vendor/rustc-ap-rustc_expand/src/module.rs

   1 use rustc_ast::{token, Attribute, Mod, Unsafe};
   2 use rustc_errors::{struct_span_err, PResult};
   3 use rustc_parse::new_parser_from_file;
   4 use rustc_session::parse::ParseSess;
   5 use rustc_session::Session;
   6 use rustc_span::source_map::{FileName, Span};
   7 use rustc_span::symbol::{sym, Ident};
   8
   9 use std::path::{self, Path, PathBuf};
  10
  11 #[derive(Clone)]
  12 pub struct Directory {
  13     pub path: PathBuf,
  14     pub ownership: DirectoryOwnership,
  15 }
  16
  17 #[derive(Copy, Clone)]
  18 pub enum DirectoryOwnership {
  19     Owned {
  20         // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`.
  21         relative: Option<Ident>,
  22     },
  23     UnownedViaBlock,
  24     UnownedViaMod,
  25 }
  26
  27 /// Information about the path to a module.
  28 // Public for rustfmt usage.
  29 pub struct ModulePath<'a> {
  30     name: String,
  31     path_exists: bool,
  32     pub result: PResult<'a, ModulePathSuccess>,
  33 }
  34
  35 // Public for rustfmt usage.
  36 pub struct ModulePathSuccess {
  37     pub path: PathBuf,
  38     pub ownership: DirectoryOwnership,
  39 }
  40
  41 crate fn parse_external_mod(
  42     sess: &Session,
  43     id: Ident,
  44     span: Span, // The span to blame on errors.
  45     unsafety: Unsafe,
  46     Directory { mut ownership, path }: Directory,
  47     attrs: &mut Vec<Attribute>,
  48     pop_mod_stack: &mut bool,
  49 ) -> (Mod, Directory) {
  50     // We bail on the first error, but that error does not cause a fatal error... (1)
  51     let result: PResult<'_, _> = try {
  52         // Extract the file path and the new ownership.
  53         let mp = submod_path(sess, id, span, &attrs, ownership, &path)?;
  54         ownership = mp.ownership;
  55
  56         // Ensure file paths are acyclic.
  57         let mut included_mod_stack = sess.parse_sess.included_mod_stack.borrow_mut();
  58         error_on_circular_module(&sess.parse_sess, span, &mp.path, &included_mod_stack)?;
  59         included_mod_stack.push(mp.path.clone());
  60         *pop_mod_stack = true; // We have pushed, so notify caller.
  61         drop(included_mod_stack);
  62
  63         // Actually parse the external file as a module.
  64         let mut parser = new_parser_from_file(&sess.parse_sess, &mp.path, Some(span));
  65         let mut module = parser.parse_mod(&token::Eof, unsafety)?;
  66         module.0.inline = false;
  67         module
  68     };
  69     // (1) ...instead, we return a dummy module.
  70     let (module, mut new_attrs) = result.map_err(|mut err| err.emit()).unwrap_or_else(|_| {
  71         let module = Mod { inner: Span::default(), unsafety, items: Vec::new(), inline: false };
  72         (module, Vec::new())
  73     });
  74     attrs.append(&mut new_attrs);
  75
  76     // Extract the directory path for submodules of `module`.
  77     let path = sess.source_map().span_to_unmapped_path(module.inner);
  78     let mut path = match path {
  79         FileName::Real(name) => name.into_local_path(),
  80         other => PathBuf::from(other.to_string()),
  81     };
  82     path.pop();
  83
  84     (module, Directory { ownership, path })
  85 }
  86
  87 fn error_on_circular_module<'a>(
  88     sess: &'a ParseSess,
  89     span: Span,
  90     path: &Path,
  91     included_mod_stack: &[PathBuf],
  92 ) -> PResult<'a, ()> {
  93     if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
  94         let mut err = String::from("circular modules: ");
  95         for p in &included_mod_stack[i..] {
  96             err.push_str(&p.to_string_lossy());
  97             err.push_str(" -> ");
  98         }
  99         err.push_str(&path.to_string_lossy());
 100         return Err(sess.span_diagnostic.struct_span_err(span, &err[..]));
 101     }
 102     Ok(())
 103 }
 104
 105 crate fn push_directory(
 106     sess: &Session,
 107     id: Ident,
 108     attrs: &[Attribute],
 109     Directory { mut ownership, mut path }: Directory,
 110 ) -> Directory {
 111     if let Some(filename) = sess.first_attr_value_str_by_name(attrs, sym::path) {
 112         path.push(&*filename.as_str());
 113         ownership = DirectoryOwnership::Owned { relative: None };
 114     } else {
 115         // We have to push on the current module name in the case of relative
 116         // paths in order to ensure that any additional module paths from inline
 117         // `mod x { ... }` come after the relative extension.
