rustc_attr_parsing/
validate_attr.rs

1//! Meta-syntax validation logic of attributes for post-expansion.
2
3use std::convert::identity;
4use std::slice;
5
6use rustc_ast::token::Delimiter;
7use rustc_ast::tokenstream::DelimSpan;
8use rustc_ast::{
9    self as ast, AttrArgs, Attribute, DelimArgs, MetaItem, MetaItemInner, MetaItemKind, Safety,
10};
11use rustc_errors::{Applicability, PResult};
12use rustc_feature::{AttributeTemplate, BUILTIN_ATTRIBUTE_MAP, BuiltinAttribute, template};
13use rustc_hir::AttrPath;
14use rustc_hir::lints::AttributeLintKind;
15use rustc_parse::parse_in;
16use rustc_session::errors::report_lit_error;
17use rustc_session::lint::builtin::ILL_FORMED_ATTRIBUTE_INPUT;
18use rustc_session::parse::ParseSess;
19use rustc_span::{Span, Symbol, sym};
20
21use crate::{AttributeParser, Late, session_diagnostics as errors};
22
23pub fn check_attr(psess: &ParseSess, attr: &Attribute) {
24    if attr.is_doc_comment() || attr.has_name(sym::cfg_trace) || attr.has_name(sym::cfg_attr_trace)
25    {
26        return;
27    }
28
29    let builtin_attr_info = attr.name().and_then(|name| BUILTIN_ATTRIBUTE_MAP.get(&name));
30
31    // Check input tokens for built-in and key-value attributes.
32    match builtin_attr_info {
33        Some(BuiltinAttribute { name, .. }) => {
34            if AttributeParser::<Late>::is_parsed_attribute(slice::from_ref(&name)) {
35                return;
36            }
37            match parse_meta(psess, attr) {
38                // Don't check safety again, we just did that
39                Ok(meta) => {
40                    // FIXME The only unparsed builtin attributes that are left are the lint attributes, so we can hardcode the template here
41                    let lint_attrs = [sym::forbid, sym::allow, sym::warn, sym::deny, sym::expect];
42                    if !lint_attrs.contains(name) {
    ::core::panicking::panic("assertion failed: lint_attrs.contains(name)")
};assert!(lint_attrs.contains(name));
43
44                    let template = ::rustc_feature::AttributeTemplate {
    word: false,
    list: Some(&["lint1", "lint1, lint2, ...",
                    r#"lint1, lint2, lint3, reason = "...""#]),
    one_of: &[],
    name_value_str: None,
    docs: Some("https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"),
}template!(
45                        List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
46                        "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
47                    );
48                    check_builtin_meta_item(psess, &meta, attr.style, *name, template, false)
49                }
50                Err(err) => {
51                    err.emit();
52                }
53            }
54        }
55        _ => {
56            let attr_item = attr.get_normal_item();
57            if let AttrArgs::Eq { .. } = attr_item.args.unparsed_ref().unwrap() {
58                // All key-value attributes are restricted to meta-item syntax.
59                match parse_meta(psess, attr) {
60                    Ok(_) => {}
61                    Err(err) => {
62                        err.emit();
63                    }
64                }
65            }
66        }
67    }
68}
69
70pub fn parse_meta<'a>(psess: &'a ParseSess, attr: &Attribute) -> PResult<'a, MetaItem> {
71    let item = attr.get_normal_item();
72    Ok(MetaItem {
73        unsafety: item.unsafety,
74        span: attr.span,
75        path: item.path.clone(),
76        kind: match &item.args.unparsed_ref().unwrap() {
77            AttrArgs::Empty => MetaItemKind::Word,
78            AttrArgs::Delimited(DelimArgs { dspan, delim, tokens }) => {
79                check_meta_bad_delim(psess, *dspan, *delim);
80                let nmis =
81                    parse_in(psess, tokens.clone(), "meta list", |p| p.parse_meta_seq_top())?;
82                MetaItemKind::List(nmis)
83            }
84            AttrArgs::Eq { expr, .. } => {
85                if let ast::ExprKind::Lit(token_lit) = expr.kind {
86                    let res = ast::MetaItemLit::from_token_lit(token_lit, expr.span);
87                    let res = match res {
88                        Ok(lit) => {
89                            if token_lit.suffix.is_some() {
90                                let mut err = psess.dcx().struct_span_err(
91                                    expr.span,
92                                    "suffixed literals are not allowed in attributes",
93                                );
94                                err.help(
95                                    "instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), \
96                                    use an unsuffixed version (`1`, `1.0`, etc.)",
97                                );
98                                return Err(err);
99                            } else {
100                                MetaItemKind::NameValue(lit)
101                            }
102                        }
103                        Err(err) => {
104                            let guar = report_lit_error(psess, err, token_lit, expr.span);
105                            let lit = ast::MetaItemLit {
106                                symbol: token_lit.symbol,
107                                suffix: token_lit.suffix,
108                                kind: ast::LitKind::Err(guar),
109                                span: expr.span,
110                            };
111                            MetaItemKind::NameValue(lit)
112                        }
113                    };
114                    res
115                } else {
116                    // Example cases:
117                    // - `#[foo = 1+1]`: results in `ast::ExprKind::Binary`.
118                    // - `#[foo = include_str!("nonexistent-file.rs")]`:
119                    //   results in `ast::ExprKind::Err`. In that case we delay
120                    //   the error because an earlier error will have already
121                    //   been reported.
