PInvoke skill test *IGNORE THIS* by adityamandaleeka · Pull Request #58 · dotnet/skills

adityamandaleeka · 2026-02-20T05:29:59Z

No description provided.

…er and README conventions

…klist

…ling

…ct references - Expand frontmatter description with trigger info (when to use / not use) - Remove redundant When to Use / When Not to Use body sections - Trim type mapping to dangerous-only entries inline; full table in references/type-mapping.md - Move blittable structs, common pitfalls, failure modes, resources to references/ - Reduce SKILL.md from ~510 to 285 lines

… portability notes

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…ing notes

Copilot

Pull request overview

Adds a new dotnet-pinvoke skill with supporting reference documentation and a basic evaluation test suite to validate expected P/Invoke declarations across TFMs.

Changes:

Introduces dotnet-pinvoke skill guide (SKILL.md) covering signatures, marshalling, lifetime, SafeHandle, and diagnostics.
Adds reference docs for native-to-.NET type mapping and common diagnostics/pitfalls.
Adds an eval scenario file to test LibraryImport vs DllImport expectations.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
`src/dotnet/tests/dotnet-pinvoke/eval.yaml`	Adds eval scenarios for generating P/Invoke declarations for .NET 8 and .NET Framework
`src/dotnet/skills/dotnet-pinvoke/SKILL.md`	New skill documentation for P/Invoke/LibraryImport workflow and best practices
`src/dotnet/skills/dotnet-pinvoke/references/type-mapping.md`	New reference table for native-to-.NET type mappings and struct layout guidance
`src/dotnet/skills/dotnet-pinvoke/references/diagnostics.md`	New reference for common P/Invoke pitfalls and debugging approach

Comments suppressed due to low confidence (1)

src/dotnet/skills/dotnet-pinvoke/references/type-mapping.md:26

This reference recommends CLong/CULong for C long, but those types are .NET 7+ and won’t be available when targeting .NET Framework. Since this doc/skill explicitly covers .NET Framework, please add a framework-specific note (e.g., conditional compilation using int on Windows and long on Unix, or a custom typedef/struct approach) so readers don’t end up with uncompilable signatures.

| C / Win32 Type | .NET Type | Why It's Dangerous |
|----------------|-----------|-------------------|
| `long` | **`CLong`** | C `long` is 32-bit on Windows, 64-bit on 64-bit Unix — never use `int` or `long`. With `LibraryImport`, requires `[assembly: DisableRuntimeMarshalling]` or you get SYSLIB1051. With `DllImport`, works without it |
| `size_t` | `nuint` | Pointer-sized. Never use `ulong` — causes stack corruption on 32-bit |

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Copilot · 2026-02-20T05:33:10Z

src/dotnet/skills/dotnet-pinvoke/SKILL.md

+```csharp
+[DllImport("mylib")]
+private static extern int ProcessRecords(
+    [In] Record[] records, nuint count, out uint outProcessed);
+```


Several DllImport examples use nuint for size_t (e.g., ProcessRecords). That won’t compile for .NET Framework consumers of this guidance; nuint is .NET 5+/C# 9+. Consider documenting UIntPtr as the .NET Framework/legacy equivalent (and nuint for modern TFMs), or show framework-specific variants so the examples are accurate for both targets.

Copilot · 2026-02-20T05:33:11Z

src/dotnet/skills/dotnet-pinvoke/references/type-mapping.md

+| `long` | **`CLong`** | C `long` is 32-bit on Windows, 64-bit on 64-bit Unix — never use `int` or `long`. With `LibraryImport`, requires `[assembly: DisableRuntimeMarshalling]` or you get SYSLIB1051. With `DllImport`, works without it |
+| `size_t` | `nuint` | Pointer-sized. Never use `ulong` — causes stack corruption on 32-bit |
+| `intptr_t` | `nint` | Pointer-sized |
+| `BOOL` (Win32) | `int` | Not `bool` — Win32 `BOOL` is 4 bytes |


The type mapping table unconditionally maps size_t to nuint and intptr_t to nint, but those types don’t exist on .NET Framework. Add a note/row for legacy TFMs (e.g., map to UIntPtr/IntPtr) so the reference remains correct when the target framework is .NET Framework.

This issue also appears on line 23 of the same file.

Copilot · 2026-02-20T05:33:11Z

src/dotnet/skills/dotnet-pinvoke/references/diagnostics.md

+
+| Pitfall | Impact | Solution |
+|---------|--------|----------|
+| `int` for `size_t` | Stack corruption on 64-bit | Use `nuint` |


Diagnostics table recommends nuint as the fix for size_t misuse, but for .NET Framework (and other pre-.NET 5 TFMs) the appropriate fix is UIntPtr. Consider updating this row to mention both (nuint on .NET 5+; UIntPtr on .NET Framework) to avoid generating uncompilable guidance.

Suggested change

| `int` for `size_t` | Stack corruption on 64-bit | Use `nuint` |

| `int` for `size_t` | Stack corruption on 64-bit | Use `nuint` (.NET 5+) or `UIntPtr` (pre-.NET 5, including .NET Framework) |

Copilot · 2026-02-20T05:33:12Z

src/dotnet/tests/dotnet-pinvoke/eval.yaml

@@ -0,0 +1,55 @@
+scenarios:
+  - name: "Generate LibraryImport declaration from C header (.NET Core 5+)"


Scenario name says ".NET Core 5+" but the prompt targets .NET 8 and the assertions require LibraryImport, which is only available on .NET 7+. This mismatch makes the scenario requirements unclear; update the scenario name (and/or prompt) to align with the minimum TFM for LibraryImport.

