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reverse binding order in matches to allow the subbinding of copyable fields in bindings after @ #78638

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Merged
merged 7 commits into from
Nov 5, 2020
Merged

reverse binding order in matches to allow the subbinding of copyable fields in bindings after @ #78638

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c93d25b
reverse binding order in matches ...
vn-ki Nov 1, 2020
5dee38d
update some ui tests and update move ref drop semantics output
vn-ki Nov 2, 2020
9088807
update mir tests
vn-ki Nov 2, 2020
6bdce7b
new fix method and update tests
vn-ki Nov 2, 2020
f422e81
preserve bindings order for Some
vn-ki Nov 3, 2020
f44f96d
add tests
vn-ki Nov 3, 2020
5827fba
review comments
vn-ki Nov 3, 2020
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25 changes: 23 additions & 2 deletions compiler/rustc_mir_build/src/build/matches/simplify.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
candidate: &mut Candidate<'pat, 'tcx>,
) -> bool {
// repeatedly simplify match pairs until fixed point is reached
debug!("simplify_candidate(candidate={:?})", candidate);
let mut new_bindings = Vec::new();
loop {
let match_pairs = mem::take(&mut candidate.match_pairs);

Expand All @@ -56,7 +58,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {

let mut changed = false;
for match_pair in match_pairs {
match self.simplify_match_pair(match_pair, candidate) {
match self.simplify_match_pair(match_pair, candidate, &mut new_bindings) {
Ok(()) => {
changed = true;
}
Expand All @@ -65,13 +67,31 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
}
}
// issue #69971: the binding order should be right to left if there are more
// bindings after `@` to please the borrow checker
// Ex
// struct NonCopyStruct {
// copy_field: u32,
// }
//
// fn foo1(x: NonCopyStruct) {
// let y @ NonCopyStruct { copy_field: z } = x;
// // the above should turn into
// let z = x.copy_field;
// let y = x;
// }
new_bindings.extend_from_slice(&candidate.bindings);
mem::swap(&mut candidate.bindings, &mut new_bindings);
new_bindings.clear();

if !changed {
// Move or-patterns to the end, because they can result in us
// creating additional candidates, so we want to test them as
// late as possible.
candidate
.match_pairs
.sort_by_key(|pair| matches!(*pair.pattern.kind, PatKind::Or { .. }));
debug!("simplify_candidate: simplifed {:?}", candidate);
return false; // if we were not able to simplify any, done.
}
}
Expand Down Expand Up @@ -104,6 +124,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
&mut self,
match_pair: MatchPair<'pat, 'tcx>,
candidate: &mut Candidate<'pat, 'tcx>,
bindings: &mut Vec<Binding<'tcx>>,
) -> Result<(), MatchPair<'pat, 'tcx>> {
let tcx = self.hir.tcx();
match *match_pair.pattern.kind {
Expand Down Expand Up @@ -131,7 +152,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}

PatKind::Binding { name, mutability, mode, var, ty, ref subpattern, is_primary: _ } => {
candidate.bindings.push(Binding {
bindings.push(Binding {
name,
mutability,
span: match_pair.pattern.span,
Expand Down
6 changes: 3 additions & 3 deletions src/test/mir-opt/early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff
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Expand Up @@ -52,13 +52,13 @@
- }
-
- bb3: {
StorageLive(_8); // scope 0 at $DIR/early_otherwise_branch.rs:5:15: 5:16
_8 = (((_3.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch.rs:5:15: 5:16
StorageLive(_9); // scope 0 at $DIR/early_otherwise_branch.rs:5:24: 5:25
_9 = (((_3.1: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch.rs:5:24: 5:25
StorageLive(_8); // scope 0 at $DIR/early_otherwise_branch.rs:5:15: 5:16
_8 = (((_3.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch.rs:5:15: 5:16
_0 = const 0_u32; // scope 1 at $DIR/early_otherwise_branch.rs:5:31: 5:32
StorageDead(_9); // scope 0 at $DIR/early_otherwise_branch.rs:5:31: 5:32
StorageDead(_8); // scope 0 at $DIR/early_otherwise_branch.rs:5:31: 5:32
StorageDead(_9); // scope 0 at $DIR/early_otherwise_branch.rs:5:31: 5:32
- goto -> bb4; // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 7:6
+ goto -> bb3; // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 7:6
}
Expand Down
6 changes: 3 additions & 3 deletions src/test/mir-opt/early_otherwise_branch.opt2.EarlyOtherwiseBranch.diff
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Expand Up @@ -59,13 +59,13 @@
-
- bb4: {
+ bb2: {
StorageLive(_9); // scope 0 at $DIR/early_otherwise_branch.rs:13:15: 13:16
_9 = (((_3.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch.rs:13:15: 13:16
StorageLive(_10); // scope 0 at $DIR/early_otherwise_branch.rs:13:24: 13:25
_10 = (((_3.1: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch.rs:13:24: 13:25
StorageLive(_9); // scope 0 at $DIR/early_otherwise_branch.rs:13:15: 13:16
_9 = (((_3.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch.rs:13:15: 13:16
_0 = const 0_u32; // scope 1 at $DIR/early_otherwise_branch.rs:13:31: 13:32
StorageDead(_10); // scope 0 at $DIR/early_otherwise_branch.rs:13:31: 13:32
StorageDead(_9); // scope 0 at $DIR/early_otherwise_branch.rs:13:31: 13:32
StorageDead(_10); // scope 0 at $DIR/early_otherwise_branch.rs:13:31: 13:32
- goto -> bb6; // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 16:6
+ goto -> bb4; // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 16:6
}
Expand Down
12 changes: 6 additions & 6 deletions src/test/mir-opt/early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff
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Expand Up @@ -71,16 +71,16 @@

- bb4: {
+ bb3: {
StorageLive(_11); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:15: 6:16
_11 = (((_4.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:15: 6:16
StorageLive(_12); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:24: 6:25
_12 = (((_4.1: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:24: 6:25
StorageLive(_13); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:33: 6:34
_13 = (((_4.2: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:33: 6:34
StorageLive(_12); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:24: 6:25
_12 = (((_4.1: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:24: 6:25
StorageLive(_11); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:15: 6:16
_11 = (((_4.0: std::option::Option<u32>) as Some).0: u32); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:15: 6:16
_0 = const 0_u32; // scope 1 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:40: 6:41
StorageDead(_13); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:40: 6:41
StorageDead(_12); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:40: 6:41
StorageDead(_11); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:40: 6:41
StorageDead(_12); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:40: 6:41
StorageDead(_13); // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:6:40: 6:41
- goto -> bb5; // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 8:6
+ goto -> bb4; // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 8:6
}
Expand Down
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