[release/9.0-staging] Fix hostfxr.h to be valid C again. (#110060)

src/native/corehost/hostfxr.h

@@ -1,12 +1,17 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-#ifndef __HOSTFXR_H__
-#define __HOSTFXR_H__
+#ifndef HAVE_HOSTFXR_H
+#define HAVE_HOSTFXR_H
 
 #include <stddef.h>
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif // __cplusplus
+
 #if defined(_WIN32)
     #define HOSTFXR_CALLTYPE __cdecl
     #ifdef _WCHAR_T_DEFINED
@@ -296,10 +301,6 @@ struct hostfxr_dotnet_environment_sdk_info
     const char_t* path;
 };
 
-typedef void(HOSTFXR_CALLTYPE* hostfxr_get_dotnet_environment_info_result_fn)(
-    const struct hostfxr_dotnet_environment_info* info,
-    void* result_context);
-
 struct hostfxr_dotnet_environment_framework_info
 {
     size_t size;
@@ -322,6 +323,10 @@ struct hostfxr_dotnet_environment_info
     const struct hostfxr_dotnet_environment_framework_info* frameworks;
 };
 
+typedef void(HOSTFXR_CALLTYPE* hostfxr_get_dotnet_environment_info_result_fn)(
+    const struct hostfxr_dotnet_environment_info* info,
+    void* result_context);
+
 //
 // Returns available SDKs and frameworks.
 //
@@ -384,7 +389,7 @@ struct hostfxr_resolve_frameworks_result
 };
 
 typedef void (HOSTFXR_CALLTYPE* hostfxr_resolve_frameworks_result_fn)(
-    const hostfxr_resolve_frameworks_result* result,
+    const struct hostfxr_resolve_frameworks_result* result,
     void* result_context);
 
 //
@@ -411,8 +416,12 @@ typedef void (HOSTFXR_CALLTYPE* hostfxr_resolve_frameworks_result_fn)(
 //
 typedef int32_t(HOSTFXR_CALLTYPE* hostfxr_resolve_frameworks_for_runtime_config_fn)(
     const char_t* runtime_config_path,
-    /*opt*/ const hostfxr_initialize_parameters* parameters,
+    /*opt*/ const struct hostfxr_initialize_parameters* parameters,
     /*opt*/ hostfxr_resolve_frameworks_result_fn callback,
     /*opt*/ void* result_context);
 
-#endif //__HOSTFXR_H__
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
+#endif // HAVE_HOSTFXR_H

src/native/corehost/test/mockhostfxr/CMakeLists.txt

@@ -1,8 +1,10 @@
 # Licensed to the .NET Foundation under one or more agreements.
 # The .NET Foundation licenses this file to you under the MIT license.
 
-add_library(mockhostfxr_2_2 SHARED mockhostfxr.cpp)
-add_library(mockhostfxr_5_0 SHARED mockhostfxr.cpp)
+set(MOCKHOSTFXR_SRC mockhostfxr.cpp test_c_api.c)
+
+add_library(mockhostfxr_2_2 SHARED ${MOCKHOSTFXR_SRC})
+add_library(mockhostfxr_5_0 SHARED ${MOCKHOSTFXR_SRC})
 
 target_link_libraries(mockhostfxr_2_2 PRIVATE libhostcommon)
 target_link_libraries(mockhostfxr_5_0 PRIVATE libhostcommon)
@@ -11,4 +13,4 @@ target_compile_definitions(mockhostfxr_2_2 PRIVATE MOCKHOSTFXR_2_2 EXPORT_SHARED
 target_compile_definitions(mockhostfxr_5_0 PRIVATE MOCKHOSTFXR_5_0 EXPORT_SHARED_API)
 
 install_with_stripped_symbols(mockhostfxr_2_2 TARGETS corehost_test)
-install_with_stripped_symbols(mockhostfxr_5_0 TARGETS corehost_test)
+install_with_stripped_symbols(mockhostfxr_5_0 TARGETS corehost_test)

src/native/corehost/test/mockhostfxr/mockhostfxr.cpp

@@ -1,3 +1,6 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
 #include "error_codes.h"
 #include "hostfxr.h"
 #include "host_startup_info.h"

src/native/corehost/test/mockhostfxr/test_c_api.c

@@ -0,0 +1,8 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+// hostfxr.h is a public API. When included in .c files, it may fail to compile
+// if C++-specific syntax is used within the extern "C" block. Since all usage of
+// this API in runtime repo are within C++ code, such breakages are not encountered
+// during normal development or testing.
+#include "hostfxr.h"