| Issue |
110273
|
| Summary |
'<Unable to determine byte size.>' in LLDB for `_BitInt`s larger than 128.
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
samw-improbable
|
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.
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