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

[Matthew Sheets]

> The original file return this when compiled with gcc 12.2.0
It appears we might not be on the same page here?  The code-check snippet posted that causes the Internal Compiler Error is _not_ failing in GCC 12, 13, or 15 but in the GCC 3.4.6 cross-compiler targeting the h8300-hitachi-coff *if* it is built by GCC 15.1.1.  The GCC 3.4.6 cross-compiler targeting the h8300-hitachi-coff has not exhibited this error if built by earlier versions of GCC, such as GCC 13.3.0.  It is seeming, then, than a problem in GCC 15 is in turn causing an ICE in the GCC 3.4.6 cross-compiler it builds.

Results of the command "gcc3/gcc/cc1plus --version" for the build that still runs as expected:
GNU C++ version 3.4.6 (h8300-hitachi-coff)
        compiled by GNU C version 13.3.0.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072


Results of the command "gcc3/gcc/cc1plus --version" for the build that is now throwing Internal Compiler Errors:
GNU C++ version 3.4.6 (h8300-hitachi-coff)
        compiled by GNU C version 15.1.1 20250626.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072


The only difference is the "compiled by GNU C version."  If that GCC 3.4.6 cross-compiler targeting the h8300-hitachi-coff is built by GCC 13.3, that GCC 3.4.6 cross-compiler targeting the h8300-hitachi-coff can build the code-check snippet; if that GCC 3.4.6 cross-compiler targeting the h8300-hitachi-coff is built by GCC 15.1.1, that GCC 3.4.6 cross-compiler targeting the h8300-hitachi-coff is now errors out with Internal Compiler Errors when attempting to build that code-check snippet.

Put another way, the behavior of the GCC 3.4.6 cross-compiler targeting the h8300-hitachi-coff changes depending on whether it is built by GCC 13.3 or GCC 15.1.

I would also note that in all cases here, the GCC 3.4.6 cross-compiler is built with the "-std=gnu89" flag.

The risk here is that as things currently stand, we might no longer have a functional cc1plus in the gcc-h8300-hms package if that gcc-h8300-hms package is compiled by GCC 15.1.1.
 * https://packages.debian.org/bookworm/amd64/gcc-h8300-hms/filelist


Thank you,
Matthew