Fix native library resolution for dotnet tools on Linux

sources/ClangSharp.Interop/clang.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation and Contributors. All Rights Reserved. Licensed under the MIT License (MIT). See License.md in the repository root for more information.
 
 using System;
+using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Runtime.CompilerServices;
@@ -29,27 +30,24 @@ private static IntPtr OnDllImport(string libraryName, Assembly assembly, DllImpo
             return nativeLibrary;
         }
 
-        if (libraryName.Equals("libclang", StringComparison.Ordinal) && TryResolveClang(assembly, searchPath, out nativeLibrary))
+        // When invoked as a dotnet tool (ClangSharpPInvokeGenerator), native libraries
+        // are co-located with the executable in the NuGet cache but aren't found
+        // by the default resolver on Unix (default dlopen only searches system paths
+        // and LD_LIBRARY_PATH), so we explicitly try the application base directory.
+        // NativeLibrary.TryLoad with an absolute path does not apply platform-specific
+        // name mangling (lib prefix, .so/.dylib/.dll suffix), so we add it explicitly.
+        var suffix = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? ".dll"
+                    : RuntimeInformation.IsOSPlatform(OSPlatform.OSX) ? ".dylib"
+                    : ".so";
+
+        if (NativeLibrary.TryLoad(Path.Combine(AppContext.BaseDirectory, libraryName + suffix), out nativeLibrary))
         {
             return nativeLibrary;
         }
 
         return IntPtr.Zero;
     }
 
-    private static bool TryResolveClang(Assembly assembly, DllImportSearchPath? searchPath, out IntPtr nativeLibrary)
-    {
-        if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
-        {
-            return NativeLibrary.TryLoad("libclang.so.20", assembly, searchPath, out nativeLibrary)
-                || NativeLibrary.TryLoad("libclang-20", assembly, searchPath, out nativeLibrary)
-                || NativeLibrary.TryLoad("libclang.so.1", assembly, searchPath, out nativeLibrary);
-        }
-
-        nativeLibrary = IntPtr.Zero;
-        return false;
-    }
-
     private static bool TryResolveLibrary(string libraryName, Assembly assembly, DllImportSearchPath? searchPath, out IntPtr nativeLibrary)
     {
         var resolveLibrary = ResolveLibrary;