feature(rome_js_analyze): no function reassign lint rule (#2895)

* hoisting function declaration for no function reassign lint rule

crates/rome_js_analyze/src/semantic_analyzers/js.rs

@@ -3,6 +3,7 @@
 use rome_analyze::declare_group;
 mod no_arguments;
 mod no_catch_assign;
+mod no_function_assign;
 mod no_label_var;
 mod no_shouty_constants;
-declare_group! { pub (crate) Js { name : "js" , rules : [no_arguments :: NoArguments , no_catch_assign :: NoCatchAssign , no_label_var :: NoLabelVar , no_shouty_constants :: NoShoutyConstants ,] } }
+declare_group! { pub (crate) Js { name : "js" , rules : [no_arguments :: NoArguments , no_catch_assign :: NoCatchAssign , no_function_assign :: NoFunctionAssign , no_label_var :: NoLabelVar , no_shouty_constants :: NoShoutyConstants ,] } }

crates/rome_js_analyze/src/semantic_analyzers/js/no_function_assign.rs

@@ -0,0 +1,164 @@
+use crate::semantic_services::Semantic;
+use rome_analyze::{context::RuleContext, declare_rule, Rule, RuleCategory, RuleDiagnostic};
+use rome_console::markup;
+use rome_js_semantic::{AllReferencesExtensions, Reference};
+use rome_js_syntax::{JsFunctionDeclaration, JsIdentifierBinding};
+use rome_rowan::AstNode;
+
+declare_rule! {
+    /// Disallow reassigning function declarations.
+    ///
+    /// ## Examples
+    ///
+    /// ### Invalid
+    ///
+    /// ```js,expect_diagnostic
+    /// function foo() { };
+    /// foo = bar;
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// function foo() {
+    ///     foo = bar;
+    ///  }
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// foo = bar;
+    /// function foo() { };
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// [foo] = bar;
+    /// function foo() { };
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// ({ x: foo = 0 } = bar);
+    /// function foo() { };
+    /// ```
+    ///
+    /// ```js,expect_diagnostic
+    /// function foo() {
+    ///     [foo] = bar;
+    ///  }
+    /// ```
+    /// ```js,expect_diagnostic
+    /// (function () {
+    ///     ({ x: foo = 0 } = bar);
+    ///     function foo() { };
+    ///  })();
+    /// ```
+    ///
+    /// ## Valid
+    ///
+    /// ```js
+    /// function foo() {
+    ///     var foo = bar;
+    ///  }
+    /// ```
+    ///
+    /// ```js
+    /// function foo(foo) {
+    ///     foo = bar;
+    ///  }
+    /// ```
+    ///
+    /// ```js
+    /// function foo() {
+    ///     var foo;
+    ///     foo = bar;
+    ///  }
+    /// ```
+    ///
+    /// ```js
+    /// var foo = () => {};
+    /// foo = bar;
+    /// ```
+    ///
+    /// ```js
+    /// var foo = function() {};
+    /// foo = bar;
+    /// ```
+    ///
+    /// ```js
+    /// var foo = function() {
+    ///     foo = bar;
+    ///  };
+    /// ```
+    ///
+    /// ```js
+    /// import bar from 'bar';
+    /// function foo() {
+    ///     var foo = bar;
+    /// }
+    /// ```
+    pub(crate) NoFunctionAssign {
+        version: "0.7.0",
+        name: "noFunctionAssign"
+    }
+}
+
+pub struct State {
+    id: JsIdentifierBinding,
+    all_writes: Vec<Reference>,
+}
+
+impl Rule for NoFunctionAssign {
+    const CATEGORY: RuleCategory = RuleCategory::Lint;
+
+    type Query = Semantic<JsFunctionDeclaration>;
+    type State = State;
+    type Signals = Option<Self::State>;
+
+    fn run(ctx: &RuleContext<Self>) -> Option<Self::State> {
+        let declaration = ctx.query();
+        let model = ctx.model();
+
+        let id = declaration.id().ok()?;
+        let id = id.as_js_identifier_binding()?;
+        let all_writes: Vec<Reference> = id.all_writes(model).collect();
+
+        if all_writes.is_empty() {
+            None
+        } else {
+            Some(State {
+                id: id.clone(),
+                all_writes,
+            })
+        }
+    }
+
+    fn diagnostic(_: &RuleContext<Self>, state: &Self::State) -> Option<RuleDiagnostic> {
+        let mut diag = RuleDiagnostic::warning(
+            state.id.syntax().text_trimmed_range(),
+            markup! {
+                "Do not reassign a function declaration."
+            },
+        );
+
+        let mut hoisted_quantity = 0;
+        for reference in state.all_writes.iter() {
+            let node = reference.node();
+            diag = diag.secondary(node.text_trimmed_range(), "Reassigned here.");
+
+            hoisted_quantity += if reference.is_using_hoisted_declaration() {
+                1
+            } else {
+                0
+            };
+        }
+
+        let diag = if hoisted_quantity > 0 {
+            diag.footer_note(
+                markup! {"Reassignment happens here because the function declaration is hoisted."},
+            )
+        } else {
+            diag
+        };
+
+        let diag = diag.footer_note(markup! {"Use a local variable instead."});
+
+        Some(diag)
+    }
+}

