feat(biome_js_analyzer): implement noImplicitAnyLet

crates/biome_diagnostics_categories/src/categories.rs

@@ -95,6 +95,7 @@ define_categories! {
     "lint/nursery/noFallthroughSwitchClause": "https://biomejs.dev/linter/rules/no-fallthrough-switch-clause",
     "lint/nursery/noGlobalIsFinite": "https://biomejs.dev/linter/rules/no-global-is-finite",
     "lint/nursery/noGlobalIsNan": "https://biomejs.dev/linter/rules/no-global-is-nan",
+    "lint/nursery/noImplicitAnyLet": "https://biomejs.dev/lint/rules/no-implicit-any-let",
     "lint/nursery/noMisleadingInstantiator": "https://biomejs.dev/linter/rules/no-misleading-instantiator",
     "lint/nursery/noUselessElse": "https://biomejs.dev/lint/rules/no-useless-else",
     "lint/nursery/noVoid": "https://biomejs.dev/linter/rules/no-void",

crates/biome_js_analyze/src/analyzers/nursery/no_implicit_any_let.rs

@@ -0,0 +1,90 @@
+use biome_analyze::{context::RuleContext, declare_rule, Ast, Rule, RuleDiagnostic};
+use biome_console::markup;
+use biome_js_syntax::{JsFileSource, JsVariableDeclaration, JsVariableDeclarator};
+
+declare_rule! {
+    /// Restrict use of implicit any type in Typescript.
+    ///
+    /// Typescript variable declaration without any `type` or `initialization` can cause issue later in the code.
+    ///
+    ///
+    ///
+    /// Source: https://www.typescriptlang.org/tsconfig#noImplicitAny
+    ///
+    /// ## Examples
+    ///
+    /// ### Invalid
+    ///
+    /// ```ts,expect_diagnostic
+    /// var a;
+    /// a = 2;
+    /// let b;
+    /// b = 1
+    /// ```
+    ///
+    /// ## Valid
+    ///
+    /// ```ts
+    /// var a = 1;
+    /// let a:number;
+    /// var b: number
+    /// var b =10;
+    /// ```
+    ///
+    pub(crate) NoImplicitAnyLet {
+        version: "next",
+        name: "noImplicitAnyLet",
+        recommended: true,
+    }
+}
+
+impl Rule for NoImplicitAnyLet {
+    type Query = Ast<JsVariableDeclaration>;
+    type State = JsVariableDeclarator;
+    type Signals = Option<Self::State>;
+    type Options = ();
+
+    fn run(ctx: &RuleContext<Self>) -> Self::Signals {
+        let source_type = ctx.source_type::<JsFileSource>().language();
+        let is_ts_source = source_type.is_typescript();
+        let node = ctx.query();
+        let is_declaration = source_type.is_definition_file();
+
+        if node.is_const() || is_declaration || !is_ts_source {
+            return None;
+        }
+
+        for declarator in node.declarators() {
+            let variable = declarator.ok()?;
+            let is_initialized = variable.initializer().is_some();
+            let is_type_annotated = variable.variable_annotation().is_some();
+            if !is_initialized && !is_type_annotated {
+                return Some(variable);
+            }
+        }
+
+        None
+    }
+
+    fn diagnostic(_: &RuleContext<Self>, node: &Self::State) -> Option<RuleDiagnostic> {
+        let variable = node
+            .id()
+            .ok()?
+            .as_any_js_binding()?
+            .as_js_identifier_binding()?
+            .name_token()
+            .ok()?;
+        Some(
+            RuleDiagnostic::new(
+                rule_category!(),
+                variable.text_range(),
+                markup! {
+                    "Variable " <Emphasis>{variable.text()}</Emphasis> " has implicitly " <Emphasis>"any"</Emphasis> " type"
+                },
+            )
+            .note(markup! {
+                "Declare type or initialize the variable with some value"
+            }),
+        )
+    }
+}

crates/biome_js_analyze/tests/specs/nursery/noImplicitAnyLet/invalid.ts

@@ -0,0 +1,13 @@
+let someVar1;
+someVar1 = '123';
+someVar1 = 123;
+
+
+var someVar1;
+someVar1 = '123';
+someVar1 = 123;
+
+
+function ex() {
+    let b;
+}

crates/biome_js_analyze/tests/specs/nursery/noImplicitAnyLet/invalid.ts.snap

@@ -0,0 +1,68 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: invalid.ts
+---
+# Input
+```js
+let someVar1;
+someVar1 = '123';
+someVar1 = 123;
+
+
+var someVar1;
+someVar1 = '123';
+someVar1 = 123;
+
+
+function ex() {
+    let b;
+}
+```
+
+# Diagnostics
+```
+invalid.ts:1:5 lint/nursery/noImplicitAnyLet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Variable someVar1 has implicitly any type
+
+  > 1 │ let someVar1;
+      │     ^^^^^^^^
+    2 │ someVar1 = '123';
+    3 │ someVar1 = 123;
+
+  i Declare type or initialize the variable with some value
+
+
+```
+
+```
+invalid.ts:6:5 lint/nursery/noImplicitAnyLet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Variable someVar1 has implicitly any type
+
+  > 6 │ var someVar1;
+      │     ^^^^^^^^
+    7 │ someVar1 = '123';
+    8 │ someVar1 = 123;
+
+  i Declare type or initialize the variable with some value
+
+
+```
+
+```
+invalid.ts:12:9 lint/nursery/noImplicitAnyLet ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Variable b has implicitly any type
+
+    11 │ function ex() {
+  > 12 │     let b;
+       │         ^
+    13 │ }
+
+  i Declare type or initialize the variable with some value
+
+
+```
+
+

crates/biome_js_analyze/tests/specs/nursery/noImplicitAnyLet/valid.ts

@@ -0,0 +1,6 @@
+/* should not generate diagnostics */
+
+ let a: number;
+ let b = 1
+ var c : string;
+ var d = "abn"

crates/biome_js_analyze/tests/specs/nursery/noImplicitAnyLet/valid.ts.snap

@@ -0,0 +1,16 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: valid.ts
+---
+# Input
+```js
+/* should not generate diagnostics */
+
+ let a: number;
+ let b = 1
+ var c : string;
+ var d = "abn"
+
+```
+
+