1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
use rustc_ast::ast::{self, Attribute, Ident, Mod};
use rustc_ast::{attr, token};
use rustc_errors::{struct_span_err, PResult};
use rustc_parse::new_parser_from_file;
use rustc_session::parse::ParseSess;
use rustc_span::source_map::{FileName, Span};
use rustc_span::symbol::sym;

use std::path::{self, Path, PathBuf};

#[derive(Clone)]
pub struct Directory {
    pub path: PathBuf,
    pub ownership: DirectoryOwnership,
}

#[derive(Copy, Clone)]
pub enum DirectoryOwnership {
    Owned {
        // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`.
        relative: Option<ast::Ident>,
    },
    UnownedViaBlock,
    UnownedViaMod,
}

/// Information about the path to a module.
// Public for rustfmt usage.
pub struct ModulePath<'a> {
    name: String,
    path_exists: bool,
    pub result: PResult<'a, ModulePathSuccess>,
}

// Public for rustfmt usage.
pub struct ModulePathSuccess {
    pub path: PathBuf,
    pub ownership: DirectoryOwnership,
}

crate fn parse_external_mod(
    sess: &ParseSess,
    id: ast::Ident,
    span: Span, // The span to blame on errors.
    Directory { mut ownership, path }: Directory,
    attrs: &mut Vec<Attribute>,
    pop_mod_stack: &mut bool,
) -> (Mod, Directory) {
    // We bail on the first error, but that error does not cause a fatal error... (1)
    let result: PResult<'_, _> = try {
        // Extract the file path and the new ownership.
        let mp = submod_path(sess, id, span, &attrs, ownership, &path)?;
        ownership = mp.ownership;

        // Ensure file paths are acyclic.
        let mut included_mod_stack = sess.included_mod_stack.borrow_mut();
        error_on_circular_module(sess, span, &mp.path, &included_mod_stack)?;
        included_mod_stack.push(mp.path.clone());
        *pop_mod_stack = true; // We have pushed, so notify caller.
        drop(included_mod_stack);

        // Actually parse the external file as a module.
        let mut module = new_parser_from_file(sess, &mp.path, Some(span)).parse_mod(&token::Eof)?;
        module.0.inline = false;
        module
    };
    // (1) ...instead, we return a dummy module.
    let (module, mut new_attrs) = result.map_err(|mut err| err.emit()).unwrap_or_default();
    attrs.append(&mut new_attrs);

    // Extract the directory path for submodules of `module`.
    let path = sess.source_map().span_to_unmapped_path(module.inner);
    let mut path = match path {
        FileName::Real(path) => path,
        other => PathBuf::from(other.to_string()),
    };
    path.pop();

    (module, Directory { ownership, path })
}

fn error_on_circular_module<'a>(
    sess: &'a ParseSess,
    span: Span,
    path: &Path,
    included_mod_stack: &[PathBuf],
) -> PResult<'a, ()> {
    if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
        let mut err = String::from("circular modules: ");
        for p in &included_mod_stack[i..] {
            err.push_str(&p.to_string_lossy());
            err.push_str(" -> ");
        }
        err.push_str(&path.to_string_lossy());
        return Err(sess.span_diagnostic.struct_span_err(span, &err[..]));
    }
    Ok(())
}

crate fn push_directory(
    id: Ident,
    attrs: &[Attribute],
    Directory { mut ownership, mut path }: Directory,
) -> Directory {
    if let Some(filename) = attr::first_attr_value_str_by_name(attrs, sym::path) {
        path.push(&*filename.as_str());
        ownership = DirectoryOwnership::Owned { relative: None };
    } else {
        // We have to push on the current module name in the case of relative
        // paths in order to ensure that any additional module paths from inline
        // `mod x { ... }` come after the relative extension.
        //
        // For example, a `mod z { ... }` inside `x/y.rs` should set the current
        // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
        if let DirectoryOwnership::Owned { relative } = &mut ownership {
            if let Some(ident) = relative.take() {
                // Remove the relative offset.
                path.push(&*ident.as_str());
            }
        }
        path.push(&*id.as_str());
    }
    Directory { ownership, path }
}

fn submod_path<'a>(
    sess: &'a ParseSess,
    id: ast::Ident,
    span: Span,
    attrs: &[Attribute],
    ownership: DirectoryOwnership,
    dir_path: &Path,
) -> PResult<'a, ModulePathSuccess> {
    if let Some(path) = submod_path_from_attr(attrs, dir_path) {
        let ownership = match path.file_name().and_then(|s| s.to_str()) {
            // All `#[path]` files are treated as though they are a `mod.rs` file.
            // This means that `mod foo;` declarations inside `#[path]`-included
            // files are siblings,
            //
            // Note that this will produce weirdness when a file named `foo.rs` is
            // `#[path]` included and contains a `mod foo;` declaration.
            // If you encounter this, it's your own darn fault :P
            Some(_) => DirectoryOwnership::Owned { relative: None },
            _ => DirectoryOwnership::UnownedViaMod,
        };
        return Ok(ModulePathSuccess { ownership, path });
    }

