[PATCH] scripts/kernel-doc: Improve Markdown results

[Danilo Cesar Lemes de Paula]

Using pandoc as the Markdown engine cause some minor side effects as
pandoc includes  main <para> tags for almost everything.
Original Markdown support approach removes those main tags, but it caused
some inconsistencies when that tag is not the main one, like:
<something>..</something>
<para>...</para>

As kernel-doc was already including a <para> tag, it causes the presence
of double <para> tags (<para><para>), which is not supported by DocBook
spec.

Html target gets away with it, so it causes no harm, although other
targets might not be so lucky (pdf as example).

We're now delegating the inclusion of the main <para> tag to pandoc
only, as it knows when it's necessary or not.

That behavior causes a corner case, the only situation where we're
certainly that <para> is not needed, which is the <refpurpose> content.
For those cases, we're using a $output_markdown_nopara = 1 control var.

Signed-off-by: Danilo Cesar Lemes de Paula <danilo.cesar@xxxxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Stephan Mueller <smueller@xxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: intel-gfx <intel-gfx@xxxxxxxxxxxxxxxxxxxxx>
Cc: dri-devel <dri-devel@xxxxxxxxxxxxxxxxxxxxx>
Cc: Graham Whaley <graham.whaley@xxxxxxxxxxxxxxx>
---
 Thanks to Graham Whaley who helped me to debug this.

 scripts/kernel-doc | 48 ++++++++++++++++++++++++++++++++++--------------
 1 file changed, 34 insertions(+), 14 deletions(-)

diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index 3850c1e..12a106c 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -288,6 +288,7 @@ my $use_markdown = 0;
 my $verbose = 0;
 my $output_mode = "man";
 my $output_preformatted = 0;
+my $output_markdown_nopara = 0;
 my $no_doc_sections = 0;
 my @highlights = @highlights_man;
 my $blankline = $blankline_man;
@@ -529,8 +530,11 @@ sub markdown_to_docbook {
 	close(CHLD_OUT);
 	close(CHLD_ERR);
 
-	# pandoc insists in adding Main <para></para>, we should remove them.
-	$content =~ s:\A\s*<para>\s*\n(.*)\n</para>\Z$:$1:egsm;
+	if ($output_markdown_nopara) {
+		# pandoc insists in adding Main <para></para>, sometimes we
+		# want to remove them.
+		$content =~ s:\A\s*<para>\s*\n(.*)\n</para>\Z$:$1:egsm;
+	}
 
 	return $content;
 }
@@ -605,7 +609,7 @@ sub output_highlight {
 	    $line =~ s/^\s*//;
 	}
 	if ($line eq ""){
-	    if (! $output_preformatted) {
+	    if (! $output_preformatted && ! $use_markdown) {
 		print $lineprefix, local_unescape($blankline);
 	    }
 	} else {
@@ -1026,7 +1030,7 @@ sub output_section_xml(%) {
 	    # programlisting is already included by pandoc
 	    print "<programlisting>\n" unless $use_markdown;
 	    $output_preformatted = 1;
-	} else {
+	} elsif (! $use_markdown) {
 	    print "<para>\n";
 	}
 	output_highlight($args{'sections'}{$section});
@@ -1034,7 +1038,7 @@ sub output_section_xml(%) {
 	if ($section =~ m/EXAMPLE/i) {
 	    print "</programlisting>\n" unless $use_markdown;
 	    print "</informalexample>\n";
-	} else {
+	} elsif (! $use_markdown) {
 	    print "</para>\n";
 	}
 	print "</refsect1>\n";
@@ -1066,7 +1070,9 @@ sub output_function_xml(%) {
     print " <refname>" . $args{'function'} . "</refname>\n";
     print " <refpurpose>\n";
     print "  ";
+    $output_markdown_nopara = 1;
     output_highlight ($args{'purpose'});
+    $output_markdown_nopara = 0;
     print " </refpurpose>\n";
     print "</refnamediv>\n";
 
@@ -1104,10 +1110,12 @@ sub output_function_xml(%) {
 	    $parameter_name =~ s/\[.*//;
 
 	    print "  <varlistentry>\n   <term><parameter>$parameter</parameter></term>\n";
-	    print "   <listitem>\n    <para>\n";
+	    print "   <listitem>\n";
+	    print "    <para>\n" unless $use_markdown;
 	    $lineprefix="     ";
 	    output_highlight($args{'parameterdescs'}{$parameter_name});
-	    print "    </para>\n   </listitem>\n  </varlistentry>\n";
+	    print "    </para>\n" unless $use_markdown;
+	    print "   </listitem>\n  </varlistentry>\n";
 	}
 	print " </variablelist>\n";
     } else {
@@ -1143,7 +1151,9 @@ sub output_struct_xml(%) {
     print " <refname>" . $args{'type'} . " " . $args{'struct'} . "</refname>\n";
     print " <refpurpose>\n";
     print "  ";
+    $output_markdown_nopara = 1;
     output_highlight ($args{'purpose'});
+    $output_markdown_nopara = 0;
     print " </refpurpose>\n";
     print "</refnamediv>\n";
 
@@ -1196,9 +1206,11 @@ sub output_struct_xml(%) {
       ($args{'parameterdescs'}{$parameter_name} ne $undescribed) || next;
       print "    <varlistentry>";
       print "      <term>$parameter</term>\n";
-      print "      <listitem><para>\n";
+      print "      <listitem>\n";
+      print "         <para>\n" unless $use_markdown;
       output_highlight($args{'parameterdescs'}{$parameter_name});
-      print "      </para></listitem>\n";
+      print "         </para>\n" unless $use_markdown;
+      print "      </listitem>\n";
       print "    </varlistentry>\n";
     }
     print "  </variablelist>\n";
@@ -1237,7 +1249,9 @@ sub output_enum_xml(%) {
     print " <refname>enum " . $args{'enum'} . "</refname>\n";
     print " <refpurpose>\n";
     print "  ";
+    $output_markdown_nopara = 1;
     output_highlight ($args{'purpose'});
+    $output_markdown_nopara = 0;
     print " </refpurpose>\n";
     print "</refnamediv>\n";
 
@@ -1267,9 +1281,11 @@ sub output_enum_xml(%) {
 
       print "    <varlistentry>";
       print "      <term>$parameter</term>\n";
-      print "      <listitem><para>\n";
+      print "      <listitem>\n";
+      print "         <para>\n" unless $use_markdown;
       output_highlight($args{'parameterdescs'}{$parameter_name});
-      print "      </para></listitem>\n";
+      print "         </para>\n" unless $use_markdown;
+      print "      </listitem>\n";
       print "    </varlistentry>\n";
     }
     print "  </variablelist>\n";
@@ -1335,14 +1351,14 @@ sub output_blockhead_xml(%) {
 	if ($section =~ m/EXAMPLE/i) {
 	    print "<example><para>\n";
 	    $output_preformatted = 1;
-	} else {
+	} elsif (! $use_markdown) {
 	    print "<para>\n";
 	}
 	output_highlight($args{'sections'}{$section});
 	$output_preformatted = 0;
 	if ($section =~ m/EXAMPLE/i) {
 	    print "</para></example>\n";
-	} else {
+	} elsif (! $use_markdown) {
 	    print "</para>";
 	}
 	if (!$args{'content-only'}) {
@@ -2684,7 +2700,11 @@ sub process_file($) {
 		{
 			if ( $1 eq "" )
 			{
-				$contents .= $blankline;
+				if ($use_markdown) {
+					$contents .= "\n";
+				} else {
+					$contents .= $blankline;
+				}
 			}
 			else
 			{
-- 
2.4.3

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