feat(transformer/typescript): remove import if only have type reference (#2001)

crates/oxc_semantic/src/builder.rs

@@ -70,6 +70,8 @@ pub struct SemanticBuilder<'a> {
     // and when we reach a value declaration we set it
     // to value like
     pub namespace_stack: Vec<SymbolId>,
+    /// If true, the current node is in the type definition
+    in_type_definition: bool,
 
     // builders
     pub nodes: AstNodes<'a>,
@@ -107,6 +109,7 @@ impl<'a> SemanticBuilder<'a> {
             current_node_id: AstNodeId::new(0),
             current_node_flags: NodeFlags::empty(),
             current_symbol_flags: SymbolFlags::empty(),
+            in_type_definition: false,
             current_scope_id,
             function_stack: vec![],
             namespace_stack: vec![],
@@ -459,17 +462,24 @@ impl<'a> SemanticBuilder<'a> {
                     .get_bindings(self.current_scope_id)
                     .get(module_declaration.id.name());
                 self.namespace_stack.push(*symbol_id.unwrap());
+                self.in_type_definition = true;
             }
             AstKind::TSTypeAliasDeclaration(type_alias_declaration) => {
                 type_alias_declaration.bind(self);
+                self.in_type_definition = true;
             }
             AstKind::TSInterfaceDeclaration(interface_declaration) => {
                 interface_declaration.bind(self);
+                self.in_type_definition = true;
             }
             AstKind::TSEnumDeclaration(enum_declaration) => {
                 enum_declaration.bind(self);
                 // TODO: const enum?
                 self.make_all_namespaces_valuelike();
+                self.in_type_definition = true;
+            }
+            AstKind::TSTypeAnnotation(_) => {
+                self.in_type_definition = true;
             }
             AstKind::TSEnumMember(enum_member) => {
                 enum_member.bind(self);
@@ -539,6 +549,13 @@ impl<'a> SemanticBuilder<'a> {
             AstKind::TSModuleBlock(_) => {
                 self.namespace_stack.pop();
             }
+            AstKind::TSEnumDeclaration(_)
+            | AstKind::TSTypeAliasDeclaration(_)
+            | AstKind::TSInterfaceDeclaration(_)
+            | AstKind::TSModuleDeclaration(_)
+            | AstKind::TSTypeAnnotation(_) => {
+                self.in_type_definition = false;
+            }
             _ => {}
         }
     }
@@ -566,6 +583,10 @@ impl<'a> SemanticBuilder<'a> {
 
     /// Resolve reference flags for the current ast node.
     fn resolve_reference_usages(&self) -> ReferenceFlag {
+        if self.in_type_definition {
+            return ReferenceFlag::Type;
+        }
+
         let mut flags = ReferenceFlag::None;
 
         if self.nodes.parent_id(self.current_node_id).is_none() {

crates/oxc_semantic/src/reference.rs

@@ -55,4 +55,8 @@ impl Reference {
     pub fn is_write(&self) -> bool {
         self.flag.is_write()
     }
+
+    pub fn is_type(&self) -> bool {
+        self.flag.is_type()
+    }
 }

crates/oxc_syntax/src/reference.rs

@@ -14,6 +14,8 @@ bitflags! {
         const None = 0;
         const Read = 1 << 0;
         const Write = 1 << 1;
+        // Used in type definitions.
+        const Type = 1 << 2;
         const ReadWrite = Self::Read.bits() | Self::Write.bits();
     }
 }
@@ -55,4 +57,9 @@ impl ReferenceFlag {
     pub const fn is_read_write(&self) -> bool {
         self.contains(Self::ReadWrite)
     }
+
+    /// The identifier is used in a type definition.
+    pub const fn is_type(&self) -> bool {
+        self.contains(Self::Type)
+    }
 }

crates/oxc_transformer/src/typescript/mod.rs

@@ -199,10 +199,7 @@ impl<'a> TypeScript<'a> {
             .scopes()
             .get_binding(root_scope_id, name)
             .map(|symbol_id| {
-                self.ctx
-                    .symbols()
-                    .get_resolved_references(symbol_id)
-                    .any(|x| x.is_read() || x.is_write())
+                self.ctx.symbols().get_resolved_references(symbol_id).any(|x| !x.is_type())
             })
             .unwrap_or_default()
     }

tasks/transform_conformance/babel.snap.md

@@ -1,4 +1,4 @@
-Passed: 298/1179
+Passed: 304/1179
 
 # All Passed:
 * babel-plugin-transform-numeric-separator
@@ -832,7 +832,7 @@ Passed: 298/1179
 * general/function-duplicate-name/input.js
 * general/object/input.js
 
-# babel-plugin-transform-typescript (67/158)
+# babel-plugin-transform-typescript (73/158)
 * class/abstract-class-decorated/input.ts
 * class/abstract-class-decorated-method/input.ts
 * class/abstract-class-decorated-parameter/input.ts
@@ -862,12 +862,7 @@ Passed: 298/1179
 * function/overloads-exports/input.mjs
 * imports/elide-injected/input.ts
 * imports/elide-no-import-specifiers/input.ts
-* imports/elide-preact/input.ts
-* imports/elide-react/input.ts
-* imports/elision/input.ts
 * imports/elision-locations/input.ts
-* imports/elision-qualifiedname/input.ts
-* imports/elision-rename/input.ts
 * imports/enum-id/input.ts
 * imports/enum-value/input.ts
 * imports/import-named-type/input.ts
@@ -877,7 +872,6 @@ Passed: 298/1179
 * imports/import=-module-to-cjs/input.ts
 * imports/only-remove-type-imports/input.ts
 * imports/parameter-decorators/input.ts
-* imports/property-signature/input.ts
 * imports/type-only-export-specifier-1/input.ts
 * imports/type-only-export-specifier-2/input.ts
 * imports/type-only-import-specifier-3/input.ts