checkpatch? (was: Re: [PATCH v3] coccinelle: misc: add uninitialized_var.cocci script)

[Joe Perches]

On Tue, 2020-09-01 at 12:48 +0300, Denis Efremov wrote:
> uninitialized_var() macro was removed from the sources [1] and
> other warning-silencing tricks were deprecated [2]. The purpose of this
> cocci script is to prevent new occurrences of uninitialized_var()
> open-coded variants.

> +(
> +* T var =@p var;
> +|
> +* T var =@p *(&(var));
> +|
> +* var =@p var
> +|
> +* var =@p *(&(var))
> +)

Adding a checkpatch test might be a good thing too.

---
 scripts/checkpatch.pl | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 149518d2a6a7..300b2659aab3 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3901,6 +3901,17 @@ sub process {
 #ignore lines not being added
 		next if ($line =~ /^[^\+]/);
 
+# check for self assigments used to avoid compiler warnings
+# e.g.:	int foo = foo, *bar = NULL;
+#	struct foo bar = *(&(bar));
+		if ($line =~ /^\+\s*(?:$Declare)?([A-Za-z_][A-Za-z\d_]*)\s*=/) {
+			my $var = $1;
+			if ($line =~ /^\+\s*(?:$Declare)?$var\s*=\s*(?:$var|\*\s*\(?\s*&\s*\(?\s*$var\s*\)?\s*\)?)\s*[;,]/) {
+				WARN("SELF_ASSIGNMENT",
+				     "Do not use self-assignments to avoid compiler warnings\n" . $herecurr);
+			}
+		}
+
 # check for dereferences that span multiple lines
 		if ($prevline =~ /^\+.*$Lval\s*(?:\.|->)\s*$/ &&
 		    $line =~ /^\+\s*(?!\#\s*(?!define\s+|if))\s*$Lval/) {