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

use std::panic::{catch_unwind, AssertUnwindSafe};
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicBool, Ordering};

use rustc_ast::ast::Crate;
use rustc_data_structures::sync::Lrc;
use rustc_errors::emitter::{stderr_destination, DynEmitter, Emitter, HumanEmitter, SilentEmitter};
use rustc_errors::translation::Translate;
use rustc_errors::{ColorConfig, DiagCtxt, DiagInner, Level as DiagnosticLevel};
use rustc_parse::new_parser_from_file;
use rustc_parse::parser::Parser;
use rustc_session::parse::ParseSess;
use rustc_span::edition::Edition;
use rustc_span::source_map::{FilePathMapping, SourceMap};

/// You can check `ParseSess` documentation [here](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_session/parse/struct.ParseSess.html)
/// and `Crate` documentation [here](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/ast/struct.Crate.html).
///
/// And to make things much simpler, I strongly recommend to use
/// the [AST visitor](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/visit/trait.Visitor.html).
/// (You can take a look at how to use it with `examples/ast.rs`.)
pub fn with_ast_parser<T, F: Fn(&ParseSess, &Crate) -> T>(
    path: &Path,
    edition: Edition,
    callback: F,
) -> Result<T, String> {
    let path = PathBuf::from(&path);

    rustc_span::create_session_if_not_set_then(edition, move |_| {
        let parser_session = create_parser_session();
        let mut parser = create_parser(&path, &parser_session)?;
        let krate = parse_crate(&mut parser)?;

        Ok(callback(&parser_session, &krate))
    })
}

/// Emit errors against every files.
struct SilentOnIgnoredFilesEmitter {
    emitter: Box<DynEmitter>,
    has_non_ignorable_parser_errors: bool,
    can_reset: Lrc<AtomicBool>,
}

impl SilentOnIgnoredFilesEmitter {
    fn handle_non_ignoreable_error(&mut self, diag: DiagInner) {
        self.has_non_ignorable_parser_errors = true;
        self.can_reset.store(false, Ordering::Release);
        self.emitter.emit_diagnostic(diag);
    }
}

impl Translate for SilentOnIgnoredFilesEmitter {
    fn fluent_bundle(&self) -> Option<&Lrc<rustc_errors::FluentBundle>> {
        self.emitter.fluent_bundle()
    }

    fn fallback_fluent_bundle(&self) -> &rustc_errors::FluentBundle {
        self.emitter.fallback_fluent_bundle()
    }
}

impl Emitter for SilentOnIgnoredFilesEmitter {
    fn source_map(&self) -> Option<&Lrc<SourceMap>> {
        None
    }

    fn emit_diagnostic(&mut self, diag: DiagInner) {
        if diag.level() == DiagnosticLevel::Fatal {
            return self.handle_non_ignoreable_error(diag);
        }
        self.handle_non_ignoreable_error(diag);
    }
}

fn default_dcx(
    source_map: Lrc<SourceMap>,
    can_reset: Lrc<AtomicBool>,
    hide_parse_errors: bool,
) -> DiagCtxt {
    let supports_color = term::stderr().map_or(false, |term| term.supports_color());
    let emit_color = if supports_color {
        ColorConfig::Auto
    } else {
        ColorConfig::Never
    };

    let fallback_bundle = rustc_errors::fallback_fluent_bundle(
        rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
        false,
    );
    let emitter = Box::new(
        HumanEmitter::new(stderr_destination(emit_color), fallback_bundle.clone())
            .sm(Some(source_map.clone())),
    );

    let emitter: Box<DynEmitter> = if hide_parse_errors {
        Box::new(SilentEmitter {
            fallback_bundle,
            fatal_dcx: DiagCtxt::new(emitter),
            fatal_note: None,
            emit_fatal_diagnostic: false,
        })
    } else {
        emitter
    };
    DiagCtxt::new(Box::new(SilentOnIgnoredFilesEmitter {
        has_non_ignorable_parser_errors: false,
        emitter,
        can_reset,
    }))
}

#[allow(clippy::arc_with_non_send_sync)]
fn create_parser_session() -> ParseSess {
    let source_map = Lrc::new(SourceMap::new(FilePathMapping::empty()));
    let can_reset_errors = Lrc::new(AtomicBool::new(false));

    let dcx = default_dcx(
        Lrc::clone(&source_map),
        Lrc::clone(&can_reset_errors),
        false,
    );
    ParseSess::with_dcx(dcx, source_map)
}

fn create_parser<'a>(file: &Path, sess: &'a ParseSess) -> Result<Parser<'a>, String> {
    catch_unwind(AssertUnwindSafe(move || {
        new_parser_from_file(sess, file, None)
    }))
    .map_err(|e| format!("failed to create parser: {:?}", e))
}

fn parse_crate(parser: &mut Parser) -> Result<Crate, String> {
    let mut parser = AssertUnwindSafe(parser);

    match catch_unwind(move || parser.parse_crate_mod()) {
        Ok(Ok(k)) => Ok(k),
        Ok(Err(db)) => {
            db.emit();
            Err(String::new())
        }
        Err(e) => Err(format!("parser panicked: {:?}", e)),
    }
}