[mono][wasm] Respect [Un]SupportedOSPlatform in the Mono pinvoke generator

[lewing]

Summary

Fixes #110870. Building a browser-wasm app that references a Windows-only P/Invoke with non-blittable parameters (e.g. the gdi32 GetCharABCWidthsFloat, which takes HandleRef / object) emits spurious diagnostics on the Mono wasm backend:

WASM0060 : Type System.Object is not blittable: Not a ValueType
WASM0062 : Type System.Runtime.InteropServices.HandleRef is not blittable: Field _wrapper is not blittable
WASM0001 : Could not get pinvoke, or callbacks for method '...GetCharABCWidthsFloat' because 'System.NotSupportedException: Unsupported parameter type ...'

Root cause

The Mono pinvoke collector (src/tasks/WasmAppBuilder/mono/PInvokeCollector.cs) analyzed every P/Invoke and callback in every referenced assembly, without consulting [SupportedOSPlatform] / [UnsupportedOSPlatform]. So a method that is only usable on Windows still had its (non-blittable) signature analyzed when targeting the browser, producing the warnings.

The CoreCLR collector already handles this — it skips a method up front via IsUnsupportedOnPlatform / EvaluatePlatformAttributes, driven by a TargetOS. That check was never ported to the Mono collector, so #110870 still reproduces on Mono while it's fixed on CoreCLR.

Fix

Mirror the CoreCLR platform check into the Mono generator:

• Thread TargetOS through ManagedToNativeGenerator → PInvokeTableGenerator → PInvokeCollector (the shared <ManagedToNativeGenerator> invocation now passes TargetOS="$(TargetOS)"; the Mono task gets a TargetOS property defaulting to browser, mirroring CoreCLR).
• Skip pinvokes and callbacks whose method, declaring type (including nesting), or assembly is unsupported on the target OS — i.e. [UnsupportedOSPlatform(target)], or a [SupportedOSPlatform(...)] list that doesn't include the target.

Only affects the Mono wasm build task; CoreCLR is unchanged.

Test

Adds PInvokeTableGeneratorTests.UnsupportedOSPlatformPInvokeIsSkipped: builds a browser app containing a [SupportedOSPlatform("windows")] non-blittable pinvoke and asserts none of WASM0001/WASM0060/WASM0062 are emitted.

Verification

Built the Mono wasm build task and ran a repro (browser app with a [SupportedOSPlatform("windows")] gdi32-style pinvoke taking HandleRef/object), plus the new WBT test:

• Without the fix: WASM0060 + WASM0062 + WASM0001 (matching the report).
• With the fix: 0 warnings; the new test passes (Debug + Release).

Note

This pull request was authored with GitHub Copilot.

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[Copilot]

Pull request overview

This PR updates the Mono WASM P/Invoke collection/generation step to respect [SupportedOSPlatform] / [UnsupportedOSPlatform] attributes, so platform-specific (e.g., Windows-only) P/Invokes and callbacks are skipped when building for browser/WASI targets and don’t emit irrelevant non-blittable/signature diagnostics.

Changes:

• Thread TargetOS through the Mono ManagedToNativeGenerator → PInvokeTableGenerator → PInvokeCollector pipeline and validate supported target values (browser, wasi).
• Add platform-attribute evaluation to the Mono PInvokeCollector and skip unsupported P/Invokes/callbacks (mirroring the CoreCLR collector behavior).
• Add a WASM build test asset + regression test asserting Windows-only non-blittable P/Invokes don’t produce WASM0001/WASM0060/WASM0062 when targeting browser.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/tasks/WasmAppBuilder/mono/PInvokeTableGenerator.cs	Passes targetOS into the Mono PInvokeCollector so platform filtering can occur during scan.
src/tasks/WasmAppBuilder/mono/PInvokeCollector.cs	Implements platform attribute evaluation/caching and skips unsupported P/Invokes and callbacks.
src/tasks/WasmAppBuilder/mono/ManagedToNativeGenerator.cs	Introduces/validates TargetOS and forwards it into PInvokeTableGenerator.
src/mono/wasm/Wasm.Build.Tests/PInvokeTableGeneratorTests.cs	Adds a regression test asserting the diagnostics are not emitted for a Windows-only P/Invoke.
src/mono/wasm/testassets/EntryPoints/PInvoke/UnsupportedOSPlatform.cs	Adds a Windows-only, intentionally non-blittable P/Invoke sample used by the new test.
src/mono/wasm/build/WasmApp.Common.targets	Passes $(TargetOS) into ManagedToNativeGenerator so the task can apply platform filtering.

