[PATCH] checkpatch: Check for quoted strings broken across lines

[Josh Triplett <josh@joshtriplett.org>]

Documentation/CodingStyle recommends not splitting quoted strings across
lines, because it breaks the ability to grep for the string.  checkpatch
already makes an exception to the 80-column rule for quoted strings to
allow this.  Rather than just allowing it, actively warn about quoted
strings split across lines.

Test case:

void context(void)
{
        pr_err("this string"
               " should produce a warning\n");
        pr_err("this multi-line string\n"
               "should not produce a warning\n");
        asm ("this asm\n\t"
             "should not produce a warning");
}

Results of checkpatch on that test case:

WARNING: quoted string split across lines
+	       " should produce a warning\n");

total: 0 errors, 1 warnings, 9 lines checked

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
---
 scripts/checkpatch.pl |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e3bfcbe..ce4d740 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1737,6 +1737,17 @@ sub process {
 			     "line over 80 characters\n" . $herecurr);
 		}
 
+# Check for strings broken across lines (breaks greppability).  Make an
+# exception when the previous string ends in a newline (multiple lines in one
+# string constant) or \n\t (common in inline assembly to indent the instruction
+# on the following line).
+		if ($line =~ /^\+\s*"/ &&
+		    $prevline =~ /"\s*$/ &&
+		    $prevrawline !~ /\\n(?:\\t)*"\s*$/) {
+			WARN("SPLIT_STRING",
+			     "quoted string split across lines\n" . $herecurr);
+		}
+
 # check for spaces before a quoted newline
 		if ($rawline =~ /^.*\".*\s\\n/) {
 			WARN("QUOTED_WHITESPACE_BEFORE_NEWLINE",
-- 
1.7.9