Optionally show fixes when using --features ecosystem_ci with cargo and --show-fixes at runtime (#4191)

* Generate fixes when using --show-fixes

Example command: `cargo run --bin ruff -- --no-cache --select F401
--show-source --show-fixes
crates/ruff/resources/test/fixtures/pyflakes/F401_9.py`

Before, `--show-fixes` was ignored:

```
crates/ruff/resources/test/fixtures/pyflakes/F401_9.py:4:22: F401 [*] `foo.baz` imported but unused
  |
4 | __all__ = ("bar",)
5 | from foo import bar, baz
  |                      ^^^ F401
  |
  = help: Remove unused import: `foo.baz`

Found 1 error.
[*] 1 potentially fixable with the --fix option.
```

After:

```
crates/ruff/resources/test/fixtures/pyflakes/F401_9.py:4:22: F401 [*] `foo.baz` imported but unused
  |
4 | __all__ = ("bar",)
5 | from foo import bar, baz
  |                      ^^^ F401
  |
  = help: Remove unused import: `foo.baz`

ℹ Suggested fix
1 1 | """Test: late-binding of `__all__`."""
2 2 |
3 3 | __all__ = ("bar",)
4   |-from foo import bar, baz
  4 |+from foo import bar

Found 1 error.
[*] 1 potentially fixable with the --fix option.
```

* Add `--format ecosystem-ci`

* cargo dev generate-all

* Put behind cargo feature

* Regenerate docs

* Don't test ecosystem_ci feature on CI

* Use top level flag instead

* Fix

* Simplify code based on #4191

* Remove old TODO comment

crates/ruff_cli/src/args.rs

@@ -291,6 +291,10 @@ pub struct CheckArgs {
         conflicts_with = "watch",
     )]
     pub show_settings: bool,
+    /// Dev-only argument to show fixes
+    #[cfg(feature = "ecosystem_ci")]
+    #[arg(long, hide = true)]
+    pub ecosystem_ci: bool,
 }
 
 #[derive(Debug, Clone, Copy, clap::ValueEnum)]

crates/ruff_cli/src/commands/run.rs

@@ -254,6 +254,8 @@ mod test {
             LogLevel::Default,
             FixMode::None,
             Flags::SHOW_VIOLATIONS,
+            #[cfg(feature = "ecosystem_ci")]
+            false,
         );
         let mut writer: Vec<u8> = Vec::new();
         // Mute the terminal color codes

crates/ruff_cli/src/lib.rs

@@ -123,6 +123,8 @@ quoting the executed command, along with the relevant file contents and `pyproje
 }
 
 fn check(args: CheckArgs, log_level: LogLevel) -> Result<ExitStatus> {
+    #[cfg(feature = "ecosystem_ci")]
+    let ecosystem_ci = args.ecosystem_ci;
     let (cli, overrides) = args.partition();
 
     // Construct the "default" settings. These are used when no `pyproject.toml`
@@ -209,7 +211,14 @@ fn check(args: CheckArgs, log_level: LogLevel) -> Result<ExitStatus> {
         return Ok(ExitStatus::Success);
     }
 
-    let printer = Printer::new(format, log_level, autofix, printer_flags);
+    let printer = Printer::new(
+        format,
+        log_level,
+        autofix,
+        printer_flags,
+        #[cfg(feature = "ecosystem_ci")]
+        ecosystem_ci,
+    );
 
     if cli.watch {
         if format != SerializationFormat::Text {

crates/ruff_cli/src/printer.rs

@@ -70,6 +70,9 @@ pub(crate) struct Printer {
     log_level: LogLevel,
     autofix_level: flags::FixMode,
     flags: Flags,
+    /// Dev-only argument to show fixes
+    #[cfg(feature = "ecosystem_ci")]
+    ecosystem_ci: bool,
 }
 
 impl Printer {
@@ -78,12 +81,15 @@ impl Printer {
         log_level: LogLevel,
         autofix_level: flags::FixMode,
         flags: Flags,
+        #[cfg(feature = "ecosystem_ci")] ecosystem_ci: bool,
     ) -> Self {
         Self {
             format,
             log_level,
             autofix_level,
             flags,
+            #[cfg(feature = "ecosystem_ci")]
+            ecosystem_ci,
         }
     }
 
@@ -179,8 +185,14 @@ impl Printer {
                 JunitEmitter::default().emit(writer, &diagnostics.messages, &context)?;
             }
             SerializationFormat::Text => {
+                #[cfg(feature = "ecosystem_ci")]
+                let show_fixes = self.ecosystem_ci && self.flags.contains(Flags::SHOW_FIXES);
+                #[cfg(not(feature = "ecosystem_ci"))]
+                let show_fixes = false;
+
                 TextEmitter::default()
                     .with_show_fix_status(show_fix_status(self.autofix_level))
+                    .with_show_fix(show_fixes)
                     .with_show_source(self.flags.contains(Flags::SHOW_SOURCE))
                     .emit(writer, &diagnostics.messages, &context)?;