src/tools/tidy/src/error_codes.rs

   1 //! Tidy check to ensure error codes are properly documented and tested.
   2 //!
   3 //! Overview of check:
   4 //!
   5 //! 1. We create a list of error codes used by the compiler. Error codes are extracted from `compiler/rustc_error_codes/src/error_codes.rs`.
   6 //!
   7 //! 2. We check that the error code has a long-form explanation in `compiler/rustc_error_codes/src/error_codes/`.
   8 //!   - The explanation is expected to contain a `doctest` that fails with the correct error code. (`EXEMPT_FROM_DOCTEST` *currently* bypasses this check)
   9 //!   - Note that other stylistic conventions for markdown files are checked in the `style.rs` tidy check.
  10 //!
  11 //! 3. We check that the error code has a UI test in `tests/ui/error-codes/`.
  12 //!   - We ensure that there is both a `Exxxx.rs` file and a corresponding `Exxxx.stderr` file.
  13 //!   - We also ensure that the error code is used in the tests.
  14 //!   - *Currently*, it is possible to opt-out of this check with the `EXEMPTED_FROM_TEST` constant.
  15 //!
  16 //! 4. We check that the error code is actually emitted by the compiler.
  17 //!   - This is done by searching `compiler/` with a regex.
  18
  19 use std::{ffi::OsStr, fs, path::Path};
  20
  21 use regex::Regex;
  22
  23 use crate::walk::{filter_dirs, walk, walk_many};
  24
  25 const ERROR_CODES_PATH: &str = "compiler/rustc_error_codes/src/error_codes.rs";
  26 const ERROR_DOCS_PATH: &str = "compiler/rustc_error_codes/src/error_codes/";
  27 const ERROR_TESTS_PATH: &str = "tests/ui/error-codes/";
  28
  29 // Error codes that (for some reason) can't have a doctest in their explanation. Error codes are still expected to provide a code example, even if untested.
  30 const IGNORE_DOCTEST_CHECK: &[&str] = &["E0464", "E0570", "E0601", "E0602", "E0640", "E0717"];
  31
  32 // Error codes that don't yet have a UI test. This list will eventually be removed.
  33 const IGNORE_UI_TEST_CHECK: &[&str] =
  34     &["E0461", "E0465", "E0514", "E0554", "E0640", "E0717", "E0729"];
  35
  36 macro_rules! verbose_print {
  37     ($verbose:expr, $($fmt:tt)*) => {
  38         if $verbose {
  39             println!("{}", format_args!($($fmt)*));
  40         }
  41     };
  42 }
  43
  44 pub fn check(root_path: &Path, search_paths: &[&Path], verbose: bool, bad: &mut bool) {
  45     let mut errors = Vec::new();
  46
  47     // Stage 1: create list
  48     let error_codes = extract_error_codes(root_path, &mut errors);
  49     if verbose {
  50         println!("Found {} error codes", error_codes.len());
  51         println!("Highest error code: `{}`", error_codes.iter().max().unwrap());
  52     }
  53
  54     // Stage 2: check list has docs
  55     let no_longer_emitted = check_error_codes_docs(root_path, &error_codes, &mut errors, verbose);
  56
  57     // Stage 3: check list has UI tests
  58     check_error_codes_tests(root_path, &error_codes, &mut errors, verbose, &no_longer_emitted);
  59
  60     // Stage 4: check list is emitted by compiler
  61     check_error_codes_used(search_paths, &error_codes, &mut errors, &no_longer_emitted, verbose);
  62
  63     // Print any errors.
  64     for error in errors {
  65         tidy_error!(bad, "{}", error);
  66     }
  67 }
  68
  69 /// Stage 1: Parses a list of error codes from `error_codes.rs`.
  70 fn extract_error_codes(root_path: &Path, errors: &mut Vec<String>) -> Vec<String> {
  71     let path = root_path.join(Path::new(ERROR_CODES_PATH));
  72     let file =
  73         fs::read_to_string(&path).unwrap_or_else(|e| panic!("failed to read `{path:?}`: {e}"));
  74
  75     let mut error_codes = Vec::new();
  76
  77     for line in file.lines() {
  78         let line = line.trim();
  79
  80         if line.starts_with('E') {
  81             let split_line = line.split_once(':');
  82
  83             // Extract the error code from the line, emitting a fatal error if it is not in a correct format.
  84             let err_code = if let Some(err_code) = split_line {
  85                 err_code.0.to_owned()
  86             } else {
  87                 errors.push(format!(
  88                     "Expected a line with the format `Exxxx: include_str!(\"..\")`, but got \"{}\" \
  89                     without a `:` delimiter",
  90                     line,
  91                 ));
  92                 continue;
  93             };
  94
  95             // If this is a duplicate of another error code, emit a fatal error.
  96             if error_codes.contains(&err_code) {
  97                 errors.push(format!("Found duplicate error code: `{}`", err_code));
  98                 continue;
  99             }
 100
 101             // Ensure that the line references the correct markdown file.
