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From:   peter@bikeshed.quignogs.org.uk
To:     Matthew Wilcox <willy@infradead.org>, linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>, linux-doc@vger.kernel.org,
        Jonathan Corbet <corbet@lwn.net>,
        Peter Lister <peter@bikeshed.quignogs.org.uk>
Subject: [PATCH v3 1/1] A compact idiom to add code examples in kerneldoc comments.
Date:   Thu, 26 Mar 2020 19:51:56 +0000
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 <20200326195156.11858-1-peter@bikeshed.quignogs.org.uk>
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From: Peter Lister <peter@bikeshed.quignogs.org.uk>

scripts/kernel-doc - When a double colon follows a section heading
(e.g. Example::), write a double colon line to the ReST output to make
the following text (e.g. a code snippet) into a literal block.

drivers/base/platform.c - Changed Example: headings to Example:: to
literalise code snippets as above.

This patch also removes two kerneldoc build warnings:
./drivers/base/platform.c:134: WARNING: Unexpected indentation.
./drivers/base/platform.c:213: WARNING: Unexpected indentation.

Signed-off-by: Peter Lister <peter@bikeshed.quignogs.org.uk>
---
 drivers/base/platform.c |  4 ++--
 scripts/kernel-doc      | 19 +++++++++++++++----
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index b5ce7b085795..47f4a9b410b2 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -128,7 +128,7 @@ EXPORT_SYMBOL_GPL(devm_platform_ioremap_resource_byname);
  * request_irq() APIs. This is the same as platform_get_irq(), except that it
  * does not print an error message if an IRQ can not be obtained.
  *
- * Example:
+ * Example::
  *		int irq = platform_get_irq_optional(pdev, 0);
  *		if (irq < 0)
  *			return irq;
@@ -207,7 +207,7 @@ EXPORT_SYMBOL_GPL(platform_get_irq_optional);
  * IRQ fails. Device drivers should check the return value for errors so as to
  * not pass a negative integer value to the request_irq() APIs.
  *
- * Example:
+ * Example::
  *		int irq = platform_get_irq(pdev, 0);
  *		if (irq < 0)
  *			return irq;
diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index f2d73f04e71d..732db3dcc402 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -362,7 +362,7 @@ my $doc_com_body = '\s*\* ?';
 my $doc_decl = $doc_com . '(\w+)';
 # @params and a strictly limited set of supported section names
 my $doc_sect = $doc_com .
-    '\s*(\@[.\w]+|\@\.\.\.|description|context|returns?|notes?|examples?)\s*:(.*)';
+    '\s*(\@[.\w]+|\@\.\.\.|description|context|returns?|notes?|examples?)\s*:(:?)(.*)';
 my $doc_content = $doc_com_body . '(.*)';
 my $doc_block = $doc_com . 'DOC:\s*(.*)?';
 my $doc_inline_start = '^\s*/\*\*\s*$';
@@ -1952,11 +1952,22 @@ sub process_body($$) {
 	    ++$warnings;
 	}
     }
-
+    # $doc_sect is a regex which searches for section names.
+    # If it matches:
+    #   $1 is the section name
+    #   $2 is a colon if the section name was followed by a double colon.
+    #   $3 is the rest of the content after the colon (or double colon).
     if (/$doc_sect/i) { # case insensitive for supported section names
 	$newsection = $1;
-	$newcontents = $2;
-
+	# If $2 is ':', the section name was followed by a double
+	# colon, so insert a line containing just '::' to make the
+	# following block into a ReST literal.  This idiom is useful
+	# for an Example section introducing a code snippet.
+	if ($2 eq ':') {
+	    $newcontents = "::\n" . $3;
+	} else {
+	    $newcontents = $3;
+	}
 	# map the supported section names to the canonical names
 	if ($newsection =~ m/^description$/i) {
 	    $newsection = $section_default;
-- 
2.25.1