Updated the comments in the code for better clarity and accuracy.

src/bmarch.c

@@ -7,7 +7,19 @@
 
 #include "bmarch.h"
 
-
+// To avoid compilation errors with modern gcc compilers due to forced function type conversion during external calls,
+// the function implementing the same logic was divided into two versions with different return types.
+// Theoretically, this should be a bug in the official code, and there should only be one version of the function with a return type of s8:
+//   1. In the header file (.h), the function is declared with a return type of s32, while in the source file (.c), the function is defined with a return type of s8.
+//   2. In such a case, if the current .c file does not include the corresponding .h file, it can be compiled successfully with the agbcc compiler,
+//      but this affects the compilation dependency relations in the Makefile.
+// If we keep only one version of the function with a return type of s8,
+// while declaring a version with a return type of s32 before external calls,
+// it can also be compiled successfully with agbcc.
+// However, since all function implementations are fully inlined in the current compilation unit,
+// the resulting assembly file (.s) will not contain the symbol for this function, causing it to disappear eventually.
+// Adding the extern keyword before the function definition can force modern gcc compilers to retain the function,
+// but this leads to the issue of the function eventually disappearing when compiled with agbcc.
 inline s32 IsBallista(struct Trap* trap) {
 
     if (!trap) {

src/bmmenu.c

@@ -1000,6 +1000,10 @@ void ItemSubMenuEnd(struct MenuProc* menu) {
     return;
 }
 
+// In theory, this function should have a second parameter, but it has never been used in the code.
+// If we keep this second parameter, calling the function in the code below after type conversion will result in compilation errors with modern gcc compilers.
+// If we remove the second parameter, it will not cause any issues even if a second parameter (i.e., the r1 register) is passed in other non-explicit calls.
+// This issue is likely due to a lack of synchronization in the official code.
 u8 MenuCommand_SelectNo(struct MenuProc* menu/*, struct MenuItemProc* menuItem*/) {
     SetTextFont(NULL);
 
@@ -1024,7 +1028,6 @@ u8 sub_8023550(struct MenuProc* menu) {
     ProcPtr proc;
 
     sub_8023538(menu);
-    // This is really caused by implicit declaration
     MenuCommand_SelectNo(menu);
 
     proc = StartOrphanMenu(&gItemSelectMenuDef);
@@ -2279,7 +2282,6 @@ u8 AttackBallistaCommandUsability(const struct MenuItemDef* def, int number) {
 
     trap = GetTrapAt(gActiveUnit->xPos, gActiveUnit->yPos);
 
-    // This is really caused by implicit declaration
     isBallista = IsBallista(trap);
 
     if (isBallista == 0) {