[github-actions]

Workflow state for the Holistic Review Orchestrator.

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[github-actions]

Holistic Review

Motivation: When building a browser/wasm app, the wasm P/Invoke collector analyzes every DllImport method regardless of platform. A Windows-only P/Invoke (e.g. GDI/USER32 with non-blittable parameters) that can never be reached on the browser was still being analyzed, producing spurious WASM0060/WASM0062/WASM0001 diagnostics and build failures (#110870).

Approach: The ManagedToNativeGenerator MSBuild task now accepts a TargetOS property (defaulting to browser, validated against browser/wasi), threaded through PInvokeTableGenerator into PInvokeCollector. The collector skips P/Invoke methods and callbacks that are unsupported on the target OS, determined by walking SupportedOSPlatform/UnsupportedOSPlatform attributes at method → declaring-type (recursively through nesting) → assembly scope, with per-type and per-assembly caches. WasmApp.Common.targets passes TargetOS to the task. A regression test asset and a [Theory] test assert the diagnostics are no longer emitted.

Summary: This is a clean, well-targeted fix. The platform-attribute resolution correctly mirrors runtime precedence (explicit method result wins over type; SupportedOSPlatform present-but-not-listing-target implies unsupported), caching is keyed appropriately, and the new TargetOS plumbing matches the already-existing pattern in the coreclr sibling (src/tasks/WasmAppBuilder/coreclr/ManagedToNativeGenerator.cs), keeping the two variants consistent. The try/catch around attribute inspection preserves the collector's prior tolerance of unresolvable attribute assemblies. The regression test uses the established CopyTestAsset/ReplaceFile/BuildProject helpers and the correct native-mono category. I found no correctness or design concerns; behavior for the default browser target is unchanged for platform-agnostic P/Invokes. Non-blocking observation: EvaluatePlatformAttributes compares the platform name by exact string equality, so a version-qualified attribute value would not match browser/wasi—harmless in practice since those targets are not version-qualified.

Detailed Findings

No actionable issues. LGTM.

Note

This review was generated by this repository's Holistic Review agentic workflow to complement the built-in Copilot review.

Generated by Holistic Review · 62 AIC · ⌖ 10.4 AIC · ⊞ 10K

[lewing]

/backport to release/10.0

[github-actions]

Started backporting to release/10.0 (link to workflow run)

[github-actions]

@lewing backporting to release/10.0 failed, the patch most likely resulted in conflicts. Please backport manually!

git am output

$ git am --3way --empty=keep --ignore-whitespace --keep-non-patch changes.patch

Applying: [wasm] Respect [Un]SupportedOSPlatform in the Mono pinvoke generator
Using index info to reconstruct a base tree...
M	src/mono/wasm/Wasm.Build.Tests/PInvokeTableGeneratorTests.cs
M	src/mono/wasm/build/WasmApp.Common.targets
A	src/tasks/WasmAppBuilder/mono/ManagedToNativeGenerator.cs
A	src/tasks/WasmAppBuilder/mono/PInvokeCollector.cs
A	src/tasks/WasmAppBuilder/mono/PInvokeTableGenerator.cs
Falling back to patching base and 3-way merge...
Auto-merging src/mono/wasm/Wasm.Build.Tests/PInvokeTableGeneratorTests.cs
Auto-merging src/mono/wasm/build/WasmApp.Common.targets
Auto-merging src/tasks/WasmAppBuilder/ManagedToNativeGenerator.cs
CONFLICT (content): Merge conflict in src/tasks/WasmAppBuilder/ManagedToNativeGenerator.cs
Auto-merging src/tasks/WasmAppBuilder/PInvokeCollector.cs
Auto-merging src/tasks/WasmAppBuilder/PInvokeTableGenerator.cs
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
Patch failed at 0001 [wasm] Respect [Un]SupportedOSPlatform in the Mono pinvoke generator
Error: The process '/usr/bin/git' failed with exit code 128

Link to workflow output