 102             let expected_filename = format!(" include_str!(\"./error_codes/{}.md\"),", err_code);
 103             if expected_filename != split_line.unwrap().1 {
 104                 errors.push(format!(
 105                     "Error code `{}` expected to reference docs with `{}` but instead found `{}` in \
 106                     `compiler/rustc_error_codes/src/error_codes.rs`",
 107                     err_code,
 108                     expected_filename,
 109                     split_line.unwrap().1,
 110                 ));
 111                 continue;
 112             }
 113
 114             error_codes.push(err_code);
 115         }
 116     }
 117
 118     error_codes
 119 }
 120
 121 /// Stage 2: Checks that long-form error code explanations exist and have doctests.
 122 fn check_error_codes_docs(
 123     root_path: &Path,
 124     error_codes: &[String],
 125     errors: &mut Vec<String>,
 126     verbose: bool,
 127 ) -> Vec<String> {
 128     let docs_path = root_path.join(Path::new(ERROR_DOCS_PATH));
 129
 130     let mut no_longer_emitted_codes = Vec::new();
 131
 132     walk(&docs_path, |_, _| false, &mut |entry, contents| {
 133         let path = entry.path();
 134
 135         // Error if the file isn't markdown.
 136         if path.extension() != Some(OsStr::new("md")) {
 137             errors.push(format!(
 138                 "Found unexpected non-markdown file in error code docs directory: {}",
 139                 path.display()
 140             ));
 141             return;
 142         }
 143
 144         // Make sure that the file is referenced in `error_codes.rs`
 145         let filename = path.file_name().unwrap().to_str().unwrap().split_once('.');
 146         let err_code = filename.unwrap().0; // `unwrap` is ok because we know the filename is in the correct format.
 147
 148         if error_codes.iter().all(|e| e != err_code) {
 149             errors.push(format!(
 150                 "Found valid file `{}` in error code docs directory without corresponding \
 151                 entry in `error_code.rs`",
 152                 path.display()
 153             ));
 154             return;
 155         }
 156
 157         let (found_code_example, found_proper_doctest, emit_ignore_warning, no_longer_emitted) =
 158             check_explanation_has_doctest(&contents, &err_code);
 159
 160         if emit_ignore_warning {
 161             verbose_print!(
 162                 verbose,
 163                 "warning: Error code `{err_code}` uses the ignore header. This should not be used, add the error code to the \
 164                 `IGNORE_DOCTEST_CHECK` constant instead."
 165             );
 166         }
 167
 168         if no_longer_emitted {
 169             no_longer_emitted_codes.push(err_code.to_owned());
 170         }
 171
 172         if !found_code_example {
 173             verbose_print!(
 174                 verbose,
 175                 "warning: Error code `{err_code}` doesn't have a code example, all error codes are expected to have one \
 176                 (even if untested)."
 177             );
 178             return;
 179         }
 180
 181         let test_ignored = IGNORE_DOCTEST_CHECK.contains(&&err_code);
 182
 183         // Check that the explanation has a doctest, and if it shouldn't, that it doesn't
 184         if !found_proper_doctest && !test_ignored {
 185             errors.push(format!(
 186                 "`{}` doesn't use its own error code in compile_fail example",
 187                 path.display(),
 188             ));
 189         } else if found_proper_doctest && test_ignored {
 190             errors.push(format!(
 191                 "`{}` has a compile_fail doctest with its own error code, it shouldn't \
 192                 be listed in `IGNORE_DOCTEST_CHECK`",
 193                 path.display(),
 194             ));
 195         }
 196     });
 197
 198     no_longer_emitted_codes
 199 }
 200
 201 /// This function returns a tuple indicating whether the provided explanation:
 202 /// a) has a code example, tested or not.
 203 /// b) has a valid doctest
 204 fn check_explanation_has_doctest(explanation: &str, err_code: &str) -> (bool, bool, bool, bool) {
 205     let mut found_code_example = false;
 206     let mut found_proper_doctest = false;
 207
 208     let mut emit_ignore_warning = false;
 209     let mut no_longer_emitted = false;
 210
 211     for line in explanation.lines() {
 212         let line = line.trim();
 213
 214         if line.starts_with("```") {
 215             found_code_example = true;
 216
 217             // Check for the `rustdoc` doctest headers.
