Rename Red Knot (#17820)

crates/ty_ide/Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+name = "ty_ide"
+version = "0.0.0"
+publish = false
+authors = { workspace = true }
+edition = { workspace = true }
+rust-version = { workspace = true }
+homepage = { workspace = true }
+documentation = { workspace = true }
+repository = { workspace = true }
+license = { workspace = true }
+
+[dependencies]
+ruff_db = { workspace = true }
+ruff_python_ast = { workspace = true }
+ruff_python_parser = { workspace = true }
+ruff_text_size = { workspace = true }
+ty_python_semantic = { workspace = true }
+
+rustc-hash = { workspace = true }
+salsa = { workspace = true }
+smallvec = { workspace = true }
+tracing = { workspace = true }
+
+[dev-dependencies]
+ty_vendored = { workspace = true }
+
+insta = { workspace = true, features = ["filters"] }
+
+[lints]
+workspace = true

crates/ty_ide/src/completion.rs

@@ -0,0 +1,39 @@
+use ruff_db::files::File;
+use ruff_db::parsed::parsed_module;
+use ruff_python_ast::visitor::source_order::SourceOrderVisitor;
+use ruff_python_ast::{AnyNodeRef, Identifier};
+use ruff_text_size::TextSize;
+
+use crate::Db;
+
+pub struct Completion {
+    pub label: String,
+}
+
+pub fn completion(db: &dyn Db, file: File, _offset: TextSize) -> Vec<Completion> {
+    let parsed = parsed_module(db.upcast(), file);
+    identifiers(parsed.syntax().into())
+        .into_iter()
+        .map(|label| Completion { label })
+        .collect()
+}
+
+fn identifiers(node: AnyNodeRef) -> Vec<String> {
+    struct Visitor {
+        identifiers: Vec<String>,
+    }
+
+    impl<'a> SourceOrderVisitor<'a> for Visitor {
+        fn visit_identifier(&mut self, id: &'a Identifier) {
+            self.identifiers.push(id.id.as_str().to_string());
+        }
+    }
+
+    let mut visitor = Visitor {
+        identifiers: vec![],
+    };
+    node.visit_source_order(&mut visitor);
+    visitor.identifiers.sort();
+    visitor.identifiers.dedup();
+    visitor.identifiers
+}

crates/ty_ide/src/db.rs

@@ -0,0 +1,138 @@
+use ruff_db::{Db as SourceDb, Upcast};
+use ty_python_semantic::Db as SemanticDb;
+
+#[salsa::db]
+pub trait Db: SemanticDb + Upcast<dyn SemanticDb> + Upcast<dyn SourceDb> {}
+
+#[cfg(test)]
+pub(crate) mod tests {
+    use std::sync::Arc;
+
+    use super::Db;
+    use ruff_db::files::{File, Files};
+    use ruff_db::system::{DbWithTestSystem, System, TestSystem};
+    use ruff_db::vendored::VendoredFileSystem;
+    use ruff_db::{Db as SourceDb, Upcast};
+    use ty_python_semantic::lint::{LintRegistry, RuleSelection};
+    use ty_python_semantic::{default_lint_registry, Db as SemanticDb, Program};
+
+    #[salsa::db]
+    #[derive(Clone)]
+    pub(crate) struct TestDb {
+        storage: salsa::Storage<Self>,
+        files: Files,
+        system: TestSystem,
+        vendored: VendoredFileSystem,
+        events: Arc<std::sync::Mutex<Vec<salsa::Event>>>,
+        rule_selection: Arc<RuleSelection>,
+    }
+
+    #[allow(dead_code)]
+    impl TestDb {
+        pub(crate) fn new() -> Self {
+            Self {
+                storage: salsa::Storage::default(),
+                system: TestSystem::default(),
+                vendored: ty_vendored::file_system().clone(),
+                events: Arc::default(),
+                files: Files::default(),
+                rule_selection: Arc::new(RuleSelection::from_registry(default_lint_registry())),
+            }
+        }
+
+        /// Takes the salsa events.
+        ///
+        /// ## Panics
+        /// If there are any pending salsa snapshots.
+        pub(crate) fn take_salsa_events(&mut self) -> Vec<salsa::Event> {
+            let inner = Arc::get_mut(&mut self.events).expect("no pending salsa snapshots");
+
+            let events = inner.get_mut().unwrap();
+            std::mem::take(&mut *events)
+        }
+
+        /// Clears the salsa events.
+        ///
+        /// ## Panics
+        /// If there are any pending salsa snapshots.
+        pub(crate) fn clear_salsa_events(&mut self) {
+            self.take_salsa_events();
+        }
+    }
+
+    impl DbWithTestSystem for TestDb {
+        fn test_system(&self) -> &TestSystem {
+            &self.system
+        }
+
+        fn test_system_mut(&mut self) -> &mut TestSystem {
+            &mut self.system
+        }
+    }
+
+    #[salsa::db]
+    impl SourceDb for TestDb {
+        fn vendored(&self) -> &VendoredFileSystem {
+            &self.vendored
+        }
+
+        fn system(&self) -> &dyn System {
+            &self.system
+        }
+
+        fn files(&self) -> &Files {
+            &self.files
+        }
+
+        fn python_version(&self) -> ruff_python_ast::PythonVersion {
+            Program::get(self).python_version(self)
+        }
+    }
+
+    impl Upcast<dyn SourceDb> for TestDb {
+        fn upcast(&self) -> &(dyn SourceDb + 'static) {
+            self
+        }
+        fn upcast_mut(&mut self) -> &mut (dyn SourceDb + 'static) {
+            self
+        }
+    }
+
+    impl Upcast<dyn SemanticDb> for TestDb {
+        fn upcast(&self) -> &(dyn SemanticDb + 'static) {
+            self
+        }
+
+        fn upcast_mut(&mut self) -> &mut dyn SemanticDb {
+            self
+        }
+    }
+
+    #[salsa::db]
+    impl SemanticDb for TestDb {
+        fn is_file_open(&self, file: File) -> bool {
+            !file.path(self).is_vendored_path()
+        }
+
+        fn rule_selection(&self) -> Arc<RuleSelection> {
+            self.rule_selection.clone()
+        }
+
+        fn lint_registry(&self) -> &LintRegistry {
+            default_lint_registry()
+        }
+    }
+
+    #[salsa::db]
+    impl Db for TestDb {}
+
+    #[salsa::db]
+    impl salsa::Database for TestDb {
+        fn salsa_event(&self, event: &dyn Fn() -> salsa::Event) {
+            let event = event();
+            tracing::trace!("event: {event:?}");
+            let mut events = self.events.lock().unwrap();
+            events.push(event);
+        }
+    }
+}

crates/ty_ide/src/find_node.rs

@@ -0,0 +1,106 @@
+use ruff_python_ast::visitor::source_order::{SourceOrderVisitor, TraversalSignal};
+use ruff_python_ast::AnyNodeRef;
+use ruff_text_size::{Ranged, TextRange};
+use std::fmt;
+use std::fmt::Formatter;
+
+/// Returns the node with a minimal range that fully contains `range`.
+///
+/// If `range` is empty and falls within a parser *synthesized* node generated during error recovery,
+/// then the first node with the given range is returned.
+///
+/// ## Panics
+/// Panics if `range` is not contained within `root`.
+pub(crate) fn covering_node(root: AnyNodeRef, range: TextRange) -> CoveringNode {
+    struct Visitor<'a> {
+        range: TextRange,
+        found: bool,
+        ancestors: Vec<AnyNodeRef<'a>>,
+    }
+
+    impl<'a> SourceOrderVisitor<'a> for Visitor<'a> {
+        fn enter_node(&mut self, node: AnyNodeRef<'a>) -> TraversalSignal {
+            // If the node fully contains the range, than it is a possible match but traverse into its children
+            // to see if there's a node with a narrower range.
+            if !self.found && node.range().contains_range(self.range) {
+                self.ancestors.push(node);
+                TraversalSignal::Traverse
+            } else {
+                TraversalSignal::Skip
+            }
+        }
+
+        fn leave_node(&mut self, node: AnyNodeRef<'a>) {
+            if !self.found && self.ancestors.last() == Some(&node) {
+                self.found = true;
+            }
+        }
+    }
+
+    assert!(
+        root.range().contains_range(range),
+        "Range is not contained within root"
+    );
+
+    let mut visitor = Visitor {
+        range,
+        found: false,
+        ancestors: Vec::new(),
+    };
+
+    root.visit_source_order(&mut visitor);
+
+    let minimal = visitor.ancestors.pop().unwrap_or(root);
+    CoveringNode {
+        node: minimal,
+        ancestors: visitor.ancestors,
+    }
+}
+
+/// The node with a minimal range that fully contains the search range.
