doc: check well-formedness of delimited sections

Having an empty line before each delimited sections is not required by
asciidoc, but it is a safety measure that prevents generating malformed
asciidoc when generating translated documentation.

When a delimited section appears just after a paragraph, the asciidoc
processor checks that the length of the delimited section header is
different from the length of the paragraph. If it is not, the asciidoc
processor will generate a title. In the original English documentation, this
is not a problem because the authors always check the output of the asciidoc
processor and fix the length of the delimited section header if it turns out
to be the same as the paragraph length. However, this is not the case for
translations, where the authors have no way to check the length of the
delimited section header or the output of the asciidoc processor. This can
lead to a section title that is not intended.

Indeed, this test also checks that titles are correctly formed, that is,
the length of the underline is equal to the length of the title (otherwise
it would not be a title but a section header).

Finally, this test checks that the delimited section are terminated within
the same file.

Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/Makefile

@@ -497,9 +497,17 @@ $(LINT_DOCS_FSCK_MSGIDS): ../fsck.h fsck-msgids.adoc
 	$(call mkdir_p_parent_template)
 	$(QUIET_GEN)$(PERL_PATH) lint-fsck-msgids.perl \
 		../fsck.h fsck-msgids.adoc $@
-
 lint-docs-fsck-msgids: $(LINT_DOCS_FSCK_MSGIDS)
 
+## Lint: delimited sections
+LINT_DOCS_DELIMITED_SECTIONS = $(patsubst %.adoc,.build/lint-docs/delimited-sections/%.ok,$(MAN_TXT))
+$(LINT_DOCS_DELIMITED_SECTIONS): lint-delimited-sections.perl
+$(LINT_DOCS_DELIMITED_SECTIONS): .build/lint-docs/delimited-sections/%.ok: %.adoc
+	$(call mkdir_p_parent_template)
+	$(QUIET_LINT_DELIMSEC)$(PERL_PATH) lint-delimited-sections.perl $< >$@
+.PHONY: lint-docs-delimited-sections
+lint-docs-delimited-sections: $(LINT_DOCS_DELIMITED_SECTIONS)
+
 lint-docs-manpages:
 	$(QUIET_GEN)./lint-manpages.sh
 
@@ -528,6 +536,7 @@ 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
+lint-docs: lint-docs-delimited-sections
 lint-docs: lint-docs-manpages
 lint-docs: lint-docs-meson
 

Documentation/RelNotes/1.6.2.4.adoc

@@ -37,3 +37,4 @@ exec >/var/tmp/1
 echo O=$(git describe maint)
 O=v1.6.2.3-38-g318b847
 git shortlog --no-merges $O..maint
+---

Documentation/diff-format.adoc

@@ -103,6 +103,7 @@ if the file was renamed on any side of history.  With
 followed by the name of the path in the merge commit.
 
 Examples for `-c` and `--cc` without `--combined-all-paths`:
+
 ------------------------------------------------
 ::100644 100644 100644 fabadb8 cc95eb0 4866510 MM	desc.c
 ::100755 100755 100755 52b7a2d 6d1ac04 d2ac7d7 RM	bar.sh

Documentation/git-commit.adoc

@@ -281,6 +281,7 @@ variable (see linkgit:git-config[1]).
 +
 --
 It is a rough equivalent for:
+
 ------
 	$ git reset --soft HEAD^
 	$ ... do something else to come up with the right tree ...

Documentation/git-fast-import.adoc

@@ -605,9 +605,11 @@ Marks must be declared (via `mark`) before they can be used.
 
 The special case of restarting an incremental import from the
 current branch value should be written as:
+
 ----
 	from refs/heads/branch^0
 ----
+
 The `^0` suffix is necessary as fast-import does not permit a branch to
 start from itself, and the branch is created in memory before the
 `from` command is even read from the input.  Adding `^0` will force

