rustc_hir/attrs/
mod.rs

1//! Data structures for representing parsed attributes in the Rust compiler.
2//! Formerly `rustc_attr_data_structures`.
3//!
4//! For detailed documentation about attribute processing,
5//! see [rustc_attr_parsing](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_attr_parsing/index.html).
6
7pub use data_structures::*;
8pub use encode_cross_crate::EncodeCrossCrate;
9pub use pretty_printing::PrintAttribute;
10
11mod data_structures;
12mod encode_cross_crate;
13mod pretty_printing;
14
15/// Finds attributes in sequences of attributes by pattern matching.
16///
17/// A little like `matches` but for attributes.
18///
19/// ```rust,ignore (illustrative)
20/// // finds the repr attribute
21/// if let Some(r) = find_attr!(attrs, AttributeKind::Repr(r) => r) {
22///
23/// }
24///
25/// // checks if one has matched
26/// if find_attr!(attrs, AttributeKind::Repr(_)) {
27///
28/// }
29/// ```
30///
31/// Often this requires you to first end up with a list of attributes.
32/// Often these are available through the `tcx`.
33///
34/// As a convenience, this macro can do that for you!
35///
36/// Instead of providing an attribute list, provide the `tcx` and a `DefId`.
37///
38/// ```rust,ignore (illustrative)
39/// find_attr!(tcx, def_id, <pattern>)
40/// ```
41///
42/// Another common case is finding attributes applied to the root of the current crate.
43/// For that, use the shortcut:
44///
45/// ```rust, ignore (illustrative)
46/// find_attr!(tcx, crate, <pattern>)
47/// ```
48#[macro_export]
49macro_rules! find_attr {
50    ($tcx: expr, crate, $pattern: pat $(if $guard: expr)?) => {
51        $crate::find_attr!($tcx, crate, $pattern $(if $guard)? => ()).is_some()
52    };
53    ($tcx: expr, crate, $pattern: pat $(if $guard: expr)? => $e: expr) => {
54        $crate::find_attr!($tcx.hir_krate_attrs(), $pattern $(if $guard)? => $e)
55    };
56
57    ($tcx: expr, $def_id: expr, $pattern: pat $(if $guard: expr)?) => {
58        $crate::find_attr!($tcx, $def_id, $pattern $(if $guard)? => ()).is_some()
59    };
60    ($tcx: expr, $def_id: expr, $pattern: pat $(if $guard: expr)? => $e: expr) => {{
61        #[allow(deprecated)] {
62            $crate::find_attr!($tcx.get_all_attrs($def_id), $pattern $(if $guard)? => $e)
63        }
64    }};
65
66
67    ($attributes_list: expr, $pattern: pat $(if $guard: expr)?) => {{
68        $crate::find_attr!($attributes_list, $pattern $(if $guard)? => ()).is_some()
69    }};
70
71    ($attributes_list: expr, $pattern: pat $(if $guard: expr)? => $e: expr) => {{
72        'done: {
73            for i in $attributes_list {
74                #[allow(unused_imports)]
75                use rustc_hir::attrs::AttributeKind::*;
76                let i: &rustc_hir::Attribute = i;
77                match i {
78                    rustc_hir::Attribute::Parsed($pattern) $(if $guard)? => {
79                        break 'done Some($e);
80                    }
81                    rustc_hir::Attribute::Unparsed(..) => {}
82                    // In lint emitting, there's a specific exception for this warning.
83                    // It's not usually emitted from inside macros from other crates
84                    // (see https://github.com/rust-lang/rust/issues/110613)
85                    // But this one is!
86                    #[deny(unreachable_patterns)]
87                    _ => {}
88                }
89            }
90
91            None
92        }
93    }};
94}
rustc_hir/attrs/mod.rs

rustc_hir/attrs/
mod.rs
