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
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
//! Contains `ParseSess` which holds state living beyond what one `Parser` might.
//! It also serves as an input to the parser itself.

use crate::config::CheckCfg;
use crate::errors::{
    CliFeatureDiagnosticHelp, FeatureDiagnosticForIssue, FeatureDiagnosticHelp, FeatureGateError,
};
use crate::lint::{
    builtin::UNSTABLE_SYNTAX_PRE_EXPANSION, BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId,
};
use rustc_ast::node_id::NodeId;
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
use rustc_data_structures::sync::{AppendOnlyVec, Lock, Lrc};
use rustc_errors::{emitter::SilentEmitter, Handler};
use rustc_errors::{
    fallback_fluent_bundle, Diagnostic, DiagnosticBuilder, DiagnosticId, DiagnosticMessage,
    EmissionGuarantee, ErrorGuaranteed, IntoDiagnostic, MultiSpan, Noted, StashKey,
};
use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
use rustc_span::edition::Edition;
use rustc_span::hygiene::ExpnId;
use rustc_span::source_map::{FilePathMapping, SourceMap};
use rustc_span::{Span, Symbol};

use rustc_ast::attr::AttrIdGenerator;
use std::str;

/// The set of keys (and, optionally, values) that define the compilation
/// environment of the crate, used to drive conditional compilation.
pub type CrateConfig = FxIndexSet<(Symbol, Option<Symbol>)>;
pub type CrateCheckConfig = CheckCfg<Symbol>;

/// Collected spans during parsing for places where a certain feature was
/// used and should be feature gated accordingly in `check_crate`.
#[derive(Default)]
pub struct GatedSpans {
    pub spans: Lock<FxHashMap<Symbol, Vec<Span>>>,
}

impl GatedSpans {
    /// Feature gate the given `span` under the given `feature`
    /// which is same `Symbol` used in `active.rs`.
    pub fn gate(&self, feature: Symbol, span: Span) {
        self.spans.borrow_mut().entry(feature).or_default().push(span);
    }

    /// Ungate the last span under the given `feature`.
    /// Panics if the given `span` wasn't the last one.
    ///
    /// Using this is discouraged unless you have a really good reason to.
    pub fn ungate_last(&self, feature: Symbol, span: Span) {
        let removed_span = self.spans.borrow_mut().entry(feature).or_default().pop().unwrap();
        debug_assert_eq!(span, removed_span);
    }

    /// Prepend the given set of `spans` onto the set in `self`.
    pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
        let mut inner = self.spans.borrow_mut();
        for (gate, mut gate_spans) in inner.drain() {
            spans.entry(gate).or_default().append(&mut gate_spans);
        }
        *inner = spans;
    }
}

#[derive(Default)]
pub struct SymbolGallery {
    /// All symbols occurred and their first occurrence span.
    pub symbols: Lock<FxHashMap<Symbol, Span>>,
}

impl SymbolGallery {
    /// Insert a symbol and its span into symbol gallery.
    /// If the symbol has occurred before, ignore the new occurrence.
    pub fn insert(&self, symbol: Symbol, span: Span) {
        self.symbols.lock().entry(symbol).or_insert(span);
    }
}

/// Construct a diagnostic for a language feature error due to the given `span`.
/// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
#[track_caller]
pub fn feature_err(
    sess: &ParseSess,
    feature: Symbol,
    span: impl Into<MultiSpan>,
    explain: impl Into<DiagnosticMessage>,
) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
    feature_err_issue(sess, feature, span, GateIssue::Language, explain)
}

/// Construct a diagnostic for a feature gate error.
///
/// This variant allows you to control whether it is a library or language feature.
/// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
#[track_caller]
pub fn feature_err_issue(
    sess: &ParseSess,
    feature: Symbol,
    span: impl Into<MultiSpan>,
    issue: GateIssue,
    explain: impl Into<DiagnosticMessage>,
) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
    let span = span.into();

    // Cancel an earlier warning for this same error, if it exists.
    if let Some(span) = span.primary_span() {
        if let Some(err) = sess.span_diagnostic.steal_diagnostic(span, StashKey::EarlySyntaxWarning)
        {
            err.cancel()
        }
    }

    let mut err = sess.create_err(FeatureGateError { span, explain: explain.into() });
    add_feature_diagnostics_for_issue(&mut err, sess, feature, issue, false);
    err
}

/// Construct a future incompatibility diagnostic for a feature gate.
///
/// This diagnostic is only a warning and *does not cause compilation to fail*.
#[track_caller]
pub fn feature_warn(sess: &ParseSess, feature: Symbol, span: Span, explain: &'static str) {
    feature_warn_issue(sess, feature, span, GateIssue::Language, explain);
}

/// Construct a future incompatibility diagnostic for a feature gate.
///
/// This diagnostic is only a warning and *does not cause compilation to fail*.
///
/// This variant allows you to control whether it is a library or language feature.
/// Almost always, you want to use this for a language feature. If so, prefer `feature_warn`.
#[allow(rustc::diagnostic_outside_of_impl)]
#[allow(rustc::untranslatable_diagnostic)]
#[track_caller]
pub fn feature_warn_issue(
    sess: &ParseSess,
    feature: Symbol,
    span: Span,
    issue: GateIssue,
    explain: &'static str,
) {
    let mut err = sess.span_diagnostic.struct_span_warn(span, explain);
    add_feature_diagnostics_for_issue(&mut err, sess, feature, issue, false);

