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Make process_obligations() greedier. #66408

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Merged
merged 1 commit into from
Dec 4, 2019
Merged

Make process_obligations() greedier. #66408

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13 changes: 12 additions & 1 deletion src/librustc_data_structures/obligation_forest/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -395,7 +395,16 @@ impl<O: ForestObligation> ObligationForest<O> {
let mut errors = vec![];
let mut stalled = true;

for index in 0..self.nodes.len() {
// Note that the loop body can append new nodes, and those new nodes
// will then be processed by subsequent iterations of the loop.
//
// We can't use an iterator for the loop because `self.nodes` is
// appended to and the borrow checker would complain. We also can't use
// `for index in 0..self.nodes.len() { ... }` because the range would
// be computed with the initial length, and we would miss the appended
// nodes. Therefore we use a `while` loop.
let mut index = 0;
while index < self.nodes.len() {
let node = &mut self.nodes[index];

debug!("process_obligations: node {} == {:?}", index, node);
Expand All @@ -406,6 +415,7 @@ impl<O: ForestObligation> ObligationForest<O> {
// out of sync with `nodes`. It's not very common, but it does
// happen, and code in `compress` has to allow for it.
if node.state.get() != NodeState::Pending {
index += 1;
continue;
}
let result = processor.process_obligation(&mut node.obligation);
Expand Down Expand Up @@ -441,6 +451,7 @@ impl<O: ForestObligation> ObligationForest<O> {
});
}
}
index += 1;
}

if stalled {
Expand Down
30 changes: 21 additions & 9 deletions src/librustc_data_structures/obligation_forest/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,7 @@ fn push_pop() {
"A" => ProcessResult::Changed(vec!["A.1", "A.2", "A.3"]),
"B" => ProcessResult::Error("B is for broken"),
"C" => ProcessResult::Changed(vec![]),
"A.1" | "A.2" | "A.3" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_| {}), DoCompleted::Yes);
Expand All @@ -94,6 +95,7 @@ fn push_pop() {
"A.2" => ProcessResult::Unchanged,
"A.3" => ProcessResult::Changed(vec!["A.3.i"]),
"D" => ProcessResult::Changed(vec!["D.1", "D.2"]),
"A.3.i" | "D.1" | "D.2" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_| {}), DoCompleted::Yes);
Expand All @@ -113,6 +115,7 @@ fn push_pop() {
"A.3.i" => ProcessResult::Changed(vec![]),
"D.1" => ProcessResult::Changed(vec!["D.1.i"]),
"D.2" => ProcessResult::Changed(vec!["D.2.i"]),
"D.1.i" | "D.2.i" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_| {}), DoCompleted::Yes);
Expand Down Expand Up @@ -161,35 +164,38 @@ fn success_in_grandchildren() {
forest.process_obligations(&mut C(|obligation| {
match *obligation {
"A" => ProcessResult::Changed(vec!["A.1", "A.2", "A.3"]),
"A.1" => ProcessResult::Changed(vec![]),
"A.2" => ProcessResult::Changed(vec!["A.2.i", "A.2.ii"]),
"A.3" => ProcessResult::Changed(vec![]),
"A.2.i" | "A.2.ii" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_| {}), DoCompleted::Yes);
assert!(ok.unwrap().is_empty());
let mut ok = ok.unwrap();
ok.sort();
assert_eq!(ok, vec!["A.1", "A.3"]);
assert!(err.is_empty());

let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations(&mut C(|obligation| {
match *obligation {
"A.1" => ProcessResult::Changed(vec![]),
"A.2" => ProcessResult::Changed(vec!["A.2.i", "A.2.ii"]),
"A.3" => ProcessResult::Changed(vec![]),
"A.2.i" => ProcessResult::Unchanged,
"A.2.ii" => ProcessResult::Changed(vec![]),
_ => unreachable!(),
}
}, |_| {}), DoCompleted::Yes);
let mut ok = ok.unwrap();
ok.sort();
assert_eq!(ok, vec!["A.1", "A.3"]);
assert_eq!(ok.unwrap(), vec!["A.2.ii"]);
assert!(err.is_empty());

let Outcome { completed: ok, errors: err, .. } =
forest.process_obligations(&mut C(|obligation| {
match *obligation {
"A.2.i" => ProcessResult::Changed(vec!["A.2.i.a"]),
"A.2.ii" => ProcessResult::Changed(vec![]),
"A.2.i.a" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_| {}), DoCompleted::Yes);
assert_eq!(ok.unwrap(), vec!["A.2.ii"]);
assert!(ok.unwrap().is_empty());
assert!(err.is_empty());

let Outcome { completed: ok, errors: err, .. } =
Expand Down Expand Up @@ -222,6 +228,7 @@ fn to_errors_no_throw() {
forest.process_obligations(&mut C(|obligation| {
match *obligation {
"A" => ProcessResult::Changed(vec!["A.1", "A.2", "A.3"]),
"A.1" | "A.2" | "A.3" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_|{}), DoCompleted::Yes);
Expand All @@ -243,6 +250,7 @@ fn diamond() {
forest.process_obligations(&mut C(|obligation| {
match *obligation {
"A" => ProcessResult::Changed(vec!["A.1", "A.2"]),
"A.1" | "A.2" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_|{}), DoCompleted::Yes);
Expand All @@ -254,6 +262,7 @@ fn diamond() {
match *obligation {
"A.1" => ProcessResult::Changed(vec!["D"]),
"A.2" => ProcessResult::Changed(vec!["D"]),
"D" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_|{}), DoCompleted::Yes);
Expand Down Expand Up @@ -282,6 +291,7 @@ fn diamond() {
forest.process_obligations(&mut C(|obligation| {
match *obligation {
"A'" => ProcessResult::Changed(vec!["A'.1", "A'.2"]),
"A'.1" | "A'.2" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_|{}), DoCompleted::Yes);
Expand All @@ -293,6 +303,7 @@ fn diamond() {
match *obligation {
"A'.1" => ProcessResult::Changed(vec!["D'", "A'"]),
"A'.2" => ProcessResult::Changed(vec!["D'"]),
"D'" | "A'" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_|{}), DoCompleted::Yes);
Expand Down Expand Up @@ -370,6 +381,7 @@ fn orphan() {
"B" => ProcessResult::Unchanged,
"C1" => ProcessResult::Changed(vec![]),
"C2" => ProcessResult::Changed(vec![]),
"D" | "E" => ProcessResult::Unchanged,
_ => unreachable!(),
}
}, |_|{}), DoCompleted::Yes);
Expand Down
4 changes: 3 additions & 1 deletion src/test/ui/traits/cycle-cache-err-60010.stderr
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Expand Up @@ -6,7 +6,7 @@ LL | _parse: <ParseQuery as Query<RootDatabase>>::Data,
|
= note: required because of the requirements on the impl of `Query<RootDatabase>` for `ParseQuery`

error[E0275]: overflow evaluating the requirement `RootDatabase: SourceDatabase`
error[E0275]: overflow evaluating the requirement `Runtime<RootDatabase>: std::panic::RefUnwindSafe`
--> $DIR/cycle-cache-err-60010.rs:31:5
|
LL | type Storage;
Expand All @@ -17,6 +17,8 @@ LL | impl Database for RootDatabase {
LL | type Storage = SalsaStorage;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: required because it appears within the type `RootDatabase`
= note: required because of the requirements on the impl of `SourceDatabase` for `RootDatabase`
= note: required because of the requirements on the impl of `Query<RootDatabase>` for `ParseQuery`
= note: required because it appears within the type `SalsaStorage`

Expand Down