src/librustdoc/clean/cfg.rs

   1 //! The representation of a `#[doc(cfg(...))]` attribute.
   2
   3 // FIXME: Once the portability lint RFC is implemented (see tracking issue #41619),
   4 // switch to use those structures instead.
   5
   6 use std::fmt::{self, Write};
   7 use std::mem;
   8 use std::ops;
   9
  10 use rustc_ast::{LitKind, MetaItem, MetaItemKind, NestedMetaItem};
  11 use rustc_data_structures::fx::FxHashSet;
  12 use rustc_feature::Features;
  13 use rustc_session::parse::ParseSess;
  14 use rustc_span::symbol::{sym, Symbol};
  15
  16 use rustc_span::Span;
  17
  18 use crate::html::escape::Escape;
  19
  20 #[cfg(test)]
  21 mod tests;
  22
  23 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
  24 pub(crate) enum Cfg {
  25     /// Accepts all configurations.
  26     True,
  27     /// Denies all configurations.
  28     False,
  29     /// A generic configuration option, e.g., `test` or `target_os = "linux"`.
  30     Cfg(Symbol, Option<Symbol>),
  31     /// Negates a configuration requirement, i.e., `not(x)`.
  32     Not(Box<Cfg>),
  33     /// Union of a list of configuration requirements, i.e., `any(...)`.
  34     Any(Vec<Cfg>),
  35     /// Intersection of a list of configuration requirements, i.e., `all(...)`.
  36     All(Vec<Cfg>),
  37 }
  38
  39 #[derive(PartialEq, Debug)]
  40 pub(crate) struct InvalidCfgError {
  41     pub(crate) msg: &'static str,
  42     pub(crate) span: Span,
  43 }
  44
  45 impl Cfg {
  46     /// Parses a `NestedMetaItem` into a `Cfg`.
  47     fn parse_nested(
  48         nested_cfg: &NestedMetaItem,
  49         exclude: &FxHashSet<Cfg>,
  50     ) -> Result<Option<Cfg>, InvalidCfgError> {
  51         match nested_cfg {
  52             NestedMetaItem::MetaItem(ref cfg) => Cfg::parse_without(cfg, exclude),
  53             NestedMetaItem::Lit(ref lit) => {
  54                 Err(InvalidCfgError { msg: "unexpected literal", span: lit.span })
  55             }
  56         }
  57     }
  58
  59     pub(crate) fn parse_without(
  60         cfg: &MetaItem,
  61         exclude: &FxHashSet<Cfg>,
  62     ) -> Result<Option<Cfg>, InvalidCfgError> {
  63         let name = match cfg.ident() {
  64             Some(ident) => ident.name,
  65             None => {
  66                 return Err(InvalidCfgError {
  67                     msg: "expected a single identifier",
  68                     span: cfg.span,
  69                 });
  70             }
  71         };
  72         match cfg.kind {
  73             MetaItemKind::Word => {
  74                 let cfg = Cfg::Cfg(name, None);
  75                 if exclude.contains(&cfg) { Ok(None) } else { Ok(Some(cfg)) }
  76             }
  77             MetaItemKind::NameValue(ref lit) => match lit.kind {
  78                 LitKind::Str(value, _) => {
  79                     let cfg = Cfg::Cfg(name, Some(value));
  80                     if exclude.contains(&cfg) { Ok(None) } else { Ok(Some(cfg)) }
  81                 }
  82                 _ => Err(InvalidCfgError {
  83                     // FIXME: if the main #[cfg] syntax decided to support non-string literals,
  84                     // this should be changed as well.
