Function link 

pub fn link<'q>(
    interner: &mut Interner,
    lang: &Lang,
    source_map: &'q SourceMap,
    ast_map: &AstMap,
    symbol_table: &SymbolTable,
    output: &mut LinkOutput,
    diagnostics: &mut Diagnostics,
)

Link query against a language grammar.

This function is decoupled from Query to allow easier testing and modularity. It orchestrates the resolution and validation phases.