On Wed, Apr 30, 2025 at 12:58:13PM +0200, Greg Kroah-Hartman wrote: > On Wed, Apr 30, 2025 at 04:09:18PM +0530, Naresh Kamboju wrote: > > Regressions on x86_64 with defconfig builds with clang-nightly toolchain > > on the stable-rc 6.1.136-rc1. clang-nightly is always a moving target so for the sake of the stable -rc reports, I would only focus on issues that appear with just those patches, as you should see this issue on 6.1.136. > > * x86_64, build > > - clang-nightly-lkftconfig > > - clang-nightly-x86_64_defconfig > > > > Regression Analysis: > > - New regression? Yes > > - Reproducibility? Yes > > > > Build regression: x86_64 clang-nightly net ip.h error default > > initialization of an object of type 'typeof (rt->dst.expires)' > > > > Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> > > > > ## Build error x86_64 > > include/net/ip.h:462:14: error: default initialization of an object of > > type 'typeof (rt->dst.expires)' (aka 'const unsigned long') leaves the > > object uninitialized and is incompatible with C++ > > [-Werror,-Wdefault-const-init-unsafe] > > 462 | if (mtu && time_before(jiffies, rt->dst.expires)) > > | ^ > > This isn't c++, so are you sure this isn't just a clang bug? Yes, it is intentional that this warns for C code, the clang maintainer felt that the default initialization behavior of const variables not marked as static or thread local was worth warning about by default. https://github.com/llvm/llvm-project/pull/137166 But it is going to be adjusted to allow the kernel to opt-out of the warning for aggregate members, as that triggers often in the kernel: https://github.com/llvm/llvm-project/pull/137961 The only instance of -Wdefault-const-init-var-unsafe that I have found so far is in typecheck(), which should be easy enough to clean up. Cheers, Nathan diff --git a/include/linux/typecheck.h b/include/linux/typecheck.h index 46b15e2aaefb..5b473c9905ae 100644 --- a/include/linux/typecheck.h +++ b/include/linux/typecheck.h @@ -7,8 +7,8 @@ * Always evaluates to 1 so you may use it easily in comparisons. */ #define typecheck(type,x) \ -({ type __dummy; \ - typeof(x) __dummy2; \ +({ type __dummy = {}; \ + typeof(x) __dummy2 = {}; \ (void)(&__dummy == &__dummy2); \ 1; \ })