  85                     msg: "value of cfg option should be a string literal",
  86                     span: lit.span,
  87                 }),
  88             },
  89             MetaItemKind::List(ref items) => {
  90                 let orig_len = items.len();
  91                 let sub_cfgs =
  92                     items.iter().filter_map(|i| Cfg::parse_nested(i, exclude).transpose());
  93                 let ret = match name {
  94                     sym::all => sub_cfgs.fold(Ok(Cfg::True), |x, y| Ok(x? & y?)),
  95                     sym::any => sub_cfgs.fold(Ok(Cfg::False), |x, y| Ok(x? | y?)),
  96                     sym::not => {
  97                         if orig_len == 1 {
  98                             let mut sub_cfgs = sub_cfgs.collect::<Vec<_>>();
  99                             if sub_cfgs.len() == 1 {
 100                                 Ok(!sub_cfgs.pop().unwrap()?)
 101                             } else {
 102                                 return Ok(None);
 103                             }
 104                         } else {
 105                             Err(InvalidCfgError { msg: "expected 1 cfg-pattern", span: cfg.span })
 106                         }
 107                     }
 108                     _ => Err(InvalidCfgError { msg: "invalid predicate", span: cfg.span }),
 109                 };
 110                 match ret {
 111                     Ok(c) => Ok(Some(c)),
 112                     Err(e) => Err(e),
 113                 }
 114             }
 115         }
 116     }
 117
 118     /// Parses a `MetaItem` into a `Cfg`.
 119     ///
 120     /// The `MetaItem` should be the content of the `#[cfg(...)]`, e.g., `unix` or
 121     /// `target_os = "redox"`.
 122     ///
 123     /// If the content is not properly formatted, it will return an error indicating what and where
 124     /// the error is.
 125     pub(crate) fn parse(cfg: &MetaItem) -> Result<Cfg, InvalidCfgError> {
 126         Self::parse_without(cfg, &FxHashSet::default()).map(|ret| ret.unwrap())
 127     }
 128
 129     /// Checks whether the given configuration can be matched in the current session.
 130     ///
 131     /// Equivalent to `attr::cfg_matches`.
 132     // FIXME: Actually make use of `features`.
 133     pub(crate) fn matches(&self, parse_sess: &ParseSess, features: Option<&Features>) -> bool {
 134         match *self {
 135             Cfg::False => false,
 136             Cfg::True => true,
 137             Cfg::Not(ref child) => !child.matches(parse_sess, features),
 138             Cfg::All(ref sub_cfgs) => {
 139                 sub_cfgs.iter().all(|sub_cfg| sub_cfg.matches(parse_sess, features))
 140             }
 141             Cfg::Any(ref sub_cfgs) => {
 142                 sub_cfgs.iter().any(|sub_cfg| sub_cfg.matches(parse_sess, features))
 143             }
 144             Cfg::Cfg(name, value) => parse_sess.config.contains(&(name, value)),
 145         }
 146     }
 147
 148     /// Whether the configuration consists of just `Cfg` or `Not`.
 149     fn is_simple(&self) -> bool {
 150         match *self {
 151             Cfg::False | Cfg::True | Cfg::Cfg(..) | Cfg::Not(..) => true,
 152             Cfg::All(..) | Cfg::Any(..) => false,
 153         }
 154     }
 155
 156     /// Whether the configuration consists of just `Cfg`, `Not` or `All`.
 157     fn is_all(&self) -> bool {
 158         match *self {
 159             Cfg::False | Cfg::True | Cfg::Cfg(..) | Cfg::Not(..) | Cfg::All(..) => true,
 160             Cfg::Any(..) => false,
 161         }
 162     }
 163
 164     /// Renders the configuration for human display, as a short HTML description.
 165     pub(crate) fn render_short_html(&self) -> String {
 166         let mut msg = Display(self, Format::ShortHtml).to_string();
 167         if self.should_capitalize_first_letter() {
 168             if let Some(i) = msg.find(|c: char| c.is_ascii_alphanumeric()) {
 169                 msg[i..i + 1].make_ascii_uppercase();
 170             }
 171         }
 172         msg
 173     }
 174
 175     /// Renders the configuration for long display, as a long HTML description.
 176     pub(crate) fn render_long_html(&self) -> String {
 177         let on = if self.should_use_with_in_description() { "with" } else { "on" };
 178
 179         let mut msg =
 180             format!("Available {on} <strong>{}</strong>", Display(self, Format::LongHtml));
 181         if self.should_append_only_to_description() {
 182             msg.push_str(" only");
 183         }
 184         msg.push('.');
 185         msg
 186     }
 187
 188     /// Renders the configuration for long display, as a long plain text description.
