clippy_dev/src/new_lint.rs

   1 use crate::clippy_project_root;
   2 use indoc::{formatdoc, writedoc};
   3 use std::fmt::Write as _;
   4 use std::fs::{self, OpenOptions};
   5 use std::io::prelude::*;
   6 use std::io::{self, ErrorKind};
   7 use std::path::{Path, PathBuf};
   8
   9 struct LintData<'a> {
  10     pass: &'a str,
  11     name: &'a str,
  12     category: &'a str,
  13     ty: Option<&'a str>,
  14     project_root: PathBuf,
  15 }
  16
  17 trait Context {
  18     fn context<C: AsRef<str>>(self, text: C) -> Self;
  19 }
  20
  21 impl<T> Context for io::Result<T> {
  22     fn context<C: AsRef<str>>(self, text: C) -> Self {
  23         match self {
  24             Ok(t) => Ok(t),
  25             Err(e) => {
  26                 let message = format!("{}: {e}", text.as_ref());
  27                 Err(io::Error::new(ErrorKind::Other, message))
  28             },
  29         }
  30     }
  31 }
  32
  33 /// Creates the files required to implement and test a new lint and runs `update_lints`.
  34 ///
  35 /// # Errors
  36 ///
  37 /// This function errors out if the files couldn't be created or written to.
  38 pub fn create(
  39     pass: Option<&String>,
  40     lint_name: Option<&String>,
  41     category: Option<&str>,
  42     mut ty: Option<&str>,
  43     msrv: bool,
  44 ) -> io::Result<()> {
  45     if category == Some("cargo") && ty.is_none() {
  46         // `cargo` is a special category, these lints should always be in `clippy_lints/src/cargo`
  47         ty = Some("cargo");
  48     }
  49
  50     let lint = LintData {
  51         pass: pass.map_or("", String::as_str),
  52         name: lint_name.expect("`name` argument is validated by clap"),
  53         category: category.expect("`category` argument is validated by clap"),
  54         ty,
  55         project_root: clippy_project_root(),
  56     };
  57
  58     create_lint(&lint, msrv).context("Unable to create lint implementation")?;
  59     create_test(&lint).context("Unable to create a test for the new lint")?;
  60
  61     if lint.ty.is_none() {
  62         add_lint(&lint, msrv).context("Unable to add lint to clippy_lints/src/lib.rs")?;
  63     }
  64
  65     Ok(())
  66 }
  67
  68 fn create_lint(lint: &LintData<'_>, enable_msrv: bool) -> io::Result<()> {
  69     if let Some(ty) = lint.ty {
  70         create_lint_for_ty(lint, enable_msrv, ty)
  71     } else {
  72         let lint_contents = get_lint_file_contents(lint, enable_msrv);
  73         let lint_path = format!("clippy_lints/src/{}.rs", lint.name);
  74         write_file(lint.project_root.join(&lint_path), lint_contents.as_bytes())?;
  75         println!("Generated lint file: `{lint_path}`");
  76
  77         Ok(())
  78     }
  79 }
  80
  81 fn create_test(lint: &LintData<'_>) -> io::Result<()> {
  82     fn create_project_layout<P: Into<PathBuf>>(lint_name: &str, location: P, case: &str, hint: &str) -> io::Result<()> {
  83         let mut path = location.into().join(case);
  84         fs::create_dir(&path)?;
  85         write_file(path.join("Cargo.toml"), get_manifest_contents(lint_name, hint))?;
  86
  87         path.push("src");
  88         fs::create_dir(&path)?;
  89         let header = format!("// compile-flags: --crate-name={lint_name}");
  90         write_file(path.join("main.rs"), get_test_file_contents(lint_name, Some(&header)))?;
  91
  92         Ok(())
  93     }
  94
  95     if lint.category == "cargo" {
  96         let relative_test_dir = format!("tests/ui-cargo/{}", lint.name);
