Fixed _Generic mpack_write() string literals under Clang

Author: ludocode

src/mpack/mpack-writer.h

@@ -808,7 +808,7 @@ MPACK_HEADER_END
  * types when passed uncast, so be careful when using them.
  */
 #define mpack_write(writer, value) \
-    _Generic((value),                               \
+    _Generic(((void)0, value),                      \
               int8_t: mpack_write_i8,               \
              int16_t: mpack_write_i16,              \
              int32_t: mpack_write_i32,              \

test/test-write.c

@@ -885,6 +885,10 @@ static void test_write_generic(void) {
     // const char *
     TEST_SIMPLE_WRITE("\xc0", mpack_write(&writer, (const char *)NULL));
     TEST_SIMPLE_WRITE("\xa4""1337", mpack_write(&writer, (const char *)"1337"));
+
+    // string literals
+    TEST_SIMPLE_WRITE("\xa0", mpack_write(&writer, ""));
+    TEST_SIMPLE_WRITE("\xa4""1337", mpack_write(&writer, "1337"));
 }
 
 static void test_write_generic_kv(void) {
@@ -909,9 +913,11 @@ static void test_write_generic_kv(void) {
     TEST_SIMPLE_WRITE("\xa3""foo""\xcb\xc0\x09\x21\xfb\x53\xc8\xd4\xf1", mpack_write_kv(&writer, key, (double)-3.14159265));
     TEST_SIMPLE_WRITE("\xa3""foo""\xc2", mpack_write_kv(&writer, key, (bool)false));
 
-    // char *, const char *
+    // char *, const char *, literal
     TEST_SIMPLE_WRITE("\xa3""foo""\xa3""bar", mpack_write_kv(&writer, key, (char *)value));
     TEST_SIMPLE_WRITE("\xa3""foo""\xa3""bar", mpack_write_kv(&writer, key, (const char *)value));
+    TEST_SIMPLE_WRITE("\xa3""foo""\xa3""bar", mpack_write_kv(&writer, key, value));
+    TEST_SIMPLE_WRITE("\xa3""foo""\xa3""bar", mpack_write_kv(&writer, key, "bar"));
 }
 
 #endif