+pub(crate) struct CoveringNode<'a> {
+    /// The node with a minimal range that fully contains the search range.
+    node: AnyNodeRef<'a>,
+
+    /// The node's ancestor (the spine up to the root).
+    ancestors: Vec<AnyNodeRef<'a>>,
+}
+
+impl<'a> CoveringNode<'a> {
+    pub(crate) fn node(&self) -> AnyNodeRef<'a> {
+        self.node
+    }
+
+    /// Returns the node's parent.
+    pub(crate) fn parent(&self) -> Option<AnyNodeRef<'a>> {
+        self.ancestors.last().copied()
+    }
+
+    /// Finds the minimal node that fully covers the range and fulfills the given predicate.
+    pub(crate) fn find(mut self, f: impl Fn(AnyNodeRef<'a>) -> bool) -> Result<Self, Self> {
+        if f(self.node) {
+            return Ok(self);
+        }
+
+        match self.ancestors.iter().rposition(|node| f(*node)) {
+            Some(index) => {
+                let node = self.ancestors[index];
+                self.ancestors.truncate(index);
+
+                Ok(Self {
+                    node,
+                    ancestors: self.ancestors,
+                })
+            }
+            None => Err(self),
+        }
+    }
+}
+
+impl fmt::Debug for CoveringNode<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("NodeWithAncestors")
+            .field(&self.node)
+            .finish()
+    }
+}

crates/ty_ide/src/goto.rs

@@ -0,0 +1,851 @@
+use crate::find_node::covering_node;
+use crate::{Db, HasNavigationTargets, NavigationTargets, RangedValue};
+use ruff_db::files::{File, FileRange};
+use ruff_db::parsed::{parsed_module, ParsedModule};
+use ruff_python_ast::{self as ast, AnyNodeRef};
+use ruff_python_parser::TokenKind;
+use ruff_text_size::{Ranged, TextRange, TextSize};
+use ty_python_semantic::types::Type;
+use ty_python_semantic::{HasType, SemanticModel};
+
+pub fn goto_type_definition(
+    db: &dyn Db,
+    file: File,
+    offset: TextSize,
+) -> Option<RangedValue<NavigationTargets>> {
+    let parsed = parsed_module(db.upcast(), file);
+    let goto_target = find_goto_target(parsed, offset)?;
+
+    let model = SemanticModel::new(db.upcast(), file);
+    let ty = goto_target.inferred_type(&model)?;
+
+    tracing::debug!(
+        "Inferred type of covering node is {}",
+        ty.display(db.upcast())
+    );
+
+    let navigation_targets = ty.navigation_targets(db);
+
+    Some(RangedValue {
+        range: FileRange::new(file, goto_target.range()),
+        value: navigation_targets,
+    })
+}
+
+#[derive(Clone, Copy, Debug)]
+pub(crate) enum GotoTarget<'a> {
+    Expression(ast::ExprRef<'a>),
+    FunctionDef(&'a ast::StmtFunctionDef),
+    ClassDef(&'a ast::StmtClassDef),
+    Parameter(&'a ast::Parameter),
+    Alias(&'a ast::Alias),
+
+    /// Go to on the module name of an import from
+    /// ```py
+    /// from foo import bar
+    ///      ^^^
+    /// ```
+    ImportedModule(&'a ast::StmtImportFrom),
+
+    /// Go to on the exception handler variable
+    /// ```py
+    /// try: ...
+    /// except Exception as e: ...
+    ///                     ^
+    /// ```
+    ExceptVariable(&'a ast::ExceptHandlerExceptHandler),
+
+    /// Go to on a keyword argument
+    /// ```py
+    /// test(a = 1)
+    ///      ^
+    /// ```
+    KeywordArgument(&'a ast::Keyword),
+
+    /// Go to on the rest parameter of a pattern match
+    ///
+    /// ```py
+    /// match x:
+    ///     case {"a": a, "b": b, **rest}: ...
+    ///                             ^^^^
+    /// ```
+    PatternMatchRest(&'a ast::PatternMatchMapping),
+
+    /// Go to on a keyword argument of a class pattern
+    ///
+    /// ```py
+    /// match Point3D(0, 0, 0):
+    ///     case Point3D(x=0, y=0, z=0): ...
+    ///                  ^    ^    ^
+    /// ```
+    PatternKeywordArgument(&'a ast::PatternKeyword),
+
+    /// Go to on a pattern star argument
+    ///
+    /// ```py
+    /// match array:
+    ///     case [*args]: ...
+    ///            ^^^^
+    PatternMatchStarName(&'a ast::PatternMatchStar),
+
+    /// Go to on the name of a pattern match as pattern
+    ///
+    /// ```py
+    /// match x:
+    ///     case [x] as y: ...
+    ///                 ^
+    PatternMatchAsName(&'a ast::PatternMatchAs),
+
+    /// Go to on the name of a type variable
+    ///
+    /// ```py
+    /// type Alias[T: int = bool] = list[T]
+    ///            ^
+    /// ```
+    TypeParamTypeVarName(&'a ast::TypeParamTypeVar),
+
+    /// Go to on the name of a type param spec
+    ///
+    /// ```py
+    /// type Alias[**P = [int, str]] = Callable[P, int]
+    ///              ^
+    /// ```
+    TypeParamParamSpecName(&'a ast::TypeParamParamSpec),
+
+    /// Go to on the name of a type var tuple
+    ///
+    /// ```py
+    /// type Alias[*Ts = ()] = tuple[*Ts]
+    ///             ^^
+    /// ```
+    TypeParamTypeVarTupleName(&'a ast::TypeParamTypeVarTuple),
+
+    NonLocal {
+        identifier: &'a ast::Identifier,
+    },
+    Globals {
+        identifier: &'a ast::Identifier,
+    },
+}
+
+impl<'db> GotoTarget<'db> {
+    pub(crate) fn inferred_type(self, model: &SemanticModel<'db>) -> Option<Type<'db>> {
+        let ty = match self {
+            GotoTarget::Expression(expression) => expression.inferred_type(model),
+            GotoTarget::FunctionDef(function) => function.inferred_type(model),
+            GotoTarget::ClassDef(class) => class.inferred_type(model),
+            GotoTarget::Parameter(parameter) => parameter.inferred_type(model),
+            GotoTarget::Alias(alias) => alias.inferred_type(model),
+            GotoTarget::ExceptVariable(except) => except.inferred_type(model),
+            GotoTarget::KeywordArgument(argument) => {
+                // TODO: Pyright resolves the declared type of the matching parameter. This seems more accurate
+                // than using the inferred value.
