1/// Asserts that the trait is a child of all of the other traits.
2///
3/// Related:
4/// - [`assert_trait_super_all!`]
5///
6/// # Examples
7///
8/// All types that implement [`Copy`] must implement [`Clone`]:
9///
10/// ```
11/// # #[macro_use] extern crate static_assertions; fn main() {}
12/// assert_trait_sub_all!(Copy: Clone);
13/// ```
14///
15/// All types that implement [`Ord`] must implement [`PartialEq`], [`Eq`], and
16/// [`PartialOrd`]:
17///
18/// ```
19/// # #[macro_use] extern crate static_assertions; fn main() {}
20/// assert_trait_sub_all!(Ord: PartialEq, Eq, PartialOrd);
21/// ```
22///
23/// The following example fails to compile because [`Eq`] is not required for
24/// [`PartialOrd`]:
25///
26/// ```compile_fail
27/// # #[macro_use] extern crate static_assertions; fn main() {}
28/// assert_trait_sub_all!(PartialOrd: Eq);
29/// ```
30///
31/// [`assert_trait_super_all!`]: macro.assert_trait_super_all.html
32///
33/// [`Copy`]:       https://doc.rust-lang.org/std/marker/trait.Copy.html
34/// [`Clone`]:      https://doc.rust-lang.org/std/clone/trait.Clone.html
35/// [`Ord`]:        https://doc.rust-lang.org/std/cmp/trait.Ord.html
36/// [`PartialOrd`]: https://doc.rust-lang.org/std/cmp/trait.PartialOrd.html
37/// [`Eq`]:         https://doc.rust-lang.org/std/cmp/trait.Eq.html
38/// [`PartialEq`]:  https://doc.rust-lang.org/std/cmp/trait.PartialEq.html
39#[macro_export]
40macro_rules! assert_trait_sub_all {
41    ($sub:path: $($super:path),+ $(,)?) => {
42        const _: () = {
43            // One scope per super-trait.
44            $({
45                #[allow(non_camel_case_types)]
46                trait __Impl_Implication: $super {}
47
48                // Can only be implemented for `$sub` types if `$super` is
49                // also implemented.
50                impl<T: $sub> __Impl_Implication for T {}
51            })+
52        };
53    };
54}
55
56/// Asserts that the trait is a parent of all of the other traits.
57///
58/// Related:
59/// - [`assert_trait_sub_all!`]
60///
61/// # Examples
62///
63/// With this, traits `A` and `B` can both be tested to require [`Copy`] on a
64/// single line:
65///
66/// ```
67/// # use static_assertions::assert_trait_super_all;
68/// trait A: Copy {}
69/// trait B: Copy {}
70///
71/// assert_trait_super_all!(Copy: A, B);
72/// ```
73///
74/// Otherwise, each sub-trait would require its own call to
75/// [`assert_trait_sub_all!`]:
76///
77/// ```
78/// # #[macro_use] extern crate static_assertions; fn main() {}
79/// # trait A: Copy {}
80/// # trait B: Copy {}
81/// assert_trait_sub_all!(A: Copy);
82/// assert_trait_sub_all!(B: Copy);
83/// ```
84///
85/// The following example fails to compile because trait `C` does not require
86/// [`Copy`]:
87///
88/// ```compile_fail
89/// # use static_assertions::assert_trait_super_all;
90/// # trait A: Copy {}
91/// # trait B: Copy {}
92/// trait C {}
93///
94/// assert_trait_super_all!(Copy: A, B, C);
95/// ```
96///
97/// [`assert_trait_sub_all!`]: macro.assert_trait_sub_all.html
98///
99/// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html
100#[macro_export(local_inner_macros)]
101macro_rules! assert_trait_super_all {
102    ($super:path: $($sub:path),+ $(,)?) => {
103        $(assert_trait_sub_all!($sub: $super);)+
104    };
105}
106