aaa

Cargo.lock

@@ -155,6 +155,8 @@ dependencies = [
  "prettyplease",
  "proc-macro2",
  "quote",
+ "rustfix",
+ "serde_json",
  "syn",
  "walkdir",
 ]
@@ -965,9 +967,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.46"
+version = "1.0.48"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94e2ef8dbfc347b10c094890f778ee2e36ca9bb4262e86dc99cd217e35f3470b"
+checksum = "e9d89e5dba24725ae5678020bf8f1357a9aa7ff10736b551adbcd3f8d17d766f"
 dependencies = [
  "unicode-ident",
 ]
@@ -1134,9 +1136,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.85"
+version = "1.0.90"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e55a28e3aaef9d5ce0506d0a14dbba8054ddc7e499ef522dd8b26859ec9d4a44"
+checksum = "8778cc0b528968fe72abec38b5db5a20a70d148116cd9325d2bc5f5180ca3faf"
 dependencies = [
  "itoa",
  "ryu",

Cargo.toml

@@ -13,7 +13,9 @@ anyhow = "1.0.65"
 cargo = "0.65.0"
 clap = { version = "4.0.29", features = ["derive"] }
 prettyplease = "0.1.19"
-proc-macro2 = "1.0.46"
+proc-macro2 = { version = "1.0.48", features = ["span-locations"] }
 quote = "1.0.21"
+rustfix = "0.6.1"
+serde_json = "1.0.90"
 syn = { version = "1.0.101", features = ["full", "visit", "visit-mut"] }
 walkdir = "2.3.2"

src/build.rs

@@ -1,5 +1,6 @@
 use anyhow::{Context, Result};
-use std::{fmt::Display, path::PathBuf};
+use rustfix::diagnostics::Diagnostic;
+use std::{collections::HashSet, fmt::Display, path::PathBuf};
 
 use crate::Options;
 
@@ -7,6 +8,7 @@ use crate::Options;
 pub struct Build {
     mode: BuildMode,
     input_path: PathBuf,
+    no_verify: bool,
 }
 
 #[derive(Debug)]
@@ -28,6 +30,7 @@ impl Build {
         Self {
             mode,
             input_path: options.path.clone(),
+            no_verify: options.no_verify,
         }
     }
 
@@ -61,19 +64,58 @@ impl Build {
             }
         };
 
-        Ok(BuildResult { reproduces_issue })
+        Ok(BuildResult {
+            reproduces_issue,
+            no_verify: self.no_verify,
+        })
+    }
+
+    pub fn get_suggestions(&self) -> Result<(Vec<Diagnostic>, Vec<rustfix::Suggestion>)> {
+        match self.mode {
+            BuildMode::Cargo => {
+                todo!();
+            }
+            BuildMode::Script(_) => todo!(),
+            BuildMode::Rustc => {
+                let mut cmd = std::process::Command::new("rustc");
+                cmd.args(["--edition", "2018", "--error-format=json"]);
+                cmd.arg(&self.input_path);
+
+                let output = cmd.output()?.stderr;
+                let output = String::from_utf8(output)?;
+
+                let diags = serde_json::Deserializer::from_str(&output).into_iter::<Diagnostic>().collect::<Result<_, _>>()?;
+
+                let suggestions = rustfix::get_suggestions_from_json(
+                    &output,
+                    &HashSet::new(),
+                    rustfix::Filter::Everything,
+                )
+                .context("reading output as rustfix suggestions")?;
+
+                Ok((diags, suggestions))
+            }
+        }
     }
 }
 
 pub struct BuildResult {
-    pub reproduces_issue: bool,
+    reproduces_issue: bool,
+    no_verify: bool,
+}
+
+impl BuildResult {
+    pub fn reproduces_issue(&self) -> bool {
+        self.reproduces_issue || self.no_verify
+    }
 }
 
 impl Display for BuildResult {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self.reproduces_issue {
-            true => f.write_str("yes"),
-            false => f.write_str("no"),
+        match (self.reproduces_issue, self.no_verify) {
+            (true, _) => f.write_str("yes"),
+            (false, true) => f.write_str("no (ignore)"),
+            (false, false) => f.write_str("no"),
         }
     }
 }

src/lib.rs

@@ -8,11 +8,11 @@ mod expand;
 mod privatize;
 mod processor;
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use clap::Parser;
 use processor::Minimizer;
 
-use crate::{everybody_loops::EverybodyLoops, processor::Processor};
+use crate::{everybody_loops::EverybodyLoops, processor::Processor, privatize::Privatize};
 
