1. High-level AST (basically the code in AST form)
 - Elimination or otherwise disabling of #[cfg]-disabled items
 - Path resolution (leave UFCS unresolved for now)
  > Take all paths, turn into UFCS if a node points to a type
 - Root-level UFCS resoluion
  > Recursion limit on searching through traits
 - Expression-level UFCS resolution
 - Type checking/inferrence
  > Assign unique ID to all inferrence args, then resolve table using function AST
2. Mid-level IR (similar to rust's MIR)?
 - Only really useful for borrow/drop-ck



=== Rust's MIR Format ===
```
BASIC_BLOCK = BB: {STATEMENT} TERMINATOR

STATEMENT = LVALUE "=" RVALUE        // assign rvalue into lvalue
          | Drop(DROP_KIND, LVALUE)  // drop value if needed
DROP_KIND = SHALLOW                  // (see discussion below)
          | DEEP

TERMINATOR = GOTO(BB)              // normal control-flow
           | PANIC(BB)             // initiate unwinding, branching to BB for cleanup
           | IF(LVALUE, BB0, BB1)  // test LVALUE and branch to BB0 if true, else BB1
           | SWITCH(LVALUE, BB...) // load discriminant from LVALUE (which must be an enum),
                                   // and branch to BB... depending on which variant it is
           | CALL(LVALUE0 = LVALUE1(LVALUE2...), BB0, BB1)
                                   // call LVALUE1 with LVALUE2... as arguments. Write
                                   // result into LVALUE0. Branch to BB0 if it returns
                                   // normally, BB1 if it is unwinding.
           | DIVERGE               // return to caller, unwinding
           | RETURN                // return to caller normally


LVALUE = B                   // reference to a user-declared binding
       | TEMP                // a temporary introduced by the compiler
       | ARG                 // a formal argument of the fn
       | STATIC              // a reference to a static or static mut
       | RETURN              // the return pointer of the fn
       | LVALUE.f            // project a field or tuple field, like x.f or x.0
       | *LVALUE             // dereference a pointer
       | LVALUE[LVALUE]      // index into an array (see disc. below about bounds checks)
       | (LVALUE as VARIANT) // downcast to a specific variant of an enum,
                             // see the section on desugaring matches below

RVALUE = Use(LVALUE)                // just read an lvalue
       | [LVALUE; LVALUE]
       | &'REGION LVALUE
       | &'REGION mut LVALUE
       | LVALUE as TYPE
       | LVALUE <BINOP> LVALUE
       | <UNOP> LVALUE
       | Struct { f: LVALUE0, ... } // aggregates, see section below
       | (LVALUE...LVALUE)
       | [LVALUE...LVALUE]
       | CONSTANT
       | LEN(LVALUE)                // load length from a slice, see section below
       | BOX                        // malloc for builtin box, see section below
BINOP = + | - | * | / | ...         // excluding && and ||
UNOP = ! | -                        // note: no `*`, as that is part of LVALUE

CONSTANT = INT
         | UINT
         | FLOAT
         | BOOL
         | BYTES
         | STATIC_STRING
         | ITEM<SUBSTS>                 // reference to an item or constant etc
         | <P0 as TRAIT<P1...Pn>>       // projection
         | CONSTANT(CONSTANT...)        //
         | CAST(CONSTANT, TY)           // foo as bar
         | Struct { (f: CONSTANT)... }  // aggregates...
         | (CONSTANT...)                //
         | [CONSTANT...]                //
```


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