better lifetime for variables in pohibiting set

src/rsprocess/set.rs

@@ -206,9 +206,9 @@ impl Set {
     }
 
     /// Computes minimized prohibiting set from reactants and inhibitors.
-    /// Computes the powerset of the smallest reactants ∪ inhibitors set and
-    /// checks for each element of that set if they are also in all other
-    /// unions.
+    /// Computes the powerset of the union of all reactants ∪ inhibitors sets
+    /// and checks for each element of that set if they are also in all other
+    /// unions. Then minimizes the result.
     pub fn prohibiting_set(
 	reactants: &[Set],
 	inhibitors: &[Set],
@@ -229,6 +229,8 @@ impl Set {
 				inhibitors: {:?}",
 			       r, i))
 	}
+
+	let mut t = {
 	    let union = reactants.iter()
 		.zip(inhibitors.iter())
 		.map(|(sr, si)| {
@@ -242,9 +244,12 @@ impl Set {
 	    for set in union.iter() {
 		t.retain(|el| !el.intersection(set).is_empty());
 	    }
+	    t
+	};
 
 	// minimization
 	// remove sets that contain other sets
+	{
 	    let mut tmp_t = t.clone().into_iter();
 	    let mut e = tmp_t.next().unwrap_or_default();
 	    loop {
@@ -268,6 +273,7 @@ impl Set {
 		    };
 		}
 	    }
+	}
 
 	// replace pair of sets that have a common negative-positive element
 	// with set without