rustc_attr_parsing/attributes/
proc_macro_attrs.rs

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

rustc_attr_parsing/attributes/
proc_macro_attrs.rs
