Warning (1878): SPDX license identifier not provided in source file. Before publishing, consider adding a comment containing "SPDX-License-Identifier: <SPDX-License>" to each source file. Use "SPDX-License-Identifier: UNLICENSED" for non-open-source code. Please see https://spdx.org for more information.
--> error_codes/input.sol

Error (4937): No visibility specified. Did you intend to add "public"?
 --> error_codes/input.sol:2:5:
  |
2 |     function f() {
  |     ^ (Relevant source part starts here and spans across multiple lines).

Warning (3420): Source file does not specify required compiler version!
--> error_codes/input.sol

Error (4247): Expression has to be an lvalue.
 --> error_codes/input.sol:3:9:
  |
3 |         2=0;
  |         ^

Error (7407): Type int_const 0 is not implicitly convertible to expected type int_const 2.
 --> error_codes/input.sol:3:11:
  |
3 |         2=0;
  |           ^

Error (2614): Indexed expression has to be a type, mapping or array (is literal_string "")
 --> error_codes/input.sol:4:9:
  |
4 |         ""[2];
  |         ^^