minor: Add expr_bin constructor to SyntaxFactory

Author: Giga-Bowser

src/tools/rust-analyzer/crates/syntax/src/ast/syntax_factory/constructors.rs

@@ -80,6 +80,23 @@ impl SyntaxFactory {
         ast
     }
 
+    pub fn expr_bin(&self, lhs: ast::Expr, op: ast::BinaryOp, rhs: ast::Expr) -> ast::BinExpr {
+        let ast::Expr::BinExpr(ast) =
+            make::expr_bin_op(lhs.clone(), op, rhs.clone()).clone_for_update()
+        else {
+            unreachable!()
+        };
+
+        if let Some(mut mapping) = self.mappings() {
+            let mut builder = SyntaxMappingBuilder::new(ast.syntax().clone());
+            builder.map_node(lhs.syntax().clone(), ast.lhs().unwrap().syntax().clone());
+            builder.map_node(rhs.syntax().clone(), ast.rhs().unwrap().syntax().clone());
+            builder.finish(&mut mapping);
+        }
+
+        ast
+    }
+
     pub fn expr_path(&self, path: ast::Path) -> ast::Expr {
         let ast::Expr::PathExpr(ast) = make::expr_path(path.clone()).clone_for_update() else {
             unreachable!()