Fix the "double semicolon" problem where a double semicolon after a statement

that makes the following code unreachable led to an "unreachable code" warning.

src/cc65/stmt.c

@@ -741,16 +741,28 @@ int StatementBlock (struct SwitchCtrl* Switch)
     if (CurTok.Tok != TOK_RCURLY && CurTok.Tok != TOK_CEOF) {
         LineInfo* LI1 = UseLineInfo (GetDiagnosticLI ());
         int StmtFlags1 = AnyStatement (0, Switch);
-        int UnreachableWarning = 0;
+        int Unreachable = 0;            /* True if code is unreachable */
+        int UnreachableWarning = 0;     /* True if warning was output */
         while (CurTok.Tok != TOK_RCURLY && CurTok.Tok != TOK_CEOF) {
             LineInfo* LI2 = UseLineInfo (GetDiagnosticLI ());
             int StmtFlags2 = AnyStatement (0, Switch);
             if (!UnreachableWarning) {
-                /* Check if the code is unreachable because of a preceeding
+                /* If this statement is not already unreachable, check if the
-                ** jump and if the code doesn't have a jump label.
+                ** previous statement made it unreachable.
                 */
-                if ((StmtFlags1 & SF_MASK_UNREACH) != SF_NONE &&
+                if (!Unreachable) {
-                    (StmtFlags2 & SF_MASK_LABEL) == SF_NONE) {
+                    Unreachable = SF_Unreach (StmtFlags1);
+                }
+                /* If the previous statement made this one unreachable, but
+                ** this one has a label, it is not unreachable.
+                */
+                if (Unreachable && SF_Label (StmtFlags2)) {
+                    Unreachable = 0;
+                }
+                /* If this statement is unreachable but not the empty
+                ** statement, output a warning.
+                */
+                if (Unreachable && !SF_Empty (StmtFlags2)) {
                     LIUnreachableCodeWarning (LI2);
                     UnreachableWarning = 1;
                 }
@@ -873,7 +885,7 @@ int AnyStatement (int* PendingToken, struct SwitchCtrl* Switch)
         case TOK_SEMI:
             /* Empty statement. Ignore it */
             CheckSemi (PendingToken);
-            StmtFlags = SF_NONE;
+            StmtFlags = SF_EMPTY;
             break;
 
         case TOK_LCURLY:

src/cc65/stmt.h

@@ -88,6 +88,9 @@ enum {
     SF_LABEL_CASE       = 0x20000,      /* Statement preceeded by case label */
     SF_LABEL_DEFAULT    = 0x40000,      /* Statement preceeded by default label */
     SF_MASK_LABEL       = 0x70000,      /* Mask for any label */
+
+    /* And a flag to mark an empty statement */
+    SF_EMPTY            = 0x80000,      /* Empty statement */
 };
 
 /* Forward */
@@ -137,6 +140,12 @@ static inline int SF_Label (int F)
     return (F & SF_MASK_LABEL);
 }
 
+static inline int SF_Empty (int F)
+/* Check if this is the empty statement */
+{
+    return (F & SF_EMPTY);
+}
+
 
 
 /*****************************************************************************/

src/cc65/swstmt.c

@@ -393,8 +393,8 @@ void SwitchBodyStatement (struct SwitchCtrl* S, LineInfo* LI, int StmtFlags)
     /* Handle code without a label in the switch */
     if (SC_Label (S) == SC_NONE) {
         /* This is a statement that preceedes any switch labels. If the
-        ** switch is not already marked as weird, output and the current
+        ** switch is not already marked as weird and the current statement
-        ** statement has no label, output a warning about unreachable code.
+        ** has no label, output a warning about unreachable code.
         */
         if (!SC_IsWeird (S)) {
             if (!SF_Label (StmtFlags)) {