feat(noUndeclaredVariables): add checkTypes option (#4471)

Author: Conaclos

CHANGELOG.md

@@ -88,6 +88,48 @@ our [guidelines for writing a good changelog entry](https://github.com/biomejs/b
 
   Contributed by @Conaclos
 
+- [noUndeclaredVariables](https://biomejs.dev/linter/rules/no-undeclared-variables/) now provides the `checkTypes` option ([#3998](https://github.com/biomejs/biome/issues/3998)).
+
+  `noUndeclaredVariables` is inspired by the [no-undef ESLint rule](https://eslint.org/docs/latest/rules/no-undef). It reports all references that are not bound to any declarations within a module.
+  Node.js, JavaScript and TypeScript globals are ignored.
+  Bioem provides the `javascript.globals` option to list additional globals that should be ignored by the rule.
+
+  In TypeScript projects, developers often use global declaration files to declare global types.
+  Biome is currently unable to detect these global types.
+  This creates many false positives for `noUndeclaredVariables`.
+
+  TypeScript is better suited to perform this kind of check.
+  As proof of this, TypeScript ESLint doesn't provide any rule that extends the `no-undef` ESLint rule.
+
+  This is why we introduce today a new option `checkTypes` which, when it is set to `false`, ignores undeclared type references.
+  Given the following configuration...
+
+  ```json
+  {
+      "linter": {
+          "rules": {
+              "correctness": {
+                  "noUndeclaredVariables": {
+                      "level": "error",
+                      "options": { "checkTypes": false }
+                  }
+              }
+          }
+      }
+  }
+  ```
+
+  ... `UndeclaredType` is not reported by the rule.
+
+  ```ts
+  export default function(): UndeclaredType {}
+  ```
+
+  We plan to turn off the option by default in Biome 2.0
+  Also, this will bring the Biome rule closer to the [no-undef ESLint rule](https://eslint.org/docs/latest/rules/no-undef).
+
+  Contributed by @Conaclos
+
 #### Enhancements
 
 - `useExportType` and `useImportType` now ignore TypeScript declaration files ([#4416](https://github.com/biomejs/biome/pull/4416)). Contributed by @Conaclos

crates/biome_js_analyze/src/lint/correctness/no_undeclared_variables.rs

@@ -3,6 +3,7 @@ use crate::services::semantic::SemanticServices;
 use biome_analyze::context::RuleContext;
 use biome_analyze::{declare_lint_rule, Rule, RuleDiagnostic, RuleSource};
 use biome_console::markup;
+use biome_deserialize_macros::Deserializable;
 use biome_js_syntax::{
     AnyJsFunction, JsFileSource, Language, TextRange, TsAsExpression, TsReferenceType,
 };
@@ -13,6 +14,19 @@ declare_lint_rule! {
     ///
     /// If you need to allow-list some global bindings, you can use the [`javascript.globals`](/reference/configuration/#javascriptglobals) configuration.
     ///
+    /// ## Options (Since v2.0.0)
+    ///
+    /// The rule provides a `checkTypes` option that make the rule checks undeclared types.
+    /// The option defaults to `true`.
+    ///
+    /// ```json
+    /// {
+    ///     "options": {
+    ///         "checkTypes": true
+    ///     }
+    /// }
+    /// ```
+    ///
     /// ## Examples
     ///
     /// ### Invalid
@@ -43,7 +57,7 @@ impl Rule for NoUndeclaredVariables {
     type Query = SemanticServices;
     type State = (TextRange, Box<str>);
     type Signals = Box<[Self::State]>;
-    type Options = ();
+    type Options = UndeclaredVariablesOptions;
 
     fn run(ctx: &RuleContext<Self>) -> Self::Signals {
         ctx.query()
@@ -87,6 +101,10 @@ impl Rule for NoUndeclaredVariables {
                     return None;
                 }
 
+                if !ctx.options().check_types && identifier.is_only_type() {
+                    return None;
+                }
+
                 let span = token.text_trimmed_range();
                 let text = text.to_string().into_boxed_str();
                 Some((span, text))
@@ -108,6 +126,19 @@ impl Rule for NoUndeclaredVariables {
     }
 }
 
+#[derive(Clone, Debug, Deserializable, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
+#[cfg_attr(feature = "schema", derive(schemars::JsonSchema))]
+#[serde(default, rename_all = "camelCase")]
+pub struct UndeclaredVariablesOptions {
+    /// Check undeclared types.
+    check_types: bool,
+}
+impl Default for UndeclaredVariablesOptions {
+    fn default() -> Self {
+        Self { check_types: true }
+    }
+}
+
 fn is_global(reference_name: &str, source_type: &JsFileSource) -> bool {
     match source_type.language() {
         Language::JavaScript => is_js_global(reference_name),

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/ignore-types.options.json

@@ -0,0 +1,14 @@
+{
+    "linter": {
+        "rules": {
+            "correctness": {
+                "noUndeclaredVariables": {
+                    "level": "error",
+                    "options": {
+                        "checkTypes": false
+                    }
+                }
+            }
+        }
+    }
+}

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/ignore-types.ts

@@ -0,0 +1,3 @@
+export function f(): UndeclaredType {}
+
+export const X = UndeclaredVariable;

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/ignore-types.ts.snap

@@ -0,0 +1,28 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: ignore-types.ts
+snapshot_kind: text
+---
+# Input
+```ts
+export function f(): UndeclaredType {}
+
+export const X = UndeclaredVariable;
+```
+
+# Diagnostics
+```
+ignore-types.ts:3:18 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! The UndeclaredVariable variable is undeclared.
+  
+    1 │ export function f(): UndeclaredType {}
+    2 │ 
+  > 3 │ export const X = UndeclaredVariable;
+      │                  ^^^^^^^^^^^^^^^^^^
+  
+  i By default, Biome recognizes browser and Node.js globals.
+    You can ignore more globals using the javascript.globals configuration.
+  
+
+```