  97         let test_dir = lint.project_root.join(&relative_test_dir);
  98         fs::create_dir(&test_dir)?;
  99
 100         create_project_layout(lint.name, &test_dir, "fail", "Content that triggers the lint goes here")?;
 101         create_project_layout(lint.name, &test_dir, "pass", "This file should not trigger the lint")?;
 102
 103         println!("Generated test directories: `{relative_test_dir}/pass`, `{relative_test_dir}/fail`");
 104     } else {
 105         let test_path = format!("tests/ui/{}.rs", lint.name);
 106         let test_contents = get_test_file_contents(lint.name, None);
 107         write_file(lint.project_root.join(&test_path), test_contents)?;
 108
 109         println!("Generated test file: `{test_path}`");
 110     }
 111
 112     Ok(())
 113 }
 114
 115 fn add_lint(lint: &LintData<'_>, enable_msrv: bool) -> io::Result<()> {
 116     let path = "clippy_lints/src/lib.rs";
 117     let mut lib_rs = fs::read_to_string(path).context("reading")?;
 118
 119     let comment_start = lib_rs.find("// add lints here,").expect("Couldn't find comment");
 120
 121     let new_lint = if enable_msrv {
 122         format!(
 123             "store.register_{lint_pass}_pass(move |{ctor_arg}| Box::new({module_name}::{camel_name}::new(msrv)));\n    ",
 124             lint_pass = lint.pass,
 125             ctor_arg = if lint.pass == "late" { "_" } else { "" },
 126             module_name = lint.name,
 127             camel_name = to_camel_case(lint.name),
 128         )
 129     } else {
 130         format!(
 131             "store.register_{lint_pass}_pass(|{ctor_arg}| Box::new({module_name}::{camel_name}));\n    ",
 132             lint_pass = lint.pass,
 133             ctor_arg = if lint.pass == "late" { "_" } else { "" },
 134             module_name = lint.name,
 135             camel_name = to_camel_case(lint.name),
 136         )
 137     };
 138
 139     lib_rs.insert_str(comment_start, &new_lint);
 140
 141     fs::write(path, lib_rs).context("writing")
 142 }
 143
 144 fn write_file<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
 145     fn inner(path: &Path, contents: &[u8]) -> io::Result<()> {
 146         OpenOptions::new()
 147             .write(true)
 148             .create_new(true)
 149             .open(path)?
 150             .write_all(contents)
 151     }
 152
 153     inner(path.as_ref(), contents.as_ref()).context(format!("writing to file: {}", path.as_ref().display()))
 154 }
 155
 156 fn to_camel_case(name: &str) -> String {
 157     name.split('_')
 158         .map(|s| {
 159             if s.is_empty() {
 160                 String::new()
 161             } else {
 162                 [&s[0..1].to_uppercase(), &s[1..]].concat()
 163             }
 164         })
 165         .collect()
 166 }
 167
 168 pub(crate) fn get_stabilization_version() -> String {
 169     fn parse_manifest(contents: &str) -> Option<String> {
 170         let version = contents
 171             .lines()
 172             .filter_map(|l| l.split_once('='))
 173             .find_map(|(k, v)| (k.trim() == "version").then(|| v.trim()))?;
 174         let Some(("0", version)) = version.get(1..version.len() - 1)?.split_once('.') else {
 175             return None;
 176         };
 177         let (minor, patch) = version.split_once('.')?;
 178         Some(format!(
 179             "{}.{}.0",
 180             minor.parse::<u32>().ok()?,
 181             patch.parse::<u32>().ok()?
