Align NativeAOT array element size limit

[Copilot]

Description

NativeAOT rejected array element value types of exactly 65,535 bytes, while CoreCLR allows that boundary value. The validation now rejects only element sizes greater than ushort.MaxValue.

• Updated NativeAOT compiler type validation:
  • >= ushort.MaxValue → > ushort.MaxValue
• Added a focused InlineArray regression test:
  • Verifies [InlineArray(65535)] can be used as an array element type.
  • Covers NativeAOT compilation via IlcCompile.

var array = new MaxSizedArrayElement[1];

[InlineArray(65535)]
struct MaxSizedArrayElement
{
    private byte _first;
}

Test methodology

• Built the NativeAOT compiler project.
• Built and ran the new regression test on CoreCLR.
• Built and ran the NativeAOT-compiled test binary.

Additional context

This keeps NativeAOT behavior consistent with CoreCLR at the maximum supported array element size boundary.

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[MichalStrehovsky]

/azp run runtime-nativeaot-outerloop, runtime-coreclr outerloop

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[Copilot]

Pull request overview

Aligns NativeAOT’s array element-size validation with the runtime limit so that value-type array elements of exactly 65,535 bytes are accepted (matching CoreCLR behavior at the boundary). This avoids rejecting a size that still fits the GCDesc/component-size encodings used by the NativeAOT toolchain.

Changes:

• Adjusted NativeAOT type loadability validation for arrays to reject only element sizes greater than ushort.MaxValue.
• Added a new InlineArray-focused regression test project and test that exercises using an [InlineArray(65535)] struct as an array element type.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/coreclr/tools/Common/Compiler/CompilerTypeSystemContext.Validation.cs	Updates array element-size check from >= ushort.MaxValue to > ushort.MaxValue, allowing the 65,535-byte boundary.
src/tests/Loader/classloader/InlineArray/MaxArrayElementSize.csproj	Adds a new standalone test project for the regression scenario.
src/tests/Loader/classloader/InlineArray/MaxArrayElementSize.cs	Adds a test covering [InlineArray(65535)] as an array element type (size + successful array construction).

[hez2010]

Can this be backported to .NET 10 as well?

[jkotas]

This does not meet the bar for backport.