diff options
Diffstat (limited to 'src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs')
-rw-r--r-- | src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs b/src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs new file mode 100644 index 000000000..aa60d0504 --- /dev/null +++ b/src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs @@ -0,0 +1,121 @@ +//! False-positive tests to ensure we don't suggest `const` for things where it would cause a +//! compilation error. +//! The .stderr output of this test should be empty. Otherwise it's a bug somewhere. + +// aux-build:helper.rs + +#![warn(clippy::missing_const_for_fn)] +#![feature(start)] +#![feature(custom_inner_attributes)] + +extern crate helper; + +struct Game; + +// This should not be linted because it's already const +const fn already_const() -> i32 { + 32 +} + +impl Game { + // This should not be linted because it's already const + pub const fn already_const() -> i32 { + 32 + } +} + +// Allowing on this function, because it would lint, which we don't want in this case. +#[allow(clippy::missing_const_for_fn)] +fn random() -> u32 { + 42 +} + +// We should not suggest to make this function `const` because `random()` is non-const +fn random_caller() -> u32 { + random() +} + +static Y: u32 = 0; + +// We should not suggest to make this function `const` because const functions are not allowed to +// refer to a static variable +fn get_y() -> u32 { + Y + //~^ ERROR E0013 +} + +// Don't lint entrypoint functions +#[start] +fn init(num: isize, something: *const *const u8) -> isize { + 1 +} + +trait Foo { + // This should not be suggested to be made const + // (rustc doesn't allow const trait methods) + fn f() -> u32; + + // This should not be suggested to be made const either + fn g() -> u32 { + 33 + } +} + +// Don't lint in external macros (derive) +#[derive(PartialEq, Eq)] +struct Point(isize, isize); + +impl std::ops::Add for Point { + type Output = Self; + + // Don't lint in trait impls of derived methods + fn add(self, other: Self) -> Self { + Point(self.0 + other.0, self.1 + other.1) + } +} + +mod with_drop { + pub struct A; + pub struct B; + impl Drop for A { + fn drop(&mut self) {} + } + + impl A { + // This can not be const because the type implements `Drop`. + pub fn b(self) -> B { + B + } + } + + impl B { + // This can not be const because `a` implements `Drop`. + pub fn a(self, a: A) -> B { + B + } + } +} + +fn const_generic_params<T, const N: usize>(t: &[T; N]) -> &[T; N] { + t +} + +fn const_generic_return<T, const N: usize>(t: &[T]) -> &[T; N] { + let p = t.as_ptr() as *const [T; N]; + + unsafe { &*p } +} + +// Do not lint this because it calls a function whose constness is unstable. +fn unstably_const_fn() { + helper::unstably_const_fn() +} + +mod const_fn_stabilized_after_msrv { + #![clippy::msrv = "1.46.0"] + + // Do not lint this because `u8::is_ascii_digit` is stabilized as a const function in 1.47.0. + fn const_fn_stabilized_after_msrv(byte: u8) { + byte.is_ascii_digit(); + } +} |