https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119983
Bug ID: 119983
Summary: Member function in unnamed type causes internal
compiler error in module.
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: g.mjardev at gmail dot com
Target Milestone: ---
Created attachment 61228
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61228&action=edit
preprocessed source code
Inside a C++20 module file, an unnamed struct having a member function will
trigger internal compiler error on gcc14.2.
```
$ g++ -v -save-temps -std=c++20 -fmodules-ts bug.cxx
Using built-in specs.
COLLECT_GCC=C:\msys64\ucrt64\bin\g++.exe
COLLECT_LTO_WRAPPER=C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../gcc-14.2.0/configure --prefix=/ucrt64
--with-local-prefix=/ucrt64/local --build=x86_64-w64-mingw32
--host=x86_64-w64-mingw32 --target=x86_64-w64-mingw32
--with-native-system-header-dir=/ucrt64/include --libexecdir=/ucrt64/lib
--enable-bootstrap --enable-checking=release --with-arch=nocona
--with-tune=generic
--enable-languages=c,lto,c++,fortran,ada,objc,obj-c++,rust,jit --enable-shared
--enable-static --enable-libatomic --enable-threads=posix --enable-graphite
--enable-fully-dynamic-string --enable-libstdcxx-filesystem-ts
--enable-libstdcxx-time --disable-libstdcxx-pch --enable-lto --enable-libgomp
--disable-libssp --disable-multilib --disable-rpath --disable-win32-registry
--disable-nls --disable-werror --disable-symvers --with-libiconv
--with-system-zlib --with-gmp=/ucrt64 --with-mpfr=/ucrt64 --with-mpc=/ucrt64
--with-isl=/ucrt64 --with-pkgversion='Rev2, Built by MSYS2 project'
--with-bugurl=https://github.com/msys2/MINGW-packages/issues --with-gnu-as
--with-gnu-ld --disable-libstdcxx-debug --enable-plugin
--with-boot-ldflags=-static-libstdc++ --with-stage1-ldflags=-static-libstdc++
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.2.0 (Rev2, Built by MSYS2 project)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++20' '-fmodules-ts'
'-shared-libgcc' '-mtune=generic' '-march=nocona' '-dumpdir' 'a-'
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/cc1plus.exe -E
-quiet -v -iprefix C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/
-D_REENTRANT bug.cxx -mtune=generic -march=nocona -std=c++20 -fmodules-ts
-fpch-preprocess -o a-bug.ii
ignoring nonexistent directory
"C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/include"
ignoring duplicate directory
"C:/msys64/ucrt64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../include/c++/14.2.0"
ignoring duplicate directory
"C:/msys64/ucrt64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../include/c++/14.2.0/x86_64-w64-mingw32"
ignoring duplicate directory
"C:/msys64/ucrt64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../include/c++/14.2.0/backward"
ignoring duplicate directory
"C:/msys64/ucrt64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/14.2.0/include"
ignoring nonexistent directory "D:/a/msys64/ucrt64/include"
ignoring nonexistent directory "/ucrt64/include"
ignoring duplicate directory
"C:/msys64/ucrt64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/14.2.0/include-fixed"
ignoring nonexistent directory
"C:/msys64/ucrt64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/include"
ignoring nonexistent directory "D:/a/msys64/ucrt64/include"
#include "..." search starts here:
#include <...> search starts here:
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../include/c++/14.2.0
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../include/c++/14.2.0/x86_64-w64-mingw32
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../include/c++/14.2.0/backward
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/include
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../include
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/include-fixed
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++20' '-fmodules-ts'
'-shared-libgcc' '-mtune=generic' '-march=nocona' '-dumpdir' 'a-'
C:/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/cc1plus.exe
-fpreprocessed a-bug.ii -quiet -dumpdir a- -dumpbase bug.cxx -dumpbase-ext .cxx
-mtune=generic -march=nocona -std=c++20 -version -fmodules-ts -o a-bug.s
GNU C++20 (Rev2, Built by MSYS2 project) version 14.2.0 (x86_64-w64-mingw32)
compiled by GNU C version 14.2.0, GMP version 6.3.0, MPFR version
4.2.1, MPC version 1.3.1, isl version isl-0.27-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 0ae76c501e8dc149b84d2c95ded0e2f3
bug.cxx:4:10: internal compiler error: in write_unnamed_type_name, at
cp/mangle.cc:1806
4 | void aRandomFunc()
| ^~~~~~~~~~~
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
See <https://github.com/msys2/MINGW-packages/issues> for instructions.
```
While I'm using mingw w64 ucrt version of gcc, this behavior is reproduceable
https://godbolt.org/z/5oPv5bTW7 . Code compiles with gcc 13 and generates a
compiler error for gcc 15: https://godbolt.org/z/zfeefofvG . Code works with
clang 19, haven't tested other versions of clang.
Adding a name to the type fixes error with all versions. Disabling modules and
removing all module related things also fixes the error. The variable
declaration isn't required, error can be triggered with a standalone nameless
struct.
In my limited understanding of C++, code is well-formed.
