Changes necessary for hot reload to work

tools/godotcpp.py

@@ -175,6 +175,14 @@ def options(opts, env):
         )
     )
 
+    opts.Add(
+        BoolVariable(
+            key="use_hot_reload",
+            help="Enable the extra accounting required to support hot reload.",
+            default=(env.get("target", "template_debug") != "template_release"),
+        )
+    )
+
     # Add platform options
     for pl in platforms:
         tool = Tool(pl, toolpath=["tools"])
@@ -231,6 +239,9 @@ def generate(env):
 
     print("Building for architecture " + env["arch"] + " on platform " + env["platform"])
 
+    if env["use_hot_reload"]:
+        env.Append(CPPDEFINES=["HOT_RELOAD_ENABLED"])
+
     tool = Tool(env["platform"], toolpath=["tools"])
 
     if tool is None or not tool.exists(env):

tools/linux.py

@@ -14,6 +14,9 @@ def generate(env):
     if env["use_llvm"]:
         clang.generate(env)
         clangxx.generate(env)
+    elif env["use_hot_reload"]:
+        # Required for extensions to truly unload.
+        env.Append(CXXFLAGS=["-fno-gnu-unique"])
 
     env.Append(CCFLAGS=["-fPIC", "-Wwrite-strings"])
     env.Append(LINKFLAGS=["-Wl,-R,'$$ORIGIN'"])