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[SE-0298: Async/Await: Sequences] Enable by default. #35954

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Merged
merged 2 commits into from
Feb 14, 2021
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[SE-0298: Async/Await: Sequences] Enable by default. #35954

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540d2b0
[SE-0298: Async/Await: Sequences] Enable by default.
DougGregor Feb 12, 2021
dafe4fa
Fix typo in ChangeLog
DougGregor Feb 12, 2021
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14 changes: 14 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -61,6 +61,19 @@ Swift Next
}
```

* [SE-0298][]:

The "for" loop can be used to traverse asynchronous sequences in asynchronous code:

```swift
for try await line in myFile.lines() {
// Do something with each line
}
```

Asynchronous for loops use asynchronous sequences, defined by the protocol
`AsyncSequence` and its corresponding `AsyncIterator`.

**Add new entries to the top of this section, not here!**

Swift 5.4
Expand Down Expand Up @@ -8309,6 +8322,7 @@ Swift 1.0
[SE-0286]: <https://github.com/apple/swift-evolution/blob/main/proposals/0286-forward-scan-trailing-closures.md>
[SE-0287]: <https://github.com/apple/swift-evolution/blob/main/proposals/0287-implicit-member-chains.md>
[SE-0296]: <https://github.com/apple/swift-evolution/blob/main/proposals/0296-async-await.md>
[SE-0298]: <https://github.com/apple/swift-evolution/blob/main/proposals/0298-asyncsequence.md>

[SR-75]: <https://bugs.swift.org/browse/SR-75>
[SR-106]: <https://bugs.swift.org/browse/SR-106>
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6 changes: 2 additions & 4 deletions lib/Parse/ParseStmt.cpp
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Expand Up @@ -2127,11 +2127,9 @@ ParserResult<Stmt> Parser::parseStmtForEach(LabeledStmtInfo LabelInfo) {
SourceLoc AwaitLoc;
SourceLoc TryLoc;

if (shouldParseExperimentalConcurrency() &&
Tok.isContextualKeyword("await")) {
if (Tok.isContextualKeyword("await")) {
AwaitLoc = consumeToken();
} else if (shouldParseExperimentalConcurrency() &&
Tok.is(tok::kw_try)) {
} else if (Tok.is(tok::kw_try)) {
TryLoc = consumeToken();
if (Tok.isContextualKeyword("await")) {
AwaitLoc = consumeToken();
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3 changes: 2 additions & 1 deletion test/Parse/foreach_async.swift
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@@ -1,5 +1,6 @@
// RUN: %target-typecheck-verify-swift -enable-experimental-concurrency
// RUN: %target-typecheck-verify-swift
// REQUIRES: concurrency
import _Concurrency

struct AsyncRange<Bound: Comparable & Strideable>: AsyncSequence, AsyncIteratorProtocol where Bound.Stride : SignedInteger {
var range: Range<Bound>.Iterator
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