Re: [PROPOSAL] Builder, a build system integration for Emacs

[Brian Cully]

Richard Stallman <rms@gnu.org> writes:

> I have trouble understanding that.  Before dynamic libraries, we 
> used
> static libraries.  Each library was a .o file, made by 
> compilation.
>
> But how can each program have its own version of one and the 
> same
> library?  Does Rust store all libraries as **source code**
> and recompile each library each time that library is linked
> into a program?

More than that, each Rust program can have many versions of any 
particular symbol.

If program A links in libraries B and C, and B links with D 
version 1, while C links with D version 2, then A will have 
symbols from both versions of D linked in with it.

It is able to do this because when Rust does name mangling, the 
names are mangled with library metadata, including version, so 
that the symbols in the object file equivalent have unique names.

It's worth noting that Rust doesn't use standard .a/.so/.o files, 
but something like them called with a .rlib extension, which 
contains extra information not available in the aforementioned 
formats.

-bjc