https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112621
Bug ID: 112621 Summary: g++ error: "references internal linkage entity" when compiling a module interface Product: gcc Version: 13.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: amaikinono at gmail dot com Target Milestone: --- Created attachment 56641 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56641&action=edit Preprocessed files. Here's a minimal example: ``` // class.cxx export module mod; const int default_val { 0 }; export class Example { // This line causes the problem. int value { default_val }; }; ``` Compile it: ``` $ g++ -c -std=c++20 -fmodules-ts class.cxx class.cxx:5:14: error: ‘class Example’ references internal linkage entity ‘const int default_val’ 5 | export class Example | ^~~~~~~ class.cxx:1:8: error: failed to write compiled module: Bad file data 1 | export module mod; | ^~~~~~ class.cxx:1:8: note: compiled module file is ‘gcm.cache/mod.gcm’ ``` If we don't use `default_val` in the class: ``` export module mod; const int default_val { 0 }; export class Example { int value { 0 }; }; ``` or if the file is not a module interface: ``` const int default_val { 0 }; class Example { int value { default_val }; }; ``` Then it compiles. I've also reported this at <https://stackoverflow.com/questions/77461399/g-error-references-internal-linkage-entity-when-compiling-a-module-interfac>. Outputs of `gcc -v`: Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/13.2.1/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: /build/gcc/src/gcc/configure --enable-languages=ada,c,c++,d,fortran,go,lto,objc,obj-c++ --enable-bootstrap --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --with-build-config=bootstrap-lto --with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit --enable-cet=auto --enable-checking=release --enable-clocale=gnu --enable-default-pie --enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object --enable-libstdcxx-backtrace --enable-link-serialization=1 --enable-linker-build-id --enable-lto --enable-multilib --enable-plugin --enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch --disable-werror Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 13.2.1 20230801 (GCC)