 189     pub(crate) fn render_long_plain(&self) -> String {
 190         let on = if self.should_use_with_in_description() { "with" } else { "on" };
 191
 192         let mut msg = format!("Available {on} {}", Display(self, Format::LongPlain));
 193         if self.should_append_only_to_description() {
 194             msg.push_str(" only");
 195         }
 196         msg
 197     }
 198
 199     fn should_capitalize_first_letter(&self) -> bool {
 200         match *self {
 201             Cfg::False | Cfg::True | Cfg::Not(..) => true,
 202             Cfg::Any(ref sub_cfgs) | Cfg::All(ref sub_cfgs) => {
 203                 sub_cfgs.first().map(Cfg::should_capitalize_first_letter).unwrap_or(false)
 204             }
 205             Cfg::Cfg(name, _) => name == sym::debug_assertions || name == sym::target_endian,
 206         }
 207     }
 208
 209     fn should_append_only_to_description(&self) -> bool {
 210         match *self {
 211             Cfg::False | Cfg::True => false,
 212             Cfg::Any(..) | Cfg::All(..) | Cfg::Cfg(..) => true,
 213             Cfg::Not(box Cfg::Cfg(..)) => true,
 214             Cfg::Not(..) => false,
 215         }
 216     }
 217
 218     fn should_use_with_in_description(&self) -> bool {
 219         matches!(self, Cfg::Cfg(sym::target_feature, _))
 220     }
 221
 222     /// Attempt to simplify this cfg by assuming that `assume` is already known to be true, will
 223     /// return `None` if simplification managed to completely eliminate any requirements from this
 224     /// `Cfg`.
 225     ///
 226     /// See `tests::test_simplify_with` for examples.
 227     pub(crate) fn simplify_with(&self, assume: &Cfg) -> Option<Cfg> {
 228         if self == assume {
 229             return None;
 230         }
 231
 232         if let Cfg::All(a) = self {
 233             let mut sub_cfgs: Vec<Cfg> = if let Cfg::All(b) = assume {
 234                 a.iter().filter(|a| !b.contains(a)).cloned().collect()
 235             } else {
 236                 a.iter().filter(|&a| a != assume).cloned().collect()
 237             };
 238             let len = sub_cfgs.len();
 239             return match len {
 240                 0 => None,
 241                 1 => sub_cfgs.pop(),
 242                 _ => Some(Cfg::All(sub_cfgs)),
 243             };
 244         } else if let Cfg::All(b) = assume {
 245             if b.contains(self) {
 246                 return None;
 247             }
 248         }
 249
 250         Some(self.clone())
 251     }
 252 }
 253
 254 impl ops::Not for Cfg {
 255     type Output = Cfg;
 256     fn not(self) -> Cfg {
 257         match self {
 258             Cfg::False => Cfg::True,
 259             Cfg::True => Cfg::False,
 260             Cfg::Not(cfg) => *cfg,
 261             s => Cfg::Not(Box::new(s)),
 262         }
 263     }
 264 }
 265
 266 impl ops::BitAndAssign for Cfg {
 267     fn bitand_assign(&mut self, other: Cfg) {
 268         match (self, other) {
 269             (&mut Cfg::False, _) | (_, Cfg::True) => {}
 270             (s, Cfg::False) => *s = Cfg::False,
 271             (s @ &mut Cfg::True, b) => *s = b,
 272             (&mut Cfg::All(ref mut a), Cfg::All(ref mut b)) => {
