[PATCH] checkpatch: Add a --strict test for macro argument reuse and precedence

Joe Perches
2016-09-03T22:21:22Z

Add a test for reuse of macro arguments to highlight any possible
side-effects from this reuse.

Avoid this check on token name pasting and when the
argument is used in a typeof or a __builtin.

Add a test for macro arguents that have leading or trailing operators
where the argument isn't parenthesized to avoid possible precedence
issues.

These tests are noisy so make them --strict.

Signed-off-by: Joe Perches <joe@perches.com>
---

This is a slight expansion of a patch I sent a few years back.

https://lkml.org/lkml/2012/11/6/151

This one at least runs.

Maybe it's useful to find some of the possible macro misuses,
but it is _very_ noisy.

scripts/checkpatch.pl | 47 +++++++++++++++++++++++++++++++++++++++--------
1 file changed, 39 insertions(+), 8 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 8946904..921155f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4714,7 +4714,17 @@ sub process {
$has_flow_statement = 1 if ($ctx =~ /\b(goto|return)\b/);
$has_arg_concat = 1 if ($ctx =~ /\#\#/ && $ctx !~ /\#\#\s*(?:__VA_ARGS__|args)\b/);

- $dstat =~ s/^.\s*\#\s*define\s+$Ident(?:\([^\)]*\))?\s*//;
+ $dstat =~ s/^.\s*\#\s*define\s+$Ident(\([^\)]*\))?\s*//;
+ my $define_args = $1;
+ my $define_stmt = $dstat;
+ my @def_args = ();
+
+ if (defined $define_args && $define_args ne "") {
+ $define_args = substr($define_args, 1, length($define_args) - 2);
+ $define_args =~ s/\s*//g;
+ @def_args = split(",", $define_args);
+ }
+
$dstat =~ s/$;//g;
$dstat =~ s/\\\n.//g;
$dstat =~ s/^\s*//s;
@@ -4750,6 +4760,15 @@ sub process {
^\[
}x;
#print "REST<$rest> dstat<$dstat> ctx<$ctx>\n";
+
+ $ctx =~ s/\n*$//;
+ my $herectx = $here . "\n";
+ my $stmt_cnt = statement_rawlines($ctx);
+
+ for (my $n = 0; $n < $stmt_cnt; $n++) {
+ $herectx .= raw_line($linenr, $n) . "\n";
+ }
+
if ($dstat ne '' &&
$dstat !~ /^(?:$Ident|-?$Constant),$/ && # 10, // foo(),
$dstat !~ /^(?:$Ident|-?$Constant);$/ && # foo();
@@ -4765,13 +4784,6 @@ sub process {
$dstat !~ /^\(\{/ && # ({...
$ctx !~ /^.\s*#\s*define\s+TRACE_(?:SYSTEM|INCLUDE_FILE|INCLUDE_PATH)\b/)
{
- $ctx =~ s/\n*$//;
- my $herectx = $here . "\n";
- my $cnt = statement_rawlines($ctx);
-
- for (my $n = 0; $n < $cnt; $n++) {
- $herectx .= raw_line($linenr, $n) . "\n";
- }

if ($dstat =~ /;/) {
ERROR("MULTISTATEMENT_MACRO_USE_DO_WHILE",
@@ -4780,6 +4792,25 @@ sub process {
ERROR("COMPLEX_MACRO",
"Macros with complex values should be enclosed in parentheses\n" . "$herectx");
}
+
+ }
+# check if any macro arguments are reused or may have other precedence issues
+ foreach my $arg (@def_args) {
+ next if ($arg =~ /\.\.\./);
+ my $tmp = $define_stmt;
+ $tmp =~ s/\b(typeof|__typeof__|__builtin\w+|typecheck\s*\(\s*$Type\s*,|\#+)\s*\(*\s*$arg\s*\)*\b//g;
+ $tmp =~ s/\#\#\s*$arg\b//g;
+ $tmp =~ s/\b$arg\s*\#\#//g;
+ my $use_cnt = $tmp =~ s/\b$arg\b//g;
+ if ($use_cnt > 1) {
+ CHK("MACRO_ARG_REUSE",
+ "Macro argument reuse '$arg' - possible side-effects?\n" . "$herectx");
+ }
+ if ($define_stmt =~ m/\b$arg\b\s*$Operators/m ||
+ $define_stmt =~ /$Operators\s*$arg\b/m) {
+ CHK("MACRO_ARG_PRECEDENCE",
+ "Macro argument '$arg' may be better as '($arg)' to avoid precedence issues\n" . "$herectx");
+ }
}

# check for macros with flow control, but without ## concatenation
--
2.10.0.rc2.1.g053435c