Flatten anonymous bitfield sub-properties (#408 phase 2)#1727
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jevansaks merged 2 commits intoJun 13, 2026
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Phase 1 (microsoft#1721) surfaces fields nested in anonymous structs/unions as [UnscopedRef] ref accessors, but only the raw bitfield backing field was reachable that way. This forwards the computed bitfield sub-properties (e.g. PSAPI_WORKING_SET_EX_BLOCK's Valid/ShareCount/Win32Protection) as value get/set properties on the declaring struct, so they can be read and written directly as value.Field instead of value.Anonymous.Anonymous.Field. Each forwarded property delegates to the nested property (readonly get => this.Anonymous...Prop; set => ... = value) and inherits its docs via <inheritdoc>. The projected type is computed from the bitfield width (1 bit => bool, else smallest fitting integer of the backing field's signedness), matching the nested property exactly, so no narrowing occurs even when the backing field is wider (e.g. nuint backing, byte/ushort sub-properties). The raw backing field continues to be surfaced as a ref (phase 1 behavior is unchanged; this is additive). Only fields reached through anonymous holders are forwarded; bitfields under a named holder are not. Gated on C# 11 like the rest of the feature. Adds syntax-shape unit tests (PSAPI_WORKING_SET_EX_BLOCK, including the named-holder negative case and the C# 10 gate) and functional tests proving the forwarded properties alias the same storage, pack without bit overlap (exact backing-field bit pattern asserted), and isolate neighbors. Validated across net8.0, net472, and net10.0.
The aligned trailing comments in FlattenedBitfieldPropertiesPackWithoutOverlap used multiple consecutive spaces, which fails the CI -warnAsError build (SA1025). Collapse to a single space before each comment.
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Fixes #408 |
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The "Fixes" has to go in the description I'm pretty sure (which I did by editing yours) |
jevansaks
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Jun 13, 2026
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Summary
Phase 2 follow-up to #1721. Phase 1 surfaces fields nested in anonymous structs/unions as
[UnscopedRef] refaccessors on the declaring struct, but for a bitfield-bearing nested struct only the raw backing field was reachable that way. This forwards the computed bitfield sub-properties (e.g.PSAPI_WORKING_SET_EX_BLOCK''sValid/ShareCount/Win32Protection) as valueget/setproperties on the declaring struct, so callers can read and write them directly asvalue.ShareCountinstead ofvalue.Anonymous.Anonymous.ShareCount.Details
readonly get => this.Anonymous...Prop; set => ... = value;) and inherits its docs via<inheritdoc>.bool, otherwise the smallest integer of the backing field''s signedness that fits), matching the nested property exactly — so no narrowing occurs even when the backing field is wider (e.g. annuintbacking field withbyte/ushortsub-properties).ref(Phase 1 behavior unchanged; this is purely additive).Tests
StructTests): forwarding shape + types onPSAPI_WORKING_SET_EX_BLOCK, a negative case proving the sibling namedInvalidholder''s bitfields are not forwarded, and the C# 10 gate.GenerationSandbox.Tests, compiled & executed): the forwarded properties alias the same storage as the nested path; all nine sub-fields pack without bit overlap (the exact backing-field bit pattern is asserted); and writes to one field do not disturb its neighbors.Fixes #408