 273                 for c in b.drain(..) {
 274                     if !a.contains(&c) {
 275                         a.push(c);
 276                     }
 277                 }
 278             }
 279             (&mut Cfg::All(ref mut a), ref mut b) => {
 280                 if !a.contains(b) {
 281                     a.push(mem::replace(b, Cfg::True));
 282                 }
 283             }
 284             (s, Cfg::All(mut a)) => {
 285                 let b = mem::replace(s, Cfg::True);
 286                 if !a.contains(&b) {
 287                     a.push(b);
 288                 }
 289                 *s = Cfg::All(a);
 290             }
 291             (s, b) => {
 292                 if *s != b {
 293                     let a = mem::replace(s, Cfg::True);
 294                     *s = Cfg::All(vec![a, b]);
 295                 }
 296             }
 297         }
 298     }
 299 }
 300
 301 impl ops::BitAnd for Cfg {
 302     type Output = Cfg;
 303     fn bitand(mut self, other: Cfg) -> Cfg {
 304         self &= other;
 305         self
 306     }
 307 }
 308
 309 impl ops::BitOrAssign for Cfg {
 310     fn bitor_assign(&mut self, other: Cfg) {
 311         match (self, other) {
 312             (Cfg::True, _) | (_, Cfg::False) | (_, Cfg::True) => {}
 313             (s @ &mut Cfg::False, b) => *s = b,
 314             (&mut Cfg::Any(ref mut a), Cfg::Any(ref mut b)) => {
 315                 for c in b.drain(..) {
 316                     if !a.contains(&c) {
 317                         a.push(c);
 318                     }
 319                 }
 320             }
 321             (&mut Cfg::Any(ref mut a), ref mut b) => {
 322                 if !a.contains(b) {
 323                     a.push(mem::replace(b, Cfg::True));
 324                 }
 325             }
 326             (s, Cfg::Any(mut a)) => {
 327                 let b = mem::replace(s, Cfg::True);
 328                 if !a.contains(&b) {
 329                     a.push(b);
 330                 }
 331                 *s = Cfg::Any(a);
 332             }
 333             (s, b) => {
 334                 if *s != b {
 335                     let a = mem::replace(s, Cfg::True);
 336                     *s = Cfg::Any(vec![a, b]);
 337                 }
 338             }
 339         }
 340     }
 341 }
 342
 343 impl ops::BitOr for Cfg {
 344     type Output = Cfg;
 345     fn bitor(mut self, other: Cfg) -> Cfg {
 346         self |= other;
 347         self
 348     }
 349 }
 350
 351 #[derive(Clone, Copy)]
 352 enum Format {
 353     LongHtml,
 354     LongPlain,
 355     ShortHtml,
 356 }
 357
 358 impl Format {
 359     fn is_long(self) -> bool {
 360         match self {
 361             Format::LongHtml | Format::LongPlain => true,
 362             Format::ShortHtml => false,
 363         }
 364     }
 365
 366     fn is_html(self) -> bool {
 367         match self {
 368             Format::LongHtml | Format::ShortHtml => true,
 369             Format::LongPlain => false,
 370         }
 371     }
 372 }
 373
 374 /// Pretty-print wrapper for a `Cfg`. Also indicates what form of rendering should be used.