 #[derive(clap::Parser)]
 pub struct Options {
@@ -20,6 +20,8 @@ pub struct Options {
     verify_error_path: Option<PathBuf>,
     #[arg(long)]
     cargo: bool,
+    #[arg(long)]
+    no_verify: bool,
     path: PathBuf,
 }
 
@@ -28,15 +30,19 @@ pub fn minimize() -> Result<()> {
 
     let build = build::Build::new(&options);
 
-    let mut minimizer = Minimizer::new_glob_dir(&options.path, build);
+    let mut minimizer = Minimizer::new_glob_dir(&options.path, build, &options);
 
     println!("{minimizer:?}");
 
+    minimizer.delete_dead_code().context("deleting dead code")?;
+
     minimizer.run_passes([
-        //Box::new(Privarize::default()) as Box<dyn Processor>,
+        Box::new(Privatize::default()) as Box<dyn Processor>,
         Box::new(EverybodyLoops::default()) as Box<dyn Processor>,
     ])?;
 
+    minimizer.delete_dead_code().context("deleting dead code")?;
+
     /*
     let file = expand::expand(&dir).context("during expansion")?;
 

src/privatize.rs

@@ -26,9 +26,9 @@ impl VisitMut for Visitor {
 }
 
 #[derive(Default)]
-pub struct Privarize {}
+pub struct Privatize {}
 
-impl Processor for Privarize {
+impl Processor for Privatize {
     fn process_file(&mut self, krate: &mut syn::File, _: &mut ProcessChecker) -> bool {
         let mut visitor = Visitor::new();
         visitor.visit_file_mut(krate);

src/processor/files.rs

@@ -0,0 +1,80 @@
+use anyhow::{Context, Result};
+use std::{
+    fs,
+    path::{Path, PathBuf},
+};
+
+#[derive(Debug)]
+pub struct SourceFile {
+    pub path: PathBuf,
+}
+
+#[derive(Default)]
+pub struct Changes {
+    any_change: bool,
+}
+
+pub struct FileChange<'a, 'b> {
+    pub path: &'a Path,
+    content: String,
+    changes: &'b mut Changes,
+    has_written_change: bool,
+}
+
+impl FileChange<'_, '_> {
+    pub fn before_content(&self) -> &str {
+        &self.content
+    }
+
+    pub fn write(&mut self, new: &str) -> Result<()> {
+        self.has_written_change = true;
+        fs::write(&self.path, new).with_context(|| format!("writing file {}", self.path.display()))
+    }
+
+    pub fn rollback(mut self) -> Result<()> {
+        assert!(self.has_written_change);
+        self.has_written_change = false;
+        fs::write(self.path, &self.content)
+            .with_context(|| format!("writing file {}", self.path.display()))
+    }
+
+    pub fn commit(mut self) {
+        assert!(self.has_written_change);
+        self.has_written_change = false;
+        self.changes.any_change = true;
+    }
+}
+
+impl Drop for FileChange<'_, '_> {
+    fn drop(&mut self) {
+        if self.has_written_change {
+            fs::write(&self.path, self.before_content()).ok();
+            if !std::thread::panicking() {
+                panic!("File contains unsaved changes!");
+            }
+        }
+    }
+}
+
+impl SourceFile {
+    pub fn try_change<'file, 'change>(
+        &'file self,
+        changes: &'change mut Changes,
+    ) -> Result<FileChange<'file, 'change>> {
+        let path = &self.path;
+        Ok(FileChange {
+            path,
+            changes,
+            has_written_change: false,
+            content: fs::read_to_string(path)
+                .with_context(|| format!("opening file {}", path.display()))?,
+        })
+    }
+}
+
+
+impl Changes {
+    pub fn had_changes(&self) -> bool {
+        self.any_change
+    }
+}

src/processor/mod.rs

@@ -1,11 +1,13 @@
-use std::{
-    ffi::OsStr,
-    path::{Path, PathBuf},
-};
+mod files;
+mod reaper;
+
+use std::{ffi::OsStr, path::Path};
 
 use anyhow::{ensure, Context, Result};
 
-use crate::build::Build;
+use crate::{build::Build, processor::files::Changes, Options};
+
+use self::files::SourceFile;
 
 pub trait Processor {
     fn process_file(&mut self, krate: &mut syn::File, checker: &mut ProcessChecker) -> bool;
@@ -15,12 +17,13 @@ pub trait Processor {
 
 #[derive(Debug)]
 pub struct Minimizer {
-    files: Vec<PathBuf>,
+    files: Vec<SourceFile>,
     build: Build,
+    no_verify: bool,
 }
 
 impl Minimizer {
-    pub fn new_glob_dir(path: &Path, build: Build) -> Self {
+    pub fn new_glob_dir(path: &Path, build: Build, options: &Options) -> Self {
         let walk = walkdir::WalkDir::new(path);
 
         let files = walk
@@ -33,10 +36,16 @@ impl Minimizer {
                 }
             })
             .filter(|entry| entry.path().extension() == Some(OsStr::new("rs")))
-            .map(|entry| entry.into_path())
+            .map(|entry| SourceFile {
+                path: entry.into_path(),
+            })
             .collect();
 
