fix(linter/explicit-module-boundary-types): false positve with arrow fn in exported fn body (#13232)

fixes #13209

Author: camc314

crates/oxc_linter/src/rules/typescript/explicit_module_boundary_types.rs

@@ -513,6 +513,23 @@ impl<'a> Visit<'a> for ExplicitTypesChecker<'a, '_> {
         }
     }
 
+    fn visit_statements(&mut self, it: &oxc_allocator::Vec<'a, Statement<'a>>) {
+        for stmt in it {
+            match stmt {
+                Statement::ReturnStatement(_) => {
+                    self.visit_statement(stmt);
+                }
+                // Only process expression statements when they are the sole statement in the block.
+                // This is typically to handle cases like concise arrow functions or modules with a single expression.
+                // If this logic needs to be expanded to handle more cases, revisit this condition.
+                Statement::ExpressionStatement(_) if it.len() == 1 => {
+                    self.visit_statement(stmt);
+                }
+                _ => {}
+            }
+        }
+    }
+
     fn visit_variable_declarator(&mut self, var: &VariableDeclarator<'a>) {
         if self.rule.allow_typed_function_expressions && var.id.type_annotation.is_some() {
             return;
@@ -1486,6 +1503,11 @@ mod test {
                 None,
             ),
             ("export namespace B{return}", None),
+            ("function Test(): void { const _x = () => {}; } export default Test;", None),
+            (
+                "function Test(): void { const _x = () => { }; } function Test2() { return (): void => { }; } export { Test2 };",
+                None,
+            ),
         ];
 
         let fail = vec![
@@ -1965,6 +1987,10 @@ mod test {
             ",
                 None,
             ),
+            (
+                "function Test(): void { const _x = () => { }; } function Test2() { return () => { }; } export { Test2 };",
+                None,
+            ),
         ];
 
         Tester::new(

crates/oxc_linter/src/snapshots/typescript_explicit_module_boundary_types.snap

@@ -680,3 +680,9 @@ source: crates/oxc_linter/src/tester.rs
    ·               ────
  6 │                 return a;
    ╰────
+
+  ⚠ typescript-eslint(explicit-module-boundary-types): Missing return type on function
+   ╭─[explicit_module_boundary_types.tsx:1:75]
+ 1 │ function Test(): void { const _x = () => { }; } function Test2() { return () => { }; } export { Test2 };
+   ·                                                                           ──
+   ╰────