Messages in this thread | | | From | "Moore, Robert" <> | Subject | RE: [PATCH] ACPICA: fix -Wfallthrough | Date | Fri, 13 Nov 2020 21:01:24 +0000 |
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I can do it this way:
In the global header actypes.h:
#ifndef ACPI_FALLTHROUGH #define ACPI_FALLTHROUGH #endif
In the gcc-specific header (acgcc.h):
#define ACPI_FALLTHROUGH __attribute__((__fallthrough__))
This would not be #defined in the MSVC-specific header (acmsvc.h) -- thus using the default (null) in actypes.h (The per-environment headers are always included first).
(We do all macros in upper case, prefixed with "ACPI_")
If you can update your patch to use ACPI_FALLTHROUGH, I can do the rest (above).
Thanks, Bob
-----Original Message----- From: Joe Perches <joe@perches.com> Sent: Friday, November 13, 2020 8:30 AM To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>; Nick Desaulniers <ndesaulniers@google.com> Cc: Moore, Robert <robert.moore@intel.com>; Kaneda, Erik <erik.kaneda@intel.com>; Wysocki, Rafael J <rafael.j.wysocki@intel.com>; Gustavo A . R . Silva <gustavoars@kernel.org>; clang-built-linux@googlegroups.com; Len Brown <lenb@kernel.org>; linux-acpi@vger.kernel.org; devel@acpica.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH] ACPICA: fix -Wfallthrough
On Fri, 2020-11-13 at 09:14 +0100, Miguel Ojeda wrote: > On Fri, Nov 13, 2020 at 1:09 AM Nick Desaulniers > <ndesaulniers@google.com> wrote: > > > > Thank you for the explicit diagnostics observed. Something fishy is > > going on though, https://godbolt.org/z/Gbxbxa is how I expect MSVC > > to handle include/linux/compiler_attributes.h. > > > > The C preprocessor should make it such that MSVC never sees > > `__attribute__` or `__fallthrough__`; that it does begs the question. > > That would seem to imply that `#if __has_attribute(__fallthrough__)` > > somehow evaluates to true on MSVC, but my godbolt link shows it does > > not. > > > > Could the upstream ACPICA project be #define'ing something that > > could be altering this? (Or not #define'ing something?) > > > > Worst case, we could do as Joe Perches suggested and disable > > -Wfallthrough for drivers/acpi/acpica/. > > I agree, something is fishy. MSVC has several flags for conformance > and extensions support, including two full C preprocessors in newer > versions; which means we might be missing something, but I don't see > how the code in compiler_attributes.h could be confusing MSVC even in > older non-conforming versions.
I believe this has nothing to do with linux and only to do with compiling acpica for other environments like Windows.
From: https://acpica.org/
The ACPI Component Architecture (ACPICA) project provides an operating system (OS)-independent reference implementation of the Advanced Configuration and Power Interface Specification (ACPI).
It can be easily adapted to execute under any host OS.
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