rustc_attr_parsing/
safety.rs

1use rustc_ast::Safety;
2use rustc_feature::{AttributeSafety, BUILTIN_ATTRIBUTE_MAP};
3use rustc_hir::AttrPath;
4use rustc_hir::lints::{AttributeLint, AttributeLintKind};
5use rustc_span::{Span, sym};
6
7use crate::context::Stage;
8use crate::{AttributeParser, ShouldEmit};
9
10impl<'sess, S: Stage> AttributeParser<'sess, S> {
11    pub fn check_attribute_safety(
12        &mut self,
13        attr_path: &AttrPath,
14        attr_span: Span,
15        attr_safety: Safety,
16        emit_lint: &mut impl FnMut(AttributeLint<S::Id>),
17        target_id: S::Id,
18    ) {
19        if matches!(self.stage.should_emit(), ShouldEmit::Nothing) {
20            return;
21        }
22
23        let name = (attr_path.segments.len() == 1).then_some(attr_path.segments[0].name);
24        if let Some(name) = name
25            && [sym::cfg_trace, sym::cfg_attr_trace].contains(&name)
26        {
27            return;
28        }
29
30        // FIXME: We should retrieve this information from the attribute parsers instead of from `BUILTIN_ATTRIBUTE_MAP`
31        let builtin_attr_info = name.and_then(|name| BUILTIN_ATTRIBUTE_MAP.get(&name));
32        let builtin_attr_safety = builtin_attr_info.map(|x| x.safety);
33
34        match (builtin_attr_safety, attr_safety) {
35            // - Unsafe builtin attribute
36            // - User wrote `#[unsafe(..)]`, which is permitted on any edition
37            (Some(AttributeSafety::Unsafe { .. }), Safety::Unsafe(..)) => {
38                // OK
39            }
40
41            // - Unsafe builtin attribute
42            // - User did not write `#[unsafe(..)]`
43            (Some(AttributeSafety::Unsafe { unsafe_since }), Safety::Default) => {
44                let path_span = attr_path.span;
45
46                // If the `attr_item`'s span is not from a macro, then just suggest
47                // wrapping it in `unsafe(...)`. Otherwise, we suggest putting the
48                // `unsafe(`, `)` right after and right before the opening and closing
49                // square bracket respectively.
50                let diag_span = attr_span;
51
52                // Attributes can be safe in earlier editions, and become unsafe in later ones.
53                //
54                // Use the span of the attribute's name to determine the edition: the span of the
55                // attribute as a whole may be inaccurate if it was emitted by a macro.
56                //
57                // See https://github.com/rust-lang/rust/issues/142182.
58                let emit_error = match unsafe_since {
59                    None => true,
60                    Some(unsafe_since) => path_span.edition() >= unsafe_since,
61                };
62
63                if emit_error {
64                    self.stage.emit_err(
65                        self.sess,
66                        crate::session_diagnostics::UnsafeAttrOutsideUnsafe {
67                            span: path_span,
68                            suggestion:
69                                crate::session_diagnostics::UnsafeAttrOutsideUnsafeSuggestion {
70                                    left: diag_span.shrink_to_lo(),
71                                    right: diag_span.shrink_to_hi(),
72                                },
73                        },
74                    );
75                } else {
76                    emit_lint(AttributeLint {
77                        id: target_id,
78                        span: path_span,
79                        kind: AttributeLintKind::UnsafeAttrOutsideUnsafe {
80                            attribute_name_span: path_span,
81                            sugg_spans: (diag_span.shrink_to_lo(), diag_span.shrink_to_hi()),
82                        },
83                    })
84                }
85            }
86
87            // - Normal builtin attribute
88            // - Writing `#[unsafe(..)]` is not permitted on normal builtin attributes
89            (None | Some(AttributeSafety::Normal), Safety::Unsafe(unsafe_span)) => {
90                self.stage.emit_err(
91                    self.sess,
92                    crate::session_diagnostics::InvalidAttrUnsafe {
93                        span: unsafe_span,
94                        name: attr_path.clone(),
95                    },
96                );
97            }
98
99            // - Normal builtin attribute
100            // - No explicit `#[unsafe(..)]` written.
101            (None | Some(AttributeSafety::Normal), Safety::Default) => {
102                // OK
103            }
104
105            (
106                Some(AttributeSafety::Unsafe { .. } | AttributeSafety::Normal) | None,
107                Safety::Safe(..),
108            ) => {
109                self.sess.dcx().span_delayed_bug(
110                    attr_span,
111                    "`check_attribute_safety` does not expect `Safety::Safe` on attributes",
112                );
113            }
114        }
115    }
116}
rustc_attr_parsing/safety.rs

rustc_attr_parsing/
safety.rs
