Re: [PATCH v1 2/2] ACPICA: Silence 'unused-but-set variable' warning

Rafael J. Wysocki
2022-12-30T18:18:10Z

On Fri, Dec 23, 2022 at 3:24 PM Ammar Faizi <ammarfaizi2@gnuweeb.org> wrote:
>
> From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
>
> @num_carats is used for debugging, passed to the 'ACPI_DEBUG_PRINT()'
> macro. But this macro will expand to nothing when debug is disabled,
> resulting in the following (clang-16):
>
> drivers/acpi/acpica/nsaccess.c:295:6: error: variable 'num_carats' set \
> but not used [-Werror,-Wunused-but-set-variable]
> u32 num_carats;
> ^
> 1 error generated.
>
> Move the variable declaration inside the else block to reduce the scope,
> then add '(void)num_carats' to silence the warning when debug is disabled.
>
> Cc: LLVM Mailing List <llvm@lists.linux.dev>
> Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>

ACPICA changes require (at least) a pull request to be submitted to
the upstream ACPICA project on GitHub.

If such a pull request is created, please resend the Linux patch with
a Link tag pointing to that pull request.

Thanks!

> ---
> drivers/acpi/acpica/nsaccess.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/acpica/nsaccess.c b/drivers/acpi/acpica/nsaccess.c
> index a0c1a665dfc1..d73d052c5b3b 100644
> --- a/drivers/acpi/acpica/nsaccess.c
> +++ b/drivers/acpi/acpica/nsaccess.c
> @@ -292,7 +292,6 @@ acpi_ns_lookup(union acpi_generic_state *scope_info,
> struct acpi_namespace_node *current_node = NULL;
> struct acpi_namespace_node *this_node = NULL;
> u32 num_segments;
> - u32 num_carats;
> acpi_name simple_name;
> acpi_object_type type_to_check_for;
> acpi_object_type this_search_type;
> @@ -394,6 +393,7 @@ acpi_ns_lookup(union acpi_generic_state *scope_info,
> "Path is absolute from root [%p]\n",
> this_node));
> } else {
> + u32 num_carats = 0;
> /* Pathname is relative to current scope, start there */
>
> ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
> @@ -406,7 +406,6 @@ acpi_ns_lookup(union acpi_generic_state *scope_info,
> * the parent node for each prefix instance.
> */
> this_node = prefix_node;
> - num_carats = 0;
> while (*path == (u8) AML_PARENT_PREFIX) {
>
> /* Name is fully qualified, no search rules apply */
> @@ -449,6 +448,7 @@ acpi_ns_lookup(union acpi_generic_state *scope_info,
> "Search scope is [%4.4s], path has %u carat(s)\n",
> acpi_ut_get_node_name
> (this_node), num_carats));
> + (void)num_carats;
> }
> }
>
> --
> Ammar Faizi
>