 182         ))
 183     }
 184     let contents = fs::read_to_string("Cargo.toml").expect("Unable to read `Cargo.toml`");
 185     parse_manifest(&contents).expect("Unable to find package version in `Cargo.toml`")
 186 }
 187
 188 fn get_test_file_contents(lint_name: &str, header_commands: Option<&str>) -> String {
 189     let mut contents = formatdoc!(
 190         r#"
 191         #![allow(unused)]
 192         #![warn(clippy::{lint_name})]
 193
 194         fn main() {{
 195             // test code goes here
 196         }}
 197     "#
 198     );
 199
 200     if let Some(header) = header_commands {
 201         contents = format!("{header}\n{contents}");
 202     }
 203
 204     contents
 205 }
 206
 207 fn get_manifest_contents(lint_name: &str, hint: &str) -> String {
 208     formatdoc!(
 209         r#"
 210         # {hint}
 211
 212         [package]
 213         name = "{lint_name}"
 214         version = "0.1.0"
 215         publish = false
 216
 217         [workspace]
 218     "#
 219     )
 220 }
 221
 222 fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
 223     let mut result = String::new();
 224
 225     let (pass_type, pass_lifetimes, pass_import, context_import) = match lint.pass {
 226         "early" => ("EarlyLintPass", "", "use rustc_ast::ast::*;", "EarlyContext"),
 227         "late" => ("LateLintPass", "<'_>", "use rustc_hir::*;", "LateContext"),
 228         _ => {
 229             unreachable!("`pass_type` should only ever be `early` or `late`!");
 230         },
 231     };
 232
 233     let lint_name = lint.name;
 234     let category = lint.category;
 235     let name_camel = to_camel_case(lint.name);
 236     let name_upper = lint_name.to_uppercase();
 237
 238     result.push_str(&if enable_msrv {
 239         formatdoc!(
 240             r#"
 241             use clippy_utils::msrvs;
 242             {pass_import}
 243             use rustc_lint::{{{context_import}, {pass_type}, LintContext}};
 244             use rustc_semver::RustcVersion;
 245             use rustc_session::{{declare_tool_lint, impl_lint_pass}};
 246
 247         "#
 248         )
 249     } else {
 250         formatdoc!(
 251             r#"
 252             {pass_import}
 253             use rustc_lint::{{{context_import}, {pass_type}}};
 254             use rustc_session::{{declare_lint_pass, declare_tool_lint}};
 255
 256         "#
 257         )
 258     });
 259
 260     let _ = write!(result, "{}", get_lint_declaration(&name_upper, category));
 261
 262     result.push_str(&if enable_msrv {
 263         formatdoc!(
 264             r#"
 265             pub struct {name_camel} {{
 266                 msrv: Option<RustcVersion>,
 267             }}
 268
 269             impl {name_camel} {{
 270                 #[must_use]
 271                 pub fn new(msrv: Option<RustcVersion>) -> Self {{
 272                     Self {{ msrv }}
 273                 }}
 274             }}
 275
 276             impl_lint_pass!({name_camel} => [{name_upper}]);
 277
 278             impl {pass_type}{pass_lifetimes} for {name_camel} {{
 279                 extract_msrv_attr!({context_import});
 280             }}
 281
 282             // TODO: Add MSRV level to `clippy_utils/src/msrvs.rs` if needed.
 283             // TODO: Add MSRV test to `tests/ui/min_rust_version_attr.rs`.
 284             // TODO: Update msrv config comment in `clippy_lints/src/utils/conf.rs`
 285         "#
 286         )
 287     } else {
 288         formatdoc!(
 289             r#"
 290             declare_lint_pass!({name_camel} => [{name_upper}]);
 291
 292             impl {pass_type}{pass_lifetimes} for {name_camel} {{}}
 293         "#
 294         )
 295     });
 296
 297     result
 298 }
 299
 300 fn get_lint_declaration(name_upper: &str, category: &str) -> String {
 301     formatdoc!(
 302         r#"
 303             declare_clippy_lint! {{
 304                 /// ### What it does
 305                 ///
 306                 /// ### Why is this bad?
