ctor/macros/
mod.rs

1#[doc(hidden)]
2#[allow(unused)]
3pub mod __support {
4    pub use crate::__ctor_entry as ctor_entry;
5    pub use crate::__ctor_link_section as ctor_link_section;
6    pub use crate::__ctor_link_section_attr as ctor_link_section_attr;
7    pub use crate::__ctor_parse as ctor_parse;
8    pub use crate::__dtor_entry as dtor_entry;
9    pub use crate::__dtor_parse as dtor_parse;
10    pub use crate::__if_has_feature as if_has_feature;
11    pub use crate::__if_unsafe as if_unsafe;
12    pub use crate::__include_no_warn_on_missing_unsafe_feature as include_no_warn_on_missing_unsafe_feature;
13    pub use crate::__include_used_linker_feature as include_used_linker_feature;
14    pub use crate::__unify_features as unify_features;
15}
16
17/// Parse a `#[ctor]`-annotated item as if it were a proc-macro.
18///
19/// This macro supports both the `fn` and `static` forms of the `#[ctor]`
20/// attribute, including attribute parameters.
21///
22/// ```rust
23/// # #[cfg(any())] // disabled due to code sharing between ctor/dtor
24/// # mod test {
25/// # use ctor::declarative::ctor;
26/// ctor! {
27///   /// Create a ctor with a link section
28/// # #[cfg(any())]
29///   #[ctor(link_section = ".ctors")]
30///   unsafe fn foo() { /* ... */ }
31/// }
32///
33/// ctor! {
34///   #[ctor]
35/// # #[cfg(any())]
36///   static FOO: std::collections::HashMap<u32, String> = unsafe {
37///     let mut m = std::collections::HashMap::new();
38///     m.insert(1, "foo".to_string());
39///     m
40///   };
41/// }
42/// # }
43/// ```
44#[doc(hidden)]
45#[macro_export]
46macro_rules! __ctor_parse {
47    (#[ctor $(($($meta:tt)*))?] $(#[$imeta:meta])* pub ( $($extra:tt)* ) $($item:tt)*) => {
48        $crate::__support::unify_features!(next=$crate::__support::ctor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[pub($($extra)*)], item=$($item)*);
49    };
50    (#[ctor $(($($meta:tt)*))?] $(#[$imeta:meta])* pub $($item:tt)*) => {
51        $crate::__support::unify_features!(next=$crate::__support::ctor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[pub], item=$($item)*);
52    };
53    (#[ctor $(($($meta:tt)*))?] $(#[$imeta:meta])* fn $($item:tt)*) => {
54        $crate::__support::unify_features!(next=$crate::__support::ctor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[], item=fn $($item)*);
55    };
56    (#[ctor $(($($meta:tt)*))?] $(#[$imeta:meta])* unsafe $($item:tt)*) => {
57        $crate::__support::unify_features!(next=$crate::__support::ctor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[], item=unsafe $($item)*);
58    };
59    (#[ctor $(($($meta:tt)*))?] $(#[$imeta:meta])* static $($item:tt)*) => {
60        $crate::__support::unify_features!(next=$crate::__support::ctor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[], item=static $($item)*);
61    };
62    // Reorder attributes that aren't `#[ctor]`
63    (#[$imeta:meta] $($rest:tt)*) => {
64        $crate::__support::ctor_parse!(__reorder__(#[$imeta],), $($rest)*);
65    };
66    (__reorder__($(#[$imeta:meta],)*), #[ctor $(($($meta:tt)*))?] $($rest:tt)*) => {
67        $crate::__support::ctor_parse!(#[ctor $(($($meta)*))?] $(#[$imeta])* $($rest)*);
68    };
69    (__reorder__($(#[$imeta:meta],)*), #[$imeta2:meta] $($rest:tt)*) => {
70        $crate::__support::ctor_parse!(__reorder__($(#[$imeta],)*#[$imeta2],), $($rest)*);
71    };
72}
73
74/// Parse a `#[dtor]`-annotated item as if it were a proc-macro.
