Called from a symbol's semantic to check if gnuAbiTag UDA can be applied to them
Check if the provided expression references core.attribute.gnuAbiTag
Dsymbol's affected by this AttribDeclaration
Create a new scope if one or more given attributes are different from the sc's. If the returned scope != sc, the caller should pop the scope after it used.
A hook point to supply scope for members. addMember, setScope, importAll, semantic, semantic2 and semantic3 will use this.
User defined attributes look like: @foo(args, ...) @(args, ...)