https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97230
Bug ID: 97230 Summary: Invocation of non-static member function on a null instance in core constant expression should not be allowed Product: gcc Version: 10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: eligorkadaf at gmail dot com Target Milestone: --- The code below should not compile according to the C++ standart. The code: class X{ public: constexpr int foo(){ return 1; } }; int main(){ constexpr auto x = ((X*)nullptr)->foo(); } Compile and run logs: $ g++-10 -v Using built-in specs. COLLECT_GCC=g++-10 COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa:hsa OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 10-20200411-0ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none,amdgcn-amdhsa,hsa --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 10.0.1 20200411 (experimental) [master revision bb87d5cc77d:75961caccb7:f883c46b4877f637e0fa5025b4d6b5c9040ec566] (Ubuntu 10-20200411-0ubuntu1) $ g++-10 -Wall -Wextra -std=c++20 bug.cpp bug.cpp: In function ‘int main()’: bug.cpp:10:20: warning: unused variable ‘x’ [-Wunused-variable] 10 | constexpr auto x = ((X*)nullptr)->foo(); | ^ There are additional non-issue warnings whether the code is compiled by gcc trunk The godbolt link: https://godbolt.org/z/rx3axf The problem is reproducible with gcc 4.8.1, gcc 5.1 and gcc 8.1 also