+                argument.value.inferred_type(model)
+            }
+            // TODO: Support identifier targets
+            GotoTarget::PatternMatchRest(_)
+            | GotoTarget::PatternKeywordArgument(_)
+            | GotoTarget::PatternMatchStarName(_)
+            | GotoTarget::PatternMatchAsName(_)
+            | GotoTarget::ImportedModule(_)
+            | GotoTarget::TypeParamTypeVarName(_)
+            | GotoTarget::TypeParamParamSpecName(_)
+            | GotoTarget::TypeParamTypeVarTupleName(_)
+            | GotoTarget::NonLocal { .. }
+            | GotoTarget::Globals { .. } => return None,
+        };
+
+        Some(ty)
+    }
+}
+
+impl Ranged for GotoTarget<'_> {
+    fn range(&self) -> TextRange {
+        match self {
+            GotoTarget::Expression(expression) => expression.range(),
+            GotoTarget::FunctionDef(function) => function.name.range,
+            GotoTarget::ClassDef(class) => class.name.range,
+            GotoTarget::Parameter(parameter) => parameter.name.range,
+            GotoTarget::Alias(alias) => alias.name.range,
+            GotoTarget::ImportedModule(module) => module.module.as_ref().unwrap().range,
+            GotoTarget::ExceptVariable(except) => except.name.as_ref().unwrap().range,
+            GotoTarget::KeywordArgument(keyword) => keyword.arg.as_ref().unwrap().range,
+            GotoTarget::PatternMatchRest(rest) => rest.rest.as_ref().unwrap().range,
+            GotoTarget::PatternKeywordArgument(keyword) => keyword.attr.range,
+            GotoTarget::PatternMatchStarName(star) => star.name.as_ref().unwrap().range,
+            GotoTarget::PatternMatchAsName(as_name) => as_name.name.as_ref().unwrap().range,
+            GotoTarget::TypeParamTypeVarName(type_var) => type_var.name.range,
+            GotoTarget::TypeParamParamSpecName(spec) => spec.name.range,
+            GotoTarget::TypeParamTypeVarTupleName(tuple) => tuple.name.range,
+            GotoTarget::NonLocal { identifier, .. } => identifier.range,
+            GotoTarget::Globals { identifier, .. } => identifier.range,
+        }
+    }
+}
+
+pub(crate) fn find_goto_target(parsed: &ParsedModule, offset: TextSize) -> Option<GotoTarget> {
+    let token = parsed
+        .tokens()
+        .at_offset(offset)
+        .max_by_key(|token| match token.kind() {
+            TokenKind::Name
+            | TokenKind::String
+            | TokenKind::Complex
+            | TokenKind::Float
+            | TokenKind::Int => 1,
+            _ => 0,
+        })?;
+
+    let covering_node = covering_node(parsed.syntax().into(), token.range())
+        .find(|node| node.is_identifier() || node.is_expression())
+        .ok()?;
+
+    tracing::trace!("Covering node is of kind {:?}", covering_node.node().kind());
+
+    match covering_node.node() {
+        AnyNodeRef::Identifier(identifier) => match covering_node.parent() {
+            Some(AnyNodeRef::StmtFunctionDef(function)) => Some(GotoTarget::FunctionDef(function)),
+            Some(AnyNodeRef::StmtClassDef(class)) => Some(GotoTarget::ClassDef(class)),
+            Some(AnyNodeRef::Parameter(parameter)) => Some(GotoTarget::Parameter(parameter)),
+            Some(AnyNodeRef::Alias(alias)) => Some(GotoTarget::Alias(alias)),
+            Some(AnyNodeRef::StmtImportFrom(from)) => Some(GotoTarget::ImportedModule(from)),
+            Some(AnyNodeRef::ExceptHandlerExceptHandler(handler)) => {
+                Some(GotoTarget::ExceptVariable(handler))
+            }
+            Some(AnyNodeRef::Keyword(keyword)) => Some(GotoTarget::KeywordArgument(keyword)),
+            Some(AnyNodeRef::PatternMatchMapping(mapping)) => {
+                Some(GotoTarget::PatternMatchRest(mapping))
+            }
+            Some(AnyNodeRef::PatternKeyword(keyword)) => {
+                Some(GotoTarget::PatternKeywordArgument(keyword))
+            }
+            Some(AnyNodeRef::PatternMatchStar(star)) => {
+                Some(GotoTarget::PatternMatchStarName(star))
+            }
+            Some(AnyNodeRef::PatternMatchAs(as_pattern)) => {
+                Some(GotoTarget::PatternMatchAsName(as_pattern))
+            }
+            Some(AnyNodeRef::TypeParamTypeVar(var)) => Some(GotoTarget::TypeParamTypeVarName(var)),
+            Some(AnyNodeRef::TypeParamParamSpec(bound)) => {
+                Some(GotoTarget::TypeParamParamSpecName(bound))
+            }
+            Some(AnyNodeRef::TypeParamTypeVarTuple(var_tuple)) => {
+                Some(GotoTarget::TypeParamTypeVarTupleName(var_tuple))
+            }
+            Some(AnyNodeRef::ExprAttribute(attribute)) => {
+                Some(GotoTarget::Expression(attribute.into()))
+            }
+            Some(AnyNodeRef::StmtNonlocal(_)) => Some(GotoTarget::NonLocal { identifier }),
+            Some(AnyNodeRef::StmtGlobal(_)) => Some(GotoTarget::Globals { identifier }),
+            None => None,
+            Some(parent) => {
+                tracing::debug!(
+                    "Missing `GoToTarget` for identifier with parent {:?}",
+                    parent.kind()
+                );
+                None
+            }
+        },
+
+        node => node.as_expr_ref().map(GotoTarget::Expression),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{cursor_test, CursorTest, IntoDiagnostic};
+    use crate::{goto_type_definition, NavigationTarget};
+    use insta::assert_snapshot;
+    use ruff_db::diagnostic::{
+        Annotation, Diagnostic, DiagnosticId, LintName, Severity, Span, SubDiagnostic,
+    };
+    use ruff_db::files::FileRange;
+    use ruff_text_size::Ranged;
+
+    #[test]
+    fn goto_type_of_expression_with_class_type() {
+        let test = cursor_test(
+            r#"
+            class Test: ...
+
+            a<CURSOR>b = Test()
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+         --> main.py:2:19
+          |
+        2 |             class Test: ...
+          |                   ^^^^
+        3 |
+        4 |             ab = Test()
+          |
+        info: Source
+         --> main.py:4:13
+          |
+        2 |             class Test: ...
+        3 |
+        4 |             ab = Test()
+          |             ^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_function_type() {
+        let test = cursor_test(
+            r#"
+            def foo(a, b): ...
+
+            ab = foo
+
+            a<CURSOR>b
+        "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+         --> main.py:2:17
+          |
+        2 |             def foo(a, b): ...
+          |                 ^^^
+        3 |
+        4 |             ab = foo
+          |
+        info: Source
+         --> main.py:6:13
+          |
+        4 |             ab = foo
+        5 |
+        6 |             ab
+          |             ^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_union_type() {
+        let test = cursor_test(
+            r#"
+
+            def foo(a, b): ...
+
+            def bar(a, b): ...
+
+            if random.choice():
+                a = foo
+            else:
+                a = bar
+
+            a<CURSOR>
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+         --> main.py:3:17
+          |
+        3 |             def foo(a, b): ...
+          |                 ^^^
+        4 |
+        5 |             def bar(a, b): ...
+          |
+        info: Source
+          --> main.py:12:13
+           |
+        10 |                 a = bar
+        11 |
+        12 |             a
+           |             ^
+           |
+
+        info: lint:goto-type-definition: Type definition
+         --> main.py:5:17
+          |
+        3 |             def foo(a, b): ...
+        4 |
+        5 |             def bar(a, b): ...
+          |                 ^^^
+        6 |
+        7 |             if random.choice():
+          |
+        info: Source
+          --> main.py:12:13
+           |
+        10 |                 a = bar
+        11 |
+        12 |             a
+           |             ^
+           |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_module() {
+        let mut test = cursor_test(
+            r#"
+            import lib
+
+            lib<CURSOR>
+            "#,
+        );
+
+        test.write_file("lib.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+         --> lib.py:1:1
+          |
+        1 | a = 10
+          | ^^^^^^
+          |
+        info: Source
+         --> main.py:4:13
+          |
+        2 |             import lib
+        3 |
+        4 |             lib
+          |             ^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_literal_type() {
+        let test = cursor_test(
+            r#"
+            a: str = "test"
+
+            a<CURSOR>
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r#"
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/builtins.pyi:438:7
+            |
+        436 |     def __getitem__(self, key: int, /) -> str | int | None: ...
+        437 |
+        438 | class str(Sequence[str]):
+            |       ^^^
+        439 |     @overload
+        440 |     def __new__(cls, object: object = ...) -> Self: ...
+            |
+        info: Source
+         --> main.py:4:13
+          |
+        2 |             a: str = "test"
+        3 |
+        4 |             a
+          |             ^
+          |
+        "#);
+    }
+    #[test]
+    fn goto_type_of_expression_with_literal_node() {
+        let test = cursor_test(
+            r#"
+            a: str = "te<CURSOR>st"
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r#"
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/builtins.pyi:438:7
+            |
+        436 |     def __getitem__(self, key: int, /) -> str | int | None: ...
+        437 |
+        438 | class str(Sequence[str]):
+            |       ^^^
+        439 |     @overload
+        440 |     def __new__(cls, object: object = ...) -> Self: ...
+            |
+        info: Source
+         --> main.py:2:22
+          |
+        2 |             a: str = "test"
+          |                      ^^^^^^
+          |
+        "#);
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_type_var_type() {
+        let test = cursor_test(
+            r#"
+            type Alias[T: int = bool] = list[T<CURSOR>]
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+         --> main.py:2:24
+          |
+        2 |             type Alias[T: int = bool] = list[T]
+          |                        ^
+          |
+        info: Source
+         --> main.py:2:46
+          |
+        2 |             type Alias[T: int = bool] = list[T]
+          |                                              ^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_type_param_spec() {
+        let test = cursor_test(
+            r#"
+            type Alias[**P = [int, str]] = Callable[P<CURSOR>, int]
+            "#,
+        );
+
+        // TODO: Goto type definition currently doesn't work for type param specs
+        // because the inference doesn't support them yet.
