INFO.txt

LOSE INFO
ints to chars 
longs to shorts

WONT LOSE INFO
ints to floats
shorts to longs

***COERCIONS GO UP HIERARCHY***
int - float - double
result = type of operand highest on hierarchy
int + float = float
int + double = double
float + double = double

TYPE CASTING?
A - A + (int)B

***CHECKS***
1. When building parameter descriptor have
    - name of type
    - name of param
Q: is name of type valid?
    - look up name
    - if not there look up name in \e[34mprog\e[0m symbol (could be class)
    - else fails
2. When building local descriptors have
    - name of type
    - name of param
Q: is name of type valid?
    - look up name
    - if not there look up name in \e[34mprog\e[0m symbol (could be class)
    - else fails
3. When building local symbol table, have local descriptors
Q: duplicate/shadowed (local declaration of parameter/global) variable names?
    - check during insertion 
4. When building class descriptor have  (LATER)
    - name of class + superclass
    - field symbol table
    - method symbol table  
Q: Check for:
    - superclass name corresponds to class
    - no name clashes between field names of sub and superclass
    - overidden methods match param and return type decl

LOAD INSTR
Compiler looks up var name in local symbol table, parameter symbol table, field symbol table, if not found --> semantic error

LOAD ARRAY INSTR
Compiler has var name + index expr, look up var name (if not there, error), check type of expression (if not int, error)

ADD OPERATIONS
Compiler has 2 expressions
Check for - right type + both integers
Check types (produced expression for operations)

STORE INSTR
Compiler has var name + expr

DO: Look up var name
    - if in local symbol, reference local descriptor
    - if in parameter symbol, error
    - if in field symbol, reference field descriptor
    - else error
    - check type var against type expr
    
STORE ARRAY INSTR
SAME AS ABOVE - check array index is int

RETURN INSTR
Check if return type matches func type (from func decl)

CONDITIONAL INSTR
If cond expression produces boolean

*/

//WE WILL NEED GLOBAL VAR LINKED LIST - type = int/char/bool/etc.

/* THIS MANY LISTS
Global vars
Local vars - inc parameters
Classes
Functions