From 6d45a9412767eb7850ef5891b5732474bab37b4e Mon Sep 17 00:00:00 2001
From: Kugel Fuhr <98353208+kugelfuhr@users.noreply.github.com>
Date: Thu, 17 Jul 2025 16:12:48 +0200
Subject: [PATCH] Do not output a warning about a missing "return" in a
 function if the function exit is unreachable.

---
 src/cc65/error.c          | 2 +-
 src/cc65/function.c       | 7 +++++--
 test/misc/Makefile        | 4 ++--
 test/misc/flow-do-01.c    | 8 ++++----
 test/misc/flow-if-02.c    | 4 ++--
 test/misc/flow-while-01.c | 6 +++---
 6 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/cc65/error.c b/src/cc65/error.c
index a5cf4e3e8..ebd3a55c6 100644
--- a/src/cc65/error.c
+++ b/src/cc65/error.c
@@ -433,7 +433,7 @@ void UnreachableCodeWarning (void)
         */
         if (CurTok.LI && NextTok.LI) {
             if (CurTok.Tok == TOK_LCURLY) {
-                /* Do not point to the compoung statement but to the first
+                /* Do not point to the compound statement but to the first
                 ** statement within it. If the compound statement is empty
                 ** do not even output a warning. This fails of course for
                 ** nested compounds but will do the right thing in most cases.
diff --git a/src/cc65/function.c b/src/cc65/function.c
index 0e040d61d..c14372d43 100644
--- a/src/cc65/function.c
+++ b/src/cc65/function.c
@@ -453,6 +453,7 @@ void NewFunc (SymEntry* Func, FuncDesc* D)
     SymEntry*   Param;
     const Type* RType;          /* Real type used for struct parameters */
     const Type* ReturnType;     /* Return type */
+    int         StmtFlags;      /* Flow control flags for the function compound */
 
     /* Remember this function descriptor used for definition */
     GetFuncDesc (Func->Type)->FuncDef = D;
@@ -627,10 +628,12 @@ void NewFunc (SymEntry* Func, FuncDesc* D)
     CurrentFunc->TopLevelSP = StackPtr;
 
     /* Now process statements in this block checking for unreachable code */
-    StatementBlock (0);
+    StmtFlags = StatementBlock (0);
 
     /* Check if this function is missing a return value */
-    if (!F_HasVoidReturn (CurrentFunc) && !F_HasReturn (CurrentFunc)) {
+    if (!SF_Unreach (StmtFlags) &&
+        !F_HasVoidReturn (CurrentFunc) &&
+        !F_HasReturn (CurrentFunc)) {
         /* If this is the main function in a C99 environment returning an int,
         ** let it always return zero. Otherwise output a warning.
         */
diff --git a/test/misc/Makefile b/test/misc/Makefile
index 3e8b0c157..a595d82a9 100644
--- a/test/misc/Makefile
+++ b/test/misc/Makefile
@@ -156,7 +156,7 @@ $(WORKDIR)/flow-do-01.$1.$2.prg: flow-do-01.c $(ISEQUAL) | $(WORKDIR)
 	$(if $(QUIET),echo misc/flow-do-01.$1.$2.prg)
 	$(CC65) -t sim$2 -$1 -o $$@ $$< $(NULLOUT) 2>$(WORKDIR)/flow-do-01.$1.$2.out
 	$(ISEQUAL) $(WORKDIR)/flow-do-01.$1.$2.out flow-do-01.ref
-	   
+
 $(WORKDIR)/flow-if-01.$1.$2.prg: flow-if-01.c $(ISEQUAL) | $(WORKDIR)
 	$(if $(QUIET),echo misc/flow-if-01.$1.$2.prg)
 	$(CC65) -t sim$2 -$1 -o $$@ $$< $(NULLOUT) 2>$(WORKDIR)/flow-if-01.$1.$2.out
@@ -182,7 +182,7 @@ $(WORKDIR)/flow-while-02.$1.$2.prg: flow-while-02.c $(ISEQUAL) | $(WORKDIR)
 	$(CC65) -t sim$2 -$1 -o $$@ $$< $(NULLOUT) 2>$(WORKDIR)/flow-while-02.$1.$2.out
 	$(ISEQUAL) $(WORKDIR)/flow-while-02.$1.$2.out flow-while-02.ref
 
-$(WORKDIR)/limits.$1.$2.prg: limits.c $(ISEQUAL) | $(WORKDIR)	     
+$(WORKDIR)/limits.$1.$2.prg: limits.c $(ISEQUAL) | $(WORKDIR)
 	$(if $(QUIET),echo misc/limits.$1.$2.prg)
 	$(CC65) -t sim$2 -$1 -o $$(@:.prg=.s) $$< $(NULLOUT) $(CATERR)
 	$(CA65) -t sim$2 -o $$(@:.prg=.o) $$(@:.prg=.s) $(NULLERR)
diff --git a/test/misc/flow-do-01.c b/test/misc/flow-do-01.c
index 7d4cb86e2..d1997311f 100644
--- a/test/misc/flow-do-01.c
+++ b/test/misc/flow-do-01.c
@@ -43,7 +43,7 @@ static int f4(void)
 static int f5(void)
 {
     do {
-       	if (a == 2) {
+        if (a == 2) {
             break;
         }
         return a;
@@ -56,7 +56,7 @@ static int f5(void)
 static int f6(void)
 {
     do {
-       	if (a == 2) {
+        if (a == 2) {
             break;
         }
         continue;
@@ -69,11 +69,11 @@ static int f6(void)
 static int f7(void)
 {
     do {
-       	if (a == 2) {
+        if (a == 2) {
             return a;
         } else {
             continue;
-	}
+        }
     } while (1);
     /* Unreachable */
     a = 2;
diff --git a/test/misc/flow-if-02.c b/test/misc/flow-if-02.c
index 6e30d9d5f..ff60e5ce0 100644
--- a/test/misc/flow-if-02.c
+++ b/test/misc/flow-if-02.c
@@ -14,7 +14,7 @@ static int f2(void)
 {
     if (0) {
         /* Unreachable */
-	a = 1;
+        a = 1;
     } else {
         a = 2;
     }
@@ -37,7 +37,7 @@ static int f4(void)
         a = 2;
     } else {
         /* Unreachable */
-	a = 1;
+        a = 1;
     }
     return a;
 }
diff --git a/test/misc/flow-while-01.c b/test/misc/flow-while-01.c
index 5ba4f8d9f..91d1454a9 100644
--- a/test/misc/flow-while-01.c
+++ b/test/misc/flow-while-01.c
@@ -47,7 +47,7 @@ static int f5(void)
 {
     while (1) {
         ++a;
-       	if (a == 4) goto L;
+        if (a == 4) goto L;
         return a;
     }
     /* Reachable via L */
@@ -56,8 +56,8 @@ L:  a = 2;
 
 static int f6(void)
 {
-    while (0) { 
-	/* Unreachable but no warning */
+    while (0) {
+        /* Unreachable but no warning */
     }
     a = 2;
     return a;