    // Decorate this as a future-incompatibility lint as in rustc_middle::lint::struct_lint_level
    let lint = UNSTABLE_SYNTAX_PRE_EXPANSION;
    let future_incompatible = lint.future_incompatible.as_ref().unwrap();
    err.code(DiagnosticId::Lint {
        name: lint.name_lower(),
        has_future_breakage: false,
        is_force_warn: false,
    });
    err.warn(lint.desc);
    err.note(format!("for more information, see {}", future_incompatible.reference));

    // A later feature_err call can steal and cancel this warning.
    err.stash(span, StashKey::EarlySyntaxWarning);
}

/// Adds the diagnostics for a feature to an existing error.
pub fn add_feature_diagnostics(err: &mut Diagnostic, sess: &ParseSess, feature: Symbol) {
    add_feature_diagnostics_for_issue(err, sess, feature, GateIssue::Language, false);
}

/// Adds the diagnostics for a feature to an existing error.
///
/// This variant allows you to control whether it is a library or language feature.
/// Almost always, you want to use this for a language feature. If so, prefer
/// `add_feature_diagnostics`.
pub fn add_feature_diagnostics_for_issue(
    err: &mut Diagnostic,
    sess: &ParseSess,
    feature: Symbol,
    issue: GateIssue,
    feature_from_cli: bool,
) {
    if let Some(n) = find_feature_issue(feature, issue) {
        err.subdiagnostic(FeatureDiagnosticForIssue { n });
    }

    // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
    if sess.unstable_features.is_nightly_build() {
        if feature_from_cli {
            err.subdiagnostic(CliFeatureDiagnosticHelp { feature });
        } else {
            err.subdiagnostic(FeatureDiagnosticHelp { feature });
        }
    }
}

/// Info about a parsing session.
pub struct ParseSess {
    pub span_diagnostic: Handler,
    pub unstable_features: UnstableFeatures,
    pub config: CrateConfig,
    pub check_config: CrateCheckConfig,
    pub edition: Edition,
    /// Places where raw identifiers were used. This is used to avoid complaining about idents
    /// clashing with keywords in new editions.
    pub raw_identifier_spans: AppendOnlyVec<Span>,
    /// Places where identifiers that contain invalid Unicode codepoints but that look like they
    /// should be. Useful to avoid bad tokenization when encountering emoji. We group them to
    /// provide a single error per unique incorrect identifier.
    pub bad_unicode_identifiers: Lock<FxHashMap<Symbol, Vec<Span>>>,
    source_map: Lrc<SourceMap>,
    pub buffered_lints: Lock<Vec<BufferedEarlyLint>>,
    /// Contains the spans of block expressions that could have been incomplete based on the
    /// operation token that followed it, but that the parser cannot identify without further
    /// analysis.
    pub ambiguous_block_expr_parse: Lock<FxHashMap<Span, Span>>,
    pub gated_spans: GatedSpans,
    pub symbol_gallery: SymbolGallery,
    /// Environment variables accessed during the build and their values when they exist.
    pub env_depinfo: Lock<FxHashSet<(Symbol, Option<Symbol>)>>,
    /// File paths accessed during the build.
    pub file_depinfo: Lock<FxHashSet<Symbol>>,
    /// Whether cfg(version) should treat the current release as incomplete
    pub assume_incomplete_release: bool,
    /// Spans passed to `proc_macro::quote_span`. Each span has a numerical
    /// identifier represented by its position in the vector.
    pub proc_macro_quoted_spans: AppendOnlyVec<Span>,
    /// Used to generate new `AttrId`s. Every `AttrId` is unique.
    pub attr_id_generator: AttrIdGenerator,
}

impl ParseSess {
    /// Used for testing.
    pub fn new(locale_resources: Vec<&'static str>, file_path_mapping: FilePathMapping) -> Self {
        let fallback_bundle = fallback_fluent_bundle(locale_resources, false);
        let sm = Lrc::new(SourceMap::new(file_path_mapping));
        let handler = Handler::with_tty_emitter(Some(sm.clone()), fallback_bundle);
        ParseSess::with_span_handler(handler, sm)
    }

    pub fn with_span_handler(handler: Handler, source_map: Lrc<SourceMap>) -> Self {
        Self {
            span_diagnostic: handler,
            unstable_features: UnstableFeatures::from_environment(None),
            config: FxIndexSet::default(),
            check_config: CrateCheckConfig::default(),
            edition: ExpnId::root().expn_data().edition,
            raw_identifier_spans: Default::default(),
            bad_unicode_identifiers: Lock::new(Default::default()),
            source_map,
            buffered_lints: Lock::new(vec![]),
            ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
            gated_spans: GatedSpans::default(),
            symbol_gallery: SymbolGallery::default(),
            env_depinfo: Default::default(),
            file_depinfo: Default::default(),
            assume_incomplete_release: false,
            proc_macro_quoted_spans: Default::default(),
            attr_id_generator: AttrIdGenerator::new(),
        }
    }

    pub fn with_silent_emitter(fatal_note: Option<String>) -> Self {
        let fallback_bundle = fallback_fluent_bundle(Vec::new(), false);
        let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
        let fatal_handler = Handler::with_tty_emitter(None, fallback_bundle).disable_warnings();
        let handler = Handler::with_emitter(Box::new(SilentEmitter { fatal_handler, fatal_note }))
            .disable_warnings();
        ParseSess::with_span_handler(handler, sm)
    }

