[Debian-lego-team] FYI: GCC 15 appears to generate faulty h8300-hitachi-coff cross-compiler binaries

[Matthew Sheets]

In attempting to compile the h8300-hitachi-coff-toolchain with GCC 15, the binaries generated by GCC 15 appears to erroneously cause an Internal Compiler Error within the h8300-hitachi-coff cross-compiler.

In particular, the following "checking for exception model to use" configure test that used to pass with a GCC 13-built cross-compiler now fails with a GCC 15-built cross-compiler:

Command with relative paths:
build/gcc3/gcc/cc1plus -quiet -nostdinc++ -nostdinc -iprefix build/gcc3/gcc/../lib/gcc/h8300-hitachi-coff/3.4.6/ -isystem build/gcc3/gcc/include -isystem build/gcc3/h8300-hitachi-coff/newlib/include -isystem build/gcc3/h8300-hitachi-coff/newlib/targ-include -isystem ../sym-combined/gcc3/newlib/libc/include conftest.cc -quiet -dumpbase conftest.cc -auxbase conftest -g -Os -o - -frandom-seed=0

The "conftest.cc" file:
struct S { ~S(); };
void bar();
void foo()
{
  S s;
  bar();
}


The error message in config.log:
configure:4988: checking for exception model to use
…
configure:5021: internal compiler error: in grokdeclarator, at cp/decl.c:6783
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.
Preprocessed source stored into /tmp/ccqoUKPU.out file, please attach this to your bugreport.
configure:5035: $? = 1
configure:5062: error: unable to detect exception model


OpenSUSE Tumbleweed had just updated its GCC package to 15 last month [1] (version was 15.1.1 25250626 at the time of this test), and GCC 13.3-based compilers on both Ubuntu and openSUSE Tumbleweed have been able to build the cross-compiler without issue.  At the moment, I'm not sure of the best way to narrow the scope of this issue such that the more specific issues apparently within GCC 15 might see corrective action.


Thank you,
Matthew

[1] https://news.opensuse.org/2025/07/03/tw-monthly-update-june/