 118         //
 119         // For example, a `mod z { ... }` inside `x/y.rs` should set the current
 120         // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
 121         if let DirectoryOwnership::Owned { relative } = &mut ownership {
 122             if let Some(ident) = relative.take() {
 123                 // Remove the relative offset.
 124                 path.push(&*ident.as_str());
 125             }
 126         }
 127         path.push(&*id.as_str());
 128     }
 129     Directory { ownership, path }
 130 }
 131
 132 fn submod_path<'a>(
 133     sess: &'a Session,
 134     id: Ident,
 135     span: Span,
 136     attrs: &[Attribute],
 137     ownership: DirectoryOwnership,
 138     dir_path: &Path,
 139 ) -> PResult<'a, ModulePathSuccess> {
 140     if let Some(path) = submod_path_from_attr(sess, attrs, dir_path) {
 141         let ownership = match path.file_name().and_then(|s| s.to_str()) {
 142             // All `#[path]` files are treated as though they are a `mod.rs` file.
 143             // This means that `mod foo;` declarations inside `#[path]`-included
 144             // files are siblings,
 145             //
 146             // Note that this will produce weirdness when a file named `foo.rs` is
 147             // `#[path]` included and contains a `mod foo;` declaration.
 148             // If you encounter this, it's your own darn fault :P
 149             Some(_) => DirectoryOwnership::Owned { relative: None },
 150             _ => DirectoryOwnership::UnownedViaMod,
 151         };
 152         return Ok(ModulePathSuccess { ownership, path });
 153     }
 154
 155     let relative = match ownership {
 156         DirectoryOwnership::Owned { relative } => relative,
 157         DirectoryOwnership::UnownedViaBlock | DirectoryOwnership::UnownedViaMod => None,
 158     };
 159     let ModulePath { path_exists, name, result } =
 160         default_submod_path(&sess.parse_sess, id, span, relative, dir_path);
 161     match ownership {
 162         DirectoryOwnership::Owned { .. } => Ok(result?),
 163         DirectoryOwnership::UnownedViaBlock => {
 164             let _ = result.map_err(|mut err| err.cancel());
 165             error_decl_mod_in_block(&sess.parse_sess, span, path_exists, &name)
 166         }
 167         DirectoryOwnership::UnownedViaMod => {
 168             let _ = result.map_err(|mut err| err.cancel());
 169             error_cannot_declare_mod_here(&sess.parse_sess, span, path_exists, &name)
 170         }
 171     }
 172 }
 173
 174 fn error_decl_mod_in_block<'a, T>(
 175     sess: &'a ParseSess,
 176     span: Span,
 177     path_exists: bool,
 178     name: &str,
 179 ) -> PResult<'a, T> {
 180     let msg = "Cannot declare a non-inline module inside a block unless it has a path attribute";
 181     let mut err = sess.span_diagnostic.struct_span_err(span, msg);
 182     if path_exists {
 183         let msg = format!("Maybe `use` the module `{}` instead of redeclaring it", name);
 184         err.span_note(span, &msg);
 185     }
 186     Err(err)
 187 }
 188
 189 fn error_cannot_declare_mod_here<'a, T>(
 190     sess: &'a ParseSess,
 191     span: Span,
 192     path_exists: bool,
 193     name: &str,
 194 ) -> PResult<'a, T> {
 195     let mut err =
 196         sess.span_diagnostic.struct_span_err(span, "cannot declare a new module at this location");
 197     if !span.is_dummy() {
 198         if let FileName::Real(src_name) = sess.source_map().span_to_filename(span) {
 199             let src_path = src_name.into_local_path();
 200             if let Some(stem) = src_path.file_stem() {
 201                 let mut dest_path = src_path.clone();
 202                 dest_path.set_file_name(stem);
 203                 dest_path.push("mod.rs");
 204                 err.span_note(
 205                     span,
 206                     &format!(
 207                         "maybe move this module `{}` to its own directory via `{}`",
 208                         src_path.display(),
 209                         dest_path.display()
 210                     ),
 211                 );
 212             }
 213         }
 214     }
 215     if path_exists {
 216         err.span_note(
 217             span,
 218             &format!("... or maybe `use` the module `{}` instead of possibly redeclaring it", name),
 219         );
 220     }
 221     Err(err)
 222 }
 223
 224 /// Derive a submodule path from the first found `#[path = "path_string"]`.
