[ty] Add GitHub output format (#20358)

## Summary

This PR wires up the GitHub output format moved to `ruff_db` in #20320
to the ty CLI.

It's a bit smaller than the GitLab version (#20155) because some of the
helpers were already in place, but I did factor out a few
`DisplayDiagnosticConfig` constructor calls in Ruff. I also exposed the
`GithubRenderer` and a wrapper `DisplayGithubDiagnostics` type because
we needed a way to configure the program name displayed in the GitHub
diagnostics. This was previously hard-coded to `Ruff`:

<img width="675" height="247" alt="image"
src="https://github.com/user-attachments/assets/592da860-d2f5-4abd-bc5a-66071d742509"
/>

Another option would be to drop the program name in the output format,
but I think it can be helpful in workflows with multiple programs
emitting annotations (such as Ruff and ty!)

## Test Plan

New CLI test, and a manual test with `--config 'terminal.output-format =
"github"'`

crates/ruff/src/printer.rs

@@ -10,7 +10,8 @@ use ruff_linter::linter::FixTable;
 use serde::Serialize;
 
 use ruff_db::diagnostic::{
-    Diagnostic, DiagnosticFormat, DisplayDiagnosticConfig, DisplayDiagnostics, SecondaryCode,
+    Diagnostic, DiagnosticFormat, DisplayDiagnosticConfig, DisplayDiagnostics,
+    DisplayGithubDiagnostics, GithubRenderer, SecondaryCode,
 };
 use ruff_linter::fs::relativize_path;
 use ruff_linter::logging::LogLevel;
@@ -224,32 +225,26 @@ impl Printer {
         let context = EmitterContext::new(&diagnostics.notebook_indexes);
         let fixables = FixableStatistics::try_from(diagnostics, self.unsafe_fixes);
 
+        let config = DisplayDiagnosticConfig::default().preview(preview);
+
         match self.format {
             OutputFormat::Json => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::Json)
-                    .preview(preview);
+                let config = config.format(DiagnosticFormat::Json);
                 let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }
             OutputFormat::Rdjson => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::Rdjson)
-                    .preview(preview);
+                let config = config.format(DiagnosticFormat::Rdjson);
                 let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }
             OutputFormat::JsonLines => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::JsonLines)
-                    .preview(preview);
+                let config = config.format(DiagnosticFormat::JsonLines);
                 let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }
             OutputFormat::Junit => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::Junit)
-                    .preview(preview);
+                let config = config.format(DiagnosticFormat::Junit);
                 let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }
@@ -288,30 +283,22 @@ impl Printer {
                 self.write_summary_text(writer, diagnostics)?;
             }
             OutputFormat::Github => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::Github)
-                    .preview(preview);
-                let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
+                let renderer = GithubRenderer::new(&context, "Ruff");
+                let value = DisplayGithubDiagnostics::new(&renderer, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }
             OutputFormat::Gitlab => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::Gitlab)
-                    .preview(preview);
+                let config = config.format(DiagnosticFormat::Gitlab);
                 let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }
             OutputFormat::Pylint => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::Pylint)
-                    .preview(preview);
+                let config = config.format(DiagnosticFormat::Pylint);
                 let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }
             OutputFormat::Azure => {
-                let config = DisplayDiagnosticConfig::default()
-                    .format(DiagnosticFormat::Azure)
-                    .preview(preview);
+                let config = config.format(DiagnosticFormat::Azure);
                 let value = DisplayDiagnostics::new(&context, &config, &diagnostics.inner);
                 write!(writer, "{value}")?;
             }

crates/ruff_db/src/diagnostic/mod.rs

@@ -8,6 +8,7 @@ use ruff_text_size::{Ranged, TextRange, TextSize};
 
 pub use self::render::{
     DisplayDiagnostic, DisplayDiagnostics, FileResolver, Input, ceil_char_boundary,
+    github::{DisplayGithubDiagnostics, GithubRenderer},
 };
 use crate::{Db, files::File};
 

crates/ruff_db/src/diagnostic/render.rs

@@ -31,7 +31,7 @@ use pylint::PylintRenderer;
 mod azure;
 mod concise;
 mod full;
-mod github;
+pub mod github;
 #[cfg(feature = "serde")]
 mod gitlab;
 #[cfg(feature = "serde")]
@@ -145,7 +145,7 @@ impl std::fmt::Display for DisplayDiagnostics<'_> {
                 gitlab::GitlabRenderer::new(self.resolver).render(f, self.diagnostics)?;
             }
             DiagnosticFormat::Github => {
-                GithubRenderer::new(self.resolver).render(f, self.diagnostics)?;
+                GithubRenderer::new(self.resolver, "ty").render(f, self.diagnostics)?;
             }
         }
 

crates/ruff_db/src/diagnostic/render/github.rs

@@ -1,12 +1,13 @@
-use crate::diagnostic::{Diagnostic, FileResolver};
+use crate::diagnostic::{Diagnostic, FileResolver, Severity};
 
