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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43569921f6esm44884589f8f.4.2026.01.22.06.55.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jan 2026 06:55:58 -0800 (PST) Date: Thu, 22 Jan 2026 14:55:56 +0000 From: David Laight To: Andy Shevchenko Cc: kernel test robot , Nathan Chancellor , Greg Kroah-Hartman , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Mathieu Desnoyers , Arnd Bergmann , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Yury Norov , Jani Nikula , Vincent Mailhol , Kees Cook , Andrew Morton , oe-kbuild-all@lists.linux.dev, Linux Memory Management List Subject: Re: [PATCH next 11/14] bit: Strengthen compile-time tests in GENMASK() and BIT() Message-ID: <20260122145556.7d72f217@pumpkin> In-Reply-To: References: <20260121145731.3623-12-david.laight.linux@gmail.com> <202601221237.soiAkwkN-lkp@intel.com> <20260122103337.26473d1c@pumpkin> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: of16hean8tbu6nnmobkzf93dubcbujnz X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 51E7EC0009 X-HE-Tag: 1769093760-845408 X-HE-Meta: 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 WLtA9na5 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 22 Jan 2026 16:26:44 +0200 Andy Shevchenko wrote: > On Thu, Jan 22, 2026 at 10:33:37AM +0000, David Laight wrote: > > On Thu, 22 Jan 2026 12:41:22 +0800 > > kernel test robot wrote: > > > > sparse warnings: (new ones prefixed by >>) > > > kernel/kthread.c: note: in included file (through include/linux/bitmap.h, include/linux/cpumask.h, arch/mips/include/asm/processor.h, ...): > > > >> include/linux/find.h:209:45: sparse: sparse: Variable length array is used. > > > > Can we stop sparse complaining about sizeof(VLA) ? > > First of all, the LKP should install the fork of sparse by Al Viro. That will > fix tons of warnings that are related to modules and speed up the process > itself. > The problem I have is I want to generate a compile time error inside: __builtin_choose_expr(__is_constexpr(x), x && error_a(), statically_true(y) && error_b()); Neither static_assert() nor a negative bitfield can be used in error_a() because they are errors when x isn't isn't a 'constexpr', There is less of a problem for error_b() it can contain a function call, but can't contain {( ...)}. One of the compiler complained about sizeof (char [-!!(expr)]) as well. I'm not sure of anything else that can be use to get an error. I could use 0 >> -1 but that is only a warning, at least the error message is related to the bug. Any other ideas? David