Module error_codes

Tidy check to ensure error codes are properly documented and tested.

Overview of check:

1. We create a list of error codes used by the compiler. Error codes are extracted from compiler/rustc_error_codes/src/lib.rs.

2. We check that the error code has a long-form explanation in compiler/rustc_error_codes/src/error_codes/.

• The explanation is expected to contain a doctest that fails with the correct error code. (EXEMPT_FROM_DOCTEST currently bypasses this check)
• Note that other stylistic conventions for markdown files are checked in the style.rs tidy check.

3. We check that the error code has a UI test in tests/ui/error-codes/.

• We ensure that there is both a Exxxx.rs file and a corresponding Exxxx.stderr file.
• We also ensure that the error code is used in the tests.
• Currently, it is possible to opt-out of this check with the EXEMPTED_FROM_TEST constant.

4. We check that the error code is actually emitted by the compiler.

• This is done by searching compiler/ with a regex.

Macros

• verbose_print 🔒

Constants

• ERROR_CODES_PATH 🔒
• ERROR_DOCS_PATH 🔒
• ERROR_TESTS_PATH 🔒
• IGNORE_DOCTEST_CHECK 🔒
• IGNORE_UI_TEST_CHECK 🔒

Functions

• check
• check_error_codes_docs 🔒
  Stage 2: Checks that long-form error code explanations exist and have doctests.
• check_error_codes_tests 🔒
• check_error_codes_used 🔒
  Stage 4: Search compiler/ and ensure that every error code is actually used by the compiler and that no undocumented error codes exist.
• check_explanation_has_doctest 🔒
  This function returns a tuple indicating whether the provided explanation: a) has a code example, tested or not. b) has a valid doctest
• extract_error_codes 🔒
  Stage 1: Parses a list of error codes from error_codes.rs.