[PATCH] ACPICA: Silent warnings about empty body in if/else statement

[PATCH] ACPICA: Silent warnings about empty body in if/else statement

[Jean Delvare]

When ACPI debugging is disabled, I see warnings like this one:

drivers/i2c/busses/i2c-scmi.c: In function "acpi_smbus_cmi_add_cap":
drivers/i2c/busses/i2c-scmi.c:328:39: warning: suggest braces around empty body in an "else" statement [-Wempty-body]
drivers/i2c/busses/i2c-scmi.c:338:12: warning: suggest braces around empty body in an "else" statement [-Wempty-body]

It is caused by ACPI_DEBUG_PRINT (or other similar macros) to resolve
to nothing. Make them resolve to the classic "do {} while (0)" construct
instead when the compiler likes that, to silent all such warnings.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
---
 include/acpi/acoutput.h |   40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)

--- linux-3.12-rc4.orig/include/acpi/acoutput.h	2013-09-24 00:41:09.000000000 +0200
+++ linux-3.12-rc4/include/acpi/acoutput.h	2013-10-07 11:23:57.928436503 +0200
@@ -427,22 +427,32 @@
 /*
  * This is the non-debug case -- make everything go away,
  * leaving no executable debug code!
+ *
+ * Note: the ACPI_DO_WHILE0 macro is used to prevent some compilers from
+ * complaining about these constructs. On other compilers the do...while
+ * adds some extra code, so this feature is optional.
  */
-#define ACPI_DEBUG_PRINT(pl)
-#define ACPI_DEBUG_PRINT_RAW(pl)
-#define ACPI_DEBUG_EXEC(a)
-#define ACPI_DEBUG_ONLY_MEMBERS(a)
-#define ACPI_FUNCTION_NAME(a)
-#define ACPI_FUNCTION_TRACE(a)
-#define ACPI_FUNCTION_TRACE_PTR(a, b)
-#define ACPI_FUNCTION_TRACE_U32(a, b)
-#define ACPI_FUNCTION_TRACE_STR(a, b)
-#define ACPI_FUNCTION_ENTRY()
-#define ACPI_DUMP_STACK_ENTRY(a)
-#define ACPI_DUMP_OPERANDS(a, b, c)
-#define ACPI_DUMP_ENTRY(a, b)
-#define ACPI_DUMP_PATHNAME(a, b, c, d)
-#define ACPI_DUMP_BUFFER(a, b)
+#ifdef ACPI_USE_DO_WHILE_0
+#define ACPI_DO_WHILE0                  do {} while (0)
+#else
+#define ACPI_DO_WHILE0
+#endif
+
+#define ACPI_DEBUG_PRINT(pl)            ACPI_DO_WHILE0
+#define ACPI_DEBUG_PRINT_RAW(pl)        ACPI_DO_WHILE0
+#define ACPI_DEBUG_EXEC(a)              ACPI_DO_WHILE0
+#define ACPI_DEBUG_ONLY_MEMBERS(a)      ACPI_DO_WHILE0
+#define ACPI_FUNCTION_NAME(a)           ACPI_DO_WHILE0
+#define ACPI_FUNCTION_TRACE(a)          ACPI_DO_WHILE0
+#define ACPI_FUNCTION_TRACE_PTR(a, b)   ACPI_DO_WHILE0
+#define ACPI_FUNCTION_TRACE_U32(a, b)   ACPI_DO_WHILE0
+#define ACPI_FUNCTION_TRACE_STR(a, b)   ACPI_DO_WHILE0
+#define ACPI_FUNCTION_ENTRY()           ACPI_DO_WHILE0
+#define ACPI_DUMP_STACK_ENTRY(a)        ACPI_DO_WHILE0
+#define ACPI_DUMP_OPERANDS(a, b, c)     ACPI_DO_WHILE0
+#define ACPI_DUMP_ENTRY(a, b)           ACPI_DO_WHILE0
+#define ACPI_DUMP_PATHNAME(a, b, c, d)  ACPI_DO_WHILE0
+#define ACPI_DUMP_BUFFER(a, b)          ACPI_DO_WHILE0
 #define ACPI_IS_DEBUG_ENABLED(level, component) 0
 
