Auto merge of #515 - fitzgen:monotone-framework, r=emilio

Discover which template type parameters are actually used

This is just landing the initial analysis, and does not start leveraging this analysis's results instead of using the `Item::signature_contains_named_type` method yet.

r? @emilio

Author: bors-servo

src/ir/item.rs

@@ -472,6 +472,13 @@ impl Item {
         self.kind().as_type()
     }
 
+    /// Is this item a named template type parameter?
+    pub fn is_named(&self) -> bool {
+        self.as_type()
+            .map(|ty| ty.is_named())
+            .unwrap_or(false)
+    }
+
     /// Get a reference to this item's underlying `Function`. Panic if this is
     /// some other kind of item.
     pub fn expect_function(&self) -> &Function {

src/ir/mod.rs

@@ -14,6 +14,7 @@ pub mod item;
 pub mod item_kind;
 pub mod layout;
 pub mod module;
+pub mod named;
 pub mod traversal;
 pub mod ty;
 pub mod var;