index 5acf083ce3c..11bd56f79a7 100644
--- a/meson.build
+++ b/meson.build
@@ -1848,6 +1848,47 @@ endif
 vectorize_cflags = cc.get_supported_arguments(['-ftree-vectorize'])
 unroll_loops_cflags = cc.get_supported_arguments(['-funroll-loops'])
 
+# They aren't used for building PostgreSQL itself because Meson does
+# everything internally. They are used by extensions via pg_config or
+# Makefile.global.
+common_builtin_flags = []
+
+warning_level = get_option('warning_level')
+# See https://mesonbuild.com/Builtin-options.html#details-for-warning_level for
+# warning_level values.
+#
+# We don't use "/W*" flags here because we don't need to care about MSVC here.
+#
+# We don't have "warning_level == 3" and "warning_level ==
+# 'everything'" here because we don't use these warning levels.
+if warning_level == '1'
+  common_builtin_flags += ['-Wall']
+elif warning_level == '2'
+  common_builtin_flags += ['-Wall', '-Wextra']
+endif
+
+if get_option('debug')
+  common_builtin_flags += ['-g']
+endif
+
+optimization = get_option('optimization')
+if optimization == '0'
+  common_builtin_flags += ['-O0']
+elif optimization == '1'
+  common_builtin_flags += ['-O1']
+elif optimization == '2'
+  common_builtin_flags += ['-O2']
+elif optimization == '3'
+  common_builtin_flags += ['-O3']
+elif optimization == 's'
+  common_builtin_flags += ['-Os']
+endif
+
+cflags_builtin = cc.get_supported_arguments(common_builtin_flags)
+if llvm.found()
+  cxxflags_builtin = cpp.get_supported_arguments(common_builtin_flags)
+endif
+
 common_warning_flags = [
   '-Wmissing-prototypes',
   '-Wpointer-arith',
diff --git a/src/include/meson.build b/src/include/meson.build
index a28f115d867..58b7a9c1e7e 100644
--- a/src/include/meson.build
+++ b/src/include/meson.build
@@ -44,9 +44,9 @@ config_paths_data.set_quoted('MANDIR', dir_prefix / dir_man)
 
 var_cc = ' '.join(cc.cmd_array())
 var_cpp = ' '.join(cc.cmd_array() + ['-E'])
-var_cflags = ' '.join(cflags + cflags_warn + get_option('c_args'))
+var_cflags = ' '.join(cflags + cflags_builtin + cflags_warn + get_option('c_args'))
 if llvm.found()
-  var_cxxflags = ' '.join(cxxflags + cxxflags_warn + get_option('cpp_args'))
+  var_cxxflags = ' '.join(cxxflags + cxxflags_builtin + cxxflags_warn + get_option('cpp_args'))
 else
   var_cxxflags = ''
 endif
-- 
2.43.0