cp-tree.h (warn_float_equal): Declare.

        * cp-tree.h (warn_float_equal): Declare.
        * decl2.c (warn_float_equal): Define.
        (lang_decode_option): Recognize -W[no-]float-equal.
        * typeck.c (build_binary_op_nodefault): Conditionally warn
        about equality tests of floating point types.

From-SVN: r29721

gcc/cp/ChangeLog

+Thu Sep 30 00:13:27 1999  Dirk Zoller  <duz@rtsffm.com>
+
+	* cp-tree.h (warn_float_equal): Declare.
+	* decl2.c (warn_float_equal): Define.
+	(lang_decode_option): Recognize -W[no-]float-equal.
+	* typeck.c (build_binary_op_nodefault): Conditionally warn
+	about equality tests of floating point types.
+
 1999-09-29  Jason Merrill  <jason@yorick.cygnus.com>
 
 	Support normal type_info-based EH mechanisms with -fno-rtti.

gcc/cp/cp-tree.h

@@ -893,6 +893,10 @@ extern int warn_missing_braces;
 
 extern int warn_sign_compare;
 
+/* Warn about testing equality of floating point numbers. */
+
+extern int warn_float_equal;
+
 /* Warn about a subscript that has type char.  */
 
 extern int warn_char_subscripts;

gcc/cp/decl2.c

@@ -277,6 +277,10 @@ int warn_missing_braces;
 
 int warn_sign_compare;
 
+/* Warn about testing equality of floating point numbers. */
+
+int warn_float_equal = 0;
+
 /* Warn about *printf or *scanf format/argument anomalies.  */
 
 int warn_format;
@@ -689,6 +693,8 @@ lang_decode_option (argc, argv)
 	warn_missing_braces = setting;
       else if (!strcmp (p, "sign-compare"))
 	warn_sign_compare = setting;
+      else if (!strcmp (p, "float-equal"))
+	warn_float_equal = setting;
       else if (!strcmp (p, "format"))
 	warn_format = setting;
       else if (!strcmp (p, "conversion"))

gcc/cp/typeck.c

@@ -3574,6 +3574,9 @@ build_binary_op_nodefault (code, orig_op0, orig_op1, error_code)
 
     case EQ_EXPR:
     case NE_EXPR:
+      if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
+	warning ("comparing floating point with == or != is unsafe");
+
       build_type = boolean_type_node; 
       if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
 	   || code0 == COMPLEX_TYPE)