-pub(super) struct GithubRenderer<'a> {
+pub struct GithubRenderer<'a> {
     resolver: &'a dyn FileResolver,
+    program: &'a str,
 }
 
 impl<'a> GithubRenderer<'a> {
-    pub(super) fn new(resolver: &'a dyn FileResolver) -> Self {
-        Self { resolver }
+    pub fn new(resolver: &'a dyn FileResolver, program: &'a str) -> Self {
+        Self { resolver, program }
     }
 
     pub(super) fn render(
@@ -15,9 +16,15 @@ impl<'a> GithubRenderer<'a> {
         diagnostics: &[Diagnostic],
     ) -> std::fmt::Result {
         for diagnostic in diagnostics {
+            let severity = match diagnostic.severity() {
+                Severity::Info => "notice",
+                Severity::Warning => "warning",
+                Severity::Error | Severity::Fatal => "error",
+            };
             write!(
                 f,
-                "::error title=Ruff ({code})",
+                "::{severity} title={program} ({code})",
+                program = self.program,
                 code = diagnostic.secondary_code_or_id()
             )?;
 
@@ -75,6 +82,26 @@ impl<'a> GithubRenderer<'a> {
     }
 }
 
+pub struct DisplayGithubDiagnostics<'a> {
+    renderer: &'a GithubRenderer<'a>,
+    diagnostics: &'a [Diagnostic],
+}
+
+impl<'a> DisplayGithubDiagnostics<'a> {
+    pub fn new(renderer: &'a GithubRenderer<'a>, diagnostics: &'a [Diagnostic]) -> Self {
+        Self {
+            renderer,
+            diagnostics,
+        }
+    }
+}
+
+impl std::fmt::Display for DisplayGithubDiagnostics<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.renderer.render(f, self.diagnostics)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::diagnostic::{
@@ -103,7 +130,7 @@ mod tests {
 
         insta::assert_snapshot!(
             env.render(&diag),
-            @"::error title=Ruff (test-diagnostic)::test-diagnostic: main diagnostic message",
+            @"::error title=ty (test-diagnostic)::test-diagnostic: main diagnostic message",
         );
     }
 }

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__github__tests__output.snap

@@ -2,6 +2,6 @@
 source: crates/ruff_db/src/diagnostic/render/github.rs
 expression: env.render_diagnostics(&diagnostics)
 ---
-::error title=Ruff (F401),file=fib.py,line=1,col=8,endLine=1,endColumn=10::fib.py:1:8: F401 `os` imported but unused
-::error title=Ruff (F841),file=fib.py,line=6,col=5,endLine=6,endColumn=6::fib.py:6:5: F841 Local variable `x` is assigned to but never used
-::error title=Ruff (F821),file=undef.py,line=1,col=4,endLine=1,endColumn=5::undef.py:1:4: F821 Undefined name `a`
+::error title=ty (F401),file=fib.py,line=1,col=8,endLine=1,endColumn=10::fib.py:1:8: F401 `os` imported but unused
+::error title=ty (F841),file=fib.py,line=6,col=5,endLine=6,endColumn=6::fib.py:6:5: F841 Local variable `x` is assigned to but never used
+::error title=ty (F821),file=undef.py,line=1,col=4,endLine=1,endColumn=5::undef.py:1:4: F821 Undefined name `a`

crates/ruff_db/src/diagnostic/render/snapshots/ruff_db__diagnostic__render__github__tests__syntax_errors.snap