75///
76/// ```rust
77/// # #[cfg(any())] mod test {
78/// dtor! {
79///   #[dtor]
80///   unsafe fn foo() { /* ... */ }
81/// }
82/// # }
83#[doc(hidden)]
84#[macro_export]
85macro_rules! __dtor_parse {
86    (#[dtor $(($($meta:tt)*))?] $(#[$imeta:meta])* pub ( $($extra:tt)* ) $($item:tt)*) => {
87        $crate::__support::unify_features!(next=$crate::__support::dtor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[pub($($extra)*)], item=$($item)*);
88    };
89    (#[dtor $(($($meta:tt)*))?] $(#[$imeta:meta])* pub $($item:tt)*) => {
90        $crate::__support::unify_features!(next=$crate::__support::dtor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[pub], item=$($item)*);
91    };
92    (#[dtor $(($($meta:tt)*))?] $(#[$imeta:meta])* fn $($item:tt)*) => {
93        $crate::__support::unify_features!(next=$crate::__support::dtor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[], item=fn $($item)*);
94    };
95    (#[dtor $(($($meta:tt)*))?] $(#[$imeta:meta])* unsafe $($item:tt)*) => {
96        $crate::__support::unify_features!(next=$crate::__support::dtor_entry, meta=[$($($meta)*)?], features=[], imeta=$(#[$imeta])*, vis=[], item=unsafe $($item)*);
97    };
98    // Reorder attributes that aren't `#[dtor]`
99    (#[$imeta:meta] $($rest:tt)*) => {
100        $crate::__support::dtor_parse!(__reorder__(#[$imeta],), $($rest)*);
101    };
102    (__reorder__($(#[$imeta:meta],)*), #[dtor $(($($meta:tt)*))?] $($rest:tt)*) => {
103        $crate::__support::dtor_parse!(#[dtor $(($($meta)*))?] $(#[$imeta])* $($rest)*);
104    };
105    (__reorder__($(#[$imeta:meta],)*), #[$imeta2:meta] $($rest:tt)*) => {
106        $crate::__support::dtor_parse!(__reorder__($(#[$imeta],)*#[$imeta2],), $($rest)*);
107    };
108}
109
110/// Extract #[ctor/dtor] attribute parameters and crate features and turn them
111/// into a unified feature array.
112///
113/// Supported attributes:
114///
115/// - `used(linker)` -> feature: `used_linker`
116/// - `link_section = ...` -> feature: `(link_section = ...)`
117/// - `crate_path = ...` -> feature: `(crate_path = ...)`
118#[doc(hidden)]
119#[macro_export]
120macro_rules! __unify_features {
121    // Entry
122    (next=$next_macro:path, meta=[$($meta:tt)*], features=[$($features:tt)*], $($rest:tt)*) => {
123        $crate::__support::unify_features!(used_linker, next=$next_macro, meta=[$($meta)*], features=[$($features)*], $($rest)*);
124    };
125
126    // Add used_linker feature if cfg(feature="used_linker")
127    (used_linker, next=$next_macro:path, meta=[$($meta:tt)*], features=[$($features:tt)*], $($rest:tt)*) => {
128        $crate::__support::include_used_linker_feature!(
129            $crate::__support::unify_features!(__no_warn_on_missing_unsafe, next=$next_macro, meta=[$($meta)*], features=[used_linker,$($features)*], $($rest)*);
130            $crate::__support::unify_features!(__no_warn_on_missing_unsafe, next=$next_macro, meta=[$($meta)*], features=[$($features)*], $($rest)*);
131        );
132    };
133    // Add __no_warn_on_missing_unsafe feature if cfg(feature="__no_warn_on_missing_unsafe")
