Repository: dotnet/roslyn
File: src/Workspaces/SharedUtilitiesAndExtensions/Workspace/Core/Extensions/ISymbolExtensions.cs (C#)

Code before:
﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using Microsoft.CodeAnalysis.Editing;

namespace Microsoft.CodeAnalysis.Shared.Extensions;

internal static partial class ISymbolExtensions
{
    public static DeclarationModifiers GetSymbolModifiers(this ISymbol symbol)
    {
        // Check if the symbol is partial (definition or implementation part)
        var isPartial = symbol switch
        {
            IMethodSymbol method => method.IsPartialDefinition || method.PartialDefinitionPart != null,
            IPropertySymbol property => property.IsPartialDefinition || property.PartialDefinitionPart != null,
            IEventSymbol @event => @event.IsPartialDefinition || @event.PartialDefinitionPart != null,
            _ => false
        };

        return DeclarationModifiers.None
            .WithIsStatic(symbol.IsStatic)
            .WithIsAbstract(symbol.IsAbstract)
            .WithIsUnsafe(symbol.RequiresUnsafeModifier())
            .WithIsVirtual(symbol.IsVirtual)
            .WithIsOverride(symbol.IsOverride)
            .WithIsSealed(symbol.IsSealed)
            .WithIsRequired(symbol.IsRequired())
            .WithPartial(isPartial);
    }
}


Review comment (suggestion):
@copilot make an ISymbolExtensions.IsPartial extension for ISymbol.  Have it do the work to check IsPartialDefinition/PartialDefinitionPart/PartialImplementationPart for methods, properties and events.  Then, use that extension here and in `DeclarationModifiers From(ISymbol symbol)`

Code after:
﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using Microsoft.CodeAnalysis.Editing;

namespace Microsoft.CodeAnalysis.Shared.Extensions;

internal static partial class ISymbolExtensions
{
    public static bool IsPartial(this ISymbol symbol)
    {
        var isPartial = symbol switch
        {
            IMethodSymbol method => method.PartialDefinitionPart != null || method.PartialImplementationPart != null,
            IPropertySymbol property => property.PartialDefinitionPart != null || property.PartialImplementationPart != null,
            _ => false
        };

        if (isPartial)
            return true;

#if !ROSLYN_4_12_OR_LOWER
        return symbol is IEventSymbol @event &&
            (@event.PartialDefinitionPart != null || @event.PartialImplementationPart != null);
#else
        return false;
#endif
    }

    public static DeclarationModifiers GetSymbolModifiers(this ISymbol symbol)
    {
        return DeclarationModifiers.None
            .WithIsStatic(symbol.IsStatic)
            .WithIsAbstract(symbol.IsAbstract)
            .WithIsUnsafe(symbol.RequiresUnsafeModifier())
            .WithIsVirtual(symbol.IsVirtual)
            .WithIsOverride(symbol.IsOverride)
            .WithIsSealed(symbol.IsSealed)
            .WithIsRequired(symbol.IsRequired())
            .WithPartial(symbol.IsPartial());
    }