Add pragma once tests

test/val/pragma-once-sample-link.h

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+pragma-once-sample.h

test/val/pragma-once-sample.h

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+/*
+** !!DESCRIPTION!! Simple #pragma once directive tests
+** !!ORIGIN!!      cc65 regression tests
+** !!LICENCE!!     Public Domain
+*/
+
+#ifdef FILE_INCLUDED
+
+#error "This file should not have been included twice"
+#define INCLUDED_TWICE
+
+#else
+
+#define FILE_INCLUDED
+
+#endif
+
+
+/* a pragma once directive should work regardless of where it is located in
+   the file, as long as it is seen by the preprocessor */
+#pragma once

test/val/pragma-once-test.c

@@ -0,0 +1,27 @@
+/*
+** !!DESCRIPTION!! Simple #pragma once directive tests
+** !!ORIGIN!!      cc65 regression tests
+** !!LICENCE!!     Public Domain
+*/
+
+
+#include "pragma-once-sample.h"
+#include "pragma-once-sample.h"
+#include "pragma-once-sample-link.h"
+
+/* pragma-once-sample-link.h is a symlink to pragma-once-sample. */
+
+
+#include <stdio.h>
+
+
+int main() {
+
+#ifdef INCLUDED_TWICE
+    printf("pragma-once-sample.h included more than once\n");
+    return 1;
+#else
+    printf("pragma-once-sample included once\n");
+    return 0;
+#endif
+}