feat(linter): implement isolated_declaration (#209)

* feat(linter): implement isolated_declaration

* Implement check for class elements

* Set up Export SymbolFlag and store declaration AST in Symbol

* Fix tests and comments

crates/oxc_linter/src/ast_util.rs

@@ -186,3 +186,19 @@ impl<'a, 'b> IsConstant<'a, 'b> for SpreadElement<'a> {
         self.argument.is_constant(in_boolean_position, ctx)
     }
 }
+
+pub trait IsPrivate {
+    fn is_private(&self) -> bool;
+}
+
+impl<'a> IsPrivate for MethodDefinition<'a> {
+    fn is_private(&self) -> bool {
+        self.accessibility.map_or(false, |accessibility| accessibility == TSAccessibility::Private)
+    }
+}
+
+impl<'a> IsPrivate for PropertyDefinition<'a> {
+    fn is_private(&self) -> bool {
+        self.accessibility.map_or(false, |accessibility| accessibility == TSAccessibility::Private)
+    }
+}

crates/oxc_linter/src/rules.rs

@@ -25,5 +25,6 @@ oxc_macros::declare_all_lint_rules! {
     no_unsafe_negation,
     deepscan::uninvoked_array_callback,
     use_isnan,
-    valid_typeof
+    valid_typeof,
+    typescript::isolated_declaration
 }

crates/oxc_linter/src/rules/typescript/isolated_declaration.rs

@@ -0,0 +1,155 @@
+use oxc_ast::{
+    ast::{Class, ClassElement, Function, PropertyDefinition},
+    AstKind, Span,
+};
+use oxc_diagnostics::{
+    miette::{self, Diagnostic},
+    thiserror::Error,
+};
+use oxc_macros::declare_oxc_lint;
+use oxc_semantic::Symbol;
+
+use crate::{ast_util::IsPrivate, context::LintContext, rule::Rule};
+
+#[derive(Debug, Error, Diagnostic)]
+enum IsolatedDeclarationDiagnostic {
+    #[error("isolated-declaration: Requires type annotation on non-private property definition")]
+    #[diagnostic(severity(warning))]
+    Property(#[label] Span),
+    #[error("isolated-declaration: Requires type annotation on parameters of non-private method")]
+    #[diagnostic(severity(warning))]
+    FunctionParam(#[label] Span),
+    #[error("isolated-declaration: Requires return type annotation of non-private method")]
+    #[diagnostic(severity(warning))]
+    FunctionReturnType(#[label] Span),
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct IsolatedDeclaration;
+
+declare_oxc_lint!(
+    /// ### What it does
+    /// This rule enforces a set of restrictions on typescript files to enable "isolated declaration",
+    /// i.e., .d.ts files can be generated from a single .ts file without resolving its dependencies.
+    /// The typescript implementation is at `https://github.com/microsoft/TypeScript/pull/53463`
+    /// The thread on isolated declaration is at `https://github.com/microsoft/TypeScript/issues/47947`
+    ///
+    /// ### Why is this bad?
+    /// The restrictions allow .d.ts files to be generated based on one single .ts file, which improves the
+    /// efficiency and possible parallelism of the declaration emitting process. Furthermore, it prevents syntax
+    /// errors in one file from propagating to other dependent files.
+    ///
+    /// ### Example
+    /// ```typescript
+    /// export class Test {
+    ///   x // error under isolated declarations
+    ///   private y = 0; // no error, private field types are not serialized in declarations
+    ///   #z = 1;// no error, fields is not present in declarations
+    ///   constructor(x: number) {
+    ///     this.x = 1;
+    ///   }
+    ///   get a() { // error under isolated declarations
+    ///     return 1;
+    ///   }
+    ///   set a(value) { // error under isolated declarations
+    ///     this.x = 1;
+    ///   }
+    /// }
+    /// ```
+    IsolatedDeclaration,
+    nursery,
+);
+
+impl Rule for IsolatedDeclaration {
+    fn run_on_symbol(&self, symbol: &Symbol, ctx: &LintContext<'_>) {
+        if symbol.is_export() {
+            let declaration = ctx.nodes()[symbol.declaration()];
+            match declaration.kind() {
+                AstKind::Class(class) => Self::check_class(class, ctx),
+                AstKind::Function(function) => Self::check_function(function, ctx),
+                _ => (),
+            }
+        }
+    }
+}
+
+impl IsolatedDeclaration {
+    /// Checks that:
+    /// 1. all the parameters of the function has type annotation
+    /// 2. return type of the function has type annotation
+    pub fn check_function(function: &Function, ctx: &LintContext<'_>) {
+        let parameters = &function.params.items;
+        for param in parameters {
+            if param.pattern.type_annotation.is_none() {
+                ctx.diagnostic(IsolatedDeclarationDiagnostic::FunctionParam(param.span));
+            }
+        }
+        if function.return_type.is_none() {
+            ctx.diagnostic(IsolatedDeclarationDiagnostic::FunctionReturnType(function.span));
+        }
+    }
+
+    /// Checks that the property as a type annotation
+    pub fn check_property_definition(property: &PropertyDefinition, ctx: &LintContext<'_>) {
+        if property.type_annotation.is_none() {
+            ctx.diagnostic(IsolatedDeclarationDiagnostic::Property(property.span));
+        }
+    }
+
+    /// Checks that:
+    /// 1. All the non private methods are valid by `Self::check_function`
+    /// 2. All the non private class fields have a type annotation
+    /// 3. All the non private variables have a type annotation
+    pub fn check_class(class: &Class, ctx: &LintContext<'_>) {
+        for element in &class.body.body {
+            match element {
+                ClassElement::MethodDefinition(method) => {
+                    if !method.is_private() {
+                        Self::check_function(&method.value, ctx);
+                    }
+                }
+                ClassElement::PropertyDefinition(property) => {
+                    if !property.is_private() && !property.key.is_private_identifier() {
+                        Self::check_property_definition(property, ctx);
+                    }
+                }
+                ClassElement::TSAbstractMethodDefinition(method) => {
+                    Self::check_function(&method.method_definition.value, ctx);
+                }
+                ClassElement::TSAbstractPropertyDefinition(property) => {
+                    Self::check_property_definition(&property.property_definition, ctx);
+                }
+                ClassElement::StaticBlock(_)
+                | ClassElement::AccessorProperty(_)
+                | ClassElement::TSIndexSignature(_) => (),
+            }
+        }
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        ("export function foo(a: number): number { return a; }", None),
+        ("export class A { public a: number; }", None),
+        ("export class A { private a; }", None),
+        ("export class A { #a; }", None),
+        ("export class A { foo(): number { return 0; } }", None),
+        ("export class A { private foo() { return 0; } }", None),
+        ("export class A { public foo(a: number): number { return a; } }", None),
+    ];
+
+    let fail = vec![
+        ("export function foo(a) { return a; }", None),
+        ("export class A { public a; }", None),
+        ("export class A { foo() { return 0; } }", None),
+        ("export abstract class A { abstract foo() { return 0; } }", None),
+        ("export abstract class A { abstract a; }", None),
+        ("export class A { get foo() { return 0; } }", None),
+        ("export class A { set foo(val) { } }", None),
+    ];
+
+    Tester::new(IsolatedDeclaration::NAME, pass, fail).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/isolated_declaration.snap

