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 Lasse <charlemagnelasse@gmail.com>
Subject: Re: [PATCH v5 2/2] scripts: checkpatch: check unused parameters for
 function-like macro
Thread-Topic: [PATCH v5 2/2] scripts: checkpatch: check unused parameters for
 function-like macro
Thread-Index: AQHag9MBE6nuZEX6x0OitxYUtdLwcLFSs1aAgAFq0i4=
Date: Tue, 2 Apr 2024 00:16:40 +0000
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=0A=
> On Mon, 2024-04-01 at 14:21 +1300, Barry Song wrote:=0A=
> > From: Xining Xu <mac.xxn@outlook.com>=0A=
> >=0A=
> > If function-like macros do not utilize a parameter, it might result in =
a=0A=
> > build warning.  In our coding style guidelines, we advocate for utilizi=
ng=0A=
> > static inline functions to replace such macros.  This patch verifies=0A=
> > compliance with the new rule.=0A=
> >=0A=
> > For a macro such as the one below,=0A=
> >=0A=
> >  #define test(a) do { } while (0)=0A=
> >=0A=
> > The test result is as follows.=0A=
> >=0A=
> >  ERROR: Parameter 'a' is not used in function-like macro, please use st=
atic=0A=
> >  inline instead=0A=
> >  #21: FILE: mm/init-mm.c:20:=0A=
> >  +#define test(a) do { } while (0)=0A=
> =0A=
> This is no longer true.=0A=
> Please update the ERROR->WARN and message as below=0A=
> =0A=
> Ideally, this would have an update to=0A=
> Documentation/dev-tools/checkpatch.rst=0A=
> =0A=
> to describe the new --verbose message type=0A=
=0A=
Hi Joe,=0A=
=0A=
Thank you for the comments, here's the code:=0A=
=0A=
+# check if this is an unused argument=0A=
+if ($define_stmt !~ /\b$arg\b/) {=0A=
+	WARN("MACRO_ARG_UNUSED",=0A=
+		"Argument '$arg' is not used in function-like macro\n" . "$herectx");=0A=
+}=0A=
=0A=
and here's the document for it which is inserted into the "Macros, Attribut=
es and=0A=
Symbols" section of checkpatch.rst starting from line 909:=0A=
+=0A=
+  **MACRO_ARG_UNUSED**=0A=
+    If function-like macros do not utilize a parameter, it might result=0A=
+    in a build warning. We advocate for utilizing static inline functions=
=0A=
+    to replace such macros.=0A=
+    For example, for a macro as below::=0A=
+=0A=
+      #define test(a) do { } while (0)=0A=
+=0A=
+    there would be a warning as below::=0A=
+=0A=
+      WARNING: Parameter 'a' is not used in function-like macro, please us=
e=0A=
+      static inline instead.=0A=
=0A=
Please let me know if the document needs further re-wording to make it help=
ful enough=0A=
to the readers.=0A=
=0A=
Thanks,=0A=
Xining=0A=