+        // This snapshot should show a single target pointing to `T`
+        assert_snapshot!(test.goto_type_definition(), @"No type definitions found");
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_type_var_tuple() {
+        let test = cursor_test(
+            r#"
+            type Alias[*Ts = ()] = tuple[*Ts<CURSOR>]
+            "#,
+        );
+
+        // TODO: Goto type definition currently doesn't work for type var tuples
+        // because the inference doesn't support them yet.
+        // This snapshot should show a single target pointing to `T`
+        assert_snapshot!(test.goto_type_definition(), @"No type definitions found");
+    }
+
+    #[test]
+    fn goto_type_on_keyword_argument() {
+        let test = cursor_test(
+            r#"
+            def test(a: str): ...
+
+            test(a<CURSOR>= "123")
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r#"
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/builtins.pyi:438:7
+            |
+        436 |     def __getitem__(self, key: int, /) -> str | int | None: ...
+        437 |
+        438 | class str(Sequence[str]):
+            |       ^^^
+        439 |     @overload
+        440 |     def __new__(cls, object: object = ...) -> Self: ...
+            |
+        info: Source
+         --> main.py:4:18
+          |
+        2 |             def test(a: str): ...
+        3 |
+        4 |             test(a= "123")
+          |                  ^
+          |
+        "#);
+    }
+
+    #[test]
+    fn goto_type_on_incorrectly_typed_keyword_argument() {
+        let test = cursor_test(
+            r#"
+            def test(a: str): ...
+
+            test(a<CURSOR>= 123)
+            "#,
+        );
+
+        // TODO: This should jump to `str` and not `int` because
+        //   the keyword is typed as a string. It's only the passed argument that
+        //   is an int. Navigating to `str` would match pyright's behavior.
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/builtins.pyi:231:7
+            |
+        229 | _LiteralInteger = _PositiveInteger | _NegativeInteger | Literal[0]  # noqa: Y026  # TODO: Use TypeAlias once mypy bugs are fixed
+        230 |
+        231 | class int:
+            |       ^^^
+        232 |     @overload
+        233 |     def __new__(cls, x: ConvertibleToInt = ..., /) -> Self: ...
+            |
+        info: Source
+         --> main.py:4:18
+          |
+        2 |             def test(a: str): ...
+        3 |
+        4 |             test(a= 123)
+          |                  ^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_on_kwargs() {
+        let test = cursor_test(
+            r#"
+            def f(name: str): ...
+
+kwargs = { "name": "test"}
+
+f(**kwargs<CURSOR>)
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r#"
+        info: lint:goto-type-definition: Type definition
+            --> stdlib/builtins.pyi:1086:7
+             |
+        1084 |     def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+        1085 |
+        1086 | class dict(MutableMapping[_KT, _VT]):
+             |       ^^^^
+        1087 |     # __init__ should be kept roughly in line with `collections.UserDict.__init__`, which has similar semantics
+        1088 |     # Also multiprocessing.managers.SyncManager.dict()
+             |
+        info: Source
+         --> main.py:6:5
+          |
+        4 | kwargs = { "name": "test"}
+        5 |
+        6 | f(**kwargs)
+          |     ^^^^^^
+          |
+        "#);
+    }
+
+    #[test]
+    fn goto_type_of_expression_with_builtin() {
+        let test = cursor_test(
+            r#"
+            def foo(a: str):
+                a<CURSOR>
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/builtins.pyi:438:7
+            |
+        436 |     def __getitem__(self, key: int, /) -> str | int | None: ...
+        437 |
+        438 | class str(Sequence[str]):
+            |       ^^^
+        439 |     @overload
+        440 |     def __new__(cls, object: object = ...) -> Self: ...
+            |
+        info: Source
+         --> main.py:3:17
+          |
+        2 |             def foo(a: str):
+        3 |                 a
+          |                 ^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_definition_cursor_between_object_and_attribute() {
+        let test = cursor_test(
+            r#"
+            class X:
+                def foo(a, b): ...
+
+            x = X()
+
+            x<CURSOR>.foo()
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+         --> main.py:2:19
+          |
+        2 |             class X:
+          |                   ^
+        3 |                 def foo(a, b): ...
+          |
+        info: Source
+         --> main.py:7:13
+          |
+        5 |             x = X()
+        6 |
+        7 |             x.foo()
+          |             ^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_between_call_arguments() {
+        let test = cursor_test(
+            r#"
+            def foo(a, b): ...
+
+            foo<CURSOR>()
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+         --> main.py:2:17
+          |
+        2 |             def foo(a, b): ...
+          |                 ^^^
+        3 |
+        4 |             foo()
+          |
+        info: Source
+         --> main.py:4:13
+          |
+        2 |             def foo(a, b): ...
+        3 |
+        4 |             foo()
+          |             ^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_narrowing() {
+        let test = cursor_test(
+            r#"
+            def foo(a: str | None, b):
+                if a is not None:
+                    print(a<CURSOR>)
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/builtins.pyi:438:7
+            |
+        436 |     def __getitem__(self, key: int, /) -> str | int | None: ...
+        437 |
+        438 | class str(Sequence[str]):
+            |       ^^^
+        439 |     @overload
+        440 |     def __new__(cls, object: object = ...) -> Self: ...
+            |
+        info: Source
+         --> main.py:4:27
+          |
+        2 |             def foo(a: str | None, b):
+        3 |                 if a is not None:
+        4 |                     print(a)
+          |                           ^
+          |
+        ");
+    }
+
+    #[test]
+    fn goto_type_none() {
+        let test = cursor_test(
+            r#"
+            def foo(a: str | None, b):
+                a<CURSOR>
+            "#,
+        );
+
+        assert_snapshot!(test.goto_type_definition(), @r"
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/types.pyi:671:11
+            |
+        669 | if sys.version_info >= (3, 10):
+        670 |     @final
+        671 |     class NoneType:
+            |           ^^^^^^^^
+        672 |         def __bool__(self) -> Literal[False]: ...
+            |
+        info: Source
+         --> main.py:3:17
+          |
+        2 |             def foo(a: str | None, b):
+        3 |                 a
+          |                 ^
+          |
+
+        info: lint:goto-type-definition: Type definition
+           --> stdlib/builtins.pyi:438:7
+            |
+        436 |     def __getitem__(self, key: int, /) -> str | int | None: ...
+        437 |
+        438 | class str(Sequence[str]):
+            |       ^^^
+        439 |     @overload
+        440 |     def __new__(cls, object: object = ...) -> Self: ...
+            |
+        info: Source
+         --> main.py:3:17
+          |
+        2 |             def foo(a: str | None, b):
+        3 |                 a
+          |                 ^
+          |
+        ");
+    }
+
+    impl CursorTest {
+        fn goto_type_definition(&self) -> String {
+            let Some(targets) = goto_type_definition(&self.db, self.file, self.cursor_offset)
+            else {
+                return "No goto target found".to_string();
+            };
+
+            if targets.is_empty() {
+                return "No type definitions found".to_string();
+            }
+
+            let source = targets.range;
+            self.render_diagnostics(
+                targets
+                    .into_iter()
+                    .map(|target| GotoTypeDefinitionDiagnostic::new(source, &target)),
+            )
+        }
+    }
+
+    struct GotoTypeDefinitionDiagnostic {
+        source: FileRange,
+        target: FileRange,
+    }
+
+    impl GotoTypeDefinitionDiagnostic {
+        fn new(source: FileRange, target: &NavigationTarget) -> Self {
+            Self {
+                source,
+                target: FileRange::new(target.file(), target.focus_range()),
+            }
+        }
+    }
+
+    impl IntoDiagnostic for GotoTypeDefinitionDiagnostic {
+        fn into_diagnostic(self) -> Diagnostic {
+            let mut source = SubDiagnostic::new(Severity::Info, "Source");
+            source.annotate(Annotation::primary(
+                Span::from(self.source.file()).with_range(self.source.range()),
+            ));
+
+            let mut main = Diagnostic::new(
+                DiagnosticId::Lint(LintName::of("goto-type-definition")),
+                Severity::Info,
+                "Type definition".to_string(),
+            );
+            main.annotate(Annotation::primary(
+                Span::from(self.target.file()).with_range(self.target.range()),
+            ));
+            main.sub(source);
+
+            main
+        }
+    }
+}

crates/ty_ide/src/hover.rs

@@ -0,0 +1,781 @@
+use crate::goto::{find_goto_target, GotoTarget};
+use crate::{Db, MarkupKind, RangedValue};
+use ruff_db::files::{File, FileRange};
+use ruff_db::parsed::parsed_module;
+use ruff_text_size::{Ranged, TextSize};
+use std::fmt;
+use std::fmt::Formatter;
+use ty_python_semantic::types::Type;
+use ty_python_semantic::SemanticModel;
+
+pub fn hover(db: &dyn Db, file: File, offset: TextSize) -> Option<RangedValue<Hover>> {
+    let parsed = parsed_module(db.upcast(), file);
+    let goto_target = find_goto_target(parsed, offset)?;
+
+    if let GotoTarget::Expression(expr) = goto_target {
+        if expr.is_literal_expr() {
+            return None;
+        }
+    }
+
+    let model = SemanticModel::new(db.upcast(), file);
+    let ty = goto_target.inferred_type(&model)?;
+
+    tracing::debug!(
+        "Inferred type of covering node is {}",
+        ty.display(db.upcast())
+    );
+
+    // TODO: Add documentation of the symbol (not the type's definition).