134    (__no_warn_on_missing_unsafe, next=$next_macro:path, meta=[$($meta:tt)*], features=[$($features:tt)*], $($rest:tt)*) => {
135        $crate::__support::include_used_linker_feature!(
136            $crate::__support::unify_features!(continue, next=$next_macro, meta=[$($meta)*], features=[__no_warn_on_missing_unsafe,$($features)*], $($rest)*);
137            $crate::__support::unify_features!(continue, next=$next_macro, meta=[$($meta)*], features=[$($features)*], $($rest)*);
138        );
139    };
140
141    // Parse meta into features
142    (continue, next=$next_macro:path, meta=[used(linker) $(, $($meta:tt)* )?], features=[$($features:tt)*], $($rest:tt)*) => {
143        $crate::__support::unify_features!(continue, next=$next_macro, meta=[$($($meta)*)?], features=[used_linker,$($features)*], $($rest)*);
144    };
145    (continue, next=$next_macro:path, meta=[link_section = $section:tt $(, $($meta:tt)* )?], features=[$($features:tt)*], $($rest:tt)*) => {
146        $crate::__support::unify_features!(continue, next=$next_macro, meta=[$($($meta)*)?], features=[(link_section=$section),$($features)*], $($rest)*);
147    };
148    (continue, next=$next_macro:path, meta=[crate_path = $path:path $(, $($meta:tt)* )?], features=[$($features:tt)*], $($rest:tt)*) => {
149        $crate::__support::unify_features!(continue, next=$next_macro, meta=[$($($meta)*)?], features=[(crate_path=$path),$($features)*], $($rest)*);
150    };
151    (continue, next=$next_macro:path, meta=[anonymous $(, $($meta:tt)* )?], features=[$($features:tt)*], $($rest:tt)*) => {
152        $crate::__support::unify_features!(continue, next=$next_macro, meta=[$($($meta)*)?], features=[anonymous,$($features)*], $($rest)*);
153    };
154    (continue, next=$next_macro:path, meta=[$unknown_meta:meta $($meta:tt)*], features=[$($features:tt)*], $($rest:tt)*) => {
155        compile_error!(concat!("Unknown attribute parameter: ", stringify!($unknown_meta)));
156    };
157
158    (continue, next=$next_macro:path, meta=[], features=[$($features:tt)*], $($rest:tt)*) => {
159        $next_macro!(features=[$($features)*], $($rest)*);
160    };
161}
162
163#[doc(hidden)]
164#[macro_export]
165#[cfg(feature = "used_linker")]
166macro_rules! __include_used_linker_feature {
167    ($true:item $false:item) => {
168        $true
169    };
170}
171
172#[doc(hidden)]
173#[macro_export]
174#[cfg(not(feature = "used_linker"))]
175macro_rules! __include_used_linker_feature {
176    ($true:item $false:item) => {
177        $false
178    };
179}
180
181#[doc(hidden)]
182#[macro_export]
183#[cfg(feature = "__no_warn_on_missing_unsafe")]
184macro_rules! __include_no_warn_on_missing_unsafe_feature {
185    ($true:item $false:item) => {
186        $true
187    };
188}
189
190#[doc(hidden)]
191#[macro_export]
192#[cfg(not(feature = "__no_warn_on_missing_unsafe"))]
193macro_rules! __include_no_warn_on_missing_unsafe_feature {
194    ($true:item $false:item) => {
195        $false
196    };
197}
198
199/// If the features array contains the requested feature, generates `if_true`, else `if_false`.
200///
201/// This macro matches the features recursively.