 375 struct Display<'a>(&'a Cfg, Format);
 376
 377 fn write_with_opt_paren<T: fmt::Display>(
 378     fmt: &mut fmt::Formatter<'_>,
 379     has_paren: bool,
 380     obj: T,
 381 ) -> fmt::Result {
 382     if has_paren {
 383         fmt.write_char('(')?;
 384     }
 385     obj.fmt(fmt)?;
 386     if has_paren {
 387         fmt.write_char(')')?;
 388     }
 389     Ok(())
 390 }
 391
 392 impl<'a> fmt::Display for Display<'a> {
 393     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
 394         match *self.0 {
 395             Cfg::Not(ref child) => match **child {
 396                 Cfg::Any(ref sub_cfgs) => {
 397                     let separator =
 398                         if sub_cfgs.iter().all(Cfg::is_simple) { " nor " } else { ", nor " };
 399                     for (i, sub_cfg) in sub_cfgs.iter().enumerate() {
 400                         fmt.write_str(if i == 0 { "neither " } else { separator })?;
 401                         write_with_opt_paren(fmt, !sub_cfg.is_all(), Display(sub_cfg, self.1))?;
 402                     }
 403                     Ok(())
 404                 }
 405                 ref simple @ Cfg::Cfg(..) => write!(fmt, "non-{}", Display(simple, self.1)),
 406                 ref c => write!(fmt, "not ({})", Display(c, self.1)),
 407             },
 408
 409             Cfg::Any(ref sub_cfgs) => {
 410                 let separator = if sub_cfgs.iter().all(Cfg::is_simple) { " or " } else { ", or " };
 411
 412                 let short_longhand = self.1.is_long() && {
 413                     let all_crate_features = sub_cfgs
 414                         .iter()
 415                         .all(|sub_cfg| matches!(sub_cfg, Cfg::Cfg(sym::feature, Some(_))));
 416                     let all_target_features = sub_cfgs
 417                         .iter()
 418                         .all(|sub_cfg| matches!(sub_cfg, Cfg::Cfg(sym::target_feature, Some(_))));
 419
 420                     if all_crate_features {
 421                         fmt.write_str("crate features ")?;
 422                         true
 423                     } else if all_target_features {
 424                         fmt.write_str("target features ")?;
 425                         true
 426                     } else {
 427                         false
 428                     }
 429                 };
 430
 431                 for (i, sub_cfg) in sub_cfgs.iter().enumerate() {
 432                     if i != 0 {
 433                         fmt.write_str(separator)?;
 434                     }
 435                     if let (true, Cfg::Cfg(_, Some(feat))) = (short_longhand, sub_cfg) {
 436                         if self.1.is_html() {
 437                             write!(fmt, "<code>{}</code>", feat)?;
 438                         } else {
 439                             write!(fmt, "`{}`", feat)?;
 440                         }
 441                     } else {
 442                         write_with_opt_paren(fmt, !sub_cfg.is_all(), Display(sub_cfg, self.1))?;
 443                     }
 444                 }
 445                 Ok(())
 446             }
 447
 448             Cfg::All(ref sub_cfgs) => {
 449                 let short_longhand = self.1.is_long() && {
 450                     let all_crate_features = sub_cfgs
 451                         .iter()
 452                         .all(|sub_cfg| matches!(sub_cfg, Cfg::Cfg(sym::feature, Some(_))));
 453                     let all_target_features = sub_cfgs
 454                         .iter()
 455                         .all(|sub_cfg| matches!(sub_cfg, Cfg::Cfg(sym::target_feature, Some(_))));
 456
 457                     if all_crate_features {
 458                         fmt.write_str("crate features ")?;
 459                         true
 460                     } else if all_target_features {
 461                         fmt.write_str("target features ")?;
 462                         true
 463                     } else {
 464                         false
 465                     }
 466                 };
 467
 468                 for (i, sub_cfg) in sub_cfgs.iter().enumerate() {
 469                     if i != 0 {
 470                         fmt.write_str(" and ")?;
 471                     }
 472                     if let (true, Cfg::Cfg(_, Some(feat))) = (short_longhand, sub_cfg) {
 473                         if self.1.is_html() {
 474                             write!(fmt, "<code>{}</code>", feat)?;
 475                         } else {
 476                             write!(fmt, "`{}`", feat)?;
 477                         }
 478                     } else {
 479                         write_with_opt_paren(fmt, !sub_cfg.is_simple(), Display(sub_cfg, self.1))?;
 480                     }
 481                 }
 482                 Ok(())
 483             }
 484
 485             Cfg::True => fmt.write_str("everywhere"),
 486             Cfg::False => fmt.write_str("nowhere"),
 487
 488             Cfg::Cfg(name, value) => {
 489                 let human_readable = match (name, value) {
