<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/110273>110273</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            '<Unable to determine byte size.>' in LLDB for `_BitInt`s larger than 128.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          samw-improbable
      </td>
    </tr>
</table>

<pre>
    When I compile the code below with `clang main.cc -o main --std=c++23 -stdlib=libc++ -lc++ -g -O0`.
```c++
#include <iostream>

int main(int argc, char **argv) {
  _BitInt(64) i64 = 42;   // Works
  _BitInt(128) i128 = 42; // Works
  _BitInt(129) i129 = 42; // LLDB says '<Unable to determine byte size.>'
  _BitInt(256) i256 = 42; // LLDB says '<Unable to determine byte size.>'

  std::cout << "Hello, world!" << std::endl;
}
```

When I inspect these variables with LLDB, I get `<Unable to determine byte size.>` for the `_BitInt`s with a size larger than 128.

```
(lldb) target create "main"
Current executable set to '/home/sam/dev/lldb-bug/main' (x86_64).
(lldb) b main
Breakpoint 1: where = main`main + 15 at main.cc:4:15, address = 0x000000000000123f
(lldb) r
Process 1784543 launched: '/home/sam/dev/lldb-bug/main' (x86_64)
Process 1784543 stopped
* thread #1, name = 'main', stop reason = breakpoint 1.1
    frame #0: 0x000055555555523f main`main(argc=1, argv=0x00007fffffffddd8) at main.cc:4:15
   1    #include <iostream>
   2   
   3    int main(int argc, char **argv) {
-> 4      _BitInt(64) i64 = 42;   // Works
   5      _BitInt(128) i128 = 42; // Works
   6      _BitInt(129) i129 = 42; // LLDB says '<Unable to determine byte size.>'
   7 _BitInt(256) i256 = 42; // LLDB says '<Unable to determine byte size.>'
(lldb) frame variable
(int) argc = 1
(char **) argv = 0x00007fffffffddd8
(long) i64 = 140737353812080
(__int128) i128 = 115647419195831250335205442705798252522
(void) i129 = <Unable to determine byte size.>

(void) i256 = <Unable to determine byte size.>
```

I'm working in a codebase that makes wide use of `_BitInt(256)`, so fixing this would be super helpful! Or even if there's some plugin or something I can use with LLDB as a temporary fix would be much appreciated.

I've reproduced this bug in versions 18.1.8 and 19.1.0 of both clang and lldb.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy8Vs1u47ARfhr6MrBADvXngw9OvEYDLLC9FHsMKHFssZFEgaScpE9fkLYSb7Jo00VbIYglkt_8zzdU3pvTSLRlxR0r9is1h866rVfD89oMk7ONanpaNVa_bn92NMIDtHaYTE8QOoLWaoKGevsMzyZ0wEre9mo8waDMmLUtrG16hfXaB83kvmV4x_AOJcSF3jRM7nvTXJdh3b-9nWD9g7OSZ4zvGd-xkl_-rgeuqyjN2PazJmDy3lgfHKmByW_X7fTfjCEZwbCOr8qdWob30HbKAcMdw51ypzPDDbDqKhfg8c6EhzEwrMs8bpkyByb3kCOTdwDA8MDwAD-te_KfMQLrBBJY36D-HWZzxWw-Y75_39-BV68eGFZM3v9tjHmBYEFTIDeYkaB5DQTe_IOyGACsPqvAokwqsCj_myoWRSnFOyZ3rZ1DTAiT98AQ_0J9b2PIn63rNUPBEJftNwyNumdyyWu1_5D2W03XQjSjn6gNsRA9wVk5Ew32l0qM3kSVD3CiEOvySx6VHI7WpdJmJV8CV_KrUJVOQq_cieIpNYLAOru17aPBWPe9bmLUQ0QFaB2pQDEsl5rEy8H72TkaA9ALtXNIdnoK0dYYZjx0diCGB68GhgdNZ4aHKHjdzCeGh4uoChjWL3X5mEo2-2RBc2mDtHznSD1NNjaEYHIHzx05SkWRzpQ8tW3sRFGACktDM7nLmdyJIsZWae3I-4TiL_zmESiPn9S7y8pfnW0jSlR1XuQSejWPbUexDP7Y199L9sFOE-nFkB2EzpHSwFCKaP-ohovLDKur1LgcYeBIeTum3eYmVJlYih3g6BIeJY-mXwJQLA_K420kGdaJd-Q-aU6EI_cXTHW8PFrrxBq_i_aiVEDinn_JegCA8dTyISPmD0hwzeQ3yCE9f0KHUHzEfp0WofyM_R_RI1T_B4Z874JL1Sxs9bZtovpNyktSLN52blJ0PXG-6bhfiudNlx1Pt1kSOa9kJQtZC-T1OzU9PpoxfEyKEEWZV7nYiE1RS4EFl7JAXuQ5VryoNjUWWCy0xbA-W6N_ycyXInNLmTcylrj_BzJ-NyEeYkfHcfNkxhOYEVS6qjTKx3tLarCnNCk0wewJ7PGW75cyiEIjH1g4mpcoKHTGw7Odew0NgZ8nctBRPx3nnqGAHw7oTCOYY5wgjhhWHrwdCKZ-PpkRrEufoYvCHqBVY9L-NrBAeVAQaJisU-41qn1XN8xtB2qaHLVGBdLZR4fPBI4mZ_Xckr7Y2szJ-zM5b-zoQdSZyGpQowaxyUTGo-eNDR1crm1xIxZqttJbqTdyo1a0FRVWeV6ixFW35aoRueKCkMuc1yhQa6F0eWzqZnMs9MpskWPON1iJXHCJ2ZHrRhVUNtRWelMolnMalOmzvj8PmXWnlfF-pq0QHCu56lVDvU_3UcSRniHtxjlZ7FduG0FxEHiW89744N_FBBN62n69NWNkUtTjyP8w7j-O-NXs-m0XwuTjbSXRwcmEbm6y1g5pPp2Xn_Xk7N-pDQwPyXTP8HD17bzFfwYAAP__PkJCrg">