<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/123075>123075</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [flang] CP2K fails to compile due to assertion 'result && "Fell off the end of a type-switch"'
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            flang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          pawosm-arm
      </td>
    </tr>
</table>

<pre>
    I'm building CP2K from this SHA: https://github.com/cp2k/cp2k/commit/3905869e4cb94c1f9fc3fc3ecca6c77dece2aa01 since the next SHA (https://github.com/cp2k/cp2k/commit/4837b70ec08ad54fc946d169bea3b08710f565ab ) introduces a new code which flang cannot compile (see https://github.com/llvm/llvm-project/issues/108827 closed issue but the problem still occurs). Unfortunately, very late in the process, the compilation fails on the https://github.com/cp2k/cp2k/blob/master/src/transport.F file as such:

```
llvm/ADT/TypeSwitch.h:121: llvm::TypeSwitch<T, ResultT>::operator ResultT() [with T = mlir::Type; ResultT = {anonymous}::TargetAArch64::NRegs]: Assertion `result && "Fell off the end of a type-switch"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
```

Execution command line (including `fypp` preprocessing):

```
tools/build_utils/fypp -n src/transport.F transport.F90 mpifort -fno-backslash -c -D__FFTW3 -D__parallel -D__SCALAPACK -ffp-contract=fast -O3 -fopenmp -mcpu=native -ffree-form -D__COMPILE_ARCH="\"Linux-LLVM-flang\"" -D__COMPILE_DATE="\"Tue 14 Jan 23:36:31 UTC 2025\"" -D__COMPILE_HOST="\"host\"" -D__COMPILE_REVISION="\"git:3905869\"" -D__DATA_DIR="\"data\"" -D__SHORT_FILE__="\"transport.F\"" -I'src/' -I'obj/Linux-LLVM-flang/psmp/exts/dbcsr' transport.F90
```

The problem goes away after commenting out the following line: https://github.com/cp2k/cp2k/blob/f8b3abcd3ac413146004a9ebf8d71317c9449627/src/transport.F#L419

</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJykVk9v2z4S_TT0ZSBDIvXHOvig2BGSbdoEids9BhQ1sthSpEBScfztF5TdxtkGi-2vgCCJ5JshZ-bpjbhzcq8R1yS7Itl2wSffG7se-cG4IeJ2WDSmPa5vCS0GaCapWqn3sHmgn6CzZgDfSwdPNxVhFfTej46witCa0HovfT81S2EGQmsx0h8XDzMM0hNaszLOVnmJqWjKVCRd2QnWCYZC8FwURYsCKedxAk5qgeB7BI2vPmwIhK7-fMN0xYqmiFHEK95maSfKNG-TvGyQsyZeFUncZXnGGyC0BKm9Ne0k0AEHjQcQpkU49FL00Cmu9yC41saDMMMoFYYjOcT_lQelXn4-otGa7yjCqaRzEzpC6yRerWgBQhmHLczT0Ex-Dny0plE4gPNSKTBCTNYRWi7hq-6M9ZPmHtWR0A28oD2C4h5B6p-mAp0La2F4Oi730mjouFQOzAn3f-ezUaYhtB6482gJrZ0VhNbecu1GY_2yhi7kgztwk-iDx3i-8vh8xdU5E9V2R2i9O474dJBe9MuATmgS-DRDWKDW2zphm12I4xHdpPyOsOsTwoxouTf21wJdhRKS7OogfQ87IGwLg5L2zSFhVz_R8yoprrg2-jiYyZFiewZyu0dfVVb0eXqa-vKIe0eyAIDKObRzIkke29kZEJoTmgOhtMZQqa6bk4u6BdMBB38cMXKnaCgltJiLgO2SxNXD3XX1dA1uagbpgUMz7cFiyCl48xfEAq5bkFqoqT19RsJy10PDxQ9vucDlf1WHxNX1K4ppDi18PcFeST1z_OQn6ADJ4-44jiSPYbR4ppnUe0LLD4vujVHhOLOQPE9ezqPgAiINv7Po4r2MYRhlYDpEnTZROLpTIYhIQLR9fq7r3b_Z_DZyy5VCNQ-eNtVd9VBtPkHUdWMkjA4Be8K2HXceonsGUWdG1MMI0SDGibCt5l6-YDCwiFFn7DC72tx_fri9u36uHjc3hG1D8bINofRO6uk1urv79jmaZeE0Syh9Z7WtdteXVrsJIUnhX1wDZYRVLA-3BL7uNkBjmn3s5eb-aXfppTfOf4x8vP52-3R7_-USvZc-bHJS3fdm22pXPW9vHy_hLff8Perp5v5x91wH_8-XyItCXRiErnEqamD5PDTNd0Lr3zJG69ENI6E1vvpAibYRzgajdwz4naS7C2HcmyDUB34E3nm0M21R-8BTc9bQzihlDmEmcPmPetZZ8rpVw3gjWsZFmrAkzeM45SU23aotEpYUokzTMqfFR6JIKLtLk5LE1aJds7ZkJV_gOilYXmYFK9NFv-a0ixkykXdZmSJnSclWhWC0FUVeJIIt5DpwI06SLMnjMkuXcd6mvMVylWQlbdOYpDEOXKplkIKlsfvFLALrhLK4yBaKN6jc3O0pPeeehsZv17N2NNPekTRW0nn35sJLr-ZfhDO_t-c_gLl5ePOrAbYThiF_U0Va_FNVXExWrf-ilZ7ifVnT_wQAAP__YGi_yg">