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Fix ICE-133117

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If all subcandidates have never-pattern, we should assign false_edge_start_block to the parent candidate
if it doesn't have. merge_trivial_subcandidates does so, but if the candidate has guard it returns before the assignment.

Signed-off-by: Shunpoco <tkngsnsk313320@gmail.com>
This commit is contained in:
Shunpoco 2025-01-12 14:44:36 +00:00
parent 3a83422c13
commit 8a57fa634c
3 changed files with 52 additions and 4 deletions
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8
compiler/rustc_mir_build/src/builder/matches/mod.rs
View file

@ -1940,6 +1940,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
/// in match tree lowering.
fn merge_trivial_subcandidates(&mut self, candidate: &mut Candidate<'_, 'tcx>) {
assert!(!candidate.subcandidates.is_empty());
if candidate.false_edge_start_block.is_none() {
candidate.false_edge_start_block = candidate.subcandidates[0].false_edge_start_block;
}
if candidate.has_guard {
// FIXME(or_patterns; matthewjasper) Don't give up if we have a guard.
return;
@ -1958,10 +1962,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// This candidate is about to become a leaf, so unset `or_span`.
let or_span = candidate.or_span.take().unwrap();
let source_info = self.source_info(or_span);
if candidate.false_edge_start_block.is_none() {
candidate.false_edge_start_block = candidate.subcandidates[0].false_edge_start_block;
}
// Remove the (known-trivial) subcandidates from the candidate tree,
// so that they aren't visible after match tree lowering, and wire them

12
tests/ui/rfcs/rfc-0000-never_patterns/ICE-133117-duplicate-never-arm.rs Normal file
View file

@ -0,0 +1,12 @@
#![feature(never_patterns)]
#![allow(incomplete_features)]
fn main() {
match () {
(!|
//~^ ERROR: mismatched types
!) if true => {} //~ ERROR a never pattern is always unreachable
//~^ ERROR: mismatched types
(!|!) if true => {} //~ ERROR a never pattern is always unreachable
}
}

36
tests/ui/rfcs/rfc-0000-never_patterns/ICE-133117-duplicate-never-arm.stderr Normal file
View file

@ -0,0 +1,36 @@
error: a never pattern is always unreachable
--> $DIR/ICE-133117-duplicate-never-arm.rs:8:23
|
LL | !) if true => {}
| ^^
| |
| this will never be executed
| help: remove this expression
error: a never pattern is always unreachable
--> $DIR/ICE-133117-duplicate-never-arm.rs:10:26
|
LL | (!|!) if true => {}
| ^^
| |
| this will never be executed
| help: remove this expression
error: mismatched types
--> $DIR/ICE-133117-duplicate-never-arm.rs:6:10
|
LL | (!|
| ^ a never pattern must be used on an uninhabited type
|
= note: the matched value is of type `()`
error: mismatched types
--> $DIR/ICE-133117-duplicate-never-arm.rs:8:9
|
LL | !) if true => {}
| ^ a never pattern must be used on an uninhabited type
|
= note: the matched value is of type `()`
error: aborting due to 4 previous errors