Add a simpler empty-function test case

Author: kulp

bindgen-integration/build.rs

@@ -95,6 +95,16 @@ impl ParseCallbacks for MacroCallback {
                 }
                 *self.seen_funcs.lock().unwrap() += 1;
             }
+            "TESTMACRO_FUNCTIONAL_EMPTY_SIMPLE_ARG(x)" => {
+                if cfg!(feature = "testing_only_libclang_3_8") ||
+                    cfg!(feature = "testing_only_libclang_3_9")
+                {
+                    assert_eq!(value, &[&[b'#']]);
+                } else {
+                    assert_eq!(value, &[] as &[&[u8]]);
+                }
+                *self.seen_funcs.lock().unwrap() += 1;
+            }
             "TESTMACRO_FUNCTIONAL_TOKENIZED(a,b,c,d,e)" => {
                 assert_eq!(
                     value,
@@ -128,7 +138,7 @@ impl Drop for MacroCallback {
         );
         assert_eq!(
             *self.seen_funcs.lock().unwrap(),
-            4,
+            5,
             "func_macro handle was not called once for all relevant macros"
         );
     }

bindgen-integration/cpp/Test.h

@@ -10,6 +10,7 @@
 // different.
 #define TESTMACRO_NONFUNCTIONAL (TESTMACRO_INTEGER)
 #define TESTMACRO_FUNCTIONAL_EMPTY(TESTMACRO_INTEGER)
+#define TESTMACRO_FUNCTIONAL_EMPTY_SIMPLE_ARG(x)
 #define TESTMACRO_FUNCTIONAL_NONEMPTY(TESTMACRO_INTEGER)-TESTMACRO_INTEGER
 // Unusual spacing in the following macro is intentional, to demonstrate
 // reformatting after tokenization.