 /* Return macros must have a return statement at the minimum */


-- 
Jean Delvare
Suse L3

Re: [PATCH] ACPICA: Silent warnings about empty body in if/else statement

[Rafael J. Wysocki]

On Monday, October 07, 2013 11:45:01 AM Jean Delvare wrote:
> When ACPI debugging is disabled, I see warnings like this one:
> 
> drivers/i2c/busses/i2c-scmi.c: In function "acpi_smbus_cmi_add_cap":
> drivers/i2c/busses/i2c-scmi.c:328:39: warning: suggest braces around empty body in an "else" statement [-Wempty-body]
> drivers/i2c/busses/i2c-scmi.c:338:12: warning: suggest braces around empty body in an "else" statement [-Wempty-body]
> 
> It is caused by ACPI_DEBUG_PRINT (or other similar macros) to resolve
> to nothing. Make them resolve to the classic "do {} while (0)" construct
> instead when the compiler likes that, to silent all such warnings.

The rule is that ACPICA patches need to go via upstream ACPICA, so I CCed
the ACPICA maintainers.

Thanks!

> Signed-off-by: Jean Delvare <jdelvare@suse.de>
> Cc: Len Brown <lenb@kernel.org>
> Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
> ---
>  include/acpi/acoutput.h |   40 +++++++++++++++++++++++++---------------
>  1 file changed, 25 insertions(+), 15 deletions(-)
> 
> --- linux-3.12-rc4.orig/include/acpi/acoutput.h	2013-09-24 00:41:09.000000000 +0200
> +++ linux-3.12-rc4/include/acpi/acoutput.h	2013-10-07 11:23:57.928436503 +0200
> @@ -427,22 +427,32 @@
>  /*
>   * This is the non-debug case -- make everything go away,
>   * leaving no executable debug code!
> + *
> + * Note: the ACPI_DO_WHILE0 macro is used to prevent some compilers from
> + * complaining about these constructs. On other compilers the do...while
> + * adds some extra code, so this feature is optional.
>   */
> -#define ACPI_DEBUG_PRINT(pl)
> -#define ACPI_DEBUG_PRINT_RAW(pl)
> -#define ACPI_DEBUG_EXEC(a)
> -#define ACPI_DEBUG_ONLY_MEMBERS(a)
> -#define ACPI_FUNCTION_NAME(a)
> -#define ACPI_FUNCTION_TRACE(a)
> -#define ACPI_FUNCTION_TRACE_PTR(a, b)
> -#define ACPI_FUNCTION_TRACE_U32(a, b)
> -#define ACPI_FUNCTION_TRACE_STR(a, b)
> -#define ACPI_FUNCTION_ENTRY()
> -#define ACPI_DUMP_STACK_ENTRY(a)
> -#define ACPI_DUMP_OPERANDS(a, b, c)
> -#define ACPI_DUMP_ENTRY(a, b)
> -#define ACPI_DUMP_PATHNAME(a, b, c, d)
> -#define ACPI_DUMP_BUFFER(a, b)
> +#ifdef ACPI_USE_DO_WHILE_0
> +#define ACPI_DO_WHILE0                  do {} while (0)
> +#else
> +#define ACPI_DO_WHILE0
> +#endif
> +
> +#define ACPI_DEBUG_PRINT(pl)            ACPI_DO_WHILE0
> +#define ACPI_DEBUG_PRINT_RAW(pl)        ACPI_DO_WHILE0
> +#define ACPI_DEBUG_EXEC(a)              ACPI_DO_WHILE0
> +#define ACPI_DEBUG_ONLY_MEMBERS(a)      ACPI_DO_WHILE0
> +#define ACPI_FUNCTION_NAME(a)           ACPI_DO_WHILE0
> +#define ACPI_FUNCTION_TRACE(a)          ACPI_DO_WHILE0
> +#define ACPI_FUNCTION_TRACE_PTR(a, b)   ACPI_DO_WHILE0
> +#define ACPI_FUNCTION_TRACE_U32(a, b)   ACPI_DO_WHILE0
> +#define ACPI_FUNCTION_TRACE_STR(a, b)   ACPI_DO_WHILE0
> +#define ACPI_FUNCTION_ENTRY()           ACPI_DO_WHILE0
> +#define ACPI_DUMP_STACK_ENTRY(a)        ACPI_DO_WHILE0
> +#define ACPI_DUMP_OPERANDS(a, b, c)     ACPI_DO_WHILE0
> +#define ACPI_DUMP_ENTRY(a, b)           ACPI_DO_WHILE0
> +#define ACPI_DUMP_PATHNAME(a, b, c, d)  ACPI_DO_WHILE0
> +#define ACPI_DUMP_BUFFER(a, b)          ACPI_DO_WHILE0
>  #define ACPI_IS_DEBUG_ENABLED(level, component) 0
>  
>  /* Return macros must have a return statement at the minimum */
> 
> 
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPICA: Silent warnings about empty body in if/else statement

