From e2aab13d8a41cc85fbfd055fe0d4c4a2f803c6d5 Mon Sep 17 00:00:00 2001
From: Richard Stallman <rms@gnu.org>
Date: Fri, 14 Aug 1992 23:45:09 +0000
Subject: [PATCH] (truthvalue_conversion): Optionally warn if an
 unparenthesized assignment is used as a truth value.

From-SVN: r1853
---
 gcc/c-common.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gcc/c-common.c b/gcc/c-common.c
index 50aa60e90ae..33804c41a8d 100644
--- a/gcc/c-common.c
+++ b/gcc/c-common.c
@@ -901,6 +901,11 @@ truthvalue_conversion (expr)
 			      fold (build1 (NOP_EXPR,
 					    TREE_TYPE (TREE_OPERAND (expr, 0)),
 					    TREE_OPERAND (expr, 1))), 1);
+
+    case MODIFY_EXPR:
+      if (warn_parentheses && C_EXP_ORIGINAL_CODE (expr) == MODIFY_EXPR)
+	warning ("suggest parentheses around assignment used as truth value");
+      break;
     }
 
   return build_binary_op (NE_EXPR, expr, integer_zero_node, 1);