Mkfiles/msvc.mak: make the docs: target actually work under real nmake

The docs: target fed doc/Makefile.in directly to nmake, but that file
relies on several GNU make-only constructs nmake cannot parse at all:
the $^ automatic variable (not valid nmake macro syntax -- fatal
parse error), $< used outside of an inference rule (silently
unsupported, since nmake only defines $< within .SUFFIXES-style
rules), and the GNU-only "-include *.dep" optional wildcard include
directive (nmake only understands the unrelated "!include"
directive). Add tools/mkmsvcdocmak.pl, which rewrites just those
constructs to their explicit nmake-safe equivalents in a generated
copy (doc/Makefile.msvc), leaving doc/Makefile.in itself untouched for
the Unix/GNU make build. Verified by rewriting doc/Makefile.in this
way and building nasmdoc.pdf through it with GNU make standing in for
nmake.

Also, doc/Makefile.in expects doc/warnings.src, doc/perlbreq.src and
doc/pptok.src to have already been generated -- the Unix "doc" target
does this via the top-level Makefile.in before recursing into doc/,
but msvc.mak's docs: target had no equivalent step. warnings.src and
pptok.src already had msvc.mak rules (just not wired up as
prerequisites of docs:); perlbreq.src had no rule at all, since the
top-level Makefile.in generates it with a POSIX find/sed pipeline that
doesn't translate to Windows. Add tools/genperlbreq.pl, a portable
pure-Perl equivalent (using File::Find), and a doc\perlbreq.src rule
in msvc.mak that uses it; verified it produces output byte-identical
to the existing POSIX pipeline.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Mkfiles/msvc.mak

@@ -358,6 +358,9 @@ doc\warnings.src: asm\warnings.pl asm\warnings.dat
 	$(RUNPERL) $(srcdir)\asm\warnings.pl doc doc\warnings.src \
 		$(srcdir)\asm\warnings.dat
 
+doc\perlbreq.src: tools\genperlbreq.pl $(DIRS)
+	$(RUNPERL) tools\genperlbreq.pl $(srcdir) doc\perlbreq.src
+
 $(PERLREQ): $(DIRS)
 
 perlreq: $(PERLREQ) $(PHONY)
@@ -418,6 +421,7 @@ cleaner: clean
 
 spotless: distclean cleaner
 	-del /f doc\Makefile
+	-del /f doc\msvc.mak
 	-del doc\*~
 	-del doc\*.bak
 
@@ -425,11 +429,23 @@ strip:
 
 # Abuse doc/Makefile.in to build nasmdoc.pdf only.
 #
+# doc/Makefile.in expects doc\warnings.src, doc\perlbreq.src and
+# doc\pptok.src to already have been generated by the top-level build
+# (as the Unix "doc" target does); build them here first.
+#
+# doc/Makefile.in is written for GNU make and relies on a few
+# constructs nmake cannot parse at all ($^, $< outside an inference
+# rule, and the GNU-only "-include *.dep" directive); tools/mkmsvcdocmak.pl
+# rewrites those to their nmake-safe equivalents in a generated copy,
+# doc\msvc.mak, which is what actually gets fed to nmake below.
+#
 # Building the documentation requires Ghostscript and the Roboto /
 # Roboto Mono fonts to be installed and discoverable; see
 # doc/source.src ("Optional Build Tools") for details.
-docs:
-	cd doc && $(MAKE) /f Makefile.in srcdir=. top_srcdir=.. \
+docs: doc\warnings.src doc\perlbreq.src doc\pptok.src
+	$(RUNPERL) $(srcdir)\tools\mkmsvcdocmak.pl \
+		$(srcdir)\doc\Makefile.in doc\msvc.mak
+	cd doc && $(MAKE) /f msvc.mak srcdir=. top_srcdir=.. \
 		PERL=$(PERL) PDFOPT= nasmdoc.pdf
 