@@ -0,0 +1,59 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: isolated_declaration
+---
+
+  ⚠ isolated-declaration: Requires type annotation on parameters of non-private method
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export function foo(a) { return a; }
+   ·                     ─
+   ╰────
+
+  ⚠ isolated-declaration: Requires return type annotation of non-private method
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export function foo(a) { return a; }
+   ·        ─────────────────────────────
+   ╰────
+
+  ⚠ isolated-declaration: Requires type annotation on non-private property definition
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export class A { public a; }
+   ·                  ─────────
+   ╰────
+
+  ⚠ isolated-declaration: Requires return type annotation of non-private method
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export class A { foo() { return 0; } }
+   ·                     ────────────────
+   ╰────
+
+  ⚠ isolated-declaration: Requires return type annotation of non-private method
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export abstract class A { abstract foo() { return 0; } }
+   ·                                       ────────────────
+   ╰────
+
+  ⚠ isolated-declaration: Requires type annotation on non-private property definition
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export abstract class A { abstract a; }
+   ·                           ───────────
+   ╰────
+
+  ⚠ isolated-declaration: Requires return type annotation of non-private method
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export class A { get foo() { return 0; } }
+   ·                         ────────────────
+   ╰────
+
+  ⚠ isolated-declaration: Requires type annotation on parameters of non-private method
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export class A { set foo(val) { } }
+   ·                          ───
+   ╰────
+
+  ⚠ isolated-declaration: Requires return type annotation of non-private method
+   ╭─[isolated_declaration.tsx:1:1]
+ 1 │ export class A { set foo(val) { } }
+   ·                         ─────────
+   ╰────
+

