compiler/rustc_expand/src/module.rs

   1 use crate::base::ModuleData;
   2 use rustc_ast::ptr::P;
   3 use rustc_ast::{token, Attribute, Inline, Item};
   4 use rustc_errors::{struct_span_err, DiagnosticBuilder};
   5 use rustc_parse::new_parser_from_file;
   6 use rustc_session::parse::ParseSess;
   7 use rustc_session::Session;
   8 use rustc_span::symbol::{sym, Ident};
   9 use rustc_span::Span;
  10
  11 use std::path::{self, Path, PathBuf};
  12
  13 #[derive(Copy, Clone)]
  14 pub enum DirOwnership {
  15     Owned {
  16         // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`.
  17         relative: Option<Ident>,
  18     },
  19     UnownedViaBlock,
  20 }
  21
  22 // Public for rustfmt usage.
  23 pub struct ModulePathSuccess {
  24     pub file_path: PathBuf,
  25     pub dir_ownership: DirOwnership,
  26 }
  27
  28 crate struct ParsedExternalMod {
  29     pub items: Vec<P<Item>>,
  30     pub inner_span: Span,
  31     pub file_path: PathBuf,
  32     pub dir_path: PathBuf,
  33     pub dir_ownership: DirOwnership,
  34 }
  35
  36 pub enum ModError<'a> {
  37     CircularInclusion(Vec<PathBuf>),
  38     ModInBlock(Option<Ident>),
  39     FileNotFound(Ident, PathBuf),
  40     MultipleCandidates(Ident, String, String),
  41     ParserError(DiagnosticBuilder<'a>),
  42 }
  43
  44 crate fn parse_external_mod(
  45     sess: &Session,
  46     ident: Ident,
  47     span: Span, // The span to blame on errors.
  48     module: &ModuleData,
  49     mut dir_ownership: DirOwnership,
  50     attrs: &mut Vec<Attribute>,
  51 ) -> ParsedExternalMod {
  52     // We bail on the first error, but that error does not cause a fatal error... (1)
  53     let result: Result<_, ModError<'_>> = try {
  54         // Extract the file path and the new ownership.
  55         let mp = mod_file_path(sess, ident, &attrs, &module.dir_path, dir_ownership)?;
  56         dir_ownership = mp.dir_ownership;
  57
  58         // Ensure file paths are acyclic.
  59         if let Some(pos) = module.file_path_stack.iter().position(|p| p == &mp.file_path) {
  60             Err(ModError::CircularInclusion(module.file_path_stack[pos..].to_vec()))?;
  61         }
  62
  63         // Actually parse the external file as a module.
  64         let mut parser = new_parser_from_file(&sess.parse_sess, &mp.file_path, Some(span));
  65         let (mut inner_attrs, items, inner_span) =
  66             parser.parse_mod(&token::Eof).map_err(|err| ModError::ParserError(err))?;
  67         attrs.append(&mut inner_attrs);
  68         (items, inner_span, mp.file_path)
  69     };
  70     // (1) ...instead, we return a dummy module.
  71     let (items, inner_span, file_path) =
  72         result.map_err(|err| err.report(sess, span)).unwrap_or_default();
  73
  74     // Extract the directory path for submodules of the module.
  75     let dir_path = file_path.parent().unwrap_or(&file_path).to_owned();
  76
  77     ParsedExternalMod { items, inner_span, file_path, dir_path, dir_ownership }
  78 }
  79
  80 crate fn mod_dir_path(
  81     sess: &Session,
  82     ident: Ident,
  83     attrs: &[Attribute],
  84     module: &ModuleData,
  85     mut dir_ownership: DirOwnership,
  86     inline: Inline,
  87 ) -> (PathBuf, DirOwnership) {
  88     match inline {
  89         Inline::Yes => {
  90             if let Some(file_path) = mod_file_path_from_attr(sess, attrs, &module.dir_path) {
  91                 // For inline modules file path from `#[path]` is actually the directory path
  92                 // for historical reasons, so we don't pop the last segment here.
