[PATCH] Documentation: add lint-fsck-msgids

[Junio C Hamano <gitster@pobox.com>]

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>
---

 * So the quick-and-dirty one gets repackaged with minimum polish to
   become such a lint-doc checker.  With the MISSING_TREE_OBJECT
   removed from fsck.h header, and the fixes to the msgids.txt
   documentation applied, the result passes the check.

 Documentation/Makefile              | 11 +++++
 Documentation/lint-fsck-msgids.perl | 70 +++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100755 Documentation/lint-fsck-msgids.perl

diff --git a/Documentation/Makefile b/Documentation/Makefile
index d47acb2e25..5e1a7f655c 100644
--- a/Documentation/Makefile
+++ b/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: $(LINT_DOCS_FSCK_MSGIDS)
+
 ## Lint: list of targets above
 .PHONY: lint-docs
+lint-docs: lint-docs-fsck-msgids
 lint-docs: lint-docs-gitlink
 lint-docs: lint-docs-man-end-blurb
 lint-docs: lint-docs-man-section-order
diff --git a/Documentation/lint-fsck-msgids.perl b/Documentation/lint-fsck-msgids.perl
new file mode 100755
index 0000000000..1233ffe815
--- /dev/null
+++ b/Documentation/lint-fsck-msgids.perl
@@ -0,0 +1,70 @@
+#!/usr/bin/perl
+
+my ($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);
-- 
2.38.1-359-g84c4c6d5a5