Type convert NULL to other pointer types for function call arguments.

Fixes issue #198.

expr.cpp

@@ -3409,7 +3409,9 @@ FunctionCallExpr::TypeCheck() {
         if (t == NULL)
             return NULL;
         argTypes.push_back(t);
-        argCouldBeNULL.push_back(lIsAllIntZeros(args->exprs[i]));
+
+        argCouldBeNULL.push_back(lIsAllIntZeros(args->exprs[i]) ||
+                       dynamic_cast<NullPointerExpr *>(args->exprs[i]) != NULL);
     }
 
     FunctionSymbolExpr *fse = dynamic_cast<FunctionSymbolExpr *>(func);

tests/ptr-null-func-arg.ispc

@@ -0,0 +1,14 @@
+
+export uniform int width() { return programCount; }
+
+bool bar(float * x) {
+    return (x != 0);
+}
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    RET[programIndex] = bar(NULL);
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = 0;
+}