+    // TODO: Render the symbol's signature instead of just its type.
+    let contents = vec![HoverContent::Type(ty)];
+
+    Some(RangedValue {
+        range: FileRange::new(file, goto_target.range()),
+        value: Hover { contents },
+    })
+}
+
+pub struct Hover<'db> {
+    contents: Vec<HoverContent<'db>>,
+}
+
+impl<'db> Hover<'db> {
+    /// Renders the hover to a string using the specified markup kind.
+    pub const fn display<'a>(&'a self, db: &'a dyn Db, kind: MarkupKind) -> DisplayHover<'a> {
+        DisplayHover {
+            db,
+            hover: self,
+            kind,
+        }
+    }
+
+    fn iter(&self) -> std::slice::Iter<'_, HoverContent<'db>> {
+        self.contents.iter()
+    }
+}
+
+impl<'db> IntoIterator for Hover<'db> {
+    type Item = HoverContent<'db>;
+    type IntoIter = std::vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.contents.into_iter()
+    }
+}
+
+impl<'a, 'db> IntoIterator for &'a Hover<'db> {
+    type Item = &'a HoverContent<'db>;
+    type IntoIter = std::slice::Iter<'a, HoverContent<'db>>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+pub struct DisplayHover<'a> {
+    db: &'a dyn Db,
+    hover: &'a Hover<'a>,
+    kind: MarkupKind,
+}
+
+impl fmt::Display for DisplayHover<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        let mut first = true;
+        for content in &self.hover.contents {
+            if !first {
+                self.kind.horizontal_line().fmt(f)?;
+            }
+
+            content.display(self.db, self.kind).fmt(f)?;
+            first = false;
+        }
+
+        Ok(())
+    }
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub enum HoverContent<'db> {
+    Type(Type<'db>),
+}
+
+impl<'db> HoverContent<'db> {
+    fn display(&self, db: &'db dyn Db, kind: MarkupKind) -> DisplayHoverContent<'_, 'db> {
+        DisplayHoverContent {
+            db,
+            content: self,
+            kind,
+        }
+    }
+}
+
+pub(crate) struct DisplayHoverContent<'a, 'db> {
+    db: &'db dyn Db,
+    content: &'a HoverContent<'db>,
+    kind: MarkupKind,
+}
+
+impl fmt::Display for DisplayHoverContent<'_, '_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.content {
+            HoverContent::Type(ty) => self
+                .kind
+                .fenced_code_block(ty.display(self.db.upcast()), "text")
+                .fmt(f),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{cursor_test, CursorTest};
+    use crate::{hover, MarkupKind};
+    use insta::assert_snapshot;
+    use ruff_db::diagnostic::{
+        Annotation, Diagnostic, DiagnosticFormat, DiagnosticId, DisplayDiagnosticConfig, LintName,
+        Severity, Span,
+    };
+    use ruff_text_size::{Ranged, TextRange};
+
+    #[test]
+    fn hover_basic() {
+        let test = cursor_test(
+            r#"
+        a = 10
+
+        a<CURSOR>
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        Literal[10]
+        ---------------------------------------------
+        ```text
+        Literal[10]
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:4:9
+          |
+        2 |         a = 10
+        3 |
+        4 |         a
+          |         ^- Cursor offset
+          |         |
+          |         source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_member() {
+        let test = cursor_test(
+            r#"
+        class Foo:
+            a: int = 10
+
+            def __init__(a: int, b: str):
+                self.a = a
+                self.b: str = b
+
+        foo = Foo()
+        foo.<CURSOR>a
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        int
+        ---------------------------------------------
+        ```text
+        int
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+          --> main.py:10:9
+           |
+         9 |         foo = Foo()
+        10 |         foo.a
+           |         ^^^^-
+           |         |   |
+           |         |   Cursor offset
+           |         source
+           |
+        ");
+    }
+
+    #[test]
+    fn hover_function_typed_variable() {
+        let test = cursor_test(
+            r#"
+            def foo(a, b): ...
+
+            foo<CURSOR>
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        def foo(a, b) -> Unknown
+        ---------------------------------------------
+        ```text
+        def foo(a, b) -> Unknown
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:4:13
+          |
+        2 |             def foo(a, b): ...
+        3 |
+        4 |             foo
+          |             ^^^- Cursor offset
+          |             |
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_binary_expression() {
+        let test = cursor_test(
+            r#"
+            def foo(a: int, b: int, c: int):
+                a + b ==<CURSOR> c
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        bool
+        ---------------------------------------------
+        ```text
+        bool
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:3:17
+          |
+        2 |             def foo(a: int, b: int, c: int):
+        3 |                 a + b == c
+          |                 ^^^^^^^^-^
+          |                 |       |
+          |                 |       Cursor offset
+          |                 source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_keyword_parameter() {
+        let test = cursor_test(
+            r#"
+            def test(a: int): ...
+
+            test(a<CURSOR>= 123)
+            "#,
+        );
+
+        // TODO: This should reveal `int` because the user hovers over the parameter and not the value.
+        assert_snapshot!(test.hover(), @r"
+        Literal[123]
+        ---------------------------------------------
+        ```text
+        Literal[123]
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:4:18
+          |
+        2 |             def test(a: int): ...
+        3 |
+        4 |             test(a= 123)
+          |                  ^- Cursor offset
+          |                  |
+          |                  source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_union() {
+        let test = cursor_test(
+            r#"
+
+            def foo(a, b): ...
+
+            def bar(a, b): ...
+
+            if random.choice([True, False]):
+                a = foo
+            else:
+                a = bar
+
+            a<CURSOR>
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        (def foo(a, b) -> Unknown) | (def bar(a, b) -> Unknown)
+        ---------------------------------------------
+        ```text
+        (def foo(a, b) -> Unknown) | (def bar(a, b) -> Unknown)
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+          --> main.py:12:13
+           |
+        10 |                 a = bar
+        11 |
+        12 |             a
+           |             ^- Cursor offset
+           |             |
+           |             source
+           |
+        ");
+    }
+
+    #[test]
+    fn hover_module() {
+        let mut test = cursor_test(
+            r#"
+            import lib
+
+            li<CURSOR>b
+            "#,
+        );
+
+        test.write_file("lib.py", "a = 10").unwrap();
+
+        assert_snapshot!(test.hover(), @r"
+        <module 'lib'>
+        ---------------------------------------------
+        ```text
+        <module 'lib'>
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:4:13
+          |
+        2 |             import lib
+        3 |
+        4 |             lib
+          |             ^^-
+          |             | |
+          |             | Cursor offset
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_type_of_expression_with_type_var_type() {
+        let test = cursor_test(
+            r#"
+            type Alias[T: int = bool] = list[T<CURSOR>]
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        T
+        ---------------------------------------------
+        ```text
+        T
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:2:46
+          |
+        2 |             type Alias[T: int = bool] = list[T]
+          |                                              ^- Cursor offset
+          |                                              |
+          |                                              source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_type_of_expression_with_type_param_spec() {
+        let test = cursor_test(
+            r#"
+            type Alias[**P = [int, str]] = Callable[P<CURSOR>, int]
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        @Todo
+        ---------------------------------------------
+        ```text
+        @Todo
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:2:53
+          |
+        2 |             type Alias[**P = [int, str]] = Callable[P, int]
+          |                                                     ^- Cursor offset
+          |                                                     |
+          |                                                     source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_type_of_expression_with_type_var_tuple() {
+        let test = cursor_test(
+            r#"
+            type Alias[*Ts = ()] = tuple[*Ts<CURSOR>]
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        @Todo
+        ---------------------------------------------
+        ```text
+        @Todo
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:2:43
+          |
+        2 |             type Alias[*Ts = ()] = tuple[*Ts]
+          |                                           ^^- Cursor offset
+          |                                           |
+          |                                           source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_variable_assignment() {
+        let test = cursor_test(
+            r#"
+            value<CURSOR> = 1
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        Literal[1]
+        ---------------------------------------------
+        ```text
+        Literal[1]
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:2:13
+          |
+        2 |             value = 1
+          |             ^^^^^- Cursor offset
+          |             |
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_augmented_assignment() {
+        let test = cursor_test(
+            r#"
+            value = 1
+            value<CURSOR> += 2
+            "#,
+        );
+
+        // We currently show the *previous* value of the variable (1), not the new one (3).