202///
203/// Example: `[(link_section = ".ctors") , used_linker , __warn_on_missing_unsafe ,]`
204#[doc(hidden)]
205#[macro_export]
206#[allow(unknown_lints, edition_2024_expr_fragment_specifier)]
207macro_rules! __if_has_feature {
208    (used_linker,                 [used_linker,                     $($rest:tt)*], {$($if_true:tt)*}, {$($if_false:tt)*}) => { $($if_true)* };
209    (__no_warn_on_missing_unsafe, [__no_warn_on_missing_unsafe,     $($rest:tt)*], {$($if_true:tt)*}, {$($if_false:tt)*}) => { $($if_true)* };
210    (anonymous,                   [anonymous,                       $($rest:tt)*], {$($if_true:tt)*}, {$($if_false:tt)*}) => { $($if_true)* };
211    ((link_section(c)),           [(link_section=$section:literal), $($rest:tt)*], {$($if_true:tt)*}, {$($if_false:tt)*}) => { #[link_section = $section] $($if_true)* };
212
213    // Fallback rules
214    ($anything:tt, [$x:ident, $($rest:tt)*], {$($if_true:tt)*}, {$($if_false:tt)*}) => { $crate::__support::if_has_feature!($anything, [$($rest)*], {$($if_true)*}, {$($if_false)*}); };
215    ($anything:tt, [($x:ident=$y:expr), $($rest:tt)*], {$($if_true:tt)*}, {$($if_false:tt)*}) => { $crate::__support::if_has_feature!($anything, [$($rest)*], {$($if_true)*}, {$($if_false)*}); };
216    ($anything:tt, [], {$($if_true:tt)*}, {$($if_false:tt)*}) => { $($if_false)* };
217}
218
219#[doc(hidden)]
220#[macro_export]
221macro_rules! __if_unsafe {
222    (, {$($if_unsafe:tt)*}, {$($if_safe:tt)*}) => { $($if_safe)* };
223    (unsafe, {$($if_unsafe:tt)*}, {$($if_safe:tt)*}) => { $($if_unsafe)* };
224}
225
226#[doc(hidden)]
227#[macro_export]
228#[allow(unknown_lints, edition_2024_expr_fragment_specifier)]
229macro_rules! __ctor_entry {
230    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], item=unsafe fn $($item:tt)*) => {
231        $crate::__support::ctor_entry!(features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=unsafe, item=fn $($item)*);
232    };
233    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], item=fn $($item:tt)*) => {
234        $crate::__support::ctor_entry!(features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=, item=fn $($item)*);
235    };
236    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], item=static $ident:ident : $ty:ty = $(unsafe)? $({ $lit:literal })? $($lit2:literal)? ;) => {
237        compile_error!(concat!("Use `const ", stringify!($ident), " = ", stringify!($($lit)?$($lit2)?), ";` or `static ", stringify!($ident), ": ", stringify!($ty), " = ", stringify!($($lit)?$($lit2)?), ";` instead"));
238    };
239    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], item=static $ident:ident : $ty:ty = unsafe $($item:tt)*) => {
240        $crate::__support::ctor_entry!(features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=unsafe, item=static $ident: $ty = $($item)*);
241    };
242    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], item=static $ident:ident : $ty:ty = $($item:tt)*) => {
243        $crate::__support::ctor_entry!(features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=, item=static $ident: $ty = $($item)*);
244    };
245    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], unsafe=$($unsafe:ident)?, item=fn $ident:ident() $block:block) => {
246        $crate::__support::if_has_feature!(anonymous, $features, {
247            $crate::__support::ctor_entry!(unnamed, features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=$($unsafe)?, item=fn $ident() $block);
248        }, {
249            $crate::__support::ctor_entry!(named, features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=$($unsafe)?, item=fn $ident() $block);
250        });
251    };
252    (unnamed,features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], unsafe=$($unsafe:ident)?, item=fn $ident:ident() $block:block) => {
253        const _: () = {
254            $crate::__support::ctor_entry!(named, features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=$($unsafe)?, item=fn $ident() $block);
255        };
256    };
257    (named, features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], unsafe=$($unsafe:ident)?, item=fn $ident:ident() $block:block) => {
258        $(#[$fnmeta])*
259        #[allow(unused)]
260        $($vis)* $($unsafe)? fn $ident() {
261            #[allow(unsafe_code)]
262            {
263                $crate::__support::if_unsafe!($($unsafe)?, {}, {
264                    $crate::__support::if_has_feature!( __warn_on_missing_unsafe, $features, {
265                        #[deprecated="ctor deprecation note:\n\n \
266                        Use of #[ctor] without `unsafe fn` is deprecated. As code execution before main\n\
267                        is unsupported by most Rust runtime functions, these functions must be marked\n\
268                        `unsafe`."]
