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//@ revisions: nofallback fallback
//@ run-pass
#![allow(dead_code)]
#![allow(unused_assignments)]
#![allow(unused_variables)]
#![allow(unreachable_code)]
// Test various cases where we permit an unconstrained variable
// to fallback based on control-flow. In all of these cases,
// the type variable winds up being the target of both a `!` coercion
// and a coercion from a non-`!` variable, and hence falls back to `()`.
#![cfg_attr(fallback, feature(never_type, never_type_fallback))]
trait UnitDefault {
fn default() -> Self;
}
impl UnitDefault for u32 {
fn default() -> Self {
0
}
}
impl UnitDefault for () {
fn default() -> () {
panic!()
}
}
fn assignment() {
//[nofallback]~^ warn: this function depends on never type fallback being `()`
//[nofallback]~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
let x;
if true {
x = UnitDefault::default();
} else {
x = return;
}
}
fn assignment_rev() {
//[nofallback]~^ warn: this function depends on never type fallback being `()`
//[nofallback]~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
let x;
if true {
x = return;
} else {
x = UnitDefault::default();
}
}
fn if_then_else() {
let _x: () = if true {
UnitDefault::default()
} else {
return;
};
}
fn if_then_else_rev() {
let _x: () = if true {
return;
} else {
UnitDefault::default()
};
}
fn match_arm() {
let _x: () = match Ok(UnitDefault::default()) {
Ok(v) => v,
Err(()) => return,
};
}
fn match_arm_rev() {
let _x: () = match Ok(UnitDefault::default()) {
Err(()) => return,
Ok(v) => v,
};
}
fn loop_break() {
let _x: () = loop {
if false {
break return;
} else {
break UnitDefault::default();
}
};
}
fn loop_break_rev() {
let _x: () = loop {
if false {
break return;
} else {
break UnitDefault::default();
}
};
}
fn main() {}
|