+        // Showing the new value might be more intuitive for some users, but the actual 'use'
+        // of the `value` symbol here in read-context is `1`. This comment mainly exists to
+        // signal that it might be okay to revisit this in the future and reveal 3 instead.
+        assert_snapshot!(test.hover(), @r"
+        Literal[1]
+        ---------------------------------------------
+        ```text
+        Literal[1]
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:3:13
+          |
+        2 |             value = 1
+        3 |             value += 2
+          |             ^^^^^- Cursor offset
+          |             |
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_attribute_assignment() {
+        let test = cursor_test(
+            r#"
+            class C:
+                attr: int = 1
+
+            C.attr<CURSOR> = 2
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        Literal[2]
+        ---------------------------------------------
+        ```text
+        Literal[2]
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:5:13
+          |
+        3 |                 attr: int = 1
+        4 |
+        5 |             C.attr = 2
+          |             ^^^^^^- Cursor offset
+          |             |
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_augmented_attribute_assignment() {
+        let test = cursor_test(
+            r#"
+            class C:
+                attr = 1
+
+            C.attr<CURSOR> += 2
+            "#,
+        );
+
+        // See the comment in the `hover_augmented_assignment` test above. The same
+        // reasoning applies here.
+        assert_snapshot!(test.hover(), @r"
+        Unknown | Literal[1]
+        ---------------------------------------------
+        ```text
+        Unknown | Literal[1]
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:5:13
+          |
+        3 |                 attr = 1
+        4 |
+        5 |             C.attr += 2
+          |             ^^^^^^- Cursor offset
+          |             |
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_annotated_assignment() {
+        let test = cursor_test(
+            r#"
+        class Foo:
+            a<CURSOR>: int
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        int
+        ---------------------------------------------
+        ```text
+        int
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:3:13
+          |
+        2 |         class Foo:
+        3 |             a: int
+          |             ^- Cursor offset
+          |             |
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_annotated_assignment_with_rhs() {
+        let test = cursor_test(
+            r#"
+        class Foo:
+            a<CURSOR>: int = 1
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        Literal[1]
+        ---------------------------------------------
+        ```text
+        Literal[1]
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:3:13
+          |
+        2 |         class Foo:
+        3 |             a: int = 1
+          |             ^- Cursor offset
+          |             |
+          |             source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_annotated_attribute_assignment() {
+        let test = cursor_test(
+            r#"
+        class Foo:
+            def __init__(self, a: int):
+                self.a<CURSOR>: int = a
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        int
+        ---------------------------------------------
+        ```text
+        int
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:4:17
+          |
+        2 |         class Foo:
+        3 |             def __init__(self, a: int):
+        4 |                 self.a: int = a
+          |                 ^^^^^^- Cursor offset
+          |                 |
+          |                 source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_type_narrowing() {
+        let test = cursor_test(
+            r#"
+            def foo(a: str | None, b):
+                if a is not None:
+                    print(a<CURSOR>)
+            "#,
+        );
+
+        assert_snapshot!(test.hover(), @r"
+        str
+        ---------------------------------------------
+        ```text
+        str
+        ```
+        ---------------------------------------------
+        info: lint:hover: Hovered content is
+         --> main.py:4:27
+          |
+        2 |             def foo(a: str | None, b):
+        3 |                 if a is not None:
+        4 |                     print(a)
+          |                           ^- Cursor offset
+          |                           |
+          |                           source
+          |
+        ");
+    }
+
+    #[test]
+    fn hover_whitespace() {
+        let test = cursor_test(
+            r#"
+        class C:
+            <CURSOR>
+            foo: str = 'bar'
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @"Hover provided no content");
+    }
+
+    #[test]
+    fn hover_literal_int() {
+        let test = cursor_test(
+            r#"
+        print(
+            0 + 1<CURSOR>
+        )
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @"Hover provided no content");
+    }
+
+    #[test]
+    fn hover_literal_ellipsis() {
+        let test = cursor_test(
+            r#"
+        print(
+            .<CURSOR>..
+        )
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @"Hover provided no content");
+    }
+
+    #[test]
+    fn hover_docstring() {
+        let test = cursor_test(
+            r#"
+        def f():
+            """Lorem ipsum dolor sit amet.<CURSOR>"""
+        "#,
+        );
+
+        assert_snapshot!(test.hover(), @"Hover provided no content");
+    }
+
+    impl CursorTest {
+        fn hover(&self) -> String {
+            use std::fmt::Write;
+
+            let Some(hover) = hover(&self.db, self.file, self.cursor_offset) else {
+                return "Hover provided no content".to_string();
+            };
+
+            let source = hover.range;
+
+            let mut buf = String::new();
+
+            write!(
+                &mut buf,
+                "{plaintext}{line}{markdown}{line}",
+                plaintext = hover.display(&self.db, MarkupKind::PlainText),
+                line = MarkupKind::PlainText.horizontal_line(),
+                markdown = hover.display(&self.db, MarkupKind::Markdown),
+            )
+            .unwrap();
+
+            let config = DisplayDiagnosticConfig::default()
+                .color(false)
+                .format(DiagnosticFormat::Full);
+
+            let mut diagnostic = Diagnostic::new(
+                DiagnosticId::Lint(LintName::of("hover")),
+                Severity::Info,
+                "Hovered content is",
+            );
+            diagnostic.annotate(
+                Annotation::primary(Span::from(source.file()).with_range(source.range()))
+                    .message("source"),
+            );
+            diagnostic.annotate(
+                Annotation::secondary(
+                    Span::from(source.file()).with_range(TextRange::empty(self.cursor_offset)),
+                )
+                .message("Cursor offset"),
+            );
+
+            write!(buf, "{}", diagnostic.display(&self.db, &config)).unwrap();
+
+            buf
+        }
+    }
+}

crates/ty_ide/src/inlay_hints.rs

@@ -0,0 +1,279 @@
+use crate::Db;
+use ruff_db::files::File;
+use ruff_db::parsed::parsed_module;
+use ruff_python_ast::visitor::source_order::{self, SourceOrderVisitor, TraversalSignal};
+use ruff_python_ast::{AnyNodeRef, Expr, Stmt};
+use ruff_text_size::{Ranged, TextRange, TextSize};
+use std::fmt;
+use std::fmt::Formatter;
+use ty_python_semantic::types::Type;
+use ty_python_semantic::{HasType, SemanticModel};
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct InlayHint<'db> {
+    pub position: TextSize,
+    pub content: InlayHintContent<'db>,
+}
+
+impl<'db> InlayHint<'db> {
+    pub const fn display(&self, db: &'db dyn Db) -> DisplayInlayHint<'_, 'db> {
+        self.content.display(db)
+    }
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub enum InlayHintContent<'db> {
+    Type(Type<'db>),
+    ReturnType(Type<'db>),
+}
+
+impl<'db> InlayHintContent<'db> {
+    pub const fn display(&self, db: &'db dyn Db) -> DisplayInlayHint<'_, 'db> {
+        DisplayInlayHint { db, hint: self }
+    }
+}
+
+pub struct DisplayInlayHint<'a, 'db> {
+    db: &'db dyn Db,
+    hint: &'a InlayHintContent<'db>,
+}
+
+impl fmt::Display for DisplayInlayHint<'_, '_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self.hint {
+            InlayHintContent::Type(ty) => {
+                write!(f, ": {}", ty.display(self.db.upcast()))
+            }
+            InlayHintContent::ReturnType(ty) => {
+                write!(f, " -> {}", ty.display(self.db.upcast()))
+            }
+        }
+    }
+}
+
+pub fn inlay_hints(db: &dyn Db, file: File, range: TextRange) -> Vec<InlayHint<'_>> {
+    let mut visitor = InlayHintVisitor::new(db, file, range);
+
+    let ast = parsed_module(db.upcast(), file);
+
+    visitor.visit_body(ast.suite());
+
+    visitor.hints
+}
+
+struct InlayHintVisitor<'db> {
+    model: SemanticModel<'db>,
+    hints: Vec<InlayHint<'db>>,
+    in_assignment: bool,
+    range: TextRange,
+}
+
+impl<'db> InlayHintVisitor<'db> {
+    fn new(db: &'db dyn Db, file: File, range: TextRange) -> Self {
+        Self {
+            model: SemanticModel::new(db.upcast(), file),
+            hints: Vec::new(),
+            in_assignment: false,
+            range,
+        }
+    }
+
+    fn add_type_hint(&mut self, position: TextSize, ty: Type<'db>) {
+        self.hints.push(InlayHint {
+            position,
+            content: InlayHintContent::Type(ty),
+        });
+    }
+}
+
+impl SourceOrderVisitor<'_> for InlayHintVisitor<'_> {
+    fn enter_node(&mut self, node: AnyNodeRef<'_>) -> TraversalSignal {
+        if self.range.intersect(node.range()).is_some() {
+            TraversalSignal::Traverse
+        } else {
+            TraversalSignal::Skip
+        }
+    }
+
+    fn visit_stmt(&mut self, stmt: &Stmt) {
+        let node = AnyNodeRef::from(stmt);
+
+        if !self.enter_node(node).is_traverse() {
+            return;
+        }
+
+        match stmt {
+            Stmt::Assign(assign) => {
+                self.in_assignment = true;
+                for target in &assign.targets {
+                    self.visit_expr(target);
+                }
+                self.in_assignment = false;
+
+                return;
+            }
+            // TODO
+            Stmt::FunctionDef(_) => {}
+            Stmt::For(_) => {}
+            Stmt::Expr(_) => {
+                // Don't traverse into expression statements because we don't show any hints.