-        Self { files, build }
+        Self {
+            files,
+            build,
+            no_verify: options.no_verify,
+        }
     }
 
     pub fn run_passes<'a>(
@@ -45,23 +54,24 @@ impl Minimizer {
     ) -> Result<()> {
         let inital_build = self.build.build()?;
         println!("Initial build: {}", inital_build);
+        if !self.no_verify {
             ensure!(
-            inital_build.reproduces_issue,
+                inital_build.reproduces_issue(),
                 "Initial build must reproduce issue"
             );
+        }
 
         for mut pass in passes {
             'pass: loop {
                 println!("Starting a round of {}", pass.name());
-                let mut any_change = false;
+                let mut changes = Changes::default();
 
                 for file in &self.files {
-                    let file_display = file.display();
+                    let file_display = file.path.display();
 
-                    let before_string = std::fs::read_to_string(file)
-                        .with_context(|| format!("opening file {file_display}"))?;
+                    let mut change = file.try_change(&mut changes)?;
 
-                    let mut krate = syn::parse_file(&before_string)
+                    let mut krate = syn::parse_file(change.before_content())
                         .with_context(|| format!("parsing file {file_display}"))?;
 
                     let has_made_change = pass.process_file(&mut krate, &mut ProcessChecker {});
@@ -69,23 +79,23 @@ impl Minimizer {
                     if has_made_change {
                         let result = prettyplease::unparse(&krate);
 
-                        std::fs::write(file, &result)?;
+                        change.write(&result)?;
 
                         let after = self.build.build()?;
 
                         println!("{file_display}: After {}: {after}", pass.name());
 
-                        if after.reproduces_issue {
-                            any_change = true;
+                        if after.reproduces_issue() {
+                            change.commit();
                         } else {
-                            std::fs::write(file, before_string)?;
+                            change.rollback()?;
                         }
                     } else {
                         println!("{file_display}: After {}: no change", pass.name());
                     }
                 }
 
-                if !any_change {
+                if !changes.had_changes() {
                     println!("Finished {}", pass.name());
                     break 'pass;
                 }

