Add an unreachable!() macro.
#8992
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Rationale: having a function which fails means that the location of failure which is output is that of the unreachable() function, rather than the caller. This is part of rust-lang#8991 but is not all of it; current usage of ``std::util::unreachable()`` must remain so for the moment, until a new snapshot is made; then I will remove that function entirely in favour of using this macro.
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I'm mostly in favor of this, one mild thing I'm worried about is code bloat. The codegen for a function call is pretty small, but the codegen for the I think that this will be mostly fixed with |
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Nice! I am very much in favor. Codegen is something that can be optimised later. |
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In this case it expands to: ::std::sys::FailWithCause::fail_with("internal error: entered unreachable code",
/* file */ "foo.rs", /* line */ 10)so there's unlikely to be much codegen concern here. |
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oh that's perfect. I'm in favor but I'd want another vote or two to r+ it b/c it's a nontrivial change. |
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lgtm |
bors
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Sep 5, 2013
Rationale: having a function which fails means that the location of failure which is output is that of the unreachable() function, rather than the caller. This is part of #8991 but is not all of it; current usage of ``std::util::unreachable()`` must remain so for the moment, until a new snapshot is made; then I will remove that function entirely in favour of using this macro.
chris-morgan
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Sep 19, 2013
This is the second of two parts of rust-lang#8991, now possible as a new snapshot has been made. (The first part implemented the unreachable!() macro; it was rust-lang#8992, 6b7b8f2.) ``std::util::unreachable()`` is removed summarily; any code which used it should now use the ``unreachable!()`` macro. Closes rust-lang#9312. Closes rust-lang#8991.
bors
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Sep 20, 2013
…-two-containing-the-destruction-of-the-unreachable-function, r=alexcrichton This is the second of two parts of #8991, now possible as a new snapshot has been made. (The first part implemented the unreachable!() macro; it was #8992, 6b7b8f2.) ``std::util::unreachable()`` is removed summarily; any code which used it should now use the ``unreachable!()`` macro. Closes #9312. Closes #8991.
Jarcho
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Aug 29, 2022
feat(fix): Do not lint if the target code is inside a loop close rust-lang#8753 we consider the following code. ```rust fn main() { let vec = vec![1]; let w: Vec<usize> = vec.iter().map(|i| i * i).collect(); // <- once. for i in 0..2 { let _ = w.contains(&i); } } ``` and the clippy will issue the following warning. ```rust warning: avoid using `collect()` when not needed --> src/main.rs:3:51 | 3 | let w: Vec<usize> = vec.iter().map(|i| i * i).collect(); | ^^^^^^^ ... 6 | let _ = w.contains(&i); | -------------- the iterator could be used here instead | = note: `#[warn(clippy::needless_collect)]` on by default = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_collect help: check if the original Iterator contains an element instead of collecting then checking | 3 ~ 4 | 5 | for i in 0..2 { 6 ~ let _ = vec.iter().map(|i| i * i).any(|x| x == i); ``` Rewrite the code as indicated. ```rust fn main() { let vec = vec![1]; for i in 0..2 { let _ = vec.iter().map(|i| i * i).any(|x| x == i); // <- execute `map` every loop. } } ``` this code is valid in the compiler, but, it is different from the code before the rewrite. So, we should not lint, If `collect` is outside of a loop. Thank you in advance. --- changelog: Do not lint if the target code is inside a loop in `needless_collect`
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Rationale: having a function which fails means that the location of
failure which is output is that of the unreachable() function, rather
than the caller.
This is part of #8991 but is not all of it; current usage of
std::util::unreachable()must remain so for the moment, until a newsnapshot is made; then I will remove that function entirely in favour of
using this macro.