Ruby

Currently, Prism creates the following AST for Bar::Foo = 42

irb(main):001> Prism.parse(%q(Bar::Foo = 42)).value => @ ProgramNode (location: (1,0)-(1,13)) ├── locals: [] └── statements: @ StatementsNode (location: (1,0)-(1,13)) └── body: (length: 1) └── @ ConstantPathWriteNode (location: (1,0)-(1,13)) ├── target: │ @ ConstantPathNode (location: (1,0)-(1,8)) │ ├── parent: │ │ @ ConstantReadNode (location: (1,0)-(1,3)) │ │ └── name: :Bar │ ├── child: │ │ @ ConstantReadNode (location: (1,5)-(1,8)) │ │ └── name: :Foo │ └── delimiter_loc: (1,3)-(1,5) = "::" ├── operator_loc: (1,9)-(1,10) = "=" └── value: @ IntegerNode (location: (1,11)-(1,13)) ├── flags: decimal └── value: 42 

Note that it includes ConstantReadNode(name: :Foo). I believe this is a bug because Bar::Foo = 42 does not read a constant Foo.

Also, Foo and Bar::Foo generates the followings.

irb(main):002> Prism.parse(%q(Foo)).value => @ ProgramNode (location: (1,0)-(1,3)) ├── locals: [] └── statements: @ StatementsNode (location: (1,0)-(1,3)) └── body: (length: 1) └── @ ConstantReadNode (location: (1,0)-(1,3)) └── name: :Foo irb(main):003> Prism.parse(%q(Bar::Foo)).value => @ ProgramNode (location: (1,0)-(1,8)) ├── locals: [] └── statements: @ StatementsNode (location: (1,0)-(1,8)) └── body: (length: 1) └── @ ConstantPathNode (location: (1,0)-(1,8)) ├── parent: │ @ ConstantReadNode (location: (1,0)-(1,3)) │ └── name: :Bar ├── child: │ @ ConstantReadNode (location: (1,5)-(1,8)) │ └── name: :Foo └── delimiter_loc: (1,3)-(1,5) = "::" 

Note that both have the same subtree of ConstantReadNode(name: :Foo). It is very confusing because Foo (non-scoped read of Foo) and Bar::Foo (scoped read of Foo) have very different meanings.

I think the following design would be desirable.

# Foo::Bar=42 ConstantPathWriteNode( base: ConstantReadNode(name: ConstantNameNode(:Foo)), name: ConstantNameNode(:Bar), value: 42 ) # Foo ConstantReadNode(name: ConstantNameNode(:Foo)) # Foo::Bar ConstantPathReadNode( base: ConstantReadNode(name: ConstantNameNode(:Foo)), name: ConstantNameNode(:Bar), )