fix tests for tcc, extract failing stuff to separate simpler files to ease debugging

* Fix compiling vlib/compiler/tests/fn_test.v with tcc.

* Extract failing tests from fn_test.v so that they are more readable and easier to debug.

vlib/compiler/cheaders.v

@@ -57,8 +57,10 @@ CommonCHeaders = '
 #define TCCSKIP(x) x
 
 #ifdef __TINYC__
+#undef EMPTY_STRUCT_DECLARATION
 #undef EMPTY_STRUCT_INITIALIZATION
-#define EMPTY_STRUCT_INITIALIZATION
+#define EMPTY_STRUCT_DECLARATION char _dummy
+#define EMPTY_STRUCT_INITIALIZATION 0
 #undef EMPTY_ARRAY_OF_ELEMS
 #define EMPTY_ARRAY_OF_ELEMS(x,n) (x[n])
 #undef TCCSKIP

vlib/compiler/tests/fn_expecting_ref_but_returning_struct_test.v

@@ -0,0 +1,23 @@
+struct Foo {
+}
+fn (f Foo) str() string { return 'Foo{}' }
+
+fn process_foo(foo &Foo) {
+	println('>process_foo, called for ${foo} === ${*foo}')
+}
+
+fn get_foo() Foo {
+	println('>get_foo')
+	return Foo{}
+}
+
+/*
+// TODO: Fix this. It 'works' only with tcc, but is not stable.
+fn test_ref_fn_arg() {
+	process_foo(get_foo())
+	println(3434)
+	assert true
+}
+*/
+
+fn test_dummy(){}

vlib/compiler/tests/fn_expecting_ref_but_returning_struct_time_module_test.v

@@ -0,0 +1,21 @@
+/*
+// TODO: Fix this.
+import time
+
+// using a manual temporary intermediate variable should always work:
+fn test_call_fn_that_requires_reference_with_function_that_returns_a_struct_manual(){
+	t1 := time.random()
+	t2 := t1.calc_unix()
+	println('tmp: $t2')
+	assert true
+}
+
+// v should produce temporary intermediate variables in chained calls:
+fn test_call_fn_that_requires_reference_with_function_that_returns_a_struct_chained(){
+	res := (time.random().calc_unix())
+	println('res: $res')
+	assert true
+}
+*/
+
+fn test_dummy(){}

vlib/compiler/tests/fn_test.v

@@ -21,8 +21,6 @@ multi line comment (3)
 	multi line comment (2)
 */
 
-import time
-
 type myfn fn (int) string
 
 type myfn2 fn (a int, b int) int
@@ -120,35 +118,3 @@ fn high_fn_multi_return(a int, b fn (c []int, d []string) ([]int, []string)) {
 fn test_fns() {
 	// no asserts for now, just test function declarations above
 }
-
-struct Foo {
-}
-
-
-fn process_foo(foo &Foo) {
-}
-
-fn get_foo() Foo {
-        return Foo{}
-}
-
-
-// This used to be broken.
-fn test_ref_fn_arg() {
-	// TODO tcc bug
-	/*
-	$if !tinyc {
-		process_foo(get_foo())
-		println(3434)
-		assert true
-	}
-	*/
-	
-	/*
-	res := (time.random().calc_unix())
-	println(res)
-	assert true
-	*/
-	
-}	
-