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