GDScript: Fix mishandling of stack pointers

- Replace the for loop temporaries by locals. They cause conflicts with
  the stack when being popped, while locals are properly handled in the
  scope.
- Change the interface for the codegen so the for loop list doesn't live
  through the whole block if it's a temporary.
- Keep track of the actual amount of local variables in the stack. Using
  the size of the map is misleading in cases where multiple locals have
  the same name (which is allowed when there's no shadowing).
- Added a few debug checks for temporaries, to avoid them being wrongly
  manipulated in the future. They should not live more than a line of
  code.
- Rearrange some of compiler code to make sure the temporaries don't
  live across blocks.

1 files changed, 3 insertions, 1 deletions

diff --git a/modules/gdscript/gdscript_codegen.h b/modules/gdscript/gdscript_codegen.h
index 2616a34719..decab3df0b 100644
--- a/modules/gdscript/gdscript_codegen.h
+++ b/modules/gdscript/gdscript_codegen.h
@@ -139,7 +139,9 @@ public:
 	// virtual void write_elseif(const Address &p_condition) = 0; This kind of makes things more difficult for no real benefit.
 	virtual void write_else() = 0;
 	virtual void write_endif() = 0;
-	virtual void write_for(const Address &p_variable, const Address &p_list) = 0;
+	virtual void start_for(const GDScriptDataType &p_iterator_type, const GDScriptDataType &p_list_type) = 0;
+	virtual void write_for_assignment(const Address &p_variable, const Address &p_list) = 0;
+	virtual void write_for() = 0;
 	virtual void write_endfor() = 0;
 	virtual void start_while_condition() = 0; // Used to allow a jump to the expression evaluation.
 	virtual void write_while(const Address &p_condition) = 0;