 490                     (sym::unix, None) => "Unix",
 491                     (sym::windows, None) => "Windows",
 492                     (sym::debug_assertions, None) => "debug-assertions enabled",
 493                     (sym::target_os, Some(os)) => match os.as_str() {
 494                         "android" => "Android",
 495                         "dragonfly" => "DragonFly BSD",
 496                         "emscripten" => "Emscripten",
 497                         "freebsd" => "FreeBSD",
 498                         "fuchsia" => "Fuchsia",
 499                         "haiku" => "Haiku",
 500                         "hermit" => "HermitCore",
 501                         "illumos" => "illumos",
 502                         "ios" => "iOS",
 503                         "l4re" => "L4Re",
 504                         "linux" => "Linux",
 505                         "macos" => "macOS",
 506                         "netbsd" => "NetBSD",
 507                         "openbsd" => "OpenBSD",
 508                         "redox" => "Redox",
 509                         "solaris" => "Solaris",
 510                         "wasi" => "WASI",
 511                         "windows" => "Windows",
 512                         _ => "",
 513                     },
 514                     (sym::target_arch, Some(arch)) => match arch.as_str() {
 515                         "aarch64" => "AArch64",
 516                         "arm" => "ARM",
 517                         "asmjs" => "JavaScript",
 518                         "m68k" => "M68k",
 519                         "mips" => "MIPS",
 520                         "mips64" => "MIPS-64",
 521                         "msp430" => "MSP430",
 522                         "powerpc" => "PowerPC",
 523                         "powerpc64" => "PowerPC-64",
 524                         "riscv32" => "RISC-V RV32",
 525                         "riscv64" => "RISC-V RV64",
 526                         "s390x" => "s390x",
 527                         "sparc64" => "SPARC64",
 528                         "wasm32" | "wasm64" => "WebAssembly",
 529                         "x86" => "x86",
 530                         "x86_64" => "x86-64",
 531                         _ => "",
 532                     },
 533                     (sym::target_vendor, Some(vendor)) => match vendor.as_str() {
 534                         "apple" => "Apple",
 535                         "pc" => "PC",
 536                         "sun" => "Sun",
 537                         "fortanix" => "Fortanix",
 538                         _ => "",
 539                     },
 540                     (sym::target_env, Some(env)) => match env.as_str() {
 541                         "gnu" => "GNU",
 542                         "msvc" => "MSVC",
 543                         "musl" => "musl",
 544                         "newlib" => "Newlib",
 545                         "uclibc" => "uClibc",
 546                         "sgx" => "SGX",
 547                         _ => "",
 548                     },
 549                     (sym::target_endian, Some(endian)) => return write!(fmt, "{}-endian", endian),
 550                     (sym::target_pointer_width, Some(bits)) => return write!(fmt, "{}-bit", bits),
 551                     (sym::target_feature, Some(feat)) => match self.1 {
 552                         Format::LongHtml => {
 553                             return write!(fmt, "target feature <code>{}</code>", feat);
 554                         }
 555                         Format::LongPlain => return write!(fmt, "target feature `{}`", feat),
 556                         Format::ShortHtml => return write!(fmt, "<code>{}</code>", feat),
 557                     },
 558                     (sym::feature, Some(feat)) => match self.1 {
 559                         Format::LongHtml => {
 560                             return write!(fmt, "crate feature <code>{}</code>", feat);
 561                         }
 562                         Format::LongPlain => return write!(fmt, "crate feature `{}`", feat),
 563                         Format::ShortHtml => return write!(fmt, "<code>{}</code>", feat),
 564                     },
 565                     _ => "",
 566                 };
 567                 if !human_readable.is_empty() {
 568                     fmt.write_str(human_readable)
 569                 } else if let Some(v) = value {
 570                     if self.1.is_html() {
 571                         write!(
 572                             fmt,
 573                             r#"<code>{}="{}"</code>"#,
 574                             Escape(name.as_str()),
 575                             Escape(v.as_str())
 576                         )
 577                     } else {
 578                         write!(fmt, r#"`{}="{}"`"#, name, v)
 579                     }
 580                 } else if self.1.is_html() {
 581                     write!(fmt, "<code>{}</code>", Escape(name.as_str()))
 582                 } else {
 583                     write!(fmt, "`{}`", name)
 584                 }
 585             }
 586         }
 587     }
 588 }