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PathIo: generate System.IO forwarding APIs with a Roslyn source generator - #249
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ghostflyby wants to merge 6 commits into
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ghostflyby wants to merge 6 commits into
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…rator Add TruePath.PathIoGenerator, a Roslyn incremental source generator that fills the other partial part of PathIo (marked with GenerateSystemIoExtensionsAttribute) with forwarding extension methods for every public static File/Directory method of the current target framework, with the BCL XML documentation copied verbatim. - PathIo.cs keeps only the members with custom behavior or documentation; pure forwarders are generated (93 methods on net8.0, 66 on netstandard2.0), introducing previously missing APIs (symlinks, OpenHandle, Replace, EnumerateDirectories, GetParent, etc.). - Hand-written members win over generated ones, both by rewritten signature and by the forwarding call inside their body; File wins over Directory on duplicate signatures; path-io-exclusions.txt lists APIs deliberately not exposed. - BCL XML docs reach the generator via AdditionalFiles (the command-line compiler does not attach them to references), are extracted line-by-line to survive malformed netstandard.xml, and param/paramref names are normalized against the generated parameters; path parameters keep the historical sourceFile/destFile names. - Generated code uses short type names for imported namespaces. - Tests: generator unit tests plus a reflection completeness test asserting BCL API ⊆ generated ∪ hand-written ∪ exclusions.
…ndex - Drop dead test helpers, redundant nullability and qualifiers, an unused RenderFile parameter, and a redundant currentName check in BclDocIndex. - Store parsed XElement members in the doc index instead of raw strings: XElement.Parse is now called exactly once per member with its result actually used, instead of a validation-only call with a discarded return value followed by a second parse at emission time. The cached element is cloned before doc formatting, which renames param elements in place.
ForNeVeR
self-requested a review
October 21, 2026 09:20
- Strip the UTF-8 BOM from TruePath.sln introduced by an editor. - Add a REUSE license companion for path-io-exclusions.txt. - Pin the generator test references to the Basic.Reference.Assemblies package: discovering the SDK's reference packs from the test host's runtime directory is not reliable on CI runners where the runtime and the SDK live in different roots. The test helper now also surfaces the driver diagnostics when the expected generated tree is missing. - The completeness test now mirrors the generator's third exclusion rule: BCL overloads that hand-written members forward to with path.Value as the first argument (previously flagged Directory.Delete(string,bool)).
The SPDX tags emitted into the generated file are string literals in the generator source; REUSE picked them up as this file's own tags and failed on the trailing C# syntax inside the expression.
- Reject nested marked classes with the new TPG004 diagnostic instead of silently generating a same-named top-level class, and derive the hint name from the full type name (sanitized) so same-named types cannot collide. - Hoist the exclusion file texts and the XML documentation index into their own cached pipeline nodes: the .xml filter now happens before BclDocIndex.Build, so editing path-io-exclusions.txt no longer re-scans the ~15 MB documentation files, and the exclusion file is matched by exact file name. - Move the hand-written member analysis into the syntax-anchored ForAttributeWithMetadataName transform (equatable MarkedType payload with sorted arrays), so it is cached across edits in unrelated files instead of re-running on every compilation change. - Clone the member element inside DocFormatting.ToDocLines rather than at the call site, and read the XML documentation files through SourceText.Lines instead of ToString/Replace/Split (three fewer full copies of the text). Generated output verified byte-identical on both target frameworks before and after the change.
ghostflyby
marked this pull request as ready for review
October 21, 2026 10:12
…int names - Render every special type with its C# keyword inside generic arguments too: net10 span-based APIs like ReadOnlySpan<char> previously rendered as ReadOnlySpan<Char> because System_Char was missing from the table. - Emit the generated file under the simple type name again (PathIo.Generated.g.cs): the full-name sanitization was only needed for nested marked types, which are now rejected with TPG004. Both verified by temporarily building TruePath.SystemIo against net10.0, which generates 112 methods including the new span- and Memory-based overloads without any rule changes.
This was referenced Oct 21, 2026
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Summary
Introduce a Roslyn incremental source generator (TruePath.PathIoGenerator) that fills the other partial part of PathIo (marked with [GenerateSystemIoExtensions]) with forwarding extension methods for every public static File/Directory method of the current target framework, copying the BCL XML documentation verbatim. PathIo.cs shrinks to the members with custom behavior or documentation.
Changes
Testing