From 067b4c8c0715014ae6b61f6e4cb4e807c7e9be4e Mon Sep 17 00:00:00 2001
From: cdemirer <41021322+cdemirer@users.noreply.github.com>
Date: Mon, 27 Dec 2021 03:32:22 +0800
Subject: [PATCH] Fix type mutation upon compound assignment

---
 modules/gdscript/gdscript_analyzer.cpp | 13 +++++++------
 modules/gdscript/gdscript_compiler.cpp | 12 +++++++-----
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/modules/gdscript/gdscript_analyzer.cpp b/modules/gdscript/gdscript_analyzer.cpp
index 7b64c0564efa..88789d1ce343 100644
--- a/modules/gdscript/gdscript_analyzer.cpp
+++ b/modules/gdscript/gdscript_analyzer.cpp
@@ -1834,13 +1834,14 @@ void GDScriptAnalyzer::reduce_assignment(GDScriptParser::AssignmentNode *p_assig
 		push_error("Cannot assign a new value to a constant.", p_assignment->assignee);
 	}
 
-	if (!assignee_type.is_variant() && assigned_value_type.is_hard_type()) {
-		bool compatible = true;
-		GDScriptParser::DataType op_type = assigned_value_type;
-		if (p_assignment->operation != GDScriptParser::AssignmentNode::OP_NONE) {
-			op_type = get_operation_type(p_assignment->variant_op, assignee_type, assigned_value_type, compatible, p_assignment->assigned_value);
-		}
+	bool compatible = true;
+	GDScriptParser::DataType op_type = assigned_value_type;
+	if (p_assignment->operation != GDScriptParser::AssignmentNode::OP_NONE) {
+		op_type = get_operation_type(p_assignment->variant_op, assignee_type, assigned_value_type, compatible, p_assignment->assigned_value);
+	}
+	p_assignment->set_datatype(op_type);
 
+	if (!assignee_type.is_variant() && assigned_value_type.is_hard_type()) {
 		if (compatible) {
 			compatible = is_type_compatible(assignee_type, op_type, true);
 			if (!compatible) {
diff --git a/modules/gdscript/gdscript_compiler.cpp b/modules/gdscript/gdscript_compiler.cpp
index bba664c3283f..4fa39620732c 100644
--- a/modules/gdscript/gdscript_compiler.cpp
+++ b/modules/gdscript/gdscript_compiler.cpp
@@ -969,17 +969,19 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 
 				// Perform operator if any.
 				if (assignment->operation != GDScriptParser::AssignmentNode::OP_NONE) {
+					GDScriptCodeGenerator::Address op_result = codegen.add_temporary(_gdtype_from_datatype(assignment->get_datatype()));
 					GDScriptCodeGenerator::Address value = codegen.add_temporary(_gdtype_from_datatype(subscript->get_datatype()));
 					if (subscript->is_attribute) {
 						gen->write_get_named(value, name, prev_base);
 					} else {
 						gen->write_get(value, key, prev_base);
 					}
-					gen->write_binary_operator(value, assignment->variant_op, value, assigned);
+					gen->write_binary_operator(op_result, assignment->variant_op, value, assigned);
+					gen->pop_temporary();
 					if (assigned.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
 						gen->pop_temporary();
 					}
-					assigned = value;
+					assigned = op_result;
 				}
 
 				// Perform assignment.
@@ -1035,8 +1037,8 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 				StringName name = static_cast<GDScriptParser::IdentifierNode *>(assignment->assignee)->name;
 
 				if (has_operation) {
-					GDScriptCodeGenerator::Address op_result = codegen.add_temporary();
-					GDScriptCodeGenerator::Address member = codegen.add_temporary();
+					GDScriptCodeGenerator::Address op_result = codegen.add_temporary(_gdtype_from_datatype(assignment->get_datatype()));
+					GDScriptCodeGenerator::Address member = codegen.add_temporary(_gdtype_from_datatype(assignment->assignee->get_datatype()));
 					gen->write_get_member(member, name);
 					gen->write_binary_operator(op_result, assignment->variant_op, member, assigned_value);
 					gen->pop_temporary(); // Pop member temp.
@@ -1092,7 +1094,7 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 				bool has_operation = assignment->operation != GDScriptParser::AssignmentNode::OP_NONE;
 				if (has_operation) {
 					// Perform operation.
-					GDScriptCodeGenerator::Address op_result = codegen.add_temporary();
+					GDScriptCodeGenerator::Address op_result = codegen.add_temporary(_gdtype_from_datatype(assignment->get_datatype()));
 					GDScriptCodeGenerator::Address og_value = _parse_expression(codegen, r_error, assignment->assignee);
 					gen->write_binary_operator(op_result, assignment->variant_op, og_value, assigned_value);
 					to_assign = op_result;