    let relative = match ownership {
        DirectoryOwnership::Owned { relative } => relative,
        DirectoryOwnership::UnownedViaBlock | DirectoryOwnership::UnownedViaMod => None,
    };
    let ModulePath { path_exists, name, result } =
        default_submod_path(sess, id, span, relative, dir_path);
    match ownership {
        DirectoryOwnership::Owned { .. } => Ok(result?),
        DirectoryOwnership::UnownedViaBlock => {
            let _ = result.map_err(|mut err| err.cancel());
            error_decl_mod_in_block(sess, span, path_exists, &name)
        }
        DirectoryOwnership::UnownedViaMod => {
            let _ = result.map_err(|mut err| err.cancel());
            error_cannot_declare_mod_here(sess, span, path_exists, &name)
        }
    }
}

fn error_decl_mod_in_block<'a, T>(
    sess: &'a ParseSess,
    span: Span,
    path_exists: bool,
    name: &str,
) -> PResult<'a, T> {
    let msg = "Cannot declare a non-inline module inside a block unless it has a path attribute";
    let mut err = sess.span_diagnostic.struct_span_err(span, msg);
    if path_exists {
        let msg = format!("Maybe `use` the module `{}` instead of redeclaring it", name);
        err.span_note(span, &msg);
    }
    Err(err)
}

fn error_cannot_declare_mod_here<'a, T>(
    sess: &'a ParseSess,
    span: Span,
    path_exists: bool,
    name: &str,
) -> PResult<'a, T> {
    let mut err =
        sess.span_diagnostic.struct_span_err(span, "cannot declare a new module at this location");
    if !span.is_dummy() {
        if let FileName::Real(src_path) = sess.source_map().span_to_filename(span) {
            if let Some(stem) = src_path.file_stem() {
                let mut dest_path = src_path.clone();
                dest_path.set_file_name(stem);
                dest_path.push("mod.rs");
                err.span_note(
                    span,
                    &format!(
                        "maybe move this module `{}` to its own directory via `{}`",
                        src_path.display(),
                        dest_path.display()
                    ),
                );
            }
        }
    }
    if path_exists {
        err.span_note(
            span,
            &format!("... or maybe `use` the module `{}` instead of possibly redeclaring it", name),
        );
    }
    Err(err)
}

/// Derive a submodule path from the first found `#[path = "path_string"]`.
/// The provided `dir_path` is joined with the `path_string`.
// Public for rustfmt usage.
pub fn submod_path_from_attr(attrs: &[Attribute], dir_path: &Path) -> Option<PathBuf> {
    // Extract path string from first `#[path = "path_string"]` attribute.
    let path_string = attr::first_attr_value_str_by_name(attrs, sym::path)?;
    let path_string = path_string.as_str();

    // On windows, the base path might have the form
    // `\\?\foo\bar` in which case it does not tolerate
    // mixed `/` and `\` separators, so canonicalize
    // `/` to `\`.
    #[cfg(windows)]
    let path_string = path_string.replace("/", "\\");

    Some(dir_path.join(&*path_string))
}

/// Returns a path to a module.
// Public for rustfmt usage.
pub fn default_submod_path<'a>(
    sess: &'a ParseSess,
    id: ast::Ident,
    span: Span,
    relative: Option<ast::Ident>,
    dir_path: &Path,
) -> ModulePath<'a> {
    // If we're in a foo.rs file instead of a mod.rs file,
    // we need to look for submodules in
    // `./foo/<id>.rs` and `./foo/<id>/mod.rs` rather than
    // `./<id>.rs` and `./<id>/mod.rs`.
    let relative_prefix_string;
    let relative_prefix = if let Some(ident) = relative {
        relative_prefix_string = format!("{}{}", ident.name, path::MAIN_SEPARATOR);
        &relative_prefix_string
    } else {
        ""
    };

    let mod_name = id.name.to_string();
    let default_path_str = format!("{}{}.rs", relative_prefix, mod_name);
    let secondary_path_str =
        format!("{}{}{}mod.rs", relative_prefix, mod_name, path::MAIN_SEPARATOR);
    let default_path = dir_path.join(&default_path_str);
    let secondary_path = dir_path.join(&secondary_path_str);
    let default_exists = sess.source_map().file_exists(&default_path);
    let secondary_exists = sess.source_map().file_exists(&secondary_path);

    let result = match (default_exists, secondary_exists) {
        (true, false) => Ok(ModulePathSuccess {
            path: default_path,
            ownership: DirectoryOwnership::Owned { relative: Some(id) },
        }),
        (false, true) => Ok(ModulePathSuccess {
            path: secondary_path,
            ownership: DirectoryOwnership::Owned { relative: None },
        }),
        (false, false) => {
            let mut err = struct_span_err!(
                sess.span_diagnostic,
                span,
                E0583,
                "file not found for module `{}`",
                mod_name,
            );
            err.help(&format!(
                "to create the module `{}`, create file \"{}\"",
                mod_name,
                default_path.display(),
            ));
            Err(err)
        }
        (true, true) => {
            let mut err = struct_span_err!(
                sess.span_diagnostic,
                span,
                E0584,
                "file for module `{}` found at both {} and {}",
                mod_name,
                default_path_str,
                secondary_path_str,
            );
            err.help("delete or rename one of them to remove the ambiguity");
            Err(err)
        }
    };

    ModulePath { name: mod_name, path_exists: default_exists || secondary_exists, result }
}