rustc_attr_parsing/attributes/
prototype.rs

1//! Attributes that are only used on function prototypes.
2
3use rustc_feature::{AttributeTemplate, template};
4use rustc_hir::Target;
5use rustc_hir::attrs::{AttributeKind, MirDialect, MirPhase};
6use rustc_span::{Span, Symbol, sym};
7
8use super::{AttributeOrder, OnDuplicate};
9use crate::attributes::SingleAttributeParser;
10use crate::context::{AcceptContext, AllowedTargets, MaybeWarn, Stage};
11use crate::parser::ArgParser;
12
13pub(crate) struct CustomMirParser;
14
15impl<S: Stage> SingleAttributeParser<S> for CustomMirParser {
16    const PATH: &[rustc_span::Symbol] = &[sym::custom_mir];
17
18    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
19
20    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
21
22    const ALLOWED_TARGETS: AllowedTargets =
23        AllowedTargets::AllowList(&[MaybeWarn::Allow(Target::Fn)]);
24
25    const TEMPLATE: AttributeTemplate = template!(List: &[r#"dialect = "...", phase = "...""#]);
26
27    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
28        let Some(list) = args.list() else {
29            cx.expected_list(cx.attr_span);
30            return None;
31        };
32
33        let mut dialect = None;
34        let mut phase = None;
35        let mut failed = false;
36
37        for item in list.mixed() {
38            let Some(meta_item) = item.meta_item() else {
39                cx.expected_name_value(item.span(), None);
40                failed = true;
41                break;
42            };
43
44            if let Some(arg) = meta_item.word_is(sym::dialect) {
45                extract_value(cx, sym::dialect, arg, meta_item.span(), &mut dialect, &mut failed);
46            } else if let Some(arg) = meta_item.word_is(sym::phase) {
47                extract_value(cx, sym::phase, arg, meta_item.span(), &mut phase, &mut failed);
48            } else if let Some(word) = meta_item.path().word() {
49                let word = word.to_string();
50                cx.unknown_key(meta_item.span(), word, &["dialect", "phase"]);
51                failed = true;
52            } else {
53                cx.expected_name_value(meta_item.span(), None);
54                failed = true;
55            };
56        }
57
58        let dialect = parse_dialect(cx, dialect, &mut failed);
59        let phase = parse_phase(cx, phase, &mut failed);
60
61        if failed {
62            return None;
63        }
64
65        Some(AttributeKind::CustomMir(dialect, phase, cx.attr_span))
66    }
67}
68
69fn extract_value<S: Stage>(
70    cx: &mut AcceptContext<'_, '_, S>,
71    key: Symbol,
72    arg: &ArgParser<'_>,
73    span: Span,
74    out_val: &mut Option<(Symbol, Span)>,
75    failed: &mut bool,
76) {
77    if out_val.is_some() {
78        cx.duplicate_key(span, key);
79        *failed = true;
80        return;
81    }
82
83    let Some(val) = arg.name_value() else {
84        cx.expected_single_argument(arg.span().unwrap_or(span));
85        *failed = true;
86        return;
87    };
88
89    let Some(value_sym) = val.value_as_str() else {
90        cx.expected_string_literal(val.value_span, Some(val.value_as_lit()));
91        *failed = true;
92        return;
93    };
94
95    *out_val = Some((value_sym, val.value_span));
96}
97
98fn parse_dialect<S: Stage>(
99    cx: &mut AcceptContext<'_, '_, S>,
100    dialect: Option<(Symbol, Span)>,
101    failed: &mut bool,
102) -> Option<(MirDialect, Span)> {
103    let (dialect, span) = dialect?;
104
105    let dialect = match dialect {
106        sym::analysis => MirDialect::Analysis,
107        sym::built => MirDialect::Built,
108        sym::runtime => MirDialect::Runtime,
109
110        _ => {
111            cx.expected_specific_argument(span, vec!["analysis", "built", "runtime"]);
112            *failed = true;
113            return None;
114        }
115    };
116
117    Some((dialect, span))
118}
119
120fn parse_phase<S: Stage>(
121    cx: &mut AcceptContext<'_, '_, S>,
122    phase: Option<(Symbol, Span)>,
123    failed: &mut bool,
124) -> Option<(MirPhase, Span)> {
125    let (phase, span) = phase?;
126
127    let phase = match phase {
128        sym::initial => MirPhase::Initial,
129        sym::post_cleanup => MirPhase::PostCleanup,
130        sym::optimized => MirPhase::Optimized,
131
132        _ => {
133            cx.expected_specific_argument(span, vec!["initial", "post-cleanup", "optimized"]);
134            *failed = true;
135            return None;
136        }
137    };
138
139    Some((phase, span))
140}
rustc_attr_parsing/attributes/prototype.rs

rustc_attr_parsing/attributes/
prototype.rs
