Remove A/W probing for P/Invokes on non-Windows platforms

[AaronRobinsonMSFT]

Remove A/W probing for P/Invokes on non-Windows platforms

The Windows function convention of having a A/W suffix is now only respected on the Windows platform. Both the CoreCLR and Mono runtimes have continued this probing on non-Windows platform where the A/W suffix is not a convention. With this change the automatic addition of a A/W suffix is no longer performed on non-Windows platforms. The semantics of both runtimes on the Windows platform remain unchanged.

See dotnet/runtime#33246 for additional details.

Version introduced

.NET 5.0

Old behavior

During export discovery for P/Invokes an A/W prefix was added to the export name when probing. This was done on all platforms.

New behavior

During export discovery for P/Invokes an A/W prefix was added to the export name when probing only on the Windows platform.

Reason for change

This change was made to simplify the cross-platform probing. It is overhead that should not be incurred by the developer given non-Windows platforms don't contain this semantic.

Recommended action

In order to mitigate this change, the user should manually add the desired prefix on non-Windows platforms.

In the example below, if the export on non-Windows was FooW the following declaration would previously suffice:

[DllImport(...)]
extern static void Foo();

It is now recommended the developer update the declaration with the desired prefix:

[DllImport(...)]
extern static void FooW();

Category

• Interop

Affected APIs

DllImportAttribute.

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Issue metadata

• Issue type: breaking-change

[AaronRobinsonMSFT]

/cc @jeffschwMSFT @jkotas @akoeplinger

[gewarren]

@AaronRobinsonMSFT Is this for preview 8?

[jeffschwMSFT]

@gewarren this change has been in since an early preview of .NET 5... perhaps around Preview 3 or 4.