Refactor impl Default generation

Move the detection of a default constructor function in the analysis.
Move the logic about using Object::new into object.

src/analysis/info_base.rs

@@ -1,5 +1,5 @@
 use super::{imports::Imports, *};
-use crate::{codegen::Visibility, library, version::Version};
+use crate::{codegen::Visibility, config::gobjects::GStatus, library, version::Version};
 
 #[derive(Debug, Default)]
 pub struct InfoBase {
@@ -38,4 +38,18 @@ impl InfoBase {
             .filter(|f| f.status.need_generate() && f.kind == library::FunctionKind::Function)
             .collect()
     }
+
+    pub fn default_constructor(&self) -> Option<&functions::Info> {
+        self.functions.iter().find(|f| {
+            !f.hidden
+                && f.status.need_generate()
+                && f.kind == library::FunctionKind::Constructor
+                && f.status == GStatus::Generate
+                // For now we only look for new() with no params
+                && f.name == "new"
+                && f.parameters.rust_parameters.is_empty()
+                // Cannot generate Default implementation for Option<>
+                && f.ret.parameter.as_ref().map_or(false, |x| !*x.lib_par.nullable)
+        })
+    }
 }

src/codegen/general.rs

@@ -966,47 +966,23 @@ pub fn write_vec<T: Display>(w: &mut dyn Write, v: &[T]) -> Result<()> {
     Ok(())
 }
 
-pub fn declare_default_from_new(
+pub fn declare_default(
     w: &mut dyn Write,
     env: &Env,
     name: &str,
-    functions: &[analysis::functions::Info],
-    has_builder: bool,
+    func: &analysis::functions::Info,
 ) -> Result<()> {
-    if let Some(func) = functions.iter().find(|f| {
-        !f.hidden
-            && f.status.need_generate()
-            && f.name == "new"
-            // Cannot generate Default implementation for Option<>
-            && f.ret.parameter.as_ref().map_or(false, |x| !*x.lib_par.nullable)
-    }) {
-        if func.parameters.rust_parameters.is_empty() {
-            writeln!(w)?;
-            version_condition(w, env, None, func.version, false, 0)?;
-            writeln!(
-                w,
-                "impl Default for {name} {{
-                     fn default() -> Self {{
-                         Self::new()
-                     }}
-                 }}"
-            )?;
-        } else if has_builder {
-            // create an alternative default implementation the uses `glib::object::Object::new()`
-            writeln!(w)?;
-            version_condition(w, env, None, func.version, false, 0)?;
-            writeln!(
-                w,
-                "impl Default for {name} {{
-                     fn default() -> Self {{
-                         glib::object::Object::new::<Self>()
-                     }}
-                 }}"
-            )?;
-        }
-    }
-
-    Ok(())
+    writeln!(w)?;
+    version_condition(w, env, None, func.version, false, 0)?;
+    writeln!(
+        w,
+        "impl Default for {name} {{
+             fn default() -> Self {{
+                 Self::{}()
+             }}
+         }}",
+        &func.name
+    )
 }
 
 /// Escapes string in format suitable for placing inside double quotes.

src/codegen/object.rs

@@ -274,14 +274,7 @@ pub fn generate(
         }
 
         writeln!(w, "}}")?;
-
-        general::declare_default_from_new(
-            w,
-            env,
-            &analysis.name,
-            &analysis.functions,
-            has_builder_properties(&analysis.builder_properties),
-        )?;
+        generate_default(w, env, analysis)?;
     }
 
     trait_impls::generate(
@@ -340,6 +333,27 @@ pub fn generate(
     Ok(())
 }
 
+fn generate_default(w: &mut dyn Write, env: &Env, analysis: &analysis::object::Info) -> Result<()> {
+    let name = &analysis.name;
+    if let Some(func) = analysis.default_constructor() {
+        general::declare_default(w, env, name, func)
+    } else if has_builder_properties(&analysis.builder_properties) {
+        // create an alternative default implementation the uses `glib::object::Object::new()`
+        writeln!(w)?;
+        version_condition(w, env, None, analysis.version, false, 0)?;
+        writeln!(
+            w,
+            "impl Default for {name} {{
+                 fn default() -> Self {{
+                     glib::object::Object::new::<Self>()
+                 }}
+             }}"
+        )
+    } else {
+        Ok(())
+    }
+}
+
 fn generate_builder(w: &mut dyn Write, env: &Env, analysis: &analysis::object::Info) -> Result<()> {
     let glib_crate_name = if env.namespaces.is_glib_crate {
         "crate"

src/codegen/record.rs

@@ -113,7 +113,9 @@ pub fn generate(w: &mut dyn Write, env: &Env, analysis: &analysis::record::Info)
         writeln!(w, "}}")?;
     }
 
-    general::declare_default_from_new(w, env, &analysis.name, &analysis.functions, false)?;
+    if let Some(func) = analysis.default_constructor() {
+        general::declare_default(w, env, &analysis.name, func)?;
+    }
 
     trait_impls::generate(
         w,