 218             if line.contains("compile_fail") && line.contains(err_code) {
 219                 found_proper_doctest = true;
 220             }
 221
 222             if line.contains("ignore") {
 223                 emit_ignore_warning = true;
 224                 found_proper_doctest = true;
 225             }
 226         } else if line
 227             .starts_with("#### Note: this error code is no longer emitted by the compiler")
 228         {
 229             no_longer_emitted = true;
 230             found_code_example = true;
 231             found_proper_doctest = true;
 232         }
 233     }
 234
 235     (found_code_example, found_proper_doctest, emit_ignore_warning, no_longer_emitted)
 236 }
 237
 238 // Stage 3: Checks that each error code has a UI test in the correct directory
 239 fn check_error_codes_tests(
 240     root_path: &Path,
 241     error_codes: &[String],
 242     errors: &mut Vec<String>,
 243     verbose: bool,
 244     no_longer_emitted: &[String],
 245 ) {
 246     let tests_path = root_path.join(Path::new(ERROR_TESTS_PATH));
 247
 248     for code in error_codes {
 249         let test_path = tests_path.join(format!("{}.stderr", code));
 250
 251         if !test_path.exists() && !IGNORE_UI_TEST_CHECK.contains(&code.as_str()) {
 252             verbose_print!(
 253                 verbose,
 254                 "warning: Error code `{code}` needs to have at least one UI test in the `tests/error-codes/` directory`!"
 255             );
 256             continue;
 257         }
 258         if IGNORE_UI_TEST_CHECK.contains(&code.as_str()) {
 259             if test_path.exists() {
 260                 errors.push(format!(
 261                     "Error code `{code}` has a UI test in `tests/ui/error-codes/{code}.rs`, it shouldn't be listed in `EXEMPTED_FROM_TEST`!"
 262                 ));
 263             }
 264             continue;
 265         }
 266
 267         let file = match fs::read_to_string(&test_path) {
 268             Ok(file) => file,
 269             Err(err) => {
 270                 verbose_print!(
 271                     verbose,
 272                     "warning: Failed to read UI test file (`{}`) for `{code}` but the file exists. The test is assumed to work:\n{err}",
 273                     test_path.display()
 274                 );
 275                 continue;
 276             }
 277         };
 278
 279         if no_longer_emitted.contains(code) {
 280             // UI tests *can't* contain error codes that are no longer emitted.
 281             continue;
 282         }
 283
 284         let mut found_code = false;
 285
 286         for line in file.lines() {
 287             let s = line.trim();
 288             // Assuming the line starts with `error[E`, we can substring the error code out.
 289             if s.starts_with("error[E") {
 290                 if &s[6..11] == code {
 291                     found_code = true;
 292                     break;
 293                 }
 294             };
 295         }
 296
 297         if !found_code {
 298             verbose_print!(
 299                 verbose,
 300                 "warning: Error code {code}`` has a UI test file, but doesn't contain its own error code!"
 301             );
 302         }
 303     }
 304 }
 305
 306 /// Stage 4: Search `compiler/` and ensure that every error code is actually used by the compiler and that no undocumented error codes exist.
 307 fn check_error_codes_used(
 308     search_paths: &[&Path],
 309     error_codes: &[String],
 310     errors: &mut Vec<String>,
 311     no_longer_emitted: &[String],
 312     verbose: bool,
 313 ) {
 314     // We want error codes which match the following cases:
 315     //
 316     // * foo(a, E0111, a)
 317     // * foo(a, E0111)
 318     // * foo(E0111, a)
 319     // * #[error = "E0111"]
 320     let regex = Regex::new(r#"[(,"\s](E\d{4})[,)"]"#).unwrap();
 321
 322     let mut found_codes = Vec::new();
 323
 324     walk_many(search_paths, |path, _is_dir| filter_dirs(path), &mut |entry, contents| {
 325         let path = entry.path();
 326
 327         // Return early if we aren't looking at a source file.
 328         if path.extension() != Some(OsStr::new("rs")) {
 329             return;
 330         }
 331
 332         for line in contents.lines() {
 333             // We want to avoid parsing error codes in comments.
 334             if line.trim_start().starts_with("//") {
 335                 continue;
 336             }
 337
 338             for cap in regex.captures_iter(line) {
 339                 if let Some(error_code) = cap.get(1) {
 340                     let error_code = error_code.as_str().to_owned();
 341
 342                     if !error_codes.contains(&error_code) {
 343                         // This error code isn't properly defined, we must error.
 344                         errors.push(format!("Error code `{}` is used in the compiler but not defined and documented in `compiler/rustc_error_codes/src/error_codes.rs`.", error_code));
 345                         continue;
 346                     }
 347
 348                     // This error code can now be marked as used.
 349                     found_codes.push(error_code);
 350                 }
 351             }
 352         }
 353     });
 354
 355     for code in error_codes {
 356         if !found_codes.contains(code) && !no_longer_emitted.contains(code) {
 357             errors.push(format!(
 358                 "Error code `{code}` exists, but is not emitted by the compiler!\n\
 359                 Please mark the code as no longer emitted by adding the following note to the top of the `EXXXX.md` file:\n\
 360                 `#### Note: this error code is no longer emitted by the compiler`\n\
 361                 Also, do not forget to mark doctests that no longer apply as `ignore (error is no longer emitted)`."
 362             ));
 363         }
 364
 365         if found_codes.contains(code) && no_longer_emitted.contains(code) {
 366             verbose_print!(
 367                 verbose,
 368                 "warning: Error code `{code}` is used when it's marked as \"no longer emitted\""
 369             );
 370         }
 371     }
 372 }