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_session::lint::LintId;
6use rustc_session::lint::builtin::UNSAFE_ATTR_OUTSIDE_UNSAFE;
7use rustc_span::{Span, sym};
8
9use crate::context::Stage;
10use crate::{AttributeParser, ShouldEmit};
11
12impl<'sess, S: Stage> AttributeParser<'sess, S> {
13    pub fn check_attribute_safety(
14        &mut self,
15        attr_path: &AttrPath,
16        attr_span: Span,
17        attr_safety: Safety,
18        emit_lint: &mut impl FnMut(AttributeLint<S::Id>),
19        target_id: S::Id,
20    ) {
21        if matches!(self.stage.should_emit(), ShouldEmit::Nothing) {
22            return;
23        }
24
25        let name = (attr_path.segments.len() == 1).then_some(attr_path.segments[0].name);
26        if let Some(name) = name
27            && [sym::cfg_trace, sym::cfg_attr_trace].contains(&name)
28        {
29            return;
30        }
31
32        // FIXME: We should retrieve this information from the attribute parsers instead of from `BUILTIN_ATTRIBUTE_MAP`
33        let builtin_attr_info = name.and_then(|name| BUILTIN_ATTRIBUTE_MAP.get(&name));
34        let builtin_attr_safety = builtin_attr_info.map(|x| x.safety);
35
36        match (builtin_attr_safety, attr_safety) {
37            // - Unsafe builtin attribute
38            // - User wrote `#[unsafe(..)]`, which is permitted on any edition
39            (Some(AttributeSafety::Unsafe { .. }), Safety::Unsafe(..)) => {
40                // OK
41            }
42
43            // - Unsafe builtin attribute
44            // - User did not write `#[unsafe(..)]`
45            (Some(AttributeSafety::Unsafe { unsafe_since }), Safety::Default) => {
46                let path_span = attr_path.span;
47
48                // If the `attr_item`'s span is not from a macro, then just suggest
49                // wrapping it in `unsafe(...)`. Otherwise, we suggest putting the
50                // `unsafe(`, `)` right after and right before the opening and closing
51                // square bracket respectively.
52                let diag_span = attr_span;
53
54                // Attributes can be safe in earlier editions, and become unsafe in later ones.
55                //
56                // Use the span of the attribute's name to determine the edition: the span of the
57                // attribute as a whole may be inaccurate if it was emitted by a macro.
58                //
59                // See https://github.com/rust-lang/rust/issues/142182.
60                let emit_error = match unsafe_since {
61                    None => true,
62                    Some(unsafe_since) => path_span.edition() >= unsafe_since,
63                };
64
65                let mut not_from_proc_macro = true;
66                if diag_span.from_expansion()
67                    && let Ok(mut snippet) = self.sess.source_map().span_to_snippet(diag_span)
68                {
69                    snippet.retain(|c| !c.is_whitespace());
70                    if snippet.contains("!(") || snippet.starts_with("#[") && snippet.ends_with("]")
71                    {
72                        not_from_proc_macro = false;
73                    }
74                }
75
76                if emit_error {
77                    self.stage.emit_err(
78                        self.sess,
79                        crate::session_diagnostics::UnsafeAttrOutsideUnsafe {
80                            span: path_span,
81                            suggestion: not_from_proc_macro.then(|| {
82                                crate::session_diagnostics::UnsafeAttrOutsideUnsafeSuggestion {
83                                    left: diag_span.shrink_to_lo(),
84                                    right: diag_span.shrink_to_hi(),
85                                }
86                            }),
87                        },
88                    );
89                } else {
90                    emit_lint(AttributeLint {
91                        lint_id: LintId::of(UNSAFE_ATTR_OUTSIDE_UNSAFE),
92                        id: target_id,
93                        span: path_span,
94                        kind: AttributeLintKind::UnsafeAttrOutsideUnsafe {
95                            attribute_name_span: path_span,
96                            sugg_spans: not_from_proc_macro
97                                .then(|| (diag_span.shrink_to_lo(), diag_span.shrink_to_hi())),
98                        },
99                    })
100                }
101            }
102
103            // - Normal builtin attribute
104            // - Writing `#[unsafe(..)]` is not permitted on normal builtin attributes
105            (None | Some(AttributeSafety::Normal), Safety::Unsafe(unsafe_span)) => {
106                self.stage.emit_err(
107                    self.sess,
108                    crate::session_diagnostics::InvalidAttrUnsafe {
109                        span: unsafe_span,
110                        name: attr_path.clone(),
111                    },
112                );
113            }
114
115            // - Normal builtin attribute
116            // - No explicit `#[unsafe(..)]` written.
117            (None | Some(AttributeSafety::Normal), Safety::Default) => {
118                // OK
119            }
120
121            (
122                Some(AttributeSafety::Unsafe { .. } | AttributeSafety::Normal) | None,
123                Safety::Safe(..),
124            ) => {
125                self.sess.dcx().span_delayed_bug(
126                    attr_span,
127                    "`check_attribute_safety` does not expect `Safety::Safe` on attributes",
128                );
129            }
130        }
131    }
132}
rustc_attr_parsing/safety.rs

rustc_attr_parsing/
safety.rs
