https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127453
Bug ID: 127453
Summary: internal compiler error: in declare_module
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: 0599jiangyc at gmail dot com
Target Milestone: ---
The following code:
```cpp
module;
void foo() {
export module M; // { dg-error "unexpected module directive" }
};
export module A;
```
Resulted in this output:
```
/tmp/test.cc: In function 'void foo()':
/tmp/test.cc:3:1: error: unexpected module directive
3 | export module M; // { dg-error "unexpected module directive" }
| ^~~~~~
/tmp/test.cc: At global scope:
/tmp/test.cc:5:16: internal compiler error: in declare_module, at
cp/module.cc:22899
5 | export module A;
| ^
0x3046dcb internal_error(char const*, ...)
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-src/gcc/diagnostic-global-context.cc:787
0xdd9a1e fancy_abort(char const*, int, char const*)
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-src/gcc/diagnostics/context.cc:1813
0x828e20 declare_module(module_state*, unsigned long, bool, tree_node*,
cpp_reader*)
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-src/gcc/cp/module.cc:22899
0xfefc65 cp_parser_module_declaration
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-src/gcc/cp/parser.cc:17321
0x1025088 cp_parser_translation_unit
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-src/gcc/cp/parser.cc:5568
0x1025088 c_parse_file()
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-src/gcc/cp/parser.cc:57910
0x11b8619 c_common_parse_file()
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-src/gcc/c-family/c-opts.cc:1437
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-install/libexec/gcc/x86_64-pc-linux-gnu/17.0.0/cc1plus
-quiet -imultiarch x86_64-linux-gnu -D_GNU_SOURCE /tmp/test.cc -quiet -dumpbase
test.cc -dumpbase-ext .cc -mtune=generic -march=x86-64 -O1 -Wno-global-module
-std=c++98 -ftrapv -fmodules -o /tmp/ccmOsnyW.s
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
```
To reproduce:
```
/home/fuzz/WorkSpace/fusion-fuzz/projects/gcc/gcc-install/bin/g++ -fmodules
./test.cc
```
Compiler version:
```
g++ (GCC) 17.0.0 20260917 (experimental)
Copyright (C) 2026 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
```
Commit:
```
d373724d1ddeef9b322b6b6078fc1de8dbe27791
```
Build configuration:
```
./configure --enable-languages=c,c++ --disable-bootstrap
--enable-checking=yes,extra,rtl --disable-multilib --disable-libsanitizer
--disable-nls --disable-werror
```
Operating System:
```
Ubuntu 22.04 Host, Docker fusion-fuzz-gcc:latest
```
*This bug was found by
[fusion-fuzz](https://github.com/fusion-fuzz/fusion-fuzz)*
