https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104398
Bug ID: 104398 Summary: [c++20] ICE triggered by templated class with base class containing `using enum` Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: doodspav at gmail dot com Target Milestone: --- This code triggers an internal compiler error: ------------------------------------------------ struct E { enum class type : unsigned char { UNKNOWN }; }; struct T { using enum E::type; }; template <int N> struct U : T { int ice(int x) { return static_cast<int>(UNKNOWN); } }; int main() { U<3>().ice(3); } ------------------------------------------------ Using built-in specs. COLLECT_GCC=g++-11 COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.1.0-1ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-11 --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-bootstrap --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 --disable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-11-2V7zgg/gcc-11-11.1.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-2V7zgg/gcc-11-11.1.0/debian/tmp-gcn/usr --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2 Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 11.1.0 (Ubuntu 11.1.0-1ubuntu1~20.04) COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++20' '-shared-libgcc' '-mtune=generic' '-march=x86-64' '-dumpdir' 'a-' /usr/lib/gcc/x86_64-linux-gnu/11/cc1plus -E -quiet -v -imultiarch x86_64-linux-gnu -D_GNU_SOURCE using_enum.cpp -mtune=generic -march=x86-64 -std=c++20 -fpch-preprocess -fasynchronous-unwind-tables -fstack-protector-strong -Wformat -Wformat-security -fstack-clash-protection -fcf-protection -o a-using_enum.ii ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/11" ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/include-fixed" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /usr/include/c++/11 /usr/include/x86_64-linux-gnu/c++/11 /usr/include/c++/11/backward /usr/lib/gcc/x86_64-linux-gnu/11/include /usr/local/include /usr/include/x86_64-linux-gnu /usr/include End of search list. COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++20' '-shared-libgcc' '-mtune=generic' '-march=x86-64' '-dumpdir' 'a-' /usr/lib/gcc/x86_64-linux-gnu/11/cc1plus -fpreprocessed a-using_enum.ii -quiet -dumpdir a- -dumpbase using_enum.cpp -dumpbase-ext .cpp -mtune=generic -march=x86-64 -std=c++20 -version -fasynchronous-unwind-tables -fstack-protector-strong -Wformat -Wformat-security -fstack-clash-protection -fcf-protection -o a-using_enum.s GNU C++20 (Ubuntu 11.1.0-1ubuntu1~20.04) version 11.1.0 (x86_64-linux-gnu) compiled by GNU C version 11.1.0, GMP version 6.2.0, MPFR version 4.0.2, MPC version 1.1.0, isl version isl-0.22.1-GMP GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C++20 (Ubuntu 11.1.0-1ubuntu1~20.04) version 11.1.0 (x86_64-linux-gnu) compiled by GNU C version 11.1.0, GMP version 6.2.0, MPFR version 4.0.2, MPC version 1.1.0, isl version isl-0.22.1-GMP GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: 7a79b9a038c6e5e716b693fdb4982943 using_enum.cpp: In instantiation of ‘int U<N>::ice(int) [with int N = 3]’: using_enum.cpp:19:15: required from here using_enum.cpp:13:16: internal compiler error: in tsubst_copy, at cp/pt.c:16715 13 | return static_cast<int>(UNKNOWN); | ^~~~~~~~~~~~~~~~~~~~~~~~~ 0xe306b3 internal_error(char const*, ...) ???:0 0xe27039 fancy_abort(char const*, int, char const*) ???:0 0x10ed884 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ???:0 0x10eddd9 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ???:0 0x1178f37 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x11790e8 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x1178f95 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x122150a instantiate_decl(tree_node*, bool, bool) ???:0 0xfa3850 instantiate_pending_templates(int) ???:0 0xf9f8f3 c_parse_final_cleanups() ???:0 Please submit a full bug report System is x86_64 Intel running Ubuntu 20.04.3 LTS Potentially related bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103081 (but it has a different stack trace, so not sure if it's the same bug).