 307                 ///
 308                 /// ### Example
 309                 /// ```rust
 310                 /// // example code where clippy issues a warning
 311                 /// ```
 312                 /// Use instead:
 313                 /// ```rust
 314                 /// // example code which does not raise clippy warning
 315                 /// ```
 316                 #[clippy::version = "{}"]
 317                 pub {name_upper},
 318                 {category},
 319                 "default lint description"
 320             }}
 321         "#,
 322         get_stabilization_version(),
 323     )
 324 }
 325
 326 fn create_lint_for_ty(lint: &LintData<'_>, enable_msrv: bool, ty: &str) -> io::Result<()> {
 327     match ty {
 328         "cargo" => assert_eq!(
 329             lint.category, "cargo",
 330             "Lints of type `cargo` must have the `cargo` category"
 331         ),
 332         _ if lint.category == "cargo" => panic!("Lints of category `cargo` must have the `cargo` type"),
 333         _ => {},
 334     }
 335
 336     let ty_dir = lint.project_root.join(format!("clippy_lints/src/{ty}"));
 337     assert!(
 338         ty_dir.exists() && ty_dir.is_dir(),
 339         "Directory `{}` does not exist!",
 340         ty_dir.display()
 341     );
 342
 343     let lint_file_path = ty_dir.join(format!("{}.rs", lint.name));
 344     assert!(
 345         !lint_file_path.exists(),
 346         "File `{}` already exists",
 347         lint_file_path.display()
 348     );
 349
 350     let mod_file_path = ty_dir.join("mod.rs");
 351     let context_import = setup_mod_file(&mod_file_path, lint)?;
 352
 353     let name_upper = lint.name.to_uppercase();
 354     let mut lint_file_contents = String::new();
 355
 356     if enable_msrv {
 357         let _ = writedoc!(
 358             lint_file_contents,
 359             r#"
 360                 use clippy_utils::{{meets_msrv, msrvs}};
 361                 use rustc_lint::{{{context_import}, LintContext}};
 362                 use rustc_semver::RustcVersion;
 363
 364                 use super::{name_upper};
 365
 366                 // TODO: Adjust the parameters as necessary
 367                 pub(super) fn check(cx: &{context_import}, msrv: Option<RustcVersion>) {{
 368                     if !meets_msrv(msrv, todo!("Add a new entry in `clippy_utils/src/msrvs`")) {{
 369                         return;
 370                     }}
 371                     todo!();
 372                 }}
 373            "#,
 374             context_import = context_import,
 375             name_upper = name_upper,
 376         );
 377     } else {
 378         let _ = writedoc!(
 379             lint_file_contents,
 380             r#"
 381                 use rustc_lint::{{{context_import}, LintContext}};
 382
 383                 use super::{name_upper};
 384
 385                 // TODO: Adjust the parameters as necessary
 386                 pub(super) fn check(cx: &{context_import}) {{
 387                     todo!();
 388                 }}
 389            "#,
 390             context_import = context_import,
 391             name_upper = name_upper,
 392         );
 393     }
 394
 395     write_file(lint_file_path.as_path(), lint_file_contents)?;
 396     println!("Generated lint file: `clippy_lints/src/{ty}/{}.rs`", lint.name);
 397     println!(
 398         "Be sure to add a call to `{}::check` in `clippy_lints/src/{ty}/mod.rs`!",
 399         lint.name
 400     );
 401
 402     Ok(())
 403 }
 404
 405 #[allow(clippy::too_many_lines)]
 406 fn setup_mod_file(path: &Path, lint: &LintData<'_>) -> io::Result<&'static str> {
 407     use super::update_lints::{match_tokens, LintDeclSearchResult};
 408     use rustc_lexer::TokenKind;
 409
 410     let lint_name_upper = lint.name.to_uppercase();
 411
 412     let mut file_contents = fs::read_to_string(path)?;
 413     assert!(
 414         !file_contents.contains(&lint_name_upper),
 415         "Lint `{}` already defined in `{}`",
 416         lint.name,
 417         path.display()
 418     );
 419
 420     let mut offset = 0usize;
 421     let mut last_decl_curly_offset = None;
 422     let mut lint_context = None;
 423
 424     let mut iter = rustc_lexer::tokenize(&file_contents).map(|t| {
 425         let range = offset..offset + t.len as usize;
 426         offset = range.end;
 427
 428         LintDeclSearchResult {
 429             token_kind: t.kind,
 430             content: &file_contents[range.clone()],
 431             range,
 432         }
 433     });
 434
 435     // Find both the last lint declaration (declare_clippy_lint!) and the lint pass impl
 436     while let Some(LintDeclSearchResult { content, .. }) = iter.find(|result| result.token_kind == TokenKind::Ident) {
 437         let mut iter = iter
 438             .by_ref()
 439             .filter(|t| !matches!(t.token_kind, TokenKind::Whitespace | TokenKind::LineComment { .. }));
 440
 441         match content {
 442             "declare_clippy_lint" => {
 443                 // matches `!{`
 444                 match_tokens!(iter, Bang OpenBrace);
 445                 if let Some(LintDeclSearchResult { range, .. }) =
 446                     iter.find(|result| result.token_kind == TokenKind::CloseBrace)
 447                 {
 448                     last_decl_curly_offset = Some(range.end);
 449                 }
 450             },
 451             "impl" => {
 452                 let mut token = iter.next();
 453                 match token {
 454                     // matches <'foo>
 455                     Some(LintDeclSearchResult {
 456                         token_kind: TokenKind::Lt,
 457                         ..