crates/rome_js_analyze/tests/specs/js/noFunctionAssign.js

@@ -0,0 +1,25 @@
+function foo() { };
+foo = bar;
+
+function foo2() { foo2 = bar; }
+
+foo3 = bar;
+function foo3() { };
+
+[foo4] = bar;
+function foo4() { };
+
+({ x: foo5 = 0 } = bar);
+function foo5() { };
+
+function foo6() { [foo6] = bar; }
+
+(function () { ({ x: foo7 = 0 } = bar); function foo7() { }; })();
+
+// Valid
+function foo8() { var foo8 = bar; }
+function foo9(foo9) { foo9 = bar; }
+function foo10() { var foo10; foo10 = bar; }
+var foo11 = () => { }; foo11 = bar;
+var foo12 = function () { }; foo12 = bar;
+var foo13 = function () { foo13 = bar; };

crates/rome_js_analyze/tests/specs/js/noFunctionAssign.js.snap

@@ -0,0 +1,133 @@
+---
+source: crates/rome_js_analyze/tests/spec_tests.rs
+expression: noFunctionAssign.js
+---
+# Input
+```js
+function foo() { };
+foo = bar;
+
+function foo2() { foo2 = bar; }
+
+foo3 = bar;
+function foo3() { };
+
+[foo4] = bar;
+function foo4() { };
+
+({ x: foo5 = 0 } = bar);
+function foo5() { };
+
+function foo6() { [foo6] = bar; }
+
+(function () { ({ x: foo7 = 0 } = bar); function foo7() { }; })();
+
+// Valid
+function foo8() { var foo8 = bar; }
+function foo9(foo9) { foo9 = bar; }
+function foo10() { var foo10; foo10 = bar; }
+var foo11 = () => { }; foo11 = bar;
+var foo12 = function () { }; foo12 = bar;
+var foo13 = function () { foo13 = bar; };
+```
+
+# Diagnostics
+```
+warning[js/noFunctionAssign]: Do not reassign a function declaration.
+  ┌─ noFunctionAssign.js:1:10
+  │
+1 │ function foo() { };
+  │          ---
+2 │ foo = bar;
+  │ --- Reassigned here.
+
+=  note: Use a local variable instead.
+
+
+```
+
+```
+warning[js/noFunctionAssign]: Do not reassign a function declaration.
+  ┌─ noFunctionAssign.js:4:10
+  │
+4 │ function foo2() { foo2 = bar; }
+  │          ----     ---- Reassigned here.
+
+=  note: Use a local variable instead.
+
+
+```
+
+```
+warning[js/noFunctionAssign]: Do not reassign a function declaration.
+  ┌─ noFunctionAssign.js:7:10
+  │
+6 │ foo3 = bar;
+  │ ---- Reassigned here.
+7 │ function foo3() { };
+  │          ----
+
+=  note: Reassignment happens here because the function declaration is hoisted.
+=  note: Use a local variable instead.
+
+
+```
+
+```
+warning[js/noFunctionAssign]: Do not reassign a function declaration.
+   ┌─ noFunctionAssign.js:10:10
+   │
+ 9 │ [foo4] = bar;
+   │  ---- Reassigned here.
+10 │ function foo4() { };
+   │          ----
+
+=  note: Reassignment happens here because the function declaration is hoisted.
+=  note: Use a local variable instead.
+
+
+```
+
+```
+warning[js/noFunctionAssign]: Do not reassign a function declaration.
+   ┌─ noFunctionAssign.js:13:10
+   │
+12 │ ({ x: foo5 = 0 } = bar);
+   │       ---- Reassigned here.
+13 │ function foo5() { };
+   │          ----
+
+=  note: Reassignment happens here because the function declaration is hoisted.
+=  note: Use a local variable instead.
+
+
+```
+
+```
+warning[js/noFunctionAssign]: Do not reassign a function declaration.
+   ┌─ noFunctionAssign.js:15:10
+   │
+15 │ function foo6() { [foo6] = bar; }
+   │          ----      ---- Reassigned here.
+
+=  note: Use a local variable instead.
+
+
+```
+
+```
+warning[js/noFunctionAssign]: Do not reassign a function declaration.
+   ┌─ noFunctionAssign.js:17:50
+   │
+17 │ (function () { ({ x: foo7 = 0 } = bar); function foo7() { }; })();
+   │                      ----                        ----
+   │                      │                            
+   │                      Reassigned here.
+
+=  note: Reassignment happens here because the function declaration is hoisted.
+=  note: Use a local variable instead.
+
+
+```
+
+

crates/rome_js_semantic/src/events.rs

@@ -264,6 +264,10 @@ impl SemanticEventExtractor {
                     self.push_binding_into_scope(scope_idx, &name_token);
                 };
             }
+            Some(JS_FUNCTION_DECLARATION) => {
+                let scope_idx = self.scope_index_to_hoist_declarations();
+                self.push_binding_into_scope(scope_idx, &name_token);
+            }
             Some(_) => {
                 let scope_idx = self.scopes.len() - 1;
                 self.push_binding_into_scope(scope_idx, &name_token);