 everything: all docs nsis

tools/genperlbreq.pl

@@ -0,0 +1,45 @@
+#!/usr/bin/perl
+# SPDX-License-Identifier: BSD-2-Clause
+# Copyright 1996-2025 The NASM Authors - All Rights Reserved
+
+#
+# Scan the source tree for "use Module;" lines in *.pl/*.ph files and
+# produce doc/perlbreq.src, the list of Perl module prerequisites
+# included in the documentation.  This is a portable (pure Perl)
+# equivalent of the find/sed pipeline used by the top-level
+# Makefile.in's perlbreq.si/doc/perlbreq.src rules, for use by build
+# systems (e.g. Mkfiles/msvc.mak) that cannot rely on POSIX find/sed
+# being available.
+#
+
+use strict;
+use warnings;
+use File::Find;
+
+my ($srcdir, $outfile) = @ARGV;
+die "Usage: $0 <srcdir> <outfile>\n" unless defined($srcdir) && defined($outfile);
+
+my %mods;
+
+find({
+    wanted => sub {
+        return unless /\.p[lh]$/;
+        open(my $fh, '<', $_) or return;
+        while (my $line = <$fh>) {
+            if ($line =~ /^\s*use\s+([[:upper:]][^\s;]*)/) {
+                my $mod = $1;
+                next if $mod =~ /^Win32/;
+                $mods{$mod} = 1;
+            }
+        }
+        close($fh);
+    },
+    no_chdir => 1,
+}, $srcdir);
+
+open(my $out, '>', $outfile) or die "$0: cannot open: $outfile\n";
+foreach my $mod (sort keys %mods) {
+    print $out "\\c      $mod\n";
+}
+print $out "\\c      Win32 (if building on Windows only)\n";
+close($out);

tools/mkmsvcdocmak.pl

@@ -0,0 +1,60 @@
+#!/usr/bin/perl
+# SPDX-License-Identifier: BSD-2-Clause
+# Copyright 1996-2025 The NASM Authors - All Rights Reserved
+
+#
+# doc/Makefile.in is written for GNU make (used unmodified, via
+# autoconf substitution, on Unix).  It relies on a handful of GNU
+# make-only constructs -- the $^ automatic variable (not valid nmake
+# syntax at all: nmake's parser treats a bare "$^" as an illegal macro
+# reference and aborts), the $< automatic variable used outside of an
+# inference rule (silently unsupported by nmake, since nmake only
+# defines $< within .SUFFIXES-style inference rules), and the
+# GNU-only "-include *.dep" optional-include directive (nmake only
+# understands the "!include" directive and has no equivalent "ignore
+# missing file, glob patterns allowed" form).
+#
+# Mkfiles/msvc.mak needs to feed doc/Makefile.in directly to nmake (it
+# doesn't have its own copy of the doc build rules to maintain in
+# parallel), so this script produces an nmake-safe copy of the file by
+# rewriting just those constructs to their equivalent explicit form.
+# doc/Makefile.in itself is left untouched for the Unix/GNU make
+# build; only the copy this script writes is affected.
+#
+
+use strict;
+use warnings;
+
+my ($in, $out) = @ARGV;
+die "Usage: $0 <in> <out>\n" unless defined($in) && defined($out);
+
+open(my $ifh, '<', $in) or die "$0: cannot open: $in\n";
+open(my $ofh, '>', $out) or die "$0: cannot open: $out\n";
+
+while (my $line = <$ifh>) {
+    # insns.src: inslist.pl ../x86/insns.xda
+    #	$(RUNPERL) $^ $@
+    if (index($line, '$(RUNPERL) $^ $@') >= 0) {
+        $line =~ s/\$\(RUNPERL\) \$\^ \$\@/\$(RUNPERL) inslist.pl ..\/x86\/insns.xda \$\@/;
+    }
+
+    # $(htmltarget)/nasmdoc.dip/nasmdoc.txt: $< is the first prerequisite
+    # of $(ALLSRCS), i.e. $(SRCS) (nasmdoc.src).
+    $line =~ s/(\$\(RDSRC\)\s+(?:-ohtml html|dip|txt))\s+\$</$1 \$(SRCS)/;
+
+    # nasmdoc.pdf/nasmdoc-raw.pdf: $< is the first (only) prerequisite
+    # of interest, nasmdoc.ps.
+    $line =~ s/(\$\(PDFOPT\)\s+)\$<(\s+\$\@\s+fontpath)/$1nasmdoc.ps$2/;
+
+    # nasmdoc.pdf.xz: $< is nasmdoc-raw.pdf.
+    $line =~ s/(\$\(XZ\)\s+-9e\s+<\s+)\$<(\s+>\s+\$\@)/$1nasmdoc-raw.pdf$2/;
+
+    # GNU make-only optional wildcard include of auto-dependency files;
+    # not parseable by nmake at all, and unneeded for a one-shot build.
+    next if $line =~ /^-include\s+\*\.dep\s*$/;
+
+    print $ofh $line;
+}
+
+close($ifh);
+close($ofh);