Libstd undefined symbols when building dylib

help
4

To make it more clear, here's an extract from reference.

  • bin: ordinary executable.
  • lib: a library to be linked statically into Rust programs.
  • dylib: a library to be linked dynamically into Rust programs.
  • staticlib: a library to be linked statically into non-Rust programs.
  • cdylib: a library to be linked dynamically into non-Rust programs.

(plus rlib as mainly internal format and proc_macro, used, well, for procedural macros)