refactor(noUndeclaredVariables): set checkTypes to false by default (#5414)

Author: Conaclos

.changeset/itchy-bananas-travel.md

@@ -0,0 +1,33 @@
+---
+"@biomejs/biome": major
+---
+
+`noUndeclaredVariables` no longer reports TypeScript types.
+
+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 Biome 1.9 introduced a new option `checkTypes` which, when it is set to false, ignores undeclared type references.
+The option was set to `true` by default.
+
+This option is now set to `false` by default.
+To get the previous behavior, you have to set `checkTypes` to `true`:
+
+```json
+{
+    "linter": {
+        "rules": {
+            "correctness": {
+                "noUndeclaredVariables": {
+                    "level": "on",
+                    "options": { "checkTypes": true }
+                }
+            }
+        }
+    }
+}
+```

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

@@ -17,9 +17,9 @@ declare_lint_rule! {
     /// ## Options (Since v2.0.0)
     ///
     /// The rule provides a `checkTypes` option that make the rule checks undeclared types.
-    /// The option defaults to `true`.
+    /// The option defaults to `false`.
     ///
-    /// ```json,options
+    /// ```json
     /// {
     ///     "options": {
     ///         "checkTypes": true
@@ -126,18 +126,15 @@ impl Rule for NoUndeclaredVariables {
     }
 }
 
-#[derive(Clone, Debug, Deserializable, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
+#[derive(
+    Clone, Debug, Default, 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() {

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

@@ -3,9 +3,9 @@
         "rules": {
             "correctness": {
                 "noUndeclaredVariables": {
-                    "level": "error",
+                    "level": "on",
                     "options": {
-                        "checkTypes": false
+                        "checkTypes": true
                     }
                 }
             }

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/invalidNamesapceReference.options.json

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

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.options.json

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

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariablesTypes.options.json

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

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariablesTypes.ts

@@ -1,7 +1,6 @@
 ---
 source: crates/biome_js_analyze/tests/spec_tests.rs
-expression: noUndeclaredVariables.ts
-snapshot_kind: text
+expression: noUndeclaredVariablesTypes.ts
 ---
 # Input
 ```ts
@@ -36,7 +35,7 @@ export type Invalid<S extends number> = `Hello ${T}`
 
 # Diagnostics
 ```
-noUndeclaredVariables.ts:26:50 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+noUndeclaredVariablesTypes.ts:26:50 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━
 
   i The T variable is undeclared.
   

crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariables.ts.snap crates/biome_js_analyze/tests/specs/correctness/noUndeclaredVariables/noUndeclaredVariablesTypes.ts.snap

@@ -11,66 +11,3 @@ export type Invalid<S extends number> = `
     ${T}
 `
 ```
-
-# Diagnostics
-```
-noUndeclaredVariables.ts:1:50 lint/correctness/noUndeclaredVariables  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━
-
-  i The T variable is undeclared.
-  
-  > 1 │ export type Invalid<S extends number> = `Hello ${T}`
-      │                                                  ^
-    2 │ 
-    3 │ export type Invalid<S extends number> = `
-  
-  i By default, Biome recognizes browser and Node.js globals.
-    You can ignore more globals using the javascript.globals configuration.
-  
-  i Safe fix: Suppress rule lint/correctness/noUndeclaredVariables for this line.
-  
-    1   │ - export·type·Invalid<S·extends·number>·=·`Hello·${T}`
-      1 │ + export·type·Invalid<S·extends·number>·=·`Hello·${//·biome-ignore·lint/correctness/noUndeclaredVariables:·<explanation>
-      2 │ + T}`
-    2 3 │   
-    3 4 │   export type Invalid<S extends number> = `
-  
-  i Safe fix: Suppress rule lint/correctness/noUndeclaredVariables for the whole file.
-  
-      1 │ + /**·biome-ignore-all·lint/correctness/noUndeclaredVariables:·<explanation>·*/
-    1 2 │   export type Invalid<S extends number> = `Hello ${T}`
-    2 3 │   
-  
-
-```
-
-```
-noUndeclaredVariables.ts:5:7 lint/correctness/noUndeclaredVariables  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━
-
-  i The T variable is undeclared.
-  
-    3 │ export type Invalid<S extends number> = `
-    4 │     Hello
-  > 5 │     ${T}
-      │       ^
-    6 │ `
-  
-  i By default, Biome recognizes browser and Node.js globals.
-    You can ignore more globals using the javascript.globals configuration.
-  
-  i Safe fix: Suppress rule lint/correctness/noUndeclaredVariables for this line.
-  
-    3 3 │   export type Invalid<S extends number> = `
-    4 4 │       Hello
-    5   │ - ····${T}
-      5 │ + ····${//·biome-ignore·lint/correctness/noUndeclaredVariables:·<explanation>
-      6 │ + T}
-    6 7 │   `
-  
-  i Safe fix: Suppress rule lint/correctness/noUndeclaredVariables for the whole file.
-  
-      1 │ + /**·biome-ignore-all·lint/correctness/noUndeclaredVariables:·<explanation>·*/
-    1 2 │   export type Invalid<S extends number> = `Hello ${T}`
-    2 3 │   
-  
-
-```