item deleter pass

src/build.rs

@@ -315,6 +315,7 @@ impl Build {
     }
 }
 
+#[derive(Debug)]
 pub struct BuildResult {
     reproduces_issue: bool,
     no_verify: bool,

src/lib.rs

@@ -74,6 +74,10 @@ pub struct Options {
     #[arg(default_value = "src")]
     pub path: PathBuf,
 
+    /// A comma-seperated list of passes that should be enabled. By default, all passes are enabled.
+    #[arg(long)]
+    pub passes: Option<String>,
+
     /// A path to a script that is run to check whether code reproduces. When it exits with code 0, the
     /// problem reproduces. If `--script-path-lints` isn't set, this script is also run to get lints.
     /// For lints, the `MINIMIZE_LINTS` environment variable will be set to `1`.
@@ -119,6 +123,7 @@ pub fn minimize(options: Options) -> Result<()> {
     minimizer.run_passes([
         passes::Privatize::default().boxed(),
         passes::EverybodyLoops::default().boxed(),
+        passes::ItemDeleter::default().boxed(),
     ])?;
 
     minimizer.delete_dead_code().context("deleting dead code")?;
@@ -154,6 +159,7 @@ impl Default for Options {
             env: Vec::new(),
             project_dir: None,
             path: PathBuf::from("/the/wrong/path/you/need/to/change/it"),
+            passes: None,
             script_path: None,
             script_path_lints: None,
         }

src/passes/everybody_loops.rs

@@ -28,6 +28,8 @@ impl VisitMut for Visitor<'_> {
             [syn::Stmt::Expr(syn::Expr::Loop(syn::ExprLoop {
                 body: loop_body, ..
             }))] if loop_body.stmts.is_empty() => {}
+            // Empty bodies are empty already, no need to loopify them.
+            [] => {}
             _ if self.checker.can_process(&self.current_path) => {
                 *block = self.loop_expr.clone();
                 self.process_state = ProcessState::Changed;

src/passes/item_deleter.rs

@@ -0,0 +1,111 @@
+use quote::ToTokens;
+use syn::{
+    visit_mut::VisitMut, Item, ItemConst, ItemEnum, ItemMacro, ItemMacro2, ItemMod, ItemStatic,
+    ItemStruct, ItemTrait, ItemType, ItemUnion,
+};
+
+use crate::processor::{tracking, Pass, PassController, ProcessState, SourceFile};
+
+struct Visitor<'a> {
+    current_path: Vec<String>,
+    checker: &'a mut PassController,
+    process_state: ProcessState,
+}
+
+impl<'a> Visitor<'a> {
+    fn new(checker: &'a mut PassController) -> Self {
+        Self {
+            current_path: Vec::new(),
+            checker,
+            process_state: ProcessState::NoChange,
+        }
+    }
+
+    fn should_retain_item(&mut self) -> bool {
+        let can_process = self.checker.can_process(&self.current_path);
+        if can_process {
+            self.process_state = ProcessState::Changed;
+        }
+        !can_process
+    }
+
+    fn consider_deleting_item(&mut self, item: &Item) -> bool {
+        match item {
+            // N.B. Do not delete ItemFn because that makes testing way harder
+            // and also the dead_lint should cover it all.
+            Item::Impl(impl_) => {
+                self.current_path
+                    .push(impl_.self_ty.clone().into_token_stream().to_string());
+
+                let should_retain = self.should_retain_item();
+
+                self.current_path.pop();
+                should_retain
+            }
+            Item::Struct(ItemStruct { ident, .. })
+            | Item::Enum(ItemEnum { ident, .. })
+            | Item::Union(ItemUnion { ident, .. })
+            | Item::Const(ItemConst { ident, .. })
+            | Item::Type(ItemType { ident, .. })
+            | Item::Trait(ItemTrait { ident, .. })
+            | Item::Macro(ItemMacro {
+                ident: Some(ident), ..
+            })
+            | Item::Macro2(ItemMacro2 { ident, .. })
+            | Item::Static(ItemStatic { ident, .. })
+            | Item::Mod(ItemMod { ident, .. }) => {
+                self.current_path.push(ident.to_string());
+
+                let should_retain = self.should_retain_item();
+
+                self.current_path.pop();
+                should_retain
+            }
+            _ => true,
+        }
+    }
+}
+
+impl VisitMut for Visitor<'_> {
+    fn visit_file_mut(&mut self, file: &mut syn::File) {
+        file.items
+            .retain_mut(|item| self.consider_deleting_item(item));
+
+        syn::visit_mut::visit_file_mut(self, file);
+    }
+
+    fn visit_item_mod_mut(&mut self, module: &mut syn::ItemMod) {
+        self.current_path.push(module.ident.to_string());
+
+        if let Some((_, items)) = &mut module.content {
+            items.retain(|item| self.consider_deleting_item(item));
+        }
+
+        syn::visit_mut::visit_item_mod_mut(self, module);
+        self.current_path.pop();
+    }
+
+    tracking!(visit_item_fn_mut);
+    tracking!(visit_impl_item_method_mut);
+    tracking!(visit_item_impl_mut);
+}
+
+#[derive(Default)]
+pub struct ItemDeleter;
+
+impl Pass for ItemDeleter {
+    fn process_file(
+        &mut self,
+        krate: &mut syn::File,
+        _: &SourceFile,
+        checker: &mut PassController,
+    ) -> ProcessState {
+        let mut visitor = Visitor::new(checker);
+        visitor.visit_file_mut(krate);
+        visitor.process_state
+    }
+
+    fn name(&self) -> &'static str {
+        "item-deleter"
+    }
+}

