From 17a7b6d602ec4e0bf39078a3a9a03ef71d65cf10 Mon Sep 17 00:00:00 2001
From: Bernhard Guillon <Bernhard.Guillon@begu.org>
Date: Tue, 30 Jun 2026 21:02:59 +0200
Subject: Add C hello library with P/Invoke from Baz

---
 CMakeLists.txt        |  1 +
 baz/Baz.cs            |  5 +++++
 chello/CMakeLists.txt | 15 +++++++++++++++
 chello/hello.c        |  5 +++++
 4 files changed, 26 insertions(+)
 create mode 100644 chello/CMakeLists.txt
 create mode 100644 chello/hello.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b3973f3..4a9563a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,7 @@ set(RUNTIME_DIR ${DOTNET_ROOT}/shared/Microsoft.NETCore.App/10.0.9)
 
 include(cmake/dotnet.cmake)
 
+add_subdirectory(chello)
 add_subdirectory(baz)
 add_subdirectory(foobar)
 add_subdirectory(hello)
diff --git a/baz/Baz.cs b/baz/Baz.cs
index f3b017f..df4dd96 100644
--- a/baz/Baz.cs
+++ b/baz/Baz.cs
@@ -1,9 +1,14 @@
 using System;
+using System.Runtime.InteropServices;
 
 public class Baz
 {
+    [DllImport("hello_c")]
+    private static extern void hello_c();
+
     public static void Print()
     {
         Console.WriteLine("Baz");
+        hello_c();
     }
 }
diff --git a/chello/CMakeLists.txt b/chello/CMakeLists.txt
new file mode 100644
index 0000000..f7a276f
--- /dev/null
+++ b/chello/CMakeLists.txt
@@ -0,0 +1,15 @@
+find_program(CMAKE_C_COMPILER NAMES gcc cc)
+if(NOT CMAKE_C_COMPILER)
+    message(FATAL_ERROR "C compiler not found!")
+endif()
+
+set(OUTPUT_FILE ${CMAKE_BINARY_DIR}/libhello_c.so)
+
+add_custom_command(
+    OUTPUT ${OUTPUT_FILE}
+    COMMAND ${CMAKE_C_COMPILER} -shared -fPIC -o ${OUTPUT_FILE} ${CMAKE_CURRENT_SOURCE_DIR}/hello.c
+    DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/hello.c
+    COMMENT "Compiling hello_c shared library..."
+)
+
+add_custom_target(hello_c ALL DEPENDS ${OUTPUT_FILE})
diff --git a/chello/hello.c b/chello/hello.c
new file mode 100644
index 0000000..b99e83d
--- /dev/null
+++ b/chello/hello.c
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+void hello_c(void) {
+    printf("hello from c\n");
+}
-- 
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