122                    let msg = "attribute value must be a literal";
123                    let mut err = psess.dcx().struct_span_err(expr.span, msg);
124                    if let ast::ExprKind::Err(_) = expr.kind {
125                        err.downgrade_to_delayed_bug();
126                    }
127                    return Err(err);
128                }
129            }
130        },
131    })
132}
133
134fn check_meta_bad_delim(psess: &ParseSess, span: DelimSpan, delim: Delimiter) {
135    if let Delimiter::Parenthesis = delim {
136        return;
137    }
138    psess.dcx().emit_err(errors::MetaBadDelim {
139        span: span.entire(),
140        sugg: errors::MetaBadDelimSugg { open: span.open, close: span.close },
141    });
142}
143
144/// Checks that the given meta-item is compatible with this `AttributeTemplate`.
145fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaItemKind) -> bool {
146    let is_one_allowed_subword = |items: &[MetaItemInner]| match items {
147        [item] => item.is_word() && template.one_of.iter().any(|&word| item.has_name(word)),
148        _ => false,
149    };
150    match meta {
151        MetaItemKind::Word => template.word,
152        MetaItemKind::List(items) => template.list.is_some() || is_one_allowed_subword(items),
153        MetaItemKind::NameValue(lit) if lit.kind.is_str() => template.name_value_str.is_some(),
154        MetaItemKind::NameValue(..) => false,
155    }
156}
157
158pub fn check_builtin_meta_item(
159    psess: &ParseSess,
160    meta: &MetaItem,
161    style: ast::AttrStyle,
162    name: Symbol,
163    template: AttributeTemplate,
164    deny_unsafety: bool,
165) {
166    if !is_attr_template_compatible(&template, &meta.kind) {
167        // attrs with new parsers are locally validated so excluded here
168        emit_malformed_attribute(psess, style, meta.span, name, template);
169    }
170
171    if deny_unsafety && let Safety::Unsafe(unsafe_span) = meta.unsafety {
172        psess.dcx().emit_err(errors::InvalidAttrUnsafe {
173            span: unsafe_span,
174            name: AttrPath::from_ast(&meta.path, identity),
175        });
176    }
177}
178
179pub fn emit_malformed_attribute(
180    psess: &ParseSess,
181    style: ast::AttrStyle,
182    span: Span,
183    name: Symbol,
184    template: AttributeTemplate,
185) {
186    // Some of previously accepted forms were used in practice,
187    // report them as warnings for now.
188    let should_warn = |name| #[allow(non_exhaustive_omitted_patterns)] match name {
    sym::doc | sym::link | sym::test | sym::bench => true,
    _ => false,
}matches!(name, sym::doc | sym::link | sym::test | sym::bench);
189
190    let error_msg = ::alloc::__export::must_use({
        ::alloc::fmt::format(format_args!("malformed `{0}` attribute input",
                name))
    })format!("malformed `{name}` attribute input");
191    let mut suggestions = ::alloc::vec::Vec::new()vec![];
192    let inner = if style == ast::AttrStyle::Inner { "!" } else { "" };
193    if template.word {
194        suggestions.push(::alloc::__export::must_use({
        ::alloc::fmt::format(format_args!("#{0}[{1}]", inner, name))
    })format!("#{inner}[{name}]"));
195    }
196    if let Some(descr) = template.list {
197        for descr in descr {
198            suggestions.push(::alloc::__export::must_use({
        ::alloc::fmt::format(format_args!("#{0}[{1}({2})]", inner, name,
                descr))
    })format!("#{inner}[{name}({descr})]"));
199        }
200    }
201    suggestions.extend(template.one_of.iter().map(|&word| ::alloc::__export::must_use({
        ::alloc::fmt::format(format_args!("#{0}[{1}({2})]", inner, name,
                word))
    })format!("#{inner}[{name}({word})]")));
202    if let Some(descr) = template.name_value_str {
203        for descr in descr {
204            suggestions.push(::alloc::__export::must_use({
        ::alloc::fmt::format(format_args!("#{0}[{1} = \"{2}\"]", inner, name,
                descr))
    })format!("#{inner}[{name} = \"{descr}\"]"));
205        }
206    }
207    // If there are too many suggestions, better remove all of them as it's just noise at this
208    // point.
209    if suggestions.len() > 3 {
210        suggestions.clear();
211    }
212    if should_warn(name) {
213        psess.buffer_lint(
214            ILL_FORMED_ATTRIBUTE_INPUT,
215            span,
216            ast::CRATE_NODE_ID,
217            AttributeLintKind::IllFormedAttributeInput {
218                suggestions: suggestions.clone(),
219                docs: template.docs,
220                help: None,
221            },
222        );
223    } else {
224        suggestions.sort();
225        let mut err = psess.dcx().struct_span_err(span, error_msg).with_span_suggestions(
226            span,
227            if suggestions.len() == 1 {
228                "must be of the form"
229            } else {
230                "the following are the possible correct uses"
231            },
232            suggestions,
233            Applicability::HasPlaceholders,
234        );
235        if let Some(link) = template.docs {
236            err.note(::alloc::__export::must_use({
        ::alloc::fmt::format(format_args!("for more information, visit <{0}>",
                link))
    })format!("for more information, visit <{link}>"));
237        }
238        err.emit();
239    }
240}
rustc_attr_parsing/validate_attr.rs

rustc_attr_parsing/
validate_attr.rs
