Build everything as C++ (#1176)

include/link/patch.hpp

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: MIT */
+
+// Applying patches to SECTIONs
+#ifndef RGBDS_LINK_PATCH_H
+#define RGBDS_LINK_PATCH_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "link/section.hpp"
+
+#include "linkdefs.hpp"
+
+struct Assertion {
+	struct Patch patch;
+	// enum AssertionType type; The `patch`'s field is instead re-used
+	char *message;
+	// This would be redundant with `.section->fileSymbols`... but `section` is sometimes NULL!
+	struct Symbol **fileSymbols;
+
+	struct Assertion *next;
+};
+
+/*
+ * Checks all assertions
+ * @return true if assertion failed
+ */
+void patch_CheckAssertions(struct Assertion *assertion);
+
+/*
+ * Applies all SECTIONs' patches to them
+ */
+void patch_ApplyPatches(void);
+
+#endif // RGBDS_LINK_PATCH_H