[Qemu-devel] [PATCH] scripts/checkpatch.pl: Enforce multiline comment syntax

[Peter Maydell <peter.maydell@linaro.org>]

We now require Linux-kernel-style multiline comments:
    /*
     * line one
     * line two
     */

Enforce this in checkpatch.pl, by backporting the relevant
parts of the Linux kernel's checkpatch.pl. (The only changes
needed are that Linux's checkpatch.pl WARN() function takes
an extra argument that ours does not.)

The kernel's checkpatch does not enforce "leading /* on
a line of its own, so that part is unique to QEMU's checkpatch.

Sample warning output:

WARNING: Block comments use a leading /* on a separate line
#34: FILE: hw/intc/arm_gicv3_common.c:39:
+    /* Older versions of QEMU had a bug in the handling of state save/restore

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
I'm still not used to the leeading-/*-on-it's-own style,
so having checkpatch catch my lapses is handy...

I used WARN level severity mostly because Linux does.
---
 scripts/checkpatch.pl | 48 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 42e1c50dd80..18bc3c59c85 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1566,6 +1566,54 @@ sub process {
 # check we are in a valid C source file if not then ignore this hunk
 		next if ($realfile !~ /\.(h|c|cpp)$/);
 
+# Block comment styles
+
+		# Block comments use /* on a line of its own
+		if ($rawline !~ m@^\+.*/\*.*\*/[ \t]*$@ &&	#inline /*...*/
+		    $rawline =~ m@^\+.*/\*\*?[ \t]*.+[ \t]*$@) { # /* or /** non-blank
+			WARN("Block comments use a leading /* on a separate line\n" . $herecurr);
+		}
+
+# Block comments use * on subsequent lines
+		if ($prevline =~ /$;[ \t]*$/ &&			#ends in comment
+		    $prevrawline =~ /^\+.*?\/\*/ &&		#starting /*
+		    $prevrawline !~ /\*\/[ \t]*$/ &&		#no trailing */
+		    $rawline =~ /^\+/ &&			#line is new
+		    $rawline !~ /^\+[ \t]*\*/) {		#no leading *
+			WARN("Block comments use * on subsequent lines\n" . $hereprev);
+		}
+
+# Block comments use */ on trailing lines
+		if ($rawline !~ m@^\+[ \t]*\*/[ \t]*$@ &&	#trailing */
+		    $rawline !~ m@^\+.*/\*.*\*/[ \t]*$@ &&	#inline /*...*/
+		    $rawline !~ m@^\+.*\*{2,}/[ \t]*$@ &&	#trailing **/
+		    $rawline =~ m@^\+[ \t]*.+\*\/[ \t]*$@) {	#non blank */
+			WARN("Block comments use a trailing */ on a separate line\n" . $herecurr);
+		}
+
+# Block comment * alignment
+		if ($prevline =~ /$;[ \t]*$/ &&			#ends in comment
+		    $line =~ /^\+[ \t]*$;/ &&			#leading comment
+		    $rawline =~ /^\+[ \t]*\*/ &&		#leading *
+		    (($prevrawline =~ /^\+.*?\/\*/ &&		#leading /*
+		      $prevrawline !~ /\*\/[ \t]*$/) ||		#no trailing */
+		     $prevrawline =~ /^\+[ \t]*\*/)) {		#leading *
+			my $oldindent;
+			$prevrawline =~ m@^\+([ \t]*/?)\*@;
+			if (defined($1)) {
+				$oldindent = expand_tabs($1);
+			} else {
+				$prevrawline =~ m@^\+(.*/?)\*@;
+				$oldindent = expand_tabs($1);
+			}
+			$rawline =~ m@^\+([ \t]*)\*@;
+			my $newindent = $1;
+			$newindent = expand_tabs($newindent);
+			if (length($oldindent) ne length($newindent)) {
+				WARN("Block comments should align the * on each line\n" . $hereprev);
+			}
+		}
+
 # Check for potential 'bare' types
 		my ($stat, $cond, $line_nr_next, $remain_next, $off_next,
 		    $realline_next);
-- 
2.17.1