[m-rev.] for review: don't issue warnings over promise_pure so often

[Tyson Dowd]

Hi,

This should improve the situation with regards to sourceforge bug
514142.  It will now be ok to have both a promise_pure pragma and an
attribute on the foreign_proc.

===================================================================


Estimated hours taken: 4
Branches: main

compiler/purity.m:
	Don't issue warnings about unnecessary promise pure declarations
	if they refer to a pragma or mixed clauses and pragma clause.
	These are only marginally useful, and can cause problems.
	
	We might want a promise_pure pragma to handle multiple
	clauses with different modes, and it should still be fine to have
	promise_pure attributes on any foriegn_procs used to implement
	the predicate.


Index: compiler/purity.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/purity.m,v
retrieving revision 1.41
diff -u -r1.41 purity.m
--- compiler/purity.m	30 Jan 2002 01:40:30 -0000	1.41
+++ compiler/purity.m	8 Feb 2002 03:40:03 -0000
@@ -884,7 +884,9 @@
 		PurityCheckResult = inconsistent_promise
 	;
 		% You shouldn't promise pure unnecessarily.
-		PromisedPurity \= (impure), ActualPurity = PromisedPurity
+		% It's OK in the case of foreign_procs though.
+		PromisedPurity \= (impure), ActualPurity = PromisedPurity,
+		not pred_info_pragma_goal_type(PredInfo)
 	->
 		PurityCheckResult = unnecessary_promise_pure
 	;


-- 
       Tyson Dowd           # 
                            #  Surreal humour isn't everyone's cup of fur.
     trd at cs.mu.oz.au        # 
http://www.cs.mu.oz.au/~trd #
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