269                            const fn ctor_without_unsafe_is_deprecated() {}
270                            #[allow(unused)]
271                            static UNSAFE_WARNING: () = ctor_without_unsafe_is_deprecated();
272                    }, {});
273                });
274
275                $crate::__support::ctor_link_section!(
276                    array,
277                    features=$features,
278
279                    #[allow(non_upper_case_globals, non_snake_case)]
280                    #[doc(hidden)]
281                    static f: /*unsafe*/ extern "C" fn() -> usize =
282                    {
283                        $crate::__support::ctor_link_section!(
284                            startup,
285                            features=$features,
286
287                            #[allow(non_snake_case)]
288                            /*unsafe*/ extern "C" fn f() -> usize { unsafe { $ident(); 0 } }
289                        );
290
291                        f
292                    };
293                );
294            }
295
296            #[cfg(target_family = "wasm")]
297            {
298                static __CTOR__INITILIZED: core::sync::atomic::AtomicBool = core::sync::atomic::AtomicBool::new(false);
299                if __CTOR__INITILIZED.swap(true, core::sync::atomic::Ordering::Relaxed) {
300                    return;
301                }
302            }
303
304            $block
305        }
306    };
307    (features=$features:tt, imeta=$(#[$imeta:meta])*, vis=[$($vis:tt)*], unsafe=$($unsafe:ident)?, item=static $ident:ident : $ty:ty = $block:block;) => {
308        $(#[$imeta])*
309        $($vis)* static $ident: $ident::Static<$ty> = $ident::Static::<$ty> {
310            _storage: {
311                $crate::__support::ctor_link_section!(
312                    array,
313                    features=$features,
314
315                    #[allow(non_upper_case_globals, non_snake_case)]
316                    #[doc(hidden)]
317                    static f: /*unsafe*/ extern "C" fn() -> usize =
318                    {
319                        $crate::__support::ctor_link_section!(
320                            startup,
321                            features=$features,
322
323                            #[allow(non_snake_case)]
324                            /*unsafe*/ extern "C" fn f() -> usize { _ = &*$ident; 0 }
325                        );
326
327                        f
328                    };
329                );
330
331                ::std::sync::OnceLock::new()
332            }
333        };
334
335        impl ::core::ops::Deref for $ident::Static<$ty> {
336            type Target = $ty;
337            fn deref(&self) -> &$ty {
338                fn init() -> $ty $block
339
340                self._storage.get_or_init(move || {
341                    init()
342                })
343            }
344        }
345
346        #[doc(hidden)]
347        #[allow(non_upper_case_globals, non_snake_case)]
348        #[allow(unsafe_code)]
349        mod $ident {
350            $crate::__support::if_unsafe!($($unsafe)?, {}, {
351                $crate::__support::if_has_feature!( __warn_on_missing_unsafe, $features, {
352                    #[deprecated="ctor deprecation note:\n\n \
353                    Use of #[ctor] without `unsafe { ... }` is deprecated. As code execution before main\n\
354                    is unsupported by most Rust runtime functions, these functions must be marked\n\
355                    `unsafe`."]
