Initializing a variable with record/array element

[Sh3b0]

Code to reproduce

routine main() is
	var x : array[5] integer;
	x[1] := 1;
	var y is x[1];
	println y;
	return;
end

Expected behavior

Prints 1

Actual behavior

Prints garbage from memory, most probably the error originates from the local variable intialization code in VariableDeclarartion::visit

[TonyDecvA180XN]

The problem comes from wrong interpretation of program flow in this example. In the code:

	var x : array[5] integer;
	x[1] := 1;
	var y is x[1];
	println y;

the line x[1] := 1; is assignment which is a runtime operation, and the line var y is x[1] is a static declraration and initialization that happens on entering function. Thus, the actual program flow three is the following:

	var x : array[5] integer;
	var y is x[1];
        x[1] := 1;
	println y;

It can be confirmed by AST:

So, the problem goes to using of uninitialized variables, or more precise, element of array.
There, we have a following problem: all variables are created with default values, even records. However, arrays are allocated using CreateAlloca instruction generator which does not clear the memory and does not allow to fill the memory with default values. Maybe we could add some intrinsic to zero-fill memory after initialization.

[Sh3b0]

Maybe we can just avoid this by traversing the program in the original order it was written in.
We can have one structure that holds a list of either VariableDeclaration or RoutineDeclaration

Then, in IRGenerator::visit(ast::Program *program), we can loop on that structure and visit nodes.