 458                     }) => {
 459                         match_tokens!(iter, Lifetime { .. } Gt);
 460                         token = iter.next();
 461                     },
 462                     None => break,
 463                     _ => {},
 464                 }
 465
 466                 if let Some(LintDeclSearchResult {
 467                     token_kind: TokenKind::Ident,
 468                     content,
 469                     ..
 470                 }) = token
 471                 {
 472                     // Get the appropriate lint context struct
 473                     lint_context = match content {
 474                         "LateLintPass" => Some("LateContext"),
 475                         "EarlyLintPass" => Some("EarlyContext"),
 476                         _ => continue,
 477                     };
 478                 }
 479             },
 480             _ => {},
 481         }
 482     }
 483
 484     drop(iter);
 485
 486     let last_decl_curly_offset =
 487         last_decl_curly_offset.unwrap_or_else(|| panic!("No lint declarations found in `{}`", path.display()));
 488     let lint_context =
 489         lint_context.unwrap_or_else(|| panic!("No lint pass implementation found in `{}`", path.display()));
 490
 491     // Add the lint declaration to `mod.rs`
 492     file_contents.replace_range(
 493         // Remove the trailing newline, which should always be present
 494         last_decl_curly_offset..=last_decl_curly_offset,
 495         &format!("\n\n{}", get_lint_declaration(&lint_name_upper, lint.category)),
 496     );
 497
 498     // Add the lint to `impl_lint_pass`/`declare_lint_pass`
 499     let impl_lint_pass_start = file_contents.find("impl_lint_pass!").unwrap_or_else(|| {
 500         file_contents
 501             .find("declare_lint_pass!")
 502             .unwrap_or_else(|| panic!("failed to find `impl_lint_pass`/`declare_lint_pass`"))
 503     });
 504
 505     let mut arr_start = file_contents[impl_lint_pass_start..].find('[').unwrap_or_else(|| {
 506         panic!("malformed `impl_lint_pass`/`declare_lint_pass`");
 507     });
 508
 509     arr_start += impl_lint_pass_start;
 510
 511     let mut arr_end = file_contents[arr_start..]
 512         .find(']')
 513         .expect("failed to find `impl_lint_pass` terminator");
 514
 515     arr_end += arr_start;
 516
 517     let mut arr_content = file_contents[arr_start + 1..arr_end].to_string();
 518     arr_content.retain(|c| !c.is_whitespace());
 519
 520     let mut new_arr_content = String::new();
 521     for ident in arr_content
 522         .split(',')
 523         .chain(std::iter::once(&*lint_name_upper))
 524         .filter(|s| !s.is_empty())
 525     {
 526         let _ = write!(new_arr_content, "\n    {ident},");
 527     }
 528     new_arr_content.push('\n');
 529
 530     file_contents.replace_range(arr_start + 1..arr_end, &new_arr_content);
 531
 532     // Just add the mod declaration at the top, it'll be fixed by rustfmt
 533     file_contents.insert_str(0, &format!("mod {};\n", &lint.name));
 534
 535     let mut file = OpenOptions::new()
 536         .write(true)
 537         .truncate(true)
 538         .open(path)
 539         .context(format!("trying to open: `{}`", path.display()))?;
 540     file.write_all(file_contents.as_bytes())
 541         .context(format!("writing to file: `{}`", path.display()))?;
 542
 543     Ok(lint_context)
 544 }
 545
 546 #[test]
 547 fn test_camel_case() {
 548     let s = "a_lint";
 549     let s2 = to_camel_case(s);
 550     assert_eq!(s2, "ALint");
 551
 552     let name = "a_really_long_new_lint";
 553     let name2 = to_camel_case(name);
 554     assert_eq!(name2, "AReallyLongNewLint");
 555
 556     let name3 = "lint__name";
 557     let name4 = to_camel_case(name3);
 558     assert_eq!(name4, "LintName");
 559 }