[gjs: 3/9] arg-cache: Remove arg position from generic argument

[Philip Chimento <pchimento src gnome org>]

commit 2eb740dbcf0db9c5566a1b8ae380f9ee8c698ee8
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Sat Oct 16 21:52:05 2021 -0700

    arg-cache: Remove arg position from generic argument
    
    Not all the argument types care about their positioning, actually just a
    few of them, so we can just apply it to the types that need it.
    
    We can save 8 bits in most of these cases.

 gi/arg-cache.cpp | 15 +++++++++++++--
 gi/arg-cache.h   |  9 ---------
 2 files changed, 13 insertions(+), 11 deletions(-)
---
diff --git a/gi/arg-cache.cpp b/gi/arg-cache.cpp
index d655c564..a838643d 100644
--- a/gi/arg-cache.cpp
+++ b/gi/arg-cache.cpp
@@ -189,6 +189,16 @@ struct Nullable {
     }
 };
 
+struct Positioned {
+    void set_arg_pos(int pos) {
+        g_assert(pos <= Argument::MAX_ARGS &&
+                 "No more than 253 arguments allowed");
+        m_arg_pos = pos;
+    }
+
+    uint8_t m_arg_pos = 0;
+};
+
 struct Array : BasicType {
     uint8_t m_length_pos = 0;
 
@@ -299,7 +309,7 @@ struct GenericIn : Generic {
                  GIArgument*) override;
 };
 
-struct GenericInOut : GenericIn {
+struct GenericInOut : GenericIn, Positioned {
     bool in(JSContext*, GjsFunctionCallState*, GIArgument*,
             JS::HandleValue) override;
     bool out(JSContext*, GjsFunctionCallState*, GIArgument*,
@@ -1478,7 +1488,8 @@ std::unique_ptr<T> Argument::make(uint8_t index, const char* name,
                  "name was ignored in RETURN_VALUE parameter");
         arg->set_return_value();
     } else {
-        arg->set_arg_pos(index);
+        if constexpr (std::is_base_of_v<Arg::Positioned, T>)
+            arg->set_arg_pos(index);
         arg->m_arg_name = name;
     }
 
diff --git a/gi/arg-cache.h b/gi/arg-cache.h
index 15491601..1560c42a 100644
--- a/gi/arg-cache.h
+++ b/gi/arg-cache.h
@@ -15,7 +15,6 @@
 
 #include <girepository.h>
 #include <glib-object.h>
-#include <glib.h>  // for g_assert
 
 #include <js/TypeDecls.h>
 
@@ -99,26 +98,18 @@ struct Argument {
  protected:
     Argument() : m_skip_in(false), m_skip_out(false) {}
 
-    void set_arg_pos(int pos) {
-        g_assert(pos <= MAX_ARGS && "No more than 253 arguments allowed");
-        m_arg_pos = pos;
-    }
-
     void set_instance_parameter() {
-        m_arg_pos = INSTANCE_PARAM;
         m_arg_name = "instance parameter";
         m_skip_out = true;
     }
 
     void set_return_value() {
-        m_arg_pos = RETURN_VALUE;
         m_arg_name = "return value";
     }
 
     bool invalid(JSContext*, const char* func = nullptr) const;
 
     const char* m_arg_name = nullptr;
-    uint8_t m_arg_pos = 0;
     bool m_skip_in : 1;
     bool m_skip_out : 1;