  93                 return (file_path, DirOwnership::Owned { relative: None });
  94             }
  95
  96             // We have to push on the current module name in the case of relative
  97             // paths in order to ensure that any additional module paths from inline
  98             // `mod x { ... }` come after the relative extension.
  99             //
 100             // For example, a `mod z { ... }` inside `x/y.rs` should set the current
 101             // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
 102             let mut dir_path = module.dir_path.clone();
 103             if let DirOwnership::Owned { relative } = &mut dir_ownership {
 104                 if let Some(ident) = relative.take() {
 105                     // Remove the relative offset.
 106                     dir_path.push(&*ident.as_str());
 107                 }
 108             }
 109             dir_path.push(&*ident.as_str());
 110
 111             (dir_path, dir_ownership)
 112         }
 113         Inline::No => {
 114             // FIXME: This is a subset of `parse_external_mod` without actual parsing,
 115             // check whether the logic for unloaded, loaded and inline modules can be unified.
 116             let file_path = mod_file_path(sess, ident, &attrs, &module.dir_path, dir_ownership)
 117                 .map(|mp| {
 118                     dir_ownership = mp.dir_ownership;
 119                     mp.file_path
 120                 })
 121                 .unwrap_or_default();
 122
 123             // Extract the directory path for submodules of the module.
 124             let dir_path = file_path.parent().unwrap_or(&file_path).to_owned();
 125
 126             (dir_path, dir_ownership)
 127         }
 128     }
 129 }
 130
 131 fn mod_file_path<'a>(
 132     sess: &'a Session,
 133     ident: Ident,
 134     attrs: &[Attribute],
 135     dir_path: &Path,
 136     dir_ownership: DirOwnership,
 137 ) -> Result<ModulePathSuccess, ModError<'a>> {
 138     if let Some(file_path) = mod_file_path_from_attr(sess, attrs, dir_path) {
 139         // All `#[path]` files are treated as though they are a `mod.rs` file.
 140         // This means that `mod foo;` declarations inside `#[path]`-included
 141         // files are siblings,
 142         //
 143         // Note that this will produce weirdness when a file named `foo.rs` is
 144         // `#[path]` included and contains a `mod foo;` declaration.
 145         // If you encounter this, it's your own darn fault :P
 146         let dir_ownership = DirOwnership::Owned { relative: None };
 147         return Ok(ModulePathSuccess { file_path, dir_ownership });
 148     }
 149
 150     let relative = match dir_ownership {
 151         DirOwnership::Owned { relative } => relative,
 152         DirOwnership::UnownedViaBlock => None,
 153     };
 154     let result = default_submod_path(&sess.parse_sess, ident, relative, dir_path);
 155     match dir_ownership {
 156         DirOwnership::Owned { .. } => result,
 157         DirOwnership::UnownedViaBlock => Err(ModError::ModInBlock(match result {
 158             Ok(_) | Err(ModError::MultipleCandidates(..)) => Some(ident),
 159             _ => None,
 160         })),
 161     }
 162 }
 163
 164 /// Derive a submodule path from the first found `#[path = "path_string"]`.
 165 /// The provided `dir_path` is joined with the `path_string`.
 166 fn mod_file_path_from_attr(
 167     sess: &Session,
 168     attrs: &[Attribute],
 169     dir_path: &Path,
 170 ) -> Option<PathBuf> {
 171     // Extract path string from first `#[path = "path_string"]` attribute.
 172     let path_string = sess.first_attr_value_str_by_name(attrs, sym::path)?.as_str();
 173
 174     // On windows, the base path might have the form
 175     // `\\?\foo\bar` in which case it does not tolerate
 176     // mixed `/` and `\` separators, so canonicalize
 177     // `/` to `\`.
 178     #[cfg(windows)]
 179     let path_string = path_string.replace("/", "\\");
 180
 181     Some(dir_path.join(&*path_string))
 182 }
 183
 184 /// Returns a path to a module.