src/processor/reaper.rs

@@ -0,0 +1,229 @@
+//! Deletes dead code.
+
+use super::{files::Changes, Minimizer, Processor};
+use anyhow::{ensure, Context, Result};
+use proc_macro2::Span;
+use rustfix::{diagnostics::Diagnostic, Suggestion};
+use std::{collections::HashMap, ops::Range, path::Path};
+use syn::{visit_mut::VisitMut, ImplItem, Item};
+
+fn file_for_suggestion(suggestion: &Suggestion) -> &str {
+    &suggestion.solutions[0].replacements[0].snippet.file_name
+}
+
+impl Minimizer {
+    pub fn delete_dead_code(&mut self) -> Result<()> {
+        let inital_build = self.build.build()?;
+        println!("Before reaper: {}", inital_build);
+        if !self.no_verify {
+            ensure!(
+                inital_build.reproduces_issue(),
+                "Initial build must reproduce issue"
+            );
+        }
+
+        let (diags, suggestions) = self
+            .build
+            .get_suggestions()
+            .context("getting suggestions from rustc")?;
+
+        let mut suggestions_for_file = HashMap::<_, Vec<_>>::new();
+        for suggestion in &suggestions {
+            suggestions_for_file
+                .entry(file_for_suggestion(suggestion))
+                .or_default()
+                .push(suggestion);
+        }
+
+        // Always unconditionally apply unused imports.
+        self.apply_unused_imports(&suggestions_for_file)?;
+
+        self.run_passes([Box::new(DeleteUnusedFunctions(diags)) as Box<dyn Processor>])
+            .context("deleting unused functions")?;
+
+        Ok(())
+    }
+
+    fn apply_unused_imports<'a>(
+        &mut self,
+        suggestions: &HashMap<&str, Vec<&Suggestion>>,
+    ) -> Result<()> {
+        for (file, suggestions) in suggestions {
+            let file = self
+                .files
+                .iter()
+                .find(|source| source.path == Path::new(file))
+                .expect("unknown file");
+
+            let mut changes = &mut Changes::default();
+
+            let mut change = file.try_change(&mut changes)?;
+
+            let desired_suggestions = suggestions
+                .iter()
+                .filter(|sugg| sugg.message.contains("unused import"))
+                .cloned()
+                .cloned()
+                .collect::<Vec<_>>();
+
+            let result = rustfix::apply_suggestions(change.before_content(), &desired_suggestions)?;
+
+            change.write(&result)?;
+
+            let after = self.build.build()?;
+
+            println!("{}: After reaper: {after}", file.path.display());
+
+            if after.reproduces_issue() {
+                change.commit();
+            } else {
+                change.rollback()?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+struct DeleteUnusedFunctions(Vec<Diagnostic>);
+
+impl Processor for DeleteUnusedFunctions {
+    fn process_file(&mut self, krate: &mut syn::File, _: &mut super::ProcessChecker) -> bool {
+        let mut visitor = FindUnusedFunction::new(self.0.iter());
+        visitor.visit_file_mut(krate);
+
+        visitor.has_change
+    }
+
+    fn name(&self) -> &'static str {
+        "delete-unused-functions"
+    }
+}
+
+#[derive(Debug)]
+struct Unused {
+    name: String,
+    line: usize,
+    column: Range<usize>,
+}
+
+impl Unused {
+    fn span_matches(&self, ident_span: Span) -> bool {
+        let (start, end) = (ident_span.start(), ident_span.end());
+
+        assert_eq!(start.line, end.line);
+
+        let line_matches = self.line == start.line;
+        let column_matches = self.column.start <= start.column && self.column.end >= end.column;
+
+        line_matches && column_matches
+    }
+}
+
+struct FindUnusedFunction {
+    unused_functions: Vec<Unused>,
+    has_change: bool,
+}
+
+impl FindUnusedFunction {
+    fn new<'a>(diags: impl Iterator<Item = &'a Diagnostic>) -> Self {
+        let unused_functions = diags
+            .filter_map(|diag| {
+                // FIXME: use `code` correctly
+                if diag
+                    .code
+                    .as_ref()
+                    .map_or(false, |code| code.code != "dead_code")
+                {
+                    return None;
+                }
+
+                if !diag.message.contains("function") {
+                    return None;
+                }
+
+                let name = diag.message.split("`").nth(1)?.to_owned();
+                let span = &diag.spans[0];
+
+                assert_eq!(
+                    span.line_start, span.line_end,
+                    "encountered multiline span in dead_code"
+                );
+
+                Some(Unused {
+                    name,
+                    line: span.line_start,
+                    column: (span.column_start - 1)..(span.column_end - 1),
+                })
+            })
+            .collect();
+
+        Self {
+            unused_functions,
+            has_change: false,
+        }
+    }
+
+    fn should_retain_item(&mut self, span: Span) -> bool {
+        let span_matches = self
+            .unused_functions
+            .iter()
+            .map(|a| a.span_matches(span))
+            .filter(|&matches| matches)
+            .count();
+
+        assert!(
+            span_matches < 2,
+            "multiple dead_code spans matched identifier: {span_matches}"
+        );
+
+        if span_matches == 1 {
+            self.has_change = true;
+        }
+
+        span_matches == 0
+    }
+}
+
+impl VisitMut for FindUnusedFunction {
+    fn visit_item_impl_mut(&mut self, item_impl: &mut syn::ItemImpl) {
+        item_impl.items.retain(|item| match item {
+            ImplItem::Method(method) => {
+                let span = method.sig.ident.span();
+
+                self.should_retain_item(span)
+            }
+            _ => true,
+        });
+
+        syn::visit_mut::visit_item_impl_mut(self, item_impl);
+    }
+
+    fn visit_file_mut(&mut self, krate: &mut syn::File) {
+        krate.items.retain(|item| match item {
+            Item::Fn(func) => {
+                let span = func.sig.ident.span();
+
+                self.should_retain_item(span)
+            }
+            _ => true,
+        });
+
+        syn::visit_mut::visit_file_mut(self, krate);
+    }
+
+    fn visit_item_mod_mut(&mut self, module: &mut syn::ItemMod) {
+        if let Some((_, content)) = &mut module.content {
+            content.retain(|item| match item {
+                Item::Fn(func) => {
+                    let span = func.sig.ident.span();
+
+                    self.should_retain_item(span)
+                }
+                _ => true,
+            })
+        }
+
+        syn::visit_mut::visit_item_mod_mut(self, module);
+    }
+}

test-cases/unused-code/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "hello-world"
+version = "0.1.0"

test-cases/unused-code/Cargo.toml

@@ -0,0 +1,10 @@
+[workspace]
+
+[package]
+name = "hello-world"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

test-cases/unused-code/src/main.rs

@@ -0,0 +1,5 @@
+fn unused() {}
+
+fn main() {
+    unused();
+}