[Jean Delvare]

Le Monday 07 October 2013 à 14:11 +0200, Rafael J. Wysocki a écrit :
> On Monday, October 07, 2013 11:45:01 AM Jean Delvare wrote:
> > When ACPI debugging is disabled, I see warnings like this one:
> > 
> > drivers/i2c/busses/i2c-scmi.c: In function "acpi_smbus_cmi_add_cap":
> > drivers/i2c/busses/i2c-scmi.c:328:39: warning: suggest braces around empty body in an "else" statement [-Wempty-body]
> > drivers/i2c/busses/i2c-scmi.c:338:12: warning: suggest braces around empty body in an "else" statement [-Wempty-body]
> > 
> > It is caused by ACPI_DEBUG_PRINT (or other similar macros) to resolve
> > to nothing. Make them resolve to the classic "do {} while (0)" construct
> > instead when the compiler likes that, to silent all such warnings.
> 
> The rule is that ACPICA patches need to go via upstream ACPICA, so I CCed
> the ACPICA maintainers.

Thanks Rafael. Maybe MAINTAINERS should be adjusted accordingly.
Contributors can't guess.


Thanks,
-- 
Jean Delvare
Suse L3 Support

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Re: [PATCH] ACPICA: Silent warnings about empty body in if/else statement

[Rafael J. Wysocki]

On Monday, October 07, 2013 07:08:00 PM Jean Delvare wrote:
> Le Monday 07 October 2013 à 14:11 +0200, Rafael J. Wysocki a écrit :
> > On Monday, October 07, 2013 11:45:01 AM Jean Delvare wrote:
> > > When ACPI debugging is disabled, I see warnings like this one:
> > > 
> > > drivers/i2c/busses/i2c-scmi.c: In function "acpi_smbus_cmi_add_cap":
> > > drivers/i2c/busses/i2c-scmi.c:328:39: warning: suggest braces around empty body in an "else" statement [-Wempty-body]
> > > drivers/i2c/busses/i2c-scmi.c:338:12: warning: suggest braces around empty body in an "else" statement [-Wempty-body]
> > > 
> > > It is caused by ACPI_DEBUG_PRINT (or other similar macros) to resolve
> > > to nothing. Make them resolve to the classic "do {} while (0)" construct
> > > instead when the compiler likes that, to silent all such warnings.
> > 
> > The rule is that ACPICA patches need to go via upstream ACPICA, so I CCed
> > the ACPICA maintainers.
> 
> Thanks Rafael. Maybe MAINTAINERS should be adjusted accordingly.
> Contributors can't guess.

That actually is a good idea.  I think we'll do that.

Thanks!

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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