Add static type checks in the parser

- Resolve types for all identifiers.
- Error when identifier is not found.
- Match return type and error when not returning a value when it should.
- Check unreachable code (code after sure return).
- Match argument count and types for function calls.
- Determine if return type of function call matches the assignment.
- Do static type check with match statement when possible.
- Use type hints to determine export type.
- Check compatibility between type hint and explicit export type.

1 files changed, 12 insertions, 11 deletions

diff --git a/modules/gdscript/gdscript_functions.cpp b/modules/gdscript/gdscript_functions.cpp
index ce91e7dff3..7e98b6ced9 100644
--- a/modules/gdscript/gdscript_functions.cpp
+++ b/modules/gdscript/gdscript_functions.cpp
@@ -1663,7 +1663,7 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) {
 
 			MethodInfo mi("weakref", PropertyInfo(Variant::OBJECT, "obj"));
 			mi.return_val.type = Variant::OBJECT;
-			mi.return_val.name = "WeakRef";
+			mi.return_val.class_name = "WeakRef";
 
 			return mi;
 
@@ -1672,19 +1672,20 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) {
 
 			MethodInfo mi("funcref", PropertyInfo(Variant::OBJECT, "instance"), PropertyInfo(Variant::STRING, "funcname"));
 			mi.return_val.type = Variant::OBJECT;
-			mi.return_val.name = "FuncRef";
+			mi.return_val.class_name = "FuncRef";
 			return mi;
 
 		} break;
 		case TYPE_CONVERT: {
 
-			MethodInfo mi("convert", PropertyInfo(Variant::NIL, "what"), PropertyInfo(Variant::INT, "type"));
-			mi.return_val.type = Variant::OBJECT;
+			MethodInfo mi("convert", PropertyInfo(Variant::NIL, "what", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT), PropertyInfo(Variant::INT, "type"));
+			mi.return_val.type = Variant::NIL;
+			mi.return_val.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
 			return mi;
 		} break;
 		case TYPE_OF: {
 
-			MethodInfo mi("typeof", PropertyInfo(Variant::NIL, "what"));
+			MethodInfo mi("typeof", PropertyInfo(Variant::NIL, "what", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT));
 			mi.return_val.type = Variant::INT;
 			return mi;
 
@@ -1760,7 +1761,7 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) {
 
 		} break;
 		case VAR_TO_STR: {
-			MethodInfo mi("var2str", PropertyInfo(Variant::NIL, "var"));
+			MethodInfo mi("var2str", PropertyInfo(Variant::NIL, "var", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT));
 			mi.return_val.type = Variant::STRING;
 			return mi;
 
@@ -1773,7 +1774,7 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) {
 			return mi;
 		} break;
 		case VAR_TO_BYTES: {
-			MethodInfo mi("var2bytes", PropertyInfo(Variant::NIL, "var"));
+			MethodInfo mi("var2bytes", PropertyInfo(Variant::NIL, "var", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT));
 			mi.return_val.type = Variant::POOL_BYTE_ARRAY;
 			return mi;
 
@@ -1796,7 +1797,7 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) {
 
 			MethodInfo mi("load", PropertyInfo(Variant::STRING, "path"));
 			mi.return_val.type = Variant::OBJECT;
-			mi.return_val.name = "Resource";
+			mi.return_val.class_name = "Resource";
 			return mi;
 		} break;
 		case INST2DICT: {
@@ -1826,13 +1827,13 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) {
 		} break;
 		case TO_JSON: {
 
-			MethodInfo mi("to_json", PropertyInfo(Variant::NIL, "var"));
+			MethodInfo mi("to_json", PropertyInfo(Variant::NIL, "var", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT));
 			mi.return_val.type = Variant::STRING;
 			return mi;
 		} break;
 		case HASH: {
 
-			MethodInfo mi("hash", PropertyInfo(Variant::NIL, "var"));
+			MethodInfo mi("hash", PropertyInfo(Variant::NIL, "var", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT));
 			mi.return_val.type = Variant::INT;
 			return mi;
 		} break;
@@ -1868,7 +1869,7 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) {
 			return mi;
 		} break;
 		case LEN: {
-			MethodInfo mi("len", PropertyInfo(Variant::NIL, "var"));
+			MethodInfo mi("len", PropertyInfo(Variant::NIL, "var", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_NIL_IS_VARIANT));
 			mi.return_val.type = Variant::INT;
 			return mi;
 		} break;