Optimizer and builtin functions

[ozanh]

uGO allows to shadow builtin symbols, but this causes optimizer, that has no symbol table, to evaluate builtin function calls as if they are not shadowed as shown in the example;

string := func() { /* ... */ }
a := string(1)
println(a)

Result:

Bytecode
Modules:0
Constants:
   0: CompiledFunction
	Params:0 Variadic:false Locals:0
	Instructions:
	0000 RETURN          0
	SourceMap:map[0:0]
   1: "1"|string
Params:0 Variadic:false Locals:2
Instructions:
0000 CONSTANT        0
0003 SETLOCAL        0
0005 CONSTANT        1
0008 SETLOCAL        1
0010 GETBUILTIN      19
0012 GETLOCAL        1
0014 CALL            1    0
0017 POP
0018 RETURN          0

Output:
"1"

"1" is not the expected output. Either disable evaluating builtins or throw a meaningful error.