src/passes/mod.rs

@@ -1,4 +1,5 @@
 mod everybody_loops;
+mod item_deleter;
 mod privatize;
 
-pub use self::{everybody_loops::EverybodyLoops, privatize::Privatize};
+pub use self::{everybody_loops::EverybodyLoops, item_deleter::ItemDeleter, privatize::Privatize};

src/processor/mod.rs

@@ -56,6 +56,15 @@ pub(crate) struct Minimizer {
 }
 
 impl Minimizer {
+    fn pass_disabled(&self, name: &str) -> bool {
+        if let Some(passes) = &self.options.passes {
+            if !passes.split(",").any(|allowed| name == allowed) {
+                return true;
+            }
+        }
+        false
+    }
+
     pub(crate) fn new_glob_dir(options: Options, build: Build) -> Result<Self> {
         let path = &options.path;
         let walk = walkdir::WalkDir::new(path);
@@ -102,6 +111,9 @@ impl Minimizer {
         inital_build.require_reproduction("Initial")?;
 
         for mut pass in passes {
+            if self.pass_disabled(pass.name()) {
+                continue;
+            }
             self.run_pass(&mut *pass)?;
         }
 

src/processor/reaper.rs

@@ -18,8 +18,14 @@ fn file_for_suggestion(suggestion: &Suggestion) -> &str {
     &suggestion.solutions[0].replacements[0].snippet.file_name
 }
 
+const PASS_NAME: &str = "delete-unused-functions";
+
 impl Minimizer {
     pub fn delete_dead_code(&mut self) -> Result<()> {
+        if self.pass_disabled(PASS_NAME) {
+            return Ok(());
+        }
+
         let inital_build = self.build.build()?;
         info!("Before reaper: {inital_build}");
 
@@ -139,7 +145,7 @@ impl Pass for DeleteUnusedFunctions {
     }
 
     fn name(&self) -> &'static str {
-        "delete-unused-functions"
+        PASS_NAME
     }
 }
 

tests/minimize.rs

@@ -47,6 +47,26 @@ fn unused() -> Result<()> {
     )
 }
 
+#[test]
+fn impls() -> Result<()> {
+    // Delete unused impls
+    run_test(
+        r##"
+        pub trait Uwu {}
+        impl Uwu for () {}
+        impl Uwu for u8 {}
+
+        fn main() {}
+        "##,
+        r##"
+        fn main() {}
+        "##,
+        |opts| {
+            opts.no_verify = true;
+        },
+    )
+}
+
 #[test]
 #[cfg_attr(windows, ignore)]
 fn custom_script_success() -> Result<()> {
@@ -61,9 +81,7 @@ fn custom_script_success() -> Result<()> {
         fn main() {}
     "##,
         r##"
-    fn main() {
+    fn main() {}
-        loop {}
-    }
     "##,
         |opts| {
             opts.script_path = Some(script_path);