[Bug lto/123125] New: [RISCV] lto1: sorry, unimplemented: Currently the ‘V’ implementation requires the ‘M’ extension

[vhaudiquet343 at hotmail dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123125

            Bug ID: 123125
           Summary: [RISCV] lto1: sorry, unimplemented: Currently the ‘V’
                    implementation requires the ‘M’ extension
           Product: gcc
           Version: 15.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vhaudiquet343 at hotmail dot fr
  Target Milestone: ---

Running the `lto1` command on a riscv64 (Ubuntu 26.04 development preview)
virtual machine (-cpu rva23s64, which does have the M extension as well as V)
gives a weird warning message:

ubuntu@ubuntu:~$ /usr/libexec/gcc/riscv64-linux-gnu/15/lto1
<built-in>: sorry, unimplemented: Currently the ‘V’ implementation requires the
‘M’ extension

That seems wrong.
This does not seem to break anything, but the extension detection logic might
be wrong?