checkpatch: add --fix option for some TRAILING_STATEMENTS

Single line code like:

	if (foo) bar;

should generally be written:

	if (foo)
		bar;

Add a --fix test to do so.

This fix is not done when an ASSIGN_IN_IF in the same line exists.

Link: https://lkml.kernel.org/r/20220128185924.80137-2-joe@perches.comSigned-off-by: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -5551,6 +5551,7 @@ sub process {
 		    defined($stat) && defined($cond) &&
 		    $line =~ /\b(?:if|while|for)\s*\(/ && $line !~ /^.\s*#/) {
 			my ($s, $c) = ($stat, $cond);
+			my $fixed_assign_in_if = 0;
 
 			if ($c =~ /\bif\s*\(.*[^<>!=]=[^=].*/s) {
 				if (ERROR("ASSIGN_IN_IF",
@@ -5575,6 +5576,7 @@ sub process {
 						$newline .= ')';
 						$newline .= " {" if (defined($brace));
 						fix_insert_line($fixlinenr + 1, $newline);
+						$fixed_assign_in_if = 1;
 					}
 				}
 			}
@@ -5598,8 +5600,20 @@ sub process {
 					$stat_real = "[...]\n$stat_real";
 				}
 
-				ERROR("TRAILING_STATEMENTS",
-				      "trailing statements should be on next line\n" . $herecurr . $stat_real);
+				if (ERROR("TRAILING_STATEMENTS",
+					  "trailing statements should be on next line\n" . $herecurr . $stat_real) &&
+				    !$fixed_assign_in_if &&
+				    $cond_lines == 0 &&
+				    $fix && $perl_version_ok &&
+				    $fixed[$fixlinenr] =~ /^\+(\s*)((?:if|while|for)\s*$balanced_parens)\s*(.*)$/) {
+					my $indent = $1;
+					my $test = $2;
+					my $rest = rtrim($4);
+					if ($rest =~ /;$/) {
+						$fixed[$fixlinenr] = "\+$indent$test";
+						fix_insert_line($fixlinenr + 1, "$indent\t$rest");
+					}
+				}
 			}
 		}