Documentation/git-p4.adoc

@@ -66,6 +66,7 @@ Clone
 ~~~~~
 Generally, 'git p4 clone' is used to create a new Git directory
 from an existing p4 repository:
+
 ------------
 $ git p4 clone //depot/path/project
 ------------

Documentation/git-rebase.adoc

@@ -687,7 +687,7 @@ In addition, the following pairs of options are incompatible:
  * --fork-point and --root
 
 BEHAVIORAL DIFFERENCES
------------------------
+----------------------
 
 `git rebase` has two primary backends: 'apply' and 'merge'.  (The 'apply'
 backend used to be known as the 'am' backend, but the name led to

Documentation/git-svn.adoc

@@ -1012,9 +1012,11 @@ branch.
 
 If you do merge, note the following rule: 'git svn dcommit' will
 attempt to commit on top of the SVN commit named in
+
 ------------------------------------------------------------------------
 git log --grep=^git-svn-id: --first-parent -1
 ------------------------------------------------------------------------
+
 You 'must' therefore ensure that the most recent commit of the branch
 you want to dcommit to is the 'first' parent of the merge.  Chaos will
 ensue otherwise, especially if the first parent is an older commit on

Documentation/gitprotocol-http.adoc

@@ -318,7 +318,7 @@ Extra Parameter.
 
 
 Smart Service git-upload-pack
-------------------------------
+-----------------------------
 This service reads from the repository pointed to by `$GIT_URL`.
 
 Clients MUST first perform ref discovery with

Documentation/gitsubmodules.adoc

@@ -8,6 +8,7 @@ gitsubmodules - Mounting one repository inside another
 SYNOPSIS
 --------
  .gitmodules, $GIT_DIR/config
+
 ------------------
 git submodule
 git <command> --recurse-submodules
@@ -240,7 +241,7 @@ Workflow for a third party library
 
 
 Workflow for an artificially split repo
---------------------------------------
+---------------------------------------
 
   # Enable recursion for relevant commands, such that
   # regular commands recurse into submodules by default

Documentation/lint-delimited-sections.perl

@@ -0,0 +1,48 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+my $exit_code = 0;
+sub report {
+	my ($msg) = @_;
+	print STDERR "$ARGV:$.: $msg\n";
+	$exit_code = 1;
+}
+
+my $line_length = 0;
+my $in_section = 0;
+my $section_header = "";
+
+
+while (my $line = <>) {
+	if (($line =~ /^\+?$/) ||
+	    ($line =~ /^\[.*\]$/) ||
+	    ($line =~ /^ifdef::/)) {
+		$line_length = 0;
+	} elsif ($line =~ /^[^-.]/) {
+		$line_length = length($line);
+	} elsif (($line =~ /^-{3,}$/) || ($line =~ /^\.{3,}$/)) {
+		if ($in_section) {
+			if ($line eq $section_header) {
+				$in_section = 0;
+			}
+		next;
+		}
+		if ($line_length == 0) {
+			$in_section = 1;
+			$section_header = $line;
+			next;
+		}
+		if (($line_length != 0) && (length($line) != $line_length)) {
+			report("section delimiter not preceded by an empty line");
+		}
+		$line_length = 0;
+	}
+}
+
+if ($in_section) {
+	report("section not finished");
+}
+
+exit $exit_code;

Documentation/mergetools/vimdiff.adoc

@@ -3,6 +3,7 @@ Description
 
 When specifying `--tool=vimdiff` in `git mergetool` Git will open Vim with a 4
 windows layout distributed in the following way:
+
 ....
 ------------------------------------------
 |             |           |              |
@@ -56,6 +57,7 @@ needed in this case. The next layout definition is equivalent:
 +
 --
 If, for some reason, we are not interested in the `BASE` buffer.
+
 ....
 ------------------------------------------
 |             |           |              |
@@ -72,6 +74,7 @@ If, for some reason, we are not interested in the `BASE` buffer.
 Only the `MERGED` buffer will be shown. Note, however, that all the other
 ones are still loaded in vim, and you can access them with the "buffers"
 command.
+
 ....
 ------------------------------------------
 |                                        |
@@ -88,6 +91,7 @@ command.
 When `MERGED` is not present in the layout, you must "mark" one of the
 buffers with an arobase (`@`). That will become the buffer you need to edit and
 save after resolving the conflicts.
+
 ....
 ------------------------------------------
 |                   |                    |
@@ -106,6 +110,7 @@ save after resolving the conflicts.
 Three tabs will open: the first one is a copy of the default layout, while
 the other two only show the differences between (`BASE` and `LOCAL`) and
 (`BASE` and `REMOTE`) respectively.
+
 ....
 ------------------------------------------
 | <TAB #1> |  TAB #2  |  TAB #3  |       |
@@ -119,6 +124,7 @@ the other two only show the differences between (`BASE` and `LOCAL`) and
 |                                        |
 ------------------------------------------
 ....
+
 ....
 ------------------------------------------
 |  TAB #1  | <TAB #2> |  TAB #3  |       |
@@ -132,6 +138,7 @@ the other two only show the differences between (`BASE` and `LOCAL`) and
 |                   |                    |
 ------------------------------------------
 ....
+
 ....
 ------------------------------------------
 |  TAB #1  |  TAB #2  | <TAB #3> |       |
@@ -151,6 +158,7 @@ the other two only show the differences between (`BASE` and `LOCAL`) and
 --
 Same as the previous example, but adds a fourth tab with the same
 information as the first tab, with a different layout.
+
 ....
 ---------------------------------------------
 |  TAB #1  |  TAB #2  |  TAB #3  | <TAB #4> |

Documentation/technical/long-running-process-protocol.adoc

@@ -24,6 +24,7 @@ After the version negotiation Git sends a list of all capabilities that
 it supports and a flush packet. Git expects to read a list of desired
 capabilities, which must be a subset of the supported capabilities list,
 and a flush packet as response:
+
 ------------------------
 packet:          git> git-filter-client
 packet:          git> version=2

shared.mak

@@ -88,6 +88,7 @@ ifndef V
 
 	QUIET_LINT_GITLINK	= @echo '   ' LINT GITLINK $<;
 	QUIET_LINT_MANSEC	= @echo '   ' LINT MAN SEC $<;
+	QUIET_LINT_DELIMSEC	= @echo '   ' LINT DEL SEC $<;
 	QUIET_LINT_MANEND	= @echo '   ' LINT MAN END $<;
 
 	export V