Added support for intrinsic functions with multiple return values

Previously, such a function was an IntrinsicFunctionCall inside one expression of an ExpressionList, which the type-checker rejected.  I've had to add a new constructor to ExpressionList, and I've quickly hacked together the line in the C backend to make it work -- but it does seem to work.

backends/GenerateC.hs

@@ -1538,6 +1538,16 @@ cgenAssign m [v] (A.ExpressionList _ [e])
              tell ["="]
              call genExpression e
              tell [";"]
+cgenAssign m (v:vs) (A.IntrinsicFunctionCallList _ n es)
+    = do call genVariable v
+         tell ["=occam_",n,"("]
+         seqComma $ map (call genExpression) es
+         mapM (\v -> tell [","] >> call genActual (A.Formal A.Abbrev A.Int (A.Name
+           emptyMeta "dummy_intrinsic_param")) (A.ActualVariable v)) vs
+         tell [","]
+         genMeta m
+         tell [");"]
+         
 cgenAssign m _ _ = call genMissing "Cannot perform assignment with multiple destinations or multiple sources"
 
 --}}}

data/AST.hs

@@ -302,6 +302,8 @@ data Expression =
 data ExpressionList =
   -- | A list of expressions resulting from a function call.
   FunctionCallList Meta Name [Expression]
+  -- | A list of expressions resulting from an intrinsic function call.
+  | IntrinsicFunctionCallList Meta String [Expression]
   -- | A list of expressions resulting from, well, a list of expressions.
   | ExpressionList Meta [Expression]
   deriving (Show, Eq, Typeable, Data)

frontends/OccamPasses.hs

@@ -73,6 +73,8 @@ resolveAmbiguities = occamOnlyPass "Resolve ambiguities"
     -- FunctionCallList, since it can have multiple results.
     doExpressionList (A.ExpressionList _ [A.FunctionCall m n es])
         = return $ A.FunctionCallList m n es
+    doExpressionList (A.ExpressionList _ [A.IntrinsicFunctionCall m n es])
+        = return $ A.IntrinsicFunctionCallList m n es
     doExpressionList e = return e
 
 -- | Fold constant expressions.

frontends/OccamTypes.hs

@@ -374,16 +374,17 @@ checkFunctionCall m n es
           return rs
 
 -- | Check an intrinsic function call.
-checkIntrinsicFunctionCall :: Meta -> String -> [A.Expression] -> PassM ()
+checkIntrinsicFunctionCall :: Bool -> Meta -> String -> [A.Expression] -> PassM [A.Type]
-checkIntrinsicFunctionCall m n es
+checkIntrinsicFunctionCall usedInList m n es
     = case lookup n intrinsicFunctions of
         Just (rs, args) ->
-           do when (length rs /= 1) $
+           do when (not usedInList && length rs /= 1) $
                 dieP m $ "Function " ++ n ++ " used in an expression returns more than one value"
               let fs = [A.Formal A.ValAbbrev t (A.Name m s)
                         | (t, s) <- args]
               checkActuals m (A.Name m n)
                            fs (map A.ActualExpression es)
+              return rs
         Nothing -> dieP m $ n ++ " is not an intrinsic function"
 
 -- | Check a mobile allocation.
@@ -499,6 +500,12 @@ checkExpressionList ets el
                 diePC m $ formatCode ("Function % has wrong number of return values; found " ++ (show $ length rs) ++ ", expected " ++ (show $ length ets)) n
               sequence_ [checkType m et rt
                          | (et, rt) <- zip ets rs]
+        A.IntrinsicFunctionCallList m n es ->
+           do rs <- checkIntrinsicFunctionCall True m n es
+              when (length ets /= length rs) $
+                dieP m $ "Intrinsic function " ++ n ++ " has wrong number of return values; found " ++ (show $ length rs) ++ ", expected " ++ (show $ length ets)
+              sequence_ [checkType m et rt
+                         | (et, rt) <- zip ets rs]
         A.ExpressionList m es ->
            do when (length ets /= length es) $
                 dieP m $ "Wrong number of items in expression list; found "
@@ -1149,7 +1156,7 @@ checkExpressions = checkDepthM doExpression
               when (length rs /= 1) $
                 diePC m $ formatCode "Function % used in an expression returns more than one value" n
     doExpression (A.IntrinsicFunctionCall m s es)
-        = checkIntrinsicFunctionCall m s es
+        = checkIntrinsicFunctionCall False m s es >> return ()
     doExpression (A.SubscriptedExpr m s e)
         =  do t <- astTypeOf e
               checkSubscript m s t