From 500887ec23e57cd2c4d2db88f3996530eb97ed4f Mon Sep 17 00:00:00 2001
From: Kugel Fuhr <98353208+kugelfuhr@users.noreply.github.com>
Date: Sat, 17 May 2025 17:18:05 +0200
Subject: [PATCH] Fix #2599. The compiler handled all functions returning an
 int but without a "return" statement by silently adding "return 0" instead of
 emitting a warning. This is the desired behavior for the "main" function in
 C99 and above, but the compiler applied it to all functions.

---
 src/cc65/function.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/cc65/function.c b/src/cc65/function.c
index fed0349dd..3123079d3 100644
--- a/src/cc65/function.c
+++ b/src/cc65/function.c
@@ -636,7 +636,9 @@ void NewFunc (SymEntry* Func, FuncDesc* D)
         /* If this is the main function in a C99 environment returning an int,
         ** let it always return zero. Otherwise output a warning.
         */
-        if (IS_Get (&Standard) >= STD_C99 && GetUnqualRawTypeCode (ReturnType) == T_INT) {
+        if (F_IsMainFunc (CurrentFunc) &&
+            IS_Get (&Standard) >= STD_C99 &&
+            GetUnqualRawTypeCode (ReturnType) == T_INT) {
             g_getimmed (CF_INT | CF_CONST, 0, 0);
         } else if (IS_Get (&WarnReturnType)) {
             Warning ("Control reaches end of non-void function [-Wreturn-type]");