[llvm] [ADT] Add standalone_debug attribute to SmallVectorBase (PR #82527)

[Alexander Richardson via llvm-commits]

arichardson wrote:

Thanks for pointing me at this bug! That absolutely makes sense since I'm trying to print a variable inside libClangDriver.so. I guess LLVM_BUILD_LLVM_DYLIB=ON will not help either since I'm debugging clang. It also explains why STL types are broken in the debugger unless I use GDB (but GDB takes forever to start up so I prefer LLDB).

I agree with @dwblaikie that it's not great to add a workaround here just for LLDB if this also affects lots of other types. Maybe the better solution would be to add error handling to the lldbDataFormatters.py script that suggests recompiling `-fstandalone-debug` if it fails to look up the SmallVector members?

Another option could be to modify the CMake files to add -fstandalone-debug when LLVM is configured with BUILD_SHARED_LIBS?

https://github.com/llvm/llvm-project/pull/82527