chore: pass macro processors by reference (#4501)

# Description

## Problem\*

Resolves <!-- Link to GitHub Issue -->

## Summary\*

We're cloning unnecessarily here as we can just pass the processors by
reference.

## Additional Context



## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

---------

Co-authored-by: Jake Fecher <jfecher11@gmail.com>

compiler/noirc_driver/src/lib.rs

@@ -237,11 +237,8 @@ pub fn check_crate(
     deny_warnings: bool,
     disable_macros: bool,
 ) -> CompilationResult<()> {
-    let macros: Vec<&dyn MacroProcessor> = if disable_macros {
-        vec![]
-    } else {
-        vec![&aztec_macros::AztecMacro as &dyn MacroProcessor]
-    };
+    let macros: &[&dyn MacroProcessor] =
+        if disable_macros { &[] } else { &[&aztec_macros::AztecMacro as &dyn MacroProcessor] };
 
     let mut errors = vec![];
     let diagnostics = CrateDefMap::collect_defs(crate_id, context, macros);

compiler/noirc_frontend/src/hir/def_collector/dc_crate.rs

@@ -207,7 +207,7 @@ impl DefCollector {
         context: &mut Context,
         ast: SortedModule,
         root_file_id: FileId,
-        macro_processors: Vec<&dyn MacroProcessor>,
+        macro_processors: &[&dyn MacroProcessor],
     ) -> Vec<(CompilationError, FileId)> {
         let mut errors: Vec<(CompilationError, FileId)> = vec![];
         let crate_id = def_map.krate;
@@ -220,11 +220,7 @@ impl DefCollector {
         let crate_graph = &context.crate_graph[crate_id];
 
         for dep in crate_graph.dependencies.clone() {
-            errors.extend(CrateDefMap::collect_defs(
-                dep.crate_id,
-                context,
-                macro_processors.clone(),
-            ));
+            errors.extend(CrateDefMap::collect_defs(dep.crate_id, context, macro_processors));
 
             let dep_def_root =
                 context.def_map(&dep.crate_id).expect("ice: def map was just created").root;
@@ -257,7 +253,7 @@ impl DefCollector {
         context.def_maps.insert(crate_id, def_collector.def_map);
 
         // TODO(#4653): generalize this function
-        for macro_processor in &macro_processors {
+        for macro_processor in macro_processors {
             macro_processor
                 .process_unresolved_traits_impls(
                     &crate_id,

compiler/noirc_frontend/src/hir/def_map/mod.rs

@@ -73,7 +73,7 @@ impl CrateDefMap {
     pub fn collect_defs(
         crate_id: CrateId,
         context: &mut Context,
-        macro_processors: Vec<&dyn MacroProcessor>,
+        macro_processors: &[&dyn MacroProcessor],
     ) -> Vec<(CompilationError, FileId)> {
         // Check if this Crate has already been compiled
         // XXX: There is probably a better alternative for this.
@@ -90,7 +90,7 @@ impl CrateDefMap {
         let (ast, parsing_errors) = context.parsed_file_results(root_file_id);
         let mut ast = ast.into_sorted();
 
-        for macro_processor in &macro_processors {
+        for macro_processor in macro_processors {
             match macro_processor.process_untyped_ast(ast.clone(), &crate_id, context) {
                 Ok(processed_ast) => {
                     ast = processed_ast;
@@ -115,13 +115,7 @@ impl CrateDefMap {
         };
 
         // Now we want to populate the CrateDefMap using the DefCollector
-        errors.extend(DefCollector::collect(
-            def_map,
-            context,
-            ast,
-            root_file_id,
-            macro_processors.clone(),
-        ));
+        errors.extend(DefCollector::collect(def_map, context, ast, root_file_id, macro_processors));
 
         errors.extend(
             parsing_errors.iter().map(|e| (e.clone().into(), root_file_id)).collect::<Vec<_>>(),

compiler/noirc_frontend/src/tests.rs

@@ -81,7 +81,7 @@ mod test {
                 &mut context,
                 program.clone().into_sorted(),
                 root_file_id,
-                Vec::new(), // No macro processors
+                &[], // No macro processors
             ));
         }
         (program, context, errors)