    #[inline]
    pub fn source_map(&self) -> &SourceMap {
        &self.source_map
    }

    pub fn clone_source_map(&self) -> Lrc<SourceMap> {
        self.source_map.clone()
    }

    pub fn buffer_lint(
        &self,
        lint: &'static Lint,
        span: impl Into<MultiSpan>,
        node_id: NodeId,
        msg: impl Into<DiagnosticMessage>,
    ) {
        self.buffered_lints.with_lock(|buffered_lints| {
            buffered_lints.push(BufferedEarlyLint {
                span: span.into(),
                node_id,
                msg: msg.into(),
                lint_id: LintId::of(lint),
                diagnostic: BuiltinLintDiagnostics::Normal,
            });
        });
    }

    pub fn buffer_lint_with_diagnostic(
        &self,
        lint: &'static Lint,
        span: impl Into<MultiSpan>,
        node_id: NodeId,
        msg: impl Into<DiagnosticMessage>,
        diagnostic: BuiltinLintDiagnostics,
    ) {
        self.buffered_lints.with_lock(|buffered_lints| {
            buffered_lints.push(BufferedEarlyLint {
                span: span.into(),
                node_id,
                msg: msg.into(),
                lint_id: LintId::of(lint),
                diagnostic,
            });
        });
    }

    pub fn save_proc_macro_span(&self, span: Span) -> usize {
        self.proc_macro_quoted_spans.push(span)
    }

    pub fn proc_macro_quoted_spans(&self) -> impl Iterator<Item = (usize, Span)> + '_ {
        // This is equivalent to `.iter().copied().enumerate()`, but that isn't possible for
        // AppendOnlyVec, so we resort to this scheme.
        self.proc_macro_quoted_spans.iter_enumerated()
    }

    #[track_caller]
    pub fn create_err<'a>(
        &'a self,
        err: impl IntoDiagnostic<'a>,
    ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
        err.into_diagnostic(&self.span_diagnostic)
    }

    #[track_caller]
    pub fn emit_err<'a>(&'a self, err: impl IntoDiagnostic<'a>) -> ErrorGuaranteed {
        self.create_err(err).emit()
    }

    #[track_caller]
    pub fn create_warning<'a>(
        &'a self,
        warning: impl IntoDiagnostic<'a, ()>,
    ) -> DiagnosticBuilder<'a, ()> {
        warning.into_diagnostic(&self.span_diagnostic)
    }

    #[track_caller]
    pub fn emit_warning<'a>(&'a self, warning: impl IntoDiagnostic<'a, ()>) {
        self.create_warning(warning).emit()
    }

    #[track_caller]
    pub fn create_note<'a>(
        &'a self,
        note: impl IntoDiagnostic<'a, Noted>,
    ) -> DiagnosticBuilder<'a, Noted> {
        note.into_diagnostic(&self.span_diagnostic)
    }

    #[track_caller]
    pub fn emit_note<'a>(&'a self, note: impl IntoDiagnostic<'a, Noted>) -> Noted {
        self.create_note(note).emit()
    }

    #[track_caller]
    pub fn create_fatal<'a>(
        &'a self,
        fatal: impl IntoDiagnostic<'a, !>,
    ) -> DiagnosticBuilder<'a, !> {
        fatal.into_diagnostic(&self.span_diagnostic)
    }

    #[track_caller]
    pub fn emit_fatal<'a>(&'a self, fatal: impl IntoDiagnostic<'a, !>) -> ! {
        self.create_fatal(fatal).emit()
    }

    #[rustc_lint_diagnostics]
    #[track_caller]
    pub fn struct_err(
        &self,
        msg: impl Into<DiagnosticMessage>,
    ) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
        self.span_diagnostic.struct_err(msg)
    }

    #[rustc_lint_diagnostics]
    #[track_caller]
    pub fn struct_warn(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
        self.span_diagnostic.struct_warn(msg)
    }

    #[rustc_lint_diagnostics]
    #[track_caller]
    pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
        self.span_diagnostic.struct_fatal(msg)
    }

    #[rustc_lint_diagnostics]
    #[track_caller]
    pub fn struct_diagnostic<G: EmissionGuarantee>(
        &self,
        msg: impl Into<DiagnosticMessage>,
    ) -> DiagnosticBuilder<'_, G> {
        self.span_diagnostic.struct_diagnostic(msg)
    }
}