Multiple fixes for Windows x86 p/invoke test failures. (#3186)

[mono.git] / mono / tests / libtest.c

diff --git a/mono/tests/libtest.c b/mono/tests/libtest.c
index dbd2e9ad1cc108d8ee2ebbb383738f9b84999af4..8f1cef273f40075165310ad858c344b9fb71324f 100644 (file)
--- a/mono/tests/libtest.c
+++ b/mono/tests/libtest.c
@@ -889,12 +889,12 @@ mono_test_marshal_return_delegate (SimpleDelegate delegate)
        return delegate;
 }
 
-typedef int DelegateByrefDelegate (void *);
+typedef int (STDCALL *DelegateByrefDelegate) (void *);
 
 LIBTEST_API int STDCALL
 mono_test_marshal_delegate_ref_delegate (DelegateByrefDelegate del)
 {
-       int (*ptr) (int i);
+       int (STDCALL *ptr) (int i);
 
        del (&ptr);
 
@@ -1228,14 +1228,29 @@ mono_test_marshal_stringbuilder_ref (char **s)
        return 0;
 }
 
+#ifdef __GNUC__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wc++-compat"
+#endif
+
+/*
+* Standard C and C++ doesn't allow empty structs, empty structs will always have a size of 1 byte.
+* GCC have an extension to allow empty structs, https://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html.
+* This cause a little dilemma since runtime build using none GCC compiler will not be compatible with
+* GCC build C libraries and the other way around. On platforms where empty structs has size of 1 byte
+* it must be represented in call and cannot be dropped. On Windows x64 structs will always be represented in the call
+* meaning that an empty struct must have a representation in the callee in order to correctly follow the ABI used by the
+* C/C++ standard and the runtime.
+*/
 typedef struct {
-#ifndef __GNUC__
+#if !defined(__GNUC__) || defined(TARGET_WIN32)
     char a;
 #endif
 } EmptyStruct;
+
+#ifdef __GNUC__
 #pragma GCC diagnostic pop
+#endif
 
 LIBTEST_API int STDCALL 
 mono_test_marshal_empty_string_array (char **array)
@@ -1339,6 +1354,8 @@ mono_test_return_empty_struct (int a)
 {
        EmptyStruct s;
 
+       memset (&s, 0, sizeof (s));
+
        g_assert (a == 42);
 
        return s;