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 = AllowedTargets::AllowList(&[Allow(Target::MacroDef)]);
48    const TEMPLATE: AttributeTemplate =
49        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, ...)"]);
50    const STABILITY: AttributeStability = AttributeStability::Unstable {
    gate_name: rustc_span::sym::rustc_attrs,
    gate_check: rustc_feature::Features::rustc_attrs,
    notes: &[],
}unstable!(rustc_attrs);
51
52    fn convert(cx: &mut AcceptContext<'_, '_>, args: &ArgParser) -> Option<AttributeKind> {
53        let (builtin_name, helper_attrs) = parse_derive_like(cx, args, false)?;
54        Some(AttributeKind::RustcBuiltinMacro { builtin_name, helper_attrs })
55    }
56}
57
58fn parse_derive_like(
59    cx: &mut AcceptContext<'_, '_>,
60    args: &ArgParser,
61    trait_name_mandatory: bool,
62) -> Option<(Option<Symbol>, ThinVec<Symbol>)> {
63    let Some(list) = args.as_list() else {
64        // For #[rustc_builtin_macro], it is permitted to leave out the trait name
65        if args.as_no_args().is_ok() && !trait_name_mandatory {
66            return Some((None, ThinVec::new()));
67        }
68        let attr_span = cx.attr_span;
69        cx.adcx().expected_list(attr_span, args);
70        return None;
71    };
72    let mut items = list.mixed();
73
74    // Parse the name of the trait that is derived.
75    let Some(trait_attr) = items.next() else {
76        cx.adcx().expected_at_least_one_argument(list.span);
77        return None;
78    };
79    let Some(trait_attr) = trait_attr.meta_item() else {
80        cx.adcx().expected_not_literal(trait_attr.span());
81        return None;
82    };
83    let Some(trait_ident) = trait_attr.path().word() else {
84        cx.adcx().expected_identifier(trait_attr.path().span());
85        return None;
86    };
87    if !trait_ident.name.can_be_raw() {
88        cx.adcx().expected_identifier(trait_ident.span);
89        return None;
90    }
91    cx.expect_no_args(trait_attr.args())?;
92
93    // Parse optional attributes
94    let mut attributes = ThinVec::new();
95    if let Some(attrs) = items.next() {
96        let Some(attr_list) = attrs.meta_item() else {
97            cx.adcx().expected_not_literal(attrs.span());
98            return None;
99        };
100        if !attr_list.path().word_is(sym::attributes) {
101            cx.adcx().expected_specific_argument(attrs.span(), &[sym::attributes]);
102            return None;
103        }
104        let attr_list = cx.expect_list(attr_list.args(), attrs.span())?;
105
106        // Parse item in `attributes(...)` argument
107        for attr in attr_list.mixed() {
108            let Some(attr) = attr.meta_item() else {
109                cx.adcx().expected_identifier(attr.span());
110                return None;
111            };
112            cx.expect_no_args(attr.args())?;
113            let Some(ident) = attr.path().word() else {
114                cx.adcx().expected_identifier(attr.path().span());
115                return None;
116            };
117            if !ident.name.can_be_raw() {
118                cx.adcx().expected_identifier(ident.span);
119                return None;
120            }
121            if rustc_feature::is_builtin_attr_name(ident.name) {
122                cx.emit_lint(
123                    AMBIGUOUS_DERIVE_HELPERS,
124                    crate::diagnostics::AmbiguousDeriveHelpers,
125                    ident.span,
126                );
127            }
128            attributes.push(ident.name);
129        }
130    }
131
132    // If anything else is specified, we should reject it
133    if let Some(next) = items.next() {
134        cx.adcx().expected_no_args(next.span());
135    }
136
137    Some((Some(trait_ident.name), attributes))
138}
rustc_attr_parsing/attributes/proc_macro_attrs.rs

rustc_attr_parsing/attributes/
proc_macro_attrs.rs
