Enable support for fix --edition for 2021.

src/cargo/core/features.rs

@@ -208,15 +208,15 @@ impl Edition {
 
  /// Whether or not this edition supports the `rust_*_compatibility` lint.
  ///
- /// Ideally this would not be necessary, but currently 2021 does not have
- /// any lints, and thus `rustc` doesn't recognize it. Perhaps `rustc`
- /// could create an empty group instead?
+ /// Ideally this would not be necessary, but editions may not have any
+ /// lints, and thus `rustc` doesn't recognize it. Perhaps `rustc` could
+ /// create an empty group instead?
  pub(crate) fn supports_compat_lint(&self) -> bool {
  use Edition::*;
  match self {
  Edition2015 => false,
  Edition2018 => true,
- Edition2021 => false,
+ Edition2021 => true,
  }
  }
 

src/cargo/ops/fix.rs

@@ -330,7 +330,7 @@ pub fn fix_maybe_exec_rustc(config: &Config) -> CargoResult<bool> {
  // that we have to back it all out.
  if !fixes.files.is_empty() {
  let mut cmd = rustc.build_command();
- args.apply(&mut cmd);
+ args.apply(&mut cmd, config);
  cmd.arg("--error-format=json");
  let output = cmd.output().context("failed to spawn rustc")?;
 
@@ -369,7 +369,7 @@ pub fn fix_maybe_exec_rustc(config: &Config) -> CargoResult<bool> {
  // - If `--broken-code`, show the error messages.
  // - If the fix succeeded, show any remaining warnings.
  let mut cmd = rustc.build_command();
- args.apply(&mut cmd);
+ args.apply(&mut cmd, config);
  for arg in args.format_args {
  // Add any json/error format arguments that Cargo wants. This allows
  // things like colored output to work correctly.
@@ -457,7 +457,7 @@ fn rustfix_crate(
  // We'll generate new errors below.
  file.errors_applying_fixes.clear();
  }
- rustfix_and_fix(&mut fixes, rustc, filename, args)?;
+ rustfix_and_fix(&mut fixes, rustc, filename, args, config)?;
  let mut progress_yet_to_be_made = false;
  for (path, file) in fixes.files.iter_mut() {
  if file.errors_applying_fixes.is_empty() {
@@ -499,14 +499,15 @@ fn rustfix_and_fix(
  rustc: &ProcessBuilder,
  filename: &Path,
  args: &FixArgs,
+ config: &Config,
 ) -> Result<(), Error> {
  // If not empty, filter by these lints.
  // TODO: implement a way to specify this.
  let only = HashSet::new();
 
  let mut cmd = rustc.build_command();
  cmd.arg("--error-format=json");
- args.apply(&mut cmd);
+ args.apply(&mut cmd, config);
  let output = cmd.output().with_context(|| {
  format!(
  "failed to execute `{}`",
@@ -763,7 +764,7 @@ impl FixArgs {
  })
  }
 
- fn apply(&self, cmd: &mut Command) {
+ fn apply(&self, cmd: &mut Command, config: &Config) {
  cmd.arg(&self.file);
  cmd.args(&self.other).arg("--cap-lints=warn");
  if let Some(edition) = self.enabled_edition {
@@ -775,7 +776,13 @@ impl FixArgs {
 
  if let Some(edition) = self.prepare_for_edition {
  if edition.supports_compat_lint() {
- cmd.arg("-W").arg(format!("rust-{}-compatibility", edition));
+ if config.nightly_features_allowed {
+ cmd.arg("--force-warns")
+ .arg(format!("rust-{}-compatibility", edition))
+ .arg("-Zunstable-options");
+ } else {
+ cmd.arg("-W").arg(format!("rust-{}-compatibility", edition));
+ }
  }
  }
  }

tests/testsuite/fix.rs

@@ -1501,3 +1501,49 @@ fn rustfix_handles_multi_spans() {
  p.cargo("fix --allow-no-vcs").run();
  assert!(p.read_file("src/lib.rs").contains(r#"panic!("hey");"#));
 }
+
+#[cargo_test]
+fn fix_edition_2021() {
+ // Can migrate 2021, even when lints are allowed.
+ if !is_nightly() {
+ // 2021 is unstable
+ return;
+ }
+ let p = project()
+ .file(
+ "Cargo.toml",
+ r#"
+ [package]
+ name = "foo"
+ version = "0.1.0"
+ edition = "2018"
+ "#,
+ )
+ .file(
+ "src/lib.rs",
+ r#"
+ #![allow(ellipsis_inclusive_range_patterns)]
+
+ pub fn f() -> bool {
+ let x = 123;
+ match x {
+ 0...100 => true,
+ _ => false,
+ }
+ }
+ "#,
+ )
+ .build();
+ p.cargo("fix --edition --allow-no-vcs")
+ .masquerade_as_nightly_cargo()
+ .with_stderr(
+ "\
+[CHECKING] foo v0.1.0 [..]
+[MIGRATING] src/lib.rs from 2018 edition to 2021
+[FIXED] src/lib.rs (1 fix)
+[FINISHED] [..]
+",
+ )
+ .run();
+ assert!(p.read_file("src/lib.rs").contains(r#"0..=100 => true,"#));
+}