 225 /// The provided `dir_path` is joined with the `path_string`.
 226 pub(super) fn submod_path_from_attr(
 227     sess: &Session,
 228     attrs: &[Attribute],
 229     dir_path: &Path,
 230 ) -> Option<PathBuf> {
 231     // Extract path string from first `#[path = "path_string"]` attribute.
 232     let path_string = sess.first_attr_value_str_by_name(attrs, sym::path)?;
 233     let path_string = path_string.as_str();
 234
 235     // On windows, the base path might have the form
 236     // `\\?\foo\bar` in which case it does not tolerate
 237     // mixed `/` and `\` separators, so canonicalize
 238     // `/` to `\`.
 239     #[cfg(windows)]
 240     let path_string = path_string.replace("/", "\\");
 241
 242     Some(dir_path.join(&*path_string))
 243 }
 244
 245 /// Returns a path to a module.
 246 // Public for rustfmt usage.
 247 pub fn default_submod_path<'a>(
 248     sess: &'a ParseSess,
 249     id: Ident,
 250     span: Span,
 251     relative: Option<Ident>,
 252     dir_path: &Path,
 253 ) -> ModulePath<'a> {
 254     // If we're in a foo.rs file instead of a mod.rs file,
 255     // we need to look for submodules in
 256     // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
 257     // `./<id>.rs` and `./<id>/mod.rs`.
 258     let relative_prefix_string;
 259     let relative_prefix = if let Some(ident) = relative {
 260         relative_prefix_string = format!("{}{}", ident.name, path::MAIN_SEPARATOR);
 261         &relative_prefix_string
 262     } else {
 263         ""
 264     };
 265
 266     let mod_name = id.name.to_string();
 267     let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
 268     let secondary_path_str =
 269         format!("{}{}{}mod.rs", relative_prefix, mod_name, path::MAIN_SEPARATOR);
 270     let default_path = dir_path.join(&default_path_str);
 271     let secondary_path = dir_path.join(&secondary_path_str);
 272     let default_exists = sess.source_map().file_exists(&default_path);
 273     let secondary_exists = sess.source_map().file_exists(&secondary_path);
 274
 275     let result = match (default_exists, secondary_exists) {
 276         (true, false) => Ok(ModulePathSuccess {
 277             path: default_path,
 278             ownership: DirectoryOwnership::Owned { relative: Some(id) },
 279         }),
 280         (false, true) => Ok(ModulePathSuccess {
 281             path: secondary_path,
 282             ownership: DirectoryOwnership::Owned { relative: None },
 283         }),
 284         (false, false) => {
 285             let mut err = struct_span_err!(
 286                 sess.span_diagnostic,
 287                 span,
 288                 E0583,
 289                 "file not found for module `{}`",
 290                 mod_name,
 291             );
 292             err.help(&format!(
 293                 "to create the module `{}`, create file \"{}\"",
 294                 mod_name,
 295                 default_path.display(),
 296             ));
 297             Err(err)
 298         }
 299         (true, true) => {
 300             let mut err = struct_span_err!(
 301                 sess.span_diagnostic,
 302                 span,
 303                 E0761,
 304                 "file for module `{}` found at both {} and {}",
 305                 mod_name,
 306                 default_path_str,
 307                 secondary_path_str,
 308             );
 309             err.help("delete or rename one of them to remove the ambiguity");
 310             Err(err)
 311         }
 312     };
 313
 314     ModulePath { name: mod_name, path_exists: default_exists || secondary_exists, result }
 315 }