@@ -2,5 +2,5 @@
 source: crates/ruff_db/src/diagnostic/render/github.rs
 expression: env.render_diagnostics(&diagnostics)
 ---
-::error title=Ruff (invalid-syntax),file=syntax_errors.py,line=1,col=15,endLine=2,endColumn=1::syntax_errors.py:1:15: invalid-syntax: Expected one or more symbol names after import
-::error title=Ruff (invalid-syntax),file=syntax_errors.py,line=3,col=12,endLine=4,endColumn=1::syntax_errors.py:3:12: invalid-syntax: Expected ')', found newline
+::error title=ty (invalid-syntax),file=syntax_errors.py,line=1,col=15,endLine=2,endColumn=1::syntax_errors.py:1:15: invalid-syntax: Expected one or more symbol names after import
+::error title=ty (invalid-syntax),file=syntax_errors.py,line=3,col=12,endLine=4,endColumn=1::syntax_errors.py:3:12: invalid-syntax: Expected ')', found newline

crates/ty/docs/cli.md

@@ -63,6 +63,7 @@ over all configuration files.</p>
 <li><code>full</code>:  Print diagnostics verbosely, with context and helpful hints (default)</li>
 <li><code>concise</code>:  Print diagnostics concisely, one per line</li>
 <li><code>gitlab</code>:  Print diagnostics in the JSON format expected by GitLab Code Quality reports</li>
+<li><code>github</code>:  Print diagnostics in the format used by GitHub Actions workflow error annotations</li>
 </ul></dd><dt id="ty-check--project"><a href="#ty-check--project"><code>--project</code></a> <i>project</i></dt><dd><p>Run the command within the given project directory.</p>
 <p>All <code>pyproject.toml</code> files will be discovered by walking up the directory tree from the given project directory, as will the project's virtual environment (<code>.venv</code>) unless the <code>venv-path</code> option is set.</p>
 <p>Other command-line arguments (such as relative paths) will be resolved relative to the current working directory.</p>

crates/ty/src/args.rs

@@ -324,6 +324,9 @@ pub enum OutputFormat {
     /// Print diagnostics in the JSON format expected by GitLab Code Quality reports.
     #[value(name = "gitlab")]
     Gitlab,
+    #[value(name = "github")]
+    /// Print diagnostics in the format used by GitHub Actions workflow error annotations.
+    Github,
 }
 
 impl From<OutputFormat> for ty_project::metadata::options::OutputFormat {
@@ -332,6 +335,7 @@ impl From<OutputFormat> for ty_project::metadata::options::OutputFormat {
             OutputFormat::Full => Self::Full,
             OutputFormat::Concise => Self::Concise,
             OutputFormat::Gitlab => Self::Gitlab,
+            OutputFormat::Github => Self::Github,
         }
     }
 }

crates/ty/tests/cli/main.rs

@@ -683,6 +683,30 @@ fn gitlab_diagnostics() -> anyhow::Result<()> {
     Ok(())
 }
 
+#[test]
+fn github_diagnostics() -> anyhow::Result<()> {
+    let case = CliTest::with_file(
+        "test.py",
+        r#"
+        print(x)     # [unresolved-reference]
+        print(4[1])  # [non-subscriptable]
+        "#,
+    )?;
+
+    assert_cmd_snapshot!(case.command().arg("--output-format=github").arg("--warn").arg("unresolved-reference"), @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    ::warning title=ty (unresolved-reference),file=test.py,line=2,col=7,endLine=2,endColumn=8::test.py:2:7: unresolved-reference: Name `x` used when not defined
+    ::error title=ty (non-subscriptable),file=test.py,line=3,col=7,endLine=3,endColumn=8::test.py:3:7: non-subscriptable: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
+
+    ----- stderr -----
+    WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
+    ");
+
+    Ok(())
+}
+
 /// This tests the diagnostic format for revealed type.
 ///
 /// This test was introduced because changes were made to

crates/ty_project/src/metadata/options.rs

@@ -1077,6 +1077,10 @@ pub enum OutputFormat {
     ///
     /// [Code Quality]: https://docs.gitlab.com/ci/testing/code_quality/#code-quality-report-format
     Gitlab,
+    /// Print diagnostics in the format used by [GitHub Actions] workflow error annotations.
+    ///
+    /// [GitHub Actions]: https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-commands#setting-an-error-message
+    Github,
 }
 
 impl OutputFormat {
@@ -1096,6 +1100,7 @@ impl From<OutputFormat> for DiagnosticFormat {
             OutputFormat::Full => Self::Full,
             OutputFormat::Concise => Self::Concise,
             OutputFormat::Gitlab => Self::Gitlab,
+            OutputFormat::Github => Self::Github,
         }
     }
 }

ty.schema.json

@@ -171,6 +171,13 @@
           "enum": [
             "gitlab"
           ]
+        },
+        {
+          "description": "Print diagnostics in the format used by [GitHub Actions] workflow error annotations.\n\n[GitHub Actions]: https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-commands#setting-an-error-message",
+          "type": "string",
+          "enum": [
+            "github"
+          ]
         }
       ]
     },