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RFC2229 Add missing edge case #87996

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Aug 20, 2021
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RFC2229 Add missing edge case #87996

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7d0afae
Add missing multi variant cases
roxelo Aug 13, 2021
2e61659
Update comment and fix fmt
roxelo Aug 14, 2021
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3 changes: 3 additions & 0 deletions compiler/rustc_typeck/src/expr_use_visitor.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -265,6 +265,9 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
if def.variants.len() > 1 {
needs_to_be_read = true;
}
} else {
// If it is not ty::Adt, then it is a MultiVariant
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needs_to_be_read = true;
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I am wondering what cases might be missing here -- one silly example might be matching on a constant of type () or something like that, which is kind of a no-op.

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I am not too sure either. I am going to import all the match test cases that are here https://github.com/rust-lang/rust/tree/master/src/test/ui/match and then convert them into closure test cases and see if I found anything new

}
}
PatKind::Lit(_) | PatKind::Range(..) => {
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19 changes: 19 additions & 0 deletions src/test/ui/closures/2229_closure_analysis/issue-87988.rs
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@@ -0,0 +1,19 @@
// run-pass
// edition:2021

const LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED: i32 = 0x01;
const LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT: i32 = 0x02;

pub fn hotplug_callback(event: i32) {
let _ = || {
match event {
LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED => (),
LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT => (),
_ => (),
};
};
}

fn main() {
hotplug_callback(1);
}
44 changes: 44 additions & 0 deletions src/test/ui/closures/2229_closure_analysis/match-multi-variant.rs
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@@ -0,0 +1,44 @@
// run-pass
// edition:2021

const PATTERN_REF: &str = "Hello World";
const NUMBER: i32 = 30;
const NUMBER_POINTER: *const i32 = &NUMBER;

pub fn multi_variant_ref(event: &str) {
let _ = || {
match event {
PATTERN_REF => (),
_ => (),
};
};
}

pub fn multi_variant_str(event: String) {
let _ = || {
match event.as_str() {
"hello" => (),
_ => (),
};
};
}

pub fn multi_variant_raw_ptr(event: *const i32) {
let _ = || {
match event {
NUMBER_POINTER => (),
_ => (),
};
};
}

pub fn multi_variant_char(event: char) {
let _ = || {
match event {
'a' => (),
_ => (),
};
};
}

fn main() {}