GC traverses graph, linker traverses graph. GC = linker. I disagree.
Also if that's the description of a "smart linker", what is a "dumb linker" then?
Smart linker relates to eliminating dead code. Depending on how symbols are packaged, or how well the compiler is integrated with the linker, there's a risk of including private (i.e. non-exported) code/data in the final executable which is never referenced but is simply co-located with code or data which is linked in. But it's not really a technical term, it's a marketing term from Delphi.
Like 'optimising compiler' - are there really any non-niche compilers that do not optimise? Maybe some first-tier JITs.
Linkers have more scope for smartness. The size of a block of code can be quite sensitive to the addressing mode (near vs far for e.g. 16-bit x86, relative offsets of various widths vs absolute etc.) used for each reference. An intelligent linker can adjust the code depending on where the target ends up, altering the addressing mode. The scope for optimization here depends on the ordering in the final executable, density of references and so on.
static int foo(void) {
return 4;
}
int bar(void) {
return 42 + foo();
}
(I can't answer your question in detail because it's been a long time since I've been poking around in object files and I don't know what C/C++ compilers and linkers have been doing with them recently. I was a compiler engineer at Borland for more than 5 years, but it was years ago.)