 185 // Public for rustfmt usage.
 186 pub fn default_submod_path<'a>(
 187     sess: &'a ParseSess,
 188     ident: Ident,
 189     relative: Option<Ident>,
 190     dir_path: &Path,
 191 ) -> Result<ModulePathSuccess, ModError<'a>> {
 192     // If we're in a foo.rs file instead of a mod.rs file,
 193     // we need to look for submodules in
 194     // `./foo/<ident>.rs` and `./foo/<ident>/mod.rs` rather than
 195     // `./<ident>.rs` and `./<ident>/mod.rs`.
 196     let relative_prefix_string;
 197     let relative_prefix = if let Some(ident) = relative {
 198         relative_prefix_string = format!("{}{}", ident.name, path::MAIN_SEPARATOR);
 199         &relative_prefix_string
 200     } else {
 201         ""
 202     };
 203
 204     let mod_name = ident.name.to_string();
 205     let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
 206     let secondary_path_str =
 207         format!("{}{}{}mod.rs", relative_prefix, mod_name, path::MAIN_SEPARATOR);
 208     let default_path = dir_path.join(&default_path_str);
 209     let secondary_path = dir_path.join(&secondary_path_str);
 210     let default_exists = sess.source_map().file_exists(&default_path);
 211     let secondary_exists = sess.source_map().file_exists(&secondary_path);
 212
 213     match (default_exists, secondary_exists) {
 214         (true, false) => Ok(ModulePathSuccess {
 215             file_path: default_path,
 216             dir_ownership: DirOwnership::Owned { relative: Some(ident) },
 217         }),
 218         (false, true) => Ok(ModulePathSuccess {
 219             file_path: secondary_path,
 220             dir_ownership: DirOwnership::Owned { relative: None },
 221         }),
 222         (false, false) => Err(ModError::FileNotFound(ident, default_path)),
 223         (true, true) => {
 224             Err(ModError::MultipleCandidates(ident, default_path_str, secondary_path_str))
 225         }
 226     }
 227 }
 228
 229 impl ModError<'_> {
 230     fn report(self, sess: &Session, span: Span) {
 231         let diag = &sess.parse_sess.span_diagnostic;
 232         match self {
 233             ModError::CircularInclusion(file_paths) => {
 234                 let mut msg = String::from("circular modules: ");
 235                 for file_path in &file_paths {
 236                     msg.push_str(&file_path.display().to_string());
 237                     msg.push_str(" -> ");
 238                 }
 239                 msg.push_str(&file_paths[0].display().to_string());
 240                 diag.struct_span_err(span, &msg)
 241             }
 242             ModError::ModInBlock(ident) => {
 243                 let msg = "cannot declare a non-inline module inside a block unless it has a path attribute";
 244                 let mut err = diag.struct_span_err(span, msg);
 245                 if let Some(ident) = ident {
 246                     let note =
 247                         format!("maybe `use` the module `{}` instead of redeclaring it", ident);
 248                     err.span_note(span, &note);
 249                 }
 250                 err
 251             }
 252             ModError::FileNotFound(ident, default_path) => {
 253                 let mut err = struct_span_err!(
 254                     diag,
 255                     span,
 256                     E0583,
 257                     "file not found for module `{}`",
 258                     ident,
 259                 );
 260                 err.help(&format!(
 261                     "to create the module `{}`, create file \"{}\"",
 262                     ident,
 263                     default_path.display(),
 264                 ));
 265                 err
 266             }
 267             ModError::MultipleCandidates(ident, default_path_short, secondary_path_short) => {
 268                 let mut err = struct_span_err!(
 269                     diag,
 270                     span,
 271                     E0761,
 272                     "file for module `{}` found at both {} and {}",
 273                     ident,
 274                     default_path_short,
 275                     secondary_path_short,
 276                 );
 277                 err.help("delete or rename one of them to remove the ambiguity");
 278                 err
 279             }
 280             ModError::ParserError(err) => err,
 281         }.emit()
 282     }
 283 }