Update NativeLibrary sample (#6456)

- Add prefix to native symbol names to follow best practices for avoiding name collisions
- Make the sample work on .NET 8

Author: jkotas

core/nativeaot/NativeLibrary/Class1.cs

@@ -8,13 +8,14 @@ namespace NativeLibrary
 {
     public class Class1
     {
-        [UnmanagedCallersOnly(EntryPoint = "add")]
+        // Use common prefix for all entrypoints to avoid symbol name collisions
+        [UnmanagedCallersOnly(EntryPoint = "aotsample_add")]
         public static int Add(int a, int b)
         {
             return a + b;
         }
 
-        [UnmanagedCallersOnly(EntryPoint = "write_line")]
+        [UnmanagedCallersOnly(EntryPoint = "aotsample_write_line")]
         public static int WriteLine(IntPtr pString)
         {
             // The marshalling code is typically auto-generated by a custom tool in larger projects.
@@ -35,7 +36,7 @@ public static int WriteLine(IntPtr pString)
             return 0;
         }
 
-        [UnmanagedCallersOnly(EntryPoint = "sumstring")]
+        [UnmanagedCallersOnly(EntryPoint = "aotsample_sumstring")]
         public static IntPtr sumstring(IntPtr first, IntPtr second)
         {
             // Parse strings from the passed pointers 

core/nativeaot/NativeLibrary/LoadLibrary.c

@@ -5,11 +5,11 @@
 
 //Set this value accordingly to your workspace settings
 #if defined(_WIN32)
-#define PathToLibrary "bin\\Debug\\net8.0\\win-x64\\publish\\NativeLibrary.dll"
+#define PathToLibrary "bin\\Release\\net8.0\\win-x64\\publish\\NativeLibrary.dll"
 #elif defined(__APPLE__)
-#define PathToLibrary "./bin/Debug/net8.0/osx-x64/publish/NativeLibrary.dylib"
+#define PathToLibrary "./bin/Release/net8.0/osx-x64/publish/NativeLibrary.dylib"
 #else
-#define PathToLibrary "./bin/Debug/net8.0/linux-x64/publish/NativeLibrary.so"
+#define PathToLibrary "./bin/Release/net8.0/linux-x64/publish/NativeLibrary.so"
 #endif
 
 #ifdef _WIN32
@@ -43,11 +43,11 @@ int main()
     }
 
     // Sum two integers
-    int sum = callSumFunc(PathToLibrary, "add", 2, 8);
+    int sum = callSumFunc(PathToLibrary, "aotsample_add", 2, 8);
     printf("The sum is %d \n", sum);
 
     // Concatenate two strings
-    char *sumstring = callSumStringFunc(PathToLibrary, "sumstring", "ok", "ko");
+    char *sumstring = callSumStringFunc(PathToLibrary, "aotsample_sumstring", "ok", "ko");
     printf("The concatenated string is %s \n", sumstring);
 
     // Free string

core/nativeaot/NativeLibrary/README.md

@@ -9,7 +9,7 @@ Create a .NET class library project using `dotnet new classlib -o NativeLibrary`
 ## Building shared libraries
 
 ```bash
-> dotnet publish /p:NativeLib=Shared
+> dotnet publish /p:NativeLib=Shared --use-current-runtime
 ```
 
 The above command will drop a shared library (Windows `.dll`, macOS `.dylib`, Linux `.so`) in `./bin/Release/net8.0/[RID]/publish/` folder and will have the same name as the folder in which your source file is present.
@@ -67,7 +67,7 @@ For a C# method in the native library to be consumable by external programs, it
 Apply the attribute to the method, specifying the `EntryPoint`:
 
 ```csharp
-[UnmanagedCallersOnly(EntryPoint = "add")]
+[UnmanagedCallersOnly(EntryPoint = "aotsample_add")]
 public static int Add(int a, int b)
 {
     return a + b;
@@ -86,7 +86,7 @@ The sample [source code](Class1.cs) demonstrates common techniques used to stay
 ## Building static libraries
 
 ```bash
-> dotnet publish /p:NativeLib=Static
+> dotnet publish /p:NativeLib=Static --use-current-runtime
 ```
 
 The above command will drop a static library (Windows `.lib`, macOS/Linux `.a`) in `./bin/Release/net8.0/[RID]/publish/` folder and will have the same name as the folder in which your source file is present.