From 08eb9b7b0e2d25137a17220a4eaa0c7d53bac222 Mon Sep 17 00:00:00 2001
From: cuz <cuz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Sat, 5 Jun 2004 12:56:51 +0000
Subject: [PATCH] Check for and warn on statements that don't have an effect

git-svn-id: svn://svn.cc65.org/cc65/trunk@3097 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 src/cc65/stmt.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/cc65/stmt.c b/src/cc65/stmt.c
index ad9892707..44a98072d 100644
--- a/src/cc65/stmt.c
+++ b/src/cc65/stmt.c
@@ -519,6 +519,7 @@ int Statement (int* PendingToken)
 {
     ExprDesc Expr;
     int GotBreak;
+    CodeMark Start;
 
     /* Assume no pending token */
     if (PendingToken) {
@@ -590,6 +591,8 @@ int Statement (int* PendingToken)
      		break;
 
 	    default:
+                /* Remember the current code position */
+                Start = GetCodePos ();
 	        /* Actual statement */
                 ExprWithCheck (hie0, &Expr);
                 /* Load the result only if it is an lvalue and the type is
@@ -598,6 +601,12 @@ int Statement (int* PendingToken)
                 if (ED_IsLVal (&Expr) && IsQualVolatile (Expr.Type)) {
                     ExprLoad (CF_NONE, &Expr);
                 }
+                /* If the statement didn't generate code, and is not of type
+                 * void, emit a warning 
+                 */
+                if (GetCodePos () == Start && !IsTypeVoid (Expr.Type)) {
+                    Warning ("Statement has no effect");
+                }
 	    	CheckSemi (PendingToken);
 	}
     }
-- 
2.39.5