356                        const fn ctor_without_unsafe_is_deprecated() {}
357                        #[allow(unused)]
358                        static UNSAFE_WARNING: () = ctor_without_unsafe_is_deprecated();
359                }, {});
360            });
361
362            #[allow(non_camel_case_types, unreachable_pub)]
363            pub struct Static<T> {
364                pub _storage: ::std::sync::OnceLock<T>
365            }
366        }
367    };
368}
369
370// Code note:
371
372// You might wonder why we don't use `__attribute__((destructor))`/etc for
373// dtor. Unfortunately mingw doesn't appear to properly support section-based
374// hooks for shutdown, ie:
375
376// https://github.com/Alexpux/mingw-w64/blob/d0d7f784833bbb0b2d279310ddc6afb52fe47a46/mingw-w64-crt/crt/crtdll.c
377
378// In addition, OSX has removed support for section-based shutdown hooks after
379// warning about it for a number of years:
380
381// https://reviews.llvm.org/D45578
382
383#[doc(hidden)]
384#[macro_export]
385macro_rules! __dtor_entry {
386    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], item=fn $ident:ident() $block:block) => {
387        $crate::__support::dtor_entry!(features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=, item=fn $ident() $block);
388    };
389    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], item=unsafe fn $ident:ident() $block:block) => {
390        $crate::__support::dtor_entry!(features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=unsafe, item=fn $ident() $block);
391    };
392    (features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], unsafe=$($unsafe:ident)?, item=fn $ident:ident() $block:block) => {
393        $crate::__support::if_has_feature!(anonymous, $features, {
394            $crate::__support::dtor_entry!(unnamed, features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=$($unsafe)?, item=fn $ident() $block);
395        }, {
396            $crate::__support::dtor_entry!(named, features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=$($unsafe)?, item=fn $ident() $block);
397        });
398    };
399    (unnamed, features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], unsafe=$($unsafe:ident)?, item=fn $ident:ident() $block:block) => {
400        const _: () = {
401            $crate::__support::dtor_entry!(named, features=$features, imeta=$(#[$fnmeta])*, vis=[$($vis)*], unsafe=$($unsafe)?, item=fn $ident() $block);
402        };
403    };
404    (named, features=$features:tt, imeta=$(#[$fnmeta:meta])*, vis=[$($vis:tt)*], unsafe=$($unsafe:ident)?, item=fn $ident:ident() $block:block) => {
405        $(#[$fnmeta])*
406        #[allow(unused)]
407        $($vis)* $($unsafe)? fn $ident() {
408            #[allow(unsafe_code)]
409            {
410                $crate::__support::if_unsafe!($($unsafe)?, {}, {
411                    $crate::__support::if_has_feature!( __warn_on_missing_unsafe, $features, {
412                        #[deprecated="dtor deprecation note:\n\n \
413                        Use of #[dtor] without `unsafe fn` is deprecated. As code execution after main\n\
414                        is unsupported by most Rust runtime functions, these functions must be marked\n\
415                        `unsafe`."]
416                        const fn dtor_without_unsafe_is_deprecated() {}
417                        #[allow(unused)]
418                        static UNSAFE_WARNING: () = dtor_without_unsafe_is_deprecated();
419                    }, {});
420                });
421
422                $crate::__support::ctor_link_section!(
423                    array,
424                    features=$features,
425
426                    #[allow(non_upper_case_globals, non_snake_case)]
427                    #[doc(hidden)]
428                    static f: /*unsafe*/ extern "C" fn() -> usize =
429                    {
430                        $crate::__support::ctor_link_section!(
431                            startup,
432                            features=$features,
433
434                            #[allow(non_snake_case)]
435                            /*unsafe*/ extern "C" fn f() -> usize { unsafe { do_atexit(__dtor); 0 } }
436                        );
437
438                        f
439                    };
440                );
441
442                $crate::__support::ctor_link_section!(
443                    exit,
444                    features=$features,
445
446                    /*unsafe*/ extern "C" fn __dtor(
447                        #[cfg(target_vendor = "apple")] _: *const u8
448                    ) { unsafe { $ident() } }
449                );
450
451                #[cfg(not(target_vendor = "apple"))]
452                #[inline(always)]
453                unsafe fn do_atexit(cb: unsafe extern fn()) {
454                    /*unsafe*/ extern "C" {
455                        fn atexit(cb: unsafe extern fn());
456                    }
457                    unsafe {
458                        atexit(cb);
459                    }
460                }
461
462                // For platforms that have __cxa_atexit, we register the dtor as scoped to dso_handle
463                #[cfg(target_vendor = "apple")]
464                #[inline(always)]
465                unsafe fn do_atexit(cb: /*unsafe*/ extern "C" fn(_: *const u8)) {
466                    /*unsafe*/ extern "C" {
467                        static __dso_handle: *const u8;
468                        fn __cxa_atexit(cb: /*unsafe*/ extern "C" fn(_: *const u8), arg: *const u8, dso_handle: *const u8);
469                    }
470                    unsafe {
471                        __cxa_atexit(cb, core::ptr::null(), __dso_handle);
472                    }
473                }
474            }
475
476            $block
477        }
478    };
479}
480
481/// Annotate a block with its appropriate link section.
