For an async iterator with an [EnumeratorCancellation] cancellation token, the
hoisted-local cleanup (stfld <>u__N(this, null)) can be emitted before the
combined CancellationTokenSource disposal in the set-result and catch blocks.
CheckSetResultReturnBlock and ValidateCatchBlock only consumed that cleanup after
the disposal, so the `pos + 2 == count` test missed the dispose pattern and the
analysis failed, leaving the raw state machine (catch (object), goto case, ...).
Allow the cleanup to appear before the combined-tokens disposal as well.
Assisted-by: Copilot:claude-opus-4.8:GitHub Copilot CLI
Runtime async is a compiler feature that emits ordinary async/await (a
C# 5 construct), so reconstructing it should not require selecting C# 15.
The dedicated RuntimeAsync setting was also redundant: AsyncAwaitDecompiler
already runs the runtime-async transforms only when AsyncAwait is enabled.
Fold the behavior into the AsyncAwait setting and drop the separate toggle.
Assisted-by: Claude:claude-opus-4-8:Claude Code
For an async method on a value type Roslyn cannot keep a managed reference to the caller's struct alive across an await, so it copies *this into a local at method entry and rewrites every "this.field" access to go through the copy. The decompiler then sees an extra "AsyncInStruct asyncInStruct = *this;" prelude and renders user-level "i++" as "asyncInStruct.i++". State-machine async normally avoids this because TranslateFieldsToLocalAccess already remaps the captured-this field back to the function's own this parameter.
Detect the prelude in runtime-async methods (entry-point stloc V_X(ldobj T(ldloc this)) with the local typed as the containing value type) and rewrite every "ldloc V_X" / "ldloca V_X" to go through the function's this parameter instead, then drop the now-dead copy. The mutation semantics are unchanged — runtime-async struct methods never reflect mutations back to the caller anyway, so re-pointing the access at this is purely a fidelity restoration.
Brings AsyncInStruct.Test back to its source ("i++" / "i + xx.i"). The only remaining failure in RuntimeAsync is Issue2436 (early-return-from-nested-catch encoded as a flag).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Roslyn's runtime-async lowering uses AsyncHelpers.Await(Task) for Task awaitables (already handled by TransformAsyncHelpersAwaitToAwait in EarlyExpressionTransforms) but emits a manual GetAwaiter / get_IsCompleted / AsyncHelpers.UnsafeAwaitAwaiter / GetResult sequence for non-Task awaitables — YieldAwaitable, ConfiguredCancelableAsyncEnumerable.Enumerator from await foreach, etc. Add a new RuntimeAsyncManualAwaitTransform invoked from AsyncAwaitDecompiler's runtime-async dispatch that recognizes the three-block shape (head with stloc awaiter + IsCompleted check + branch, pause block calling UnsafeAwaitAwaiter, completed block starting with GetResult), strips the suspend machinery, and replaces the GetResult call with an Await IL instruction. When GetAwaiter takes the address of a temporary set in the same block, also drop the temporary store and use the underlying awaitable expression.
This collapses the LoadsToCatch await-Task.Yield bodies. AsyncForeach should benefit too (its MoveNextAsync awaits go through this path).
Roslyn's runtime-async lowering flattens these into a TryCatch[object] with a captured-rethrow pattern (try-finally) or a TryCatch[T] with a flag-int discriminator and a guarded post-catch body (try-catch). Add a new transform invoked from AsyncAwaitDecompiler when the state-machine matches fail and the method has the runtime-async impl bit; it pattern-matches both shapes and rewrites them back to TryFinally / TryCatch with the original catch body inlined into the handler.
The state-machine and runtime-async lowerings of try-finally use the same catch-handler shape and the same dominator-based finally-body extraction, so promote those to internal static helpers (MatchObjectStoreCatchHandler, MoveDominatedBlocksToContainer) on AwaitInFinallyTransform and call them from the new transform. Filter-bearing catches and multi-handler tries are still left to the standard pipeline.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
or implicit sequence point without creating overlapping sequence points.
If such a location cannot be found do, nothing. Fill in the
gaps with hidden sequence points.
Also emit a sequence point for
the prolog to account for seqeunce point there emitted by the C#
compiler. Without this, the debugger can stop there on a step in
using the original pdb, then decompile resulting in a no-code at this
location failure.
This was left-over from earlier versions; but ILSpy stopped caring so much about variable vs. stack slot since Roslyn started to optimize more aggressively.
The change of variable type caused problems for debug information and could even cause an assertion.
Closes#1456, closes#1562.
Sebastien Lebreton
Siegfried Pammer
Daniel Grunwald
ElektroKill
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Jackson Davis
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