std library hooks

[Walter Bright]

On 4/14/2012 1:01 AM, Vladimir Panteleev wrote:
> On Saturday, 14 April 2012 at 02:46:03 UTC, Walter Bright wrote:
>> all assert(exp) does when it trips is call a function in the library. If you
>> provide your own version of that function, the one in the library won't be
>> linked in.
>
> This indeed works, but how exactly? In what case does the linker pick one
> function (which?) and in what case does it complain about duplicate symbol
> definitions? Do they have to be in different libraries?

The linker works by looking in the library for any unresolved symbols. The 
symbol is not unresolved if you supply your own explicitly in an object file 
explicitly supplied to the linker.

The linker knows nothing about D, C, assembler, or anything but resolving symbols.