Documentation: add lint-fsck-msgids

During the initial development of the fsck-msgids.txt feature, it
has become apparent that it is very much error prone to make sure
the description in the documentation file are sorted and correctly
match what is in the fsck.h header file.

Add a quick-and-dirty Perl script and doc-lint target to sanity
check that the fsck-msgids.txt is consistent with the error type
list in the fsck.h header file.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: gitster

Documentation/Makefile

@@ -476,8 +476,19 @@ $(LINT_DOCS_MAN_SECTION_ORDER): .build/lint-docs/man-section-order/%.ok: %.txt
 .PHONY: lint-docs-man-section-order
 lint-docs-man-section-order: $(LINT_DOCS_MAN_SECTION_ORDER)
 
+.PHONY: lint-docs-fsck-msgids
+LINT_DOCS_FSCK_MSGIDS = .build/lint-docs/fsck-msgids.ok
+$(LINT_DOCS_FSCK_MSGIDS): lint-fsck-msgids.perl
+$(LINT_DOCS_FSCK_MSGIDS): ../fsck.h fsck-msgids.txt
+	$(call mkdir_p_parent_template)
+	$(QUIET_GEN)$(PERL_PATH) lint-fsck-msgids.perl \
+		../fsck.h fsck-msgids.txt $@
+
+lint-docs-fsck-msgids: $(LINT_DOCS_FSCK_MSGIDS)
+
 ## Lint: list of targets above
 .PHONY: lint-docs
+lint-docs: lint-docs-fsck-msgids
 lint-docs: lint-docs-gitlink
 lint-docs: lint-docs-man-end-blurb
 lint-docs: lint-docs-man-section-order

Documentation/lint-fsck-msgids.perl

@@ -0,0 +1,70 @@
+#!/usr/bin/perl
+
+my ($fsck_h, $fsck_msgids_txt, $okfile) = @ARGV;
+
+my (%in_fsck_h, $fh, $bad);
+
+open($fh, "<", "$fsck_h") or die;
+while (<$fh>) {
+	if (/^\s+FUNC\(([0-9A-Z_]+), ([A-Z]+)\)/) {
+		my ($name, $severity) = ($1, $2);
+		my ($first) = 1;
+		$name = join('',
+			     map {
+				     y/A-Z/a-z/;
+				     if (!$first) {
+					     s/^(.)/uc($1)/e;
+				     } else {
+					     $first = 0;
+				     }
+				     $_;
+			     }
+			     split(/_/, $name));
+		$in_fsck_h{$name} = $severity;
+	}
+}
+close($fh);
+
+open($fh, "<", "$fsck_msgids_txt") or die;
+my ($previous, $current);
+while (<$fh>) {
+	if (!defined $current) {
+		if (/^\`([a-zA-Z0-9]*)\`::/) {
+			$current = $1;
+			if ((defined $previous) &&
+			    ($current le $previous)) {
+				print STDERR "$previous >= $current in doc\n";
+				$bad = 1;
+			}
+		}
+	} elsif (/^\s+\(([A-Z]+)\) /) {
+		my ($level) = $1;
+		if (!exists $in_fsck_h{$current}) {
+			print STDERR "$current does not exist in fsck.h\n";
+			$bad = 1;
+		} elsif ($in_fsck_h{$current} eq "") {
+			print STDERR "$current defined twice\n";
+			$bad = 1;
+		} elsif ($in_fsck_h{$current} ne $level) {
+			print STDERR "$current severity $level != $in_fsck_h{$current}\n";
+			$bad = 1;
+		}
+		$previous = $current;
+		$in_fsck_h{$current} = ""; # mark as seen.
+		undef $current;
+	}
+}
+close($fh);
+
+for my $key (keys %in_fsck_h) {
+	if ($in_fsck_h{$key} ne "") {
+		print STDERR "$key not explained in doc.\n";
+		$bad = 1;
+	}
+}
+
+die if ($bad);
+
+open($fh, ">", "$okfile");
+print $fh "good\n";
+close($fh);