Add assertions

Closes #292

include/asm/output.h

@@ -20,6 +20,8 @@ extern struct Section *pSectionList, *pCurrentSection;
 
 void out_SetFileName(char *s);
 void out_CreatePatch(uint32_t type, struct Expression const *expr);
+bool out_CreateAssert(enum AssertionType type, struct Expression const *expr,
+		      char const *message);
 void out_WriteObject(void);
 
 #endif /* RGBDS_ASM_OUTPUT_H */

include/asm/warning.h

@@ -22,6 +22,7 @@ enum WarningID {
 	WARNING_OBSOLETE,
 	WARNING_SHIFT,
 	WARNING_USER,
+	WARNING_ASSERT,
 	WARNING_SHIFT_AMOUNT,
 	WARNING_TRUNCATION,
 

include/link/patch.h

@@ -10,6 +10,28 @@
 #ifndef RGBDS_LINK_PATCH_H
 #define RGBDS_LINK_PATCH_H
 
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "link/section.h"
+
+#include "linkdefs.h"
+
+struct Assertion {
+	struct Patch patch;
+	// enum AssertionType type; The `patch`'s field is instead re-used
+	struct Section *section;
+	char *message;
+
+	struct Assertion *next;
+};
+
+/**
+ * Checks all assertions
+ * @return true if assertion failed
+ */
+void patch_CheckAssertions(struct Assertion *assertion);
+
 /**
  * Applies all SECTIONs' patches to them
  */

include/linkdefs.h

@@ -14,7 +14,13 @@
 
 #define RGBDS_OBJECT_VERSION_STRING "RGB%1hhu"
 #define RGBDS_OBJECT_VERSION_NUMBER (uint8_t)9
-#define RGBDS_OBJECT_REV 1
+#define RGBDS_OBJECT_REV 2
+
+enum AssertionType {
+	ASSERT_WARN,
+	ASSERT_ERROR,
+	ASSERT_FATAL
+};
 
 enum RPNCommand {
 	RPN_ADD		= 0x00,