Re: Improve docs syntax checking and enable it in the meson build

Hi,

Thank you for looking into this!

On Mon, 16 Feb 2026 at 23:38, Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> Hi,
>
> On 2026-02-16 10:39:06 +0300, Nazir Bilal Yavuz wrote:
> > # Run validation only once, common to all subsequent targets. While
> > # we're at it, also resolve all entities (that is, copy all included
> > # files into one big file). This helps tools that don't understand
> > @@ -108,12 +128,15 @@ postgres_full_xml = custom_target('postgres-full.xml',
> > depfile: 'postgres-full.xml.d',
> > command: [xmllint, '--nonet', '--noent', '--valid',
> > '--path', '@OUTDIR@', '-o', '@OUTPUT@', '@INPUT@'],
> > - depends: doc_generated,
> > + depends: [doc_generated, sgml_check_stamp],
> > build_by_default: false,
> > )
> > docs += postgres_full_xml
> > alldocs += postgres_full_xml
>
> Not sure I love that now the entire docs build fails if there is a tab
> anywhere. It's probably ok, but ...
>
> Given you add it as a test for meson and a check for make, why not just make
> sgml_check_stamp a dependency of the test (meson) and check targets (make)?

I followed what Peter suggested here [1]. The idea was basically
running these checks while building the 'postgres.full.xml', not only
running the test.

> > +postgres_full_xml_target = 'postgres_full_xml'
> > +alias_target(postgres_full_xml_target, postgres_full_xml)
>
> Why would we want a top-level postgres_full_xml target?

The idea was using it with the 'meson compile $target' command [2]
which I will explain below.

> > if xsltproc_bin.found()
> > xsltproc_flags = [
> > @@ -308,3 +331,13 @@ endif
> > if alldocs.length() != 0
> > alias_target('alldocs', alldocs)
> > endif
> > +
> > +# Test creation of 'postgres_full_xml'.
> > +test(
> > + 'doc' / 'sgml_syntax_check',
> > + meson_bin,
> > + args: ['compile', postgres_full_xml_target],
> > + suite: 'doc'
> > +)
>
> I'm confused about this 'compile' bit here. What is that intending to do? I
> don't have such a 'compile' command in my PATH, so the test fails here...

My intent was to have a syntax check that will run while we build the
'postgres_full_xml'. And since we already have that, the test just can
try rebuilding the target with the 'meson compile $target' command
[2]. I converted this to:

# The actual test is whether postgres_full_xml can be built, as it has a
# xmllint check and also depends on sgml_check_stamp which performs the syntax
# check.
test(
'doc' / 'sgml_syntax_check',
python,
args: ['-c', ''],
depends: [postgres_full_xml],
suite: 'doc',
)

and removed the top-level postgres_full_xml target. This should work
on any platform now. Does that work for you?

> > diff --git a/doc/src/sgml/sgml_syntax_check.pl b/doc/src/sgml/sgml_syntax_check.pl
> > new file mode 100755
> > index 00000000000..61b4cd203c0
> > --- /dev/null
> > +++ b/doc/src/sgml/sgml_syntax_check.pl
> > @@ -0,0 +1,115 @@
> > +#!/usr/bin/perl
> > +#
> > +# Perl script that checks SGML/XSL syntax and formatting issues.
> > +#
> > +# doc/src/sgml/sgml_syntax_check.pl
> > +#
> > +# Copyright (c) 2026, PostgreSQL Global Development Group
> > +
> > +use strict;
> > +use warnings FATAL => 'all';
> > +use Getopt::Long;
> > +
> > +use File::Find;
> > +
> > +my $srcdir;
> > +my $builddir;
> > +my $dep_file;
> > +my $stamp_file;
> > +
> > +GetOptions(
> > + 'srcdir:s' => \$srcdir,
> > + 'builddir:s' => \$builddir,
> > + 'dep_file:s' => \$dep_file,
> > + 'stamp_file:s' => \$stamp_file) or die "$0: wrong arguments";
>
> I don't think there's a point in having a dep file here. Dependency files are
> only useful if you have dependency on *additional* files to the ones
> explicitly passed in (e.g. a .c file may depend on headers, but the headers
> aren't listed as arguments to the compiler).

We had a chat with Andres off-list about this. Andres thought the
sgml_syntax_check.pl script accepts files as in input rather than
directory. That comment was true if we directly send the file as an
input argument since meson will automatically append this file to the
dependency file. However, we rather send a directory as an input and
manually create a dependency file with the *.sgml and *.xsl files in
the directory.

> > +die "$0: --srcdir must be specified\n" unless defined $srcdir;
> > +
> > +# Find files to process - all the sgml and xsl files (including in subdirectories)
> > +my @files_to_process;
> > +my @dirs_to_search = ($srcdir);
> > +push @dirs_to_search, $builddir if defined $builddir;
> > +find(
> > + sub {
> > + return unless -f $_;
> > + return if $_ !~ /\.(sgml|xsl)$/;
> > + push @files_to_process, $File::Find::name;
> > + },
> > + @dirs_to_search,);
>
> Why is this any more complicated than just opening the file exactly in the
> passed in source dir?

Same as above, sgml_syntax_check.pl script accepts directory as in
input rather than files.

> > +# tabs and non-breaking spaces are harmless, but it is best to avoid them in SGML files
> > +sub check_tabs_and_nbsp
> > +{
> > + my $errors = 0;
> > + for my $f (@files_to_process)
> > + {
> > + open my $fh, "<:encoding(UTF-8)", $f or die "Can't open $f: $!";
> > + my $line_no = 0;
> > + while (<$fh>)
> > + {
> > + $line_no++;
> > + if (/\t/)
> > + {
> > + print STDERR "Tab found in $f:$line_no\n";
> > + $errors++;
> > + }
> > + if (/\xC2\xA0/)
> > + {
> > + print STDERR "$f:$line_no: contains non-breaking space\n";
> > + $errors++;
> > + }
> > + }
> > + close($fh);
> > + }
> > +
> > + if ($errors)
> > + {
> > + remove_stamp_file();
>
> I don't think that's needed, the stamp file needs to be newer than the inputs
> to have an effect, and here you're just removing an old one, no?

Yes, done.

> > +sub create_stamp_file
> > +{
> > + # Avoid touching existing stamp file to prevent unnecessary rebuilds
> > + if (!(-f $stamp_file))
> > + {
> > + open my $fh, '>', $stamp_file
> > + or die "can't open $stamp_file: $!";
> > + close $fh;
> > + }
> > +}
>
> Won't that *cause* rebuilds? With a stamp file you normally want the stamp
> file to be *newer* than the inputs. Which it won't be, if you don't touch it
> here.
>
> The only reason it doesn't cause quick rebuilds with meson is that ninja
> remembers the timestamps of files an avoids rebuilds if they haven't changed.

Yes, you are right. Done.

[1] https://postgr.es/m/02d46e55-418e-4cb2-ad36-c43d6172a010%40eisentraut.org
[2] https://mesonbuild.com/Commands.html#compile

--
Regards,
Nazir Bilal Yavuz
Microsoft