[Lldb-commits] [lldb] [lldb][test] Skip libc++ tests if it is linked statically (PR #113935)

[Pavel Labath via lldb-commits]

labath wrote:

> Agree with Pavel.

I'm not sure you do :P

> 
> > When libcxx is linked with a program as an archive of static libraries,
> > functions that aren't used in the program are omitted.
> 
> This really isn't the problem. The tests _want_ those symbols to not be present and make sure that we can find those in the `std` Clang module. So I'm pretty sure the issue isn't about what symbols get stripped from the library

There are different kinds of symbols going around here. The symbol you don't want to be in the binary is `std::vector<T>::at()` (because it can be generated from the c++ module and stuff). However, the implementation of `at()` will call (on the failure path) __libcxx_throw_out_of_range (or something, I forgot it's name), which is a non-template function defined only in some libc++ source (not header) file. The libc++ module will not contain a definition of that. And if the program never calls it, the symbol won't be extracted from the archive. I think the fix is to make sure this function is present (by depending on it in some way), without pulling in std::vector and friends.

https://github.com/llvm/llvm-project/pull/113935