re PR ada/34446 (gnatprep evaluating "not" operator at incorrect precidence)

2008-05-28  Vincent Celier  <celier@adacore.com>

	PR ada/34446
	* gnat_ugn.texi: Document restriction introduced on 2007-04-20 in
	preprocessing expressions

From-SVN: r136111

gcc/ada/gnat_ugn.texi

@@ -17837,6 +17837,21 @@ In this example, @i{expression} is defined by the following grammar:
 @i{expression} ::=  ( @i{expression} )
 @end smallexample
 
+The following restriction exists: it is not allowed to have "and" or "or"
+following "not" in the same expression without parentheses. For example, this
+is not allowed:
+
+@smallexample
+   not X or Y
+@end smallexample
+
+This should be one of the following:
+
+@smallexample
+   (not X) or Y
+   not (X or Y)
+@end smallexample
+
 @noindent
 For the first test (@i{expression} ::= <symbol>) the symbol must have
 either the value true or false, that is to say the right-hand of the