Suggested change

- name: "Generate LibraryImport declaration from C header (.NET Core 5+)"

- name: "Generate LibraryImport declaration from C header (.NET 8+)"

Copilot · 2026-02-20T05:33:12Z

src/dotnet/tests/dotnet-pinvoke/eval.yaml

+        value: "nuint"
+      - type: "output_contains"
+        value: "static extern"
+    rubric:
+      - "Uses DllImport instead of LibraryImport since the target is .NET Framework"
+      - "Maps size_t to nuint, not ulong"


The .NET Framework (x86) scenario asserts and rubrics for nuint, but nuint/nint are not available in .NET Framework/C# versions typically used there. For Framework guidance/tests, size_t should be represented as UIntPtr (or uint if you truly want x86-only). Update the assertions/rubric to match the correct type for .NET Framework.

Suggested change

value: "nuint"

- type: "output_contains"

value: "static extern"

rubric:

- "Uses DllImport instead of LibraryImport since the target is .NET Framework"

- "Maps size_t to nuint, not ulong"

value: "UIntPtr"

- type: "output_contains"

value: "static extern"

rubric:

- "Uses DllImport instead of LibraryImport since the target is .NET Framework"

- "Maps size_t to UIntPtr, not ulong"

Copilot · 2026-02-20T05:33:12Z

src/dotnet/skills/dotnet-pinvoke/SKILL.md

+| **Mechanism** | Runtime marshalling | Source generator (compile-time) |
+| **AOT / Trim safe** | No | Yes |
+| **String marshalling** | `CharSet` enum | `StringMarshalling` enum |
+| **Error handling** | `SetLastError` | `SetLastPInvokeError` |


LibraryImportAttribute uses SetLastError = true (same property name as DllImport); SetLastPInvokeError is not a valid attribute argument and will not compile in the examples. Replace SetLastPInvokeError with SetLastError throughout, while keeping Marshal.GetLastPInvokeError() for retrieval on .NET 7+.

Suggested change

| **Error handling** | `SetLastError` | `SetLastPInvokeError` |

| **Error handling** | `SetLastError` | `SetLastError` |

github-actions · 2026-02-20T05:42:18Z

Skill Validation Results

Skill	Scenario	Baseline	With Skill	Δ	Verdict
csharp-scripts	Test a C# language feature with a script	2.8/5	5.0/5	+2.2	✅
dotnet-pinvoke	Generate LibraryImport declaration from C header (.NET Core 5+)	4.0/5	5.0/5	+1.0	✅
dotnet-pinvoke	Generate LibraryImport declaration from C header (.NET Framework)	3.0/5	5.0/5	+2.0	✅

Model: claude-opus-4.6 | Judge: claude-opus-4.6

Full results

AaronRobinsonMSFT and others added 12 commits February 12, 2026 11:24

feat: add dotnet-pinvoke skill (initial draft)

db05d7f

refactor: rename Pinvokes folder to dotnet-pinvoke to match frontmatt…

c926ae4

…er and README conventions

docs: add failure modes and recovery section per CONTRIBUTING.md chec…

2b407a2

…klist

docs: split validation into review checklist and runnable steps

5e9cddd

docs: qualify bool/MarshalAs checklist item for DisableRuntimeMarshal…

cc5eec6

…ling

docs: clarify OS preprocessor symbols require OS-specific TFMs

bde6d50

docs: add EntryPoint property guidance for native export name mismatches

a778d1c

docs: add char*/wchar_t* to dangerous types with marshalling cost and…

41b2f1a

… portability notes

Update skills/dotnet-pinvoke/references/diagnostics.md

79bcc2c

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

docs: enhance SKILL.md with marshalling guidance and Objective-C bind…

281dcab

…ing notes

Add eval and move to correct structure.

17b8d4b

Copilot AI review requested due to automatic review settings February 20, 2026 05:30

Copilot started reviewing on behalf of adityamandaleeka February 20, 2026 05:30 View session

Copilot AI reviewed Feb 20, 2026

View reviewed changes

AaronRobinsonMSFT mentioned this pull request Feb 20, 2026

Add .NET P/Invoke skill #54

Merged

AaronRobinsonMSFT closed this pull request by merging all changes into main in 5e0845e Feb 20, 2026

AaronRobinsonMSFT deleted the arobins/interop_skill branch February 20, 2026 22:01

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PInvoke skill test IGNORE THIS#58

PInvoke skill test IGNORE THIS#58
12 commits merged intomainfrom
arobins/interop_skill

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	\| `int` for `size_t` \| Stack corruption on 64-bit \| Use `nuint` \|
	\| `int` for `size_t` \| Stack corruption on 64-bit \| Use `nuint` (.NET 5+) or `UIntPtr` (pre-.NET 5, including .NET Framework) \|

		@@ -0,0 +1,55 @@
		scenarios:
		- name: "Generate LibraryImport declaration from C header (.NET Core 5+)"

	\| Error handling \| `SetLastError` \| `SetLastPInvokeError` \|
	\| Error handling \| `SetLastError` \| `SetLastError` \|

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