+                return;
+            }
+            _ => {}
+        }
+
+        source_order::walk_stmt(self, stmt);
+    }
+
+    fn visit_expr(&mut self, expr: &'_ Expr) {
+        if !self.in_assignment {
+            return;
+        }
+
+        match expr {
+            Expr::Name(name) => {
+                if name.ctx.is_store() {
+                    let ty = expr.inferred_type(&self.model);
+                    self.add_type_hint(expr.range().end(), ty);
+                }
+            }
+            _ => {
+                source_order::walk_expr(self, expr);
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use insta::assert_snapshot;
+    use ruff_db::{
+        files::{system_path_to_file, File},
+        source::source_text,
+    };
+    use ruff_text_size::TextSize;
+
+    use crate::db::tests::TestDb;
+
+    use ruff_db::system::{DbWithWritableSystem, SystemPathBuf};
+    use ruff_python_ast::PythonVersion;
+    use ty_python_semantic::{
+        Program, ProgramSettings, PythonPath, PythonPlatform, SearchPathSettings,
+    };
+
+    pub(super) fn inlay_hint_test(source: &str) -> InlayHintTest {
+        const START: &str = "<START>";
+        const END: &str = "<END>";
+
+        let mut db = TestDb::new();
+
+        let start = source.find(START);
+        let end = source
+            .find(END)
+            .map(|x| if start.is_some() { x - START.len() } else { x })
+            .unwrap_or(source.len());
+
+        let range = TextRange::new(
+            TextSize::try_from(start.unwrap_or_default()).unwrap(),
+            TextSize::try_from(end).unwrap(),
+        );
+
+        let source = source.replace(START, "");
+        let source = source.replace(END, "");
+
+        db.write_file("main.py", source)
+            .expect("write to memory file system to be successful");
+
+        let file = system_path_to_file(&db, "main.py").expect("newly written file to existing");
+
+        Program::from_settings(
+            &db,
+            ProgramSettings {
+                python_version: PythonVersion::latest(),
+                python_platform: PythonPlatform::default(),
+                search_paths: SearchPathSettings {
+                    extra_paths: vec![],
+                    src_roots: vec![SystemPathBuf::from("/")],
+                    custom_typeshed: None,
+                    python_path: PythonPath::KnownSitePackages(vec![]),
+                },
+            },
+        )
+        .expect("Default settings to be valid");
+
+        InlayHintTest { db, file, range }
+    }
+
+    pub(super) struct InlayHintTest {
+        pub(super) db: TestDb,
+        pub(super) file: File,
+        pub(super) range: TextRange,
+    }
+
+    impl InlayHintTest {
+        fn inlay_hints(&self) -> String {
+            let hints = inlay_hints(&self.db, self.file, self.range);
+
+            let mut buf = source_text(&self.db, self.file).as_str().to_string();
+
+            let mut offset = 0;
+
+            for hint in hints {
+                let end_position = (hint.position.to_u32() as usize) + offset;
+                let hint_str = format!("[{}]", hint.display(&self.db));
+                buf.insert_str(end_position, &hint_str);
+                offset += hint_str.len();
+            }
+
+            buf
+        }
+    }
+
+    #[test]
+    fn test_assign_statement() {
+        let test = inlay_hint_test("x = 1");
+
+        assert_snapshot!(test.inlay_hints(), @r"
+        x[: Literal[1]] = 1
+        ");
+    }
+
+    #[test]
+    fn test_tuple_assignment() {
+        let test = inlay_hint_test("x, y = (1, 'abc')");
+
+        assert_snapshot!(test.inlay_hints(), @r#"
+        x[: Literal[1]], y[: Literal["abc"]] = (1, 'abc')
+        "#);
+    }
+
+    #[test]
+    fn test_nested_tuple_assignment() {
+        let test = inlay_hint_test("x, (y, z) = (1, ('abc', 2))");
+
+        assert_snapshot!(test.inlay_hints(), @r#"
+        x[: Literal[1]], (y[: Literal["abc"]], z[: Literal[2]]) = (1, ('abc', 2))
+        "#);
+    }
+
+    #[test]
+    fn test_assign_statement_with_type_annotation() {
+        let test = inlay_hint_test("x: int = 1");
+
+        assert_snapshot!(test.inlay_hints(), @r"
+        x: int = 1
+        ");
+    }
+
+    #[test]
+    fn test_assign_statement_out_of_range() {
+        let test = inlay_hint_test("<START>x = 1<END>\ny = 2");
+
+        assert_snapshot!(test.inlay_hints(), @r"
+        x[: Literal[1]] = 1
+        y = 2
+        ");
+    }
+}

crates/ty_ide/src/lib.rs

@@ -0,0 +1,298 @@
+mod completion;
+mod db;
+mod find_node;
+mod goto;
+mod hover;
+mod inlay_hints;
+mod markup;
+
+pub use completion::completion;
+pub use db::Db;
+pub use goto::goto_type_definition;
+pub use hover::hover;
+pub use inlay_hints::inlay_hints;
+pub use markup::MarkupKind;
+
+use rustc_hash::FxHashSet;
+use std::ops::{Deref, DerefMut};
+
+use ruff_db::files::{File, FileRange};
+use ruff_text_size::{Ranged, TextRange};
+use ty_python_semantic::types::{Type, TypeDefinition};
+
+/// Information associated with a text range.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub struct RangedValue<T> {
+    pub range: FileRange,
+    pub value: T,
+}
+
+impl<T> RangedValue<T> {
+    pub fn file_range(&self) -> FileRange {
+        self.range
+    }
+}
+
+impl<T> Deref for RangedValue<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.value
+    }
+}
+
+impl<T> DerefMut for RangedValue<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.value
+    }
+}
+
+impl<T> IntoIterator for RangedValue<T>
+where
+    T: IntoIterator,
+{
+    type Item = T::Item;
+    type IntoIter = T::IntoIter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.value.into_iter()
+    }
+}
+
+/// Target to which the editor can navigate to.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct NavigationTarget {
+    file: File,
+
+    /// The range that should be focused when navigating to the target.
+    ///
+    /// This is typically not the full range of the node. For example, it's the range of the class's name in a class definition.
+    ///
+    /// The `focus_range` must be fully covered by `full_range`.
+    focus_range: TextRange,
+
+    /// The range covering the entire target.
