Skip to content

Fix bad jump from yield break inside catch in async-iterator #80927

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Nov 6, 2025
Merged

Fix bad jump from yield break inside catch in async-iterator #80927

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
27b09a8
Fix bad jump from yield break inside catch in async-iterator
Oct 27, 2025
d426a36
Add another test
Oct 28, 2025
9445ba2
Address feedback
Nov 6, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 14 additions & 15 deletions ...ilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncIteratorMethodToStateMachineRewriter.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ internal sealed class AsyncIteratorMethodToStateMachineRewriter : AsyncMethodToS
/// Where should we jump to to continue the execution of disposal path.
///
/// Initially, this is the method's return value label (<see cref="AsyncMethodToStateMachineRewriter._exprReturnLabel"/>).
/// Inside a `try` or `catch` with a `finally`, we'll use the label directly preceding the `finally`.
/// Inside a `try` or `catch` with a `finally`, we'll use the label directly following the `finally`.
/// Inside a `try` or `catch` with an extracted `finally`, we will use the label preceding the extracted `finally`.
/// Inside a `finally`, we'll have no/null label (disposal continues without a jump).
/// </summary>
Expand Down Expand Up @@ -351,7 +351,8 @@ private BoundExpressionStatement SetDisposeMode(bool value)

/// <summary>
/// An async-iterator state machine has a flag indicating "dispose mode".
/// We enter dispose mode by calling DisposeAsync() when the state machine is paused on a `yield return`.
/// We enter dispose mode by calling DisposeAsync() when the state machine is paused on a `yield return`,
/// or by reaching a `yield break`.
/// DisposeAsync() will resume execution of the state machine from that state (using existing dispatch mechanism
/// to restore execution from a given state, without executing other code to get there).
///
Expand All @@ -366,21 +367,11 @@ private BoundExpressionStatement SetDisposeMode(bool value)
public override BoundNode VisitTryStatement(BoundTryStatement node)
{
var savedDisposalLabel = _currentDisposalLabel;
LabelSymbol afterFinally = null;
if (node.FinallyBlockOpt is object)
{
var finallyEntry = F.GenerateLabel("finallyEntry");
_currentDisposalLabel = finallyEntry;

// Add finallyEntry label:
// try
// {
// ...
// finallyEntry:
// }

node = node.Update(
tryBlock: F.Block(node.TryBlock, F.Label(finallyEntry)),
node.CatchBlocks, node.FinallyBlockOpt, node.FinallyLabelOpt, node.PreferFaultHandler);
afterFinally = F.GenerateLabel("afterFinally");
_currentDisposalLabel = afterFinally;
}
else if (node.FinallyLabelOpt is object)
{
Expand All @@ -389,6 +380,14 @@ public override BoundNode VisitTryStatement(BoundTryStatement node)

var result = (BoundStatement)base.VisitTryStatement(node);

if (afterFinally != null)
{
// Append a label immediately after the try-catch-finally statement,
// which disposal within `try`/`catch` blocks jumps to in order to pass control flow to the `finally` block implicitly:
// tryEnd:
result = F.Block(result, F.Label(afterFinally));
}

_currentDisposalLabel = savedDisposalLabel;

if (node.FinallyBlockOpt != null && _currentDisposalLabel is object)
Expand Down
Loading