Add members of EnumDeclaration to the symbol table(s).
Set up loc for a parse of a mixin. Append the input text to the mixin.
Find all instance fields in ad, then push them into fields.
Does semantic analysis on the public face of declarations.
Interpret a pragma(inline, x)
Determine the numerical value of the AlignmentDeclaration
Does the semantic 1 pass on the AST, which looks at symbol declarations but not initializers or function bodies.