crates/oxc_parser/src/ts/statement.rs

@@ -395,8 +395,12 @@ impl<'a> Parser<'a> {
                     self.parse_ts_declare_function(start_span, modifiers)
                         .map(Declaration::FunctionDeclaration)
                 } else if self.ts_enabled() {
-                    self.parse_ts_function_impl(start_span, FunctionKind::TSDeclaration, modifiers)
-                        .map(Declaration::FunctionDeclaration)
+                    self.parse_ts_function_impl(
+                        start_span,
+                        FunctionKind::Declaration { single_statement: true },
+                        modifiers,
+                    )
+                    .map(Declaration::FunctionDeclaration)
                 } else {
                     self.parse_function_impl(FunctionKind::Declaration { single_statement: true })
                         .map(Declaration::FunctionDeclaration)

crates/oxc_semantic/src/binder.rs

@@ -155,9 +155,7 @@ impl<'a> Binder for CatchClause<'a> {
             // unless CatchParameter is CatchParameter : BindingIdentifier
             if let BindingPatternKind::BindingIdentifier(ident) = &param.kind {
                 let includes = SymbolFlags::FunctionScopedVariable | SymbolFlags::CatchVariable;
-                // Overshadows declarations so redeclarator error is not reported here
-                let symbol_id = builder.symbols.create(ident.name.clone(), ident.span, includes);
-                builder.scope.current_scope_mut().variables.insert(ident.name.clone(), symbol_id);
+                builder.declare_shadow_symbol(&ident.name, ident.span, current_scope_id, includes);
             } else {
                 for ident in param.bound_names() {
                     builder.declare_symbol(

crates/oxc_semantic/src/builder.rs

@@ -30,6 +30,7 @@ pub struct SemanticBuilder<'a> {
     // states
     pub current_node_id: AstNodeId,
     pub current_node_flags: NodeFlags,
+    pub current_symbol_flags: SymbolFlags,
 
     // builders
     pub nodes: AstNodes<'a>,
@@ -58,6 +59,7 @@ impl<'a> SemanticBuilder<'a> {
             errors: vec![],
             current_node_id,
             current_node_flags: NodeFlags::empty(),
+            current_symbol_flags: SymbolFlags::empty(),
             nodes,
             scope,
             symbols: SymbolTable::default(),
@@ -147,7 +149,22 @@ impl<'a> SemanticBuilder<'a> {
         if let Some(symbol_id) = self.check_redeclaration(scope_id, name, span, excludes) {
             return symbol_id;
         }
-        let symbol_id = self.symbols.create(name.clone(), span, includes);
+        let includes = includes | self.current_symbol_flags;
+        let symbol_id = self.symbols.create(self.current_node_id, name.clone(), span, includes);
+        self.scope.scopes[scope_id].variables.insert(name.clone(), symbol_id);
+        symbol_id
+    }
+
+    /// Declares a `Symbol` for the node, shadowing previous declarations in the same scope.
+    pub fn declare_shadow_symbol(
+        &mut self,
+        name: &Atom,
+        span: Span,
+        scope_id: ScopeId,
+        includes: SymbolFlags,
+    ) -> SymbolId {
+        let includes = includes | self.current_symbol_flags;
+        let symbol_id = self.symbols.create(self.current_node_id, name.clone(), span, includes);
         self.scope.scopes[scope_id].variables.insert(name.clone(), symbol_id);
         symbol_id
     }
@@ -193,6 +210,7 @@ impl<'a> SemanticBuilder<'a> {
     fn enter_kind(&mut self, kind: AstKind<'a>) {
         match kind {
             AstKind::ModuleDeclaration(decl) => {
+                self.current_symbol_flags |= Self::symbol_flag_from_module_declaration(decl);
                 decl.bind(self);
             }
             AstKind::VariableDeclarator(decl) => {
@@ -233,6 +251,9 @@ impl<'a> SemanticBuilder<'a> {
             AstKind::Class(_) => {
                 self.current_node_flags -= NodeFlags::Class;
             }
+            AstKind::ModuleDeclaration(decl) => {
+                self.current_symbol_flags -= Self::symbol_flag_from_module_declaration(decl);
+            }
             _ => {}
         }
     }
@@ -267,4 +288,12 @@ impl<'a> SemanticBuilder<'a> {
             }
         }
     }
+
+    fn symbol_flag_from_module_declaration(module: &ModuleDeclaration) -> SymbolFlags {
+        if matches!(&module.kind, ModuleDeclarationKind::ImportDeclaration(_)) {
+            SymbolFlags::Import
+        } else {
+            SymbolFlags::Export
+        }
+    }
 }