llr: Don't generate unused globals

Global for which none of the properties are used can be omitted in the
generated code.

internal/compiler/generator/cpp.rs

@@ -831,7 +831,7 @@ pub fn generate(
     for glob in &llr.globals {
         let ty = if glob.is_builtin {
             format!("slint::cbindgen_private::{}", glob.name)
-        } else {
+        } else if glob.must_generate() {
             generate_global(&mut file, &conditional_includes, glob, &llr);
             file.definitions.extend(glob.aliases.iter().map(|name| {
                 Declaration::TypeAlias(TypeAlias {
@@ -840,6 +840,8 @@ pub fn generate(
                 })
             }));
             ident(&glob.name)
+        } else {
+            continue;
         };
 
         globals_struct.members.push((
@@ -954,12 +956,12 @@ fn generate_public_component(
         }),
     ));
 
-    for glob in unit.globals.iter().filter(|glob| !glob.is_builtin) {
+    for glob in unit.globals.iter().filter(|glob| glob.must_generate()) {
         component_struct.friends.push(ident(&glob.name));
     }
 
     let mut global_accessor_function_body = Vec::new();
-    for glob in unit.globals.iter().filter(|glob| glob.exported && !glob.is_builtin) {
+    for glob in unit.globals.iter().filter(|glob| glob.exported && glob.must_generate()) {
         let accessor_statement = format!(
             "{0}if constexpr(std::is_same_v<T, {1}>) {{ return *m_globals.global_{1}.get(); }}",
             if global_accessor_function_body.is_empty() { "" } else { "else " },

internal/compiler/generator/rust.rs

@@ -181,8 +181,11 @@ pub fn generate(doc: &Document, compiler_config: &CompilerConfiguration) -> Toke
         env!("CARGO_PKG_VERSION_PATCH"),
     );
 
-    let globals =
-        llr.globals.iter().filter(|glob| !glob.is_builtin).map(|glob| generate_global(glob, &llr));
+    let globals = llr
+        .globals
+        .iter()
+        .filter(|glob| glob.must_generate())
+        .map(|glob| generate_global(glob, &llr));
     let shared_globals = generate_shared_globals(&llr);
     let globals_ids = llr.globals.iter().filter(|glob| glob.exported).flat_map(|glob| {
         std::iter::once(ident(&glob.name)).chain(glob.aliases.iter().map(|x| ident(x)))
@@ -310,12 +313,20 @@ fn generate_public_component(
 }
 
 fn generate_shared_globals(llr: &llr::CompilationUnit) -> TokenStream {
-    let global_names =
-        llr.globals.iter().map(|g| format_ident!("global_{}", ident(&g.name))).collect::<Vec<_>>();
-    let global_types = llr.globals.iter().map(global_inner_name).collect::<Vec<_>>();
+    let global_names = llr
+        .globals
+        .iter()
+        .filter(|g| g.is_builtin || g.must_generate())
+        .map(|g| format_ident!("global_{}", ident(&g.name)))
+        .collect::<Vec<_>>();
+    let global_types = llr
+        .globals
+        .iter()
+        .filter(|g| g.is_builtin || g.must_generate())
+        .map(global_inner_name)
+        .collect::<Vec<_>>();
 
     quote! {
-        #[allow(dead_code)] // FIXME: some global are unused because of optimization, we should then remove them completely
         struct SharedGlobals {
             #(#global_names : ::core::pin::Pin<sp::Rc<#global_types>>,)*
             window_adapter : sp::OnceCell<sp::WindowAdapterRc>,

internal/compiler/llr/item_tree.rs

@@ -73,6 +73,15 @@ pub struct GlobalComponent {
     pub prop_analysis: Vec<crate::object_tree::PropertyAnalysis>,
 }
 
+impl GlobalComponent {
+    pub fn must_generate(&self) -> bool {
+        !self.is_builtin
+            && (self.exported
+                || !self.functions.is_empty()
+                || self.properties.iter().any(|p| p.use_count.get() > 0))
+    }
+}
+
 /// a Reference to a property, in the context of a SubComponent
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub enum PropertyReference {

internal/compiler/llr/pretty_print.rs

@@ -30,6 +30,11 @@ struct PrettyPrinter<'a> {
 
 impl<'a> PrettyPrinter<'a> {
     fn print_root(&mut self, root: &CompilationUnit) -> Result {
+        for g in &root.globals {
+            if !g.is_builtin {
+                self.print_global(root, g)?;
+            }
+        }
         for c in &root.sub_components {
             self.print_component(root, c, None)?
         }
@@ -111,6 +116,51 @@ impl<'a> PrettyPrinter<'a> {
         writeln!(self.writer, "}}")
     }
 
+    fn print_global(&mut self, root: &CompilationUnit, global: &super::GlobalComponent) -> Result {
+        let ctx = EvaluationContext::new_global(root, global, ());
+        if global.exported {
+            write!(self.writer, "export ")?;
+        }
+        let aliases = global.aliases.join(",");
+        let aliases = if aliases.is_empty() { String::new() } else { format!(" /*{aliases}*/") };
+        writeln!(self.writer, "global {} {{{aliases}", global.name)?;
+        self.indentation += 1;
+        for ((p, init), is_const) in
+            std::iter::zip(&global.properties, &global.init_values).zip(&global.const_properties)
+        {
+            self.indent()?;
+            let init = init.as_ref().map_or(String::new(), |init| {
+                format!(
+                    ": {}{}",
+                    DisplayExpression(&init.expression.borrow(), &ctx,),
+                    if init.is_constant { "/*const*/" } else { "" }
+                )
+            });
+            writeln!(
+                self.writer,
+                "property <{}> {}{init}; //use={}{}",
+                p.ty,
+                p.name,
+                p.use_count.get(),
+                if *is_const { "  const" } else { "" }
+            )?;
+        }
+        for f in &global.functions {
+            self.indent()?;
+            writeln!(
+                self.writer,
+                "function {} ({}) -> {} {{ {} }}; ",
+                f.name,
+                f.args.iter().map(ToString::to_string).join(", "),
+                f.ret_ty,
+                DisplayExpression(&f.code, &ctx)
+            )?;
+        }
+        self.indentation -= 1;
+        self.indent()?;
+        writeln!(self.writer, "}}")
+    }
+
     fn indent(&mut self) -> Result {
         for _ in 0..self.indentation {
             self.writer.write_str("    ")?;