rustc_attr_parsing/attributes/
proc_macro_attrs.rs

1use rustc_feature::AttributeStability;
2use rustc_session::lint::builtin::AMBIGUOUS_DERIVE_HELPERS;
3
4use super::prelude::*;
5
6const PROC_MACRO_ALLOWED_TARGETS: AllowedTargets<'_> =
7    AllowedTargets::AllowList(&[Allow(Target::Fn), Warn(Target::Crate), Warn(Target::MacroCall)]);
8
9pub(crate) struct ProcMacroParser;
10impl NoArgsAttributeParser for ProcMacroParser {
11    const PATH: &[Symbol] = &[sym::proc_macro];
12    const ALLOWED_TARGETS: AllowedTargets<'_> = PROC_MACRO_ALLOWED_TARGETS;
13    const STABILITY: AttributeStability = AttributeStability::Stable;
14    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::ProcMacro;
15}
16
17pub(crate) struct ProcMacroAttributeParser;
18impl NoArgsAttributeParser for ProcMacroAttributeParser {
19    const PATH: &[Symbol] = &[sym::proc_macro_attribute];
20    const ALLOWED_TARGETS: AllowedTargets<'_> = PROC_MACRO_ALLOWED_TARGETS;
21    const STABILITY: AttributeStability = AttributeStability::Stable;
22    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::ProcMacroAttribute;
23}
24
25pub(crate) struct ProcMacroDeriveParser;
26impl SingleAttributeParser for ProcMacroDeriveParser {
27    const PATH: &[Symbol] = &[sym::proc_macro_derive];
28    const ALLOWED_TARGETS: AllowedTargets<'_> = PROC_MACRO_ALLOWED_TARGETS;
29    const TEMPLATE: AttributeTemplate = crate::AttributeTemplate {
    word: false,
    list: Some(&["TraitName", "TraitName, attributes(name1, name2, ...)"]),
    one_of: &[],
    name_value_str: None,
    docs: Some("https://doc.rust-lang.org/reference/procedural-macros.html#derive-macros"),
}template!(
30        List: &["TraitName", "TraitName, attributes(name1, name2, ...)"],
31        "https://doc.rust-lang.org/reference/procedural-macros.html#derive-macros"
32    );
33    const STABILITY: AttributeStability = AttributeStability::Stable;
34
35    fn convert(cx: &mut AcceptContext<'_, '_>, args: &ArgParser) -> Option<AttributeKind> {
36        let (trait_name, helper_attrs) = parse_derive_like(cx, args, true)?;
37        Some(AttributeKind::ProcMacroDerive {
38            trait_name: trait_name.expect("Trait name is mandatory, so it is present"),
39            helper_attrs,
40        })
41    }
42}
43
44pub(crate) struct RustcBuiltinMacroParser;
45impl SingleAttributeParser for RustcBuiltinMacroParser {
46    const PATH: &[Symbol] = &[sym::rustc_builtin_macro];
47    const ALLOWED_TARGETS: AllowedTargets<'_> =
48        AllowedTargets::AllowList(&[Allow(Target::MacroDef)]);
49    const TEMPLATE: AttributeTemplate =
50        crate::AttributeTemplate {
    word: false,
    list: Some(&["TraitName", "TraitName, attributes(name1, name2, ...)"]),
    one_of: &[],
    name_value_str: None,
    docs: None,
}template!(List: &["TraitName", "TraitName, attributes(name1, name2, ...)"]);
51    const STABILITY: AttributeStability = AttributeStability::Unstable {
    gate_name: rustc_span::sym::rustc_attrs,
    gate_check: rustc_feature::Features::rustc_attrs,
    notes: &[],
}unstable!(rustc_attrs);
52
53    fn convert(cx: &mut AcceptContext<'_, '_>, args: &ArgParser) -> Option<AttributeKind> {
54        let (builtin_name, helper_attrs) = parse_derive_like(cx, args, false)?;
55        Some(AttributeKind::RustcBuiltinMacro { builtin_name, helper_attrs })
56    }
57}
58
59fn parse_derive_like(
60    cx: &mut AcceptContext<'_, '_>,
61    args: &ArgParser,
62    trait_name_mandatory: bool,
63) -> Option<(Option<Symbol>, ThinVec<Symbol>)> {
64    let Some(list) = args.as_list() else {
65        // For #[rustc_builtin_macro], it is permitted to leave out the trait name
66        if args.as_no_args().is_ok() && !trait_name_mandatory {
67            return Some((None, ThinVec::new()));
68        }
69        let attr_span = cx.attr_span;
70        cx.adcx().expected_list(attr_span, args);
71        return None;
72    };
73    let mut items = list.mixed();
74
75    // Parse the name of the trait that is derived.
76    let Some(trait_attr) = items.next() else {
77        cx.adcx().expected_at_least_one_argument(list.span);
78        return None;
79    };
80    let Some(trait_attr) = trait_attr.meta_item() else {
81        cx.adcx().expected_not_literal(trait_attr.span());
82        return None;
83    };
84    let Some(trait_ident) = trait_attr.path().word() else {
85        cx.adcx().expected_identifier(trait_attr.path().span());
86        return None;
87    };
88    if !trait_ident.name.can_be_raw() {
89        cx.adcx().expected_identifier(trait_ident.span);
90        return None;
91    }
92    cx.expect_no_args(trait_attr.args())?;
93
94    // Parse optional attributes
95    let mut attributes = ThinVec::new();
96    if let Some(attrs) = items.next() {
97        let Some(attr_list) = attrs.meta_item() else {
98            cx.adcx().expected_not_literal(attrs.span());
99            return None;
100        };
101        if !attr_list.path().word_is(sym::attributes) {
102            cx.adcx().expected_specific_argument(attrs.span(), &[sym::attributes]);
103            return None;
104        }
105        let attr_list = cx.expect_list(attr_list.args(), attrs.span())?;
106
107        // Parse item in `attributes(...)` argument
108        for attr in attr_list.mixed() {
109            let Some(attr) = attr.meta_item() else {
110                cx.adcx().expected_identifier(attr.span());
111                return None;
112            };
113            cx.expect_no_args(attr.args())?;
114            let Some(ident) = attr.path().word() else {
115                cx.adcx().expected_identifier(attr.path().span());
116                return None;
117            };
118            if !ident.name.can_be_raw() {
119                cx.adcx().expected_identifier(ident.span);
120                return None;
121            }
122            if rustc_feature::is_builtin_attr_name(ident.name) {
123                cx.emit_lint(
124                    AMBIGUOUS_DERIVE_HELPERS,
125                    crate::diagnostics::AmbiguousDeriveHelpers,
126                    ident.span,
127                );
128            }
129            attributes.push(ident.name);
130        }
131    }
132
133    // If anything else is specified, we should reject it
134    if let Some(next) = items.next() {
135        cx.adcx().expected_no_args(next.span());
136    }
137
138    Some((Some(trait_ident.name), attributes))
139}
rustc_attr_parsing/attributes/proc_macro_attrs.rs

rustc_attr_parsing/attributes/
proc_macro_attrs.rs