482#[doc(hidden)]
483#[macro_export]
484macro_rules! __ctor_link_section {
485    ($section:ident, features=$features:tt, $($block:tt)+) => {
486        $crate::__support::if_has_feature!(used_linker, $features, {
487            $crate::__support::ctor_link_section_attr!($section, $features, used(linker), $($block)+);
488        }, {
489            $crate::__support::ctor_link_section_attr!($section, $features, used, $($block)+);
490        });
491
492        #[cfg(not(any(
493            target_os = "linux",
494            target_os = "android",
495            target_os = "freebsd",
496            target_os = "netbsd",
497            target_os = "openbsd",
498            target_os = "dragonfly",
499            target_os = "illumos",
500            target_os = "haiku",
501            target_vendor = "apple",
502            target_family = "wasm",
503            windows
504        )))]
505        compile_error!("#[ctor]/#[dtor] is not supported on the current target");
506    }
507}
508
509/// Apply either the default cfg-based link section attributes, or
510/// the overridden link_section attribute.
511#[doc(hidden)]
512#[macro_export]
513macro_rules! __ctor_link_section_attr {
514    (array, $features:tt, $used:meta, $item:item) => {
515        $crate::__support::if_has_feature!((link_section(c)), $features, {
516            #[allow(unsafe_code)]
517            #[$used]
518            $item
519        }, {
520            #[allow(unsafe_code)]
521            $crate::__support::ctor_link_section_attr!(
522                [[any(
523                    target_os = "linux",
524                    target_os = "android",
525                    target_os = "freebsd",
526                    target_os = "netbsd",
527                    target_os = "openbsd",
528                    target_os = "dragonfly",
529                    target_os = "illumos",
530                    target_os = "haiku",
531                    target_family = "wasm"
532                ), ".init_array"],
533                [target_vendor = "apple", "__DATA,__mod_init_func"],
534                [windows, ".CRT$XCU"]],
535                #[$used]
536                $item
537            );
538        });
539    };
540    (startup, $features:tt, $used:meta, $item:item) => {
541        #[cfg(not(clippy))]
542        $crate::__support::ctor_link_section_attr!([[any(target_os = "linux", target_os = "android"), ".text.startup"]], $item);
543
544        #[cfg(clippy)]
545        $item
546    };
547    (exit, $features:tt, $used:meta, $item:item) => {
548        #[cfg(not(clippy))]
549        $crate::__support::ctor_link_section_attr!([[any(target_os = "linux", target_os = "android"), ".text.exit"]], $item);
550
551        #[cfg(clippy)]
552        $item
553    };
554    ([$( [$cond:meta, $literal:literal ] ),+], $item:item) => {
555        $( #[cfg_attr($cond, link_section = $literal)] )+
556        $item
557    };
558}
ctor/macros/mod.rs

ctor/macros/
mod.rs