+    full_range: TextRange,
+}
+
+impl NavigationTarget {
+    pub fn file(&self) -> File {
+        self.file
+    }
+
+    pub fn focus_range(&self) -> TextRange {
+        self.focus_range
+    }
+
+    pub fn full_range(&self) -> TextRange {
+        self.full_range
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct NavigationTargets(smallvec::SmallVec<[NavigationTarget; 1]>);
+
+impl NavigationTargets {
+    fn single(target: NavigationTarget) -> Self {
+        Self(smallvec::smallvec![target])
+    }
+
+    fn empty() -> Self {
+        Self(smallvec::SmallVec::new())
+    }
+
+    fn unique(targets: impl IntoIterator<Item = NavigationTarget>) -> Self {
+        let unique: FxHashSet<_> = targets.into_iter().collect();
+        if unique.is_empty() {
+            Self::empty()
+        } else {
+            let mut targets = unique.into_iter().collect::<Vec<_>>();
+            targets.sort_by_key(|target| (target.file, target.focus_range.start()));
+            Self(targets.into())
+        }
+    }
+
+    fn iter(&self) -> std::slice::Iter<'_, NavigationTarget> {
+        self.0.iter()
+    }
+
+    #[cfg(test)]
+    fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+impl IntoIterator for NavigationTargets {
+    type Item = NavigationTarget;
+    type IntoIter = smallvec::IntoIter<[NavigationTarget; 1]>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.into_iter()
+    }
+}
+
+impl<'a> IntoIterator for &'a NavigationTargets {
+    type Item = &'a NavigationTarget;
+    type IntoIter = std::slice::Iter<'a, NavigationTarget>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl FromIterator<NavigationTarget> for NavigationTargets {
+    fn from_iter<T: IntoIterator<Item = NavigationTarget>>(iter: T) -> Self {
+        Self::unique(iter)
+    }
+}
+
+pub trait HasNavigationTargets {
+    fn navigation_targets(&self, db: &dyn Db) -> NavigationTargets;
+}
+
+impl HasNavigationTargets for Type<'_> {
+    fn navigation_targets(&self, db: &dyn Db) -> NavigationTargets {
+        match self {
+            Type::Union(union) => union
+                .iter(db.upcast())
+                .flat_map(|target| target.navigation_targets(db))
+                .collect(),
+
+            Type::Intersection(intersection) => {
+                // Only consider the positive elements because the negative elements are mainly from narrowing constraints.
+                let mut targets = intersection
+                    .iter_positive(db.upcast())
+                    .filter(|ty| !ty.is_unknown());
+
+                let Some(first) = targets.next() else {
+                    return NavigationTargets::empty();
+                };
+
+                match targets.next() {
+                    Some(_) => {
+                        // If there are multiple types in the intersection, we can't navigate to a single one
+                        // because the type is the intersection of all those types.
+                        NavigationTargets::empty()
+                    }
+                    None => first.navigation_targets(db),
+                }
+            }
+
+            ty => ty
+                .definition(db.upcast())
+                .map(|definition| definition.navigation_targets(db))
+                .unwrap_or_else(NavigationTargets::empty),
+        }
+    }
+}
+
+impl HasNavigationTargets for TypeDefinition<'_> {
+    fn navigation_targets(&self, db: &dyn Db) -> NavigationTargets {
+        let full_range = self.full_range(db.upcast());
+        NavigationTargets::single(NavigationTarget {
+            file: full_range.file(),
+            focus_range: self.focus_range(db.upcast()).unwrap_or(full_range).range(),
+            full_range: full_range.range(),
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::db::tests::TestDb;
+    use insta::internals::SettingsBindDropGuard;
+    use ruff_db::diagnostic::{Diagnostic, DiagnosticFormat, DisplayDiagnosticConfig};
+    use ruff_db::files::{system_path_to_file, File};
+    use ruff_db::system::{DbWithWritableSystem, SystemPath, SystemPathBuf};
+    use ruff_python_ast::PythonVersion;
+    use ruff_text_size::TextSize;
+    use ty_python_semantic::{
+        Program, ProgramSettings, PythonPath, PythonPlatform, SearchPathSettings,
+    };
+
+    pub(super) fn cursor_test(source: &str) -> CursorTest {
+        let mut db = TestDb::new();
+        let cursor_offset = source.find("<CURSOR>").expect(
+            "`source`` should contain a `<CURSOR>` marker, indicating the position of the cursor.",
+        );
+
+        let mut content = source[..cursor_offset].to_string();
+        content.push_str(&source[cursor_offset + "<CURSOR>".len()..]);
+
+        db.write_file("main.py", &content)
+            .expect("write to memory file system to be successful");
+
+        let file = system_path_to_file(&db, "main.py").expect("newly written file to existing");
+
+        Program::from_settings(
+            &db,
+            ProgramSettings {
+                python_version: PythonVersion::latest(),
+                python_platform: PythonPlatform::default(),
+                search_paths: SearchPathSettings {
+                    extra_paths: vec![],
+                    src_roots: vec![SystemPathBuf::from("/")],
+                    custom_typeshed: None,
+                    python_path: PythonPath::KnownSitePackages(vec![]),
+                },
+            },
+        )
+        .expect("Default settings to be valid");
+
+        let mut insta_settings = insta::Settings::clone_current();
+        insta_settings.add_filter(r#"\\(\w\w|\s|\.|")"#, "/$1");
+        // Filter out TODO types because they are different between debug and release builds.
+        insta_settings.add_filter(r"@Todo\(.+\)", "@Todo");
+
+        let insta_settings_guard = insta_settings.bind_to_scope();
+
+        CursorTest {
+            db,
+            cursor_offset: TextSize::try_from(cursor_offset)
+                .expect("source to be smaller than 4GB"),
+            file,
+            _insta_settings_guard: insta_settings_guard,
+        }
+    }
+
+    pub(super) struct CursorTest {
+        pub(super) db: TestDb,
+        pub(super) cursor_offset: TextSize,
+        pub(super) file: File,
+        _insta_settings_guard: SettingsBindDropGuard,
+    }
+
+    impl CursorTest {
+        pub(super) fn write_file(
+            &mut self,
+            path: impl AsRef<SystemPath>,
+            content: &str,
+        ) -> std::io::Result<()> {
+            self.db.write_file(path, content)
+        }
+
+        pub(super) fn render_diagnostics<I, D>(&self, diagnostics: I) -> String
+        where
+            I: IntoIterator<Item = D>,
+            D: IntoDiagnostic,
+        {
+            use std::fmt::Write;
+
+            let mut buf = String::new();
+
+            let config = DisplayDiagnosticConfig::default()
+                .color(false)
+                .format(DiagnosticFormat::Full);
+            for diagnostic in diagnostics {
+                let diag = diagnostic.into_diagnostic();
+                write!(buf, "{}", diag.display(&self.db, &config)).unwrap();
+            }
+
+            buf
+        }
+    }
+
+    pub(super) trait IntoDiagnostic {
+        fn into_diagnostic(self) -> Diagnostic;
+    }
+}

crates/ty_ide/src/markup.rs

@@ -0,0 +1,66 @@
+use std::fmt;
+use std::fmt::Formatter;
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum MarkupKind {
+    PlainText,
+    Markdown,
+}
+
+impl MarkupKind {
+    pub(crate) const fn fenced_code_block<T>(self, code: T, language: &str) -> FencedCodeBlock<T>
+    where
+        T: fmt::Display,
+    {
+        FencedCodeBlock {
+            language,
+            code,
+            kind: self,
+        }
+    }
+
+    pub(crate) const fn horizontal_line(self) -> HorizontalLine {
+        HorizontalLine { kind: self }
+    }
+}
+
+pub(crate) struct FencedCodeBlock<'a, T> {
+    language: &'a str,
+    code: T,
+    kind: MarkupKind,
+}
+
+impl<T> fmt::Display for FencedCodeBlock<'_, T>
+where
+    T: fmt::Display,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.kind {
+            MarkupKind::PlainText => self.code.fmt(f),
+            MarkupKind::Markdown => write!(
+                f,
+                "```{language}\n{code}\n```",
+                language = self.language,
+                code = self.code
+            ),
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+pub(crate) struct HorizontalLine {
+    kind: MarkupKind,
+}
+
+impl fmt::Display for HorizontalLine {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self.kind {
+            MarkupKind::PlainText => {
+                f.write_str("\n---------------------------------------------\n")
+            }
+            MarkupKind::Markdown => {
+                write!(f, "\n---\n")
+            }
+        }
+    }
+}