rustdoc: Add index records to the doc tree

src/rustdoc/doc.rs

@@ -33,7 +33,8 @@ type itemdoc = {
 
 type moddoc = {
     item: itemdoc,
-    items: [itemtag]
+    items: [itemtag],
+    index: option<index>
 };
 
 type nmoddoc = {
@@ -109,6 +110,29 @@ type tydoc = {
     sig: option<str>
 };
 
+type index = {
+    entries: [index_entry]
+};
+
+#[doc = "
+
+A single entry in an index
+
+Fields:
+
+* kind - The type of thing being indexed, e.g. 'Module'
+* name - The name of the thing
+* brief - A description
+* link - A format-specific string representing the link target
+
+"]
+type index_entry = {
+    kind: str,
+    name: str,
+    brief: str,
+    link: str
+};
+
 #[doc = "Some helper methods on moddoc, mostly for testing"]
 impl util for moddoc {
 

src/rustdoc/extract.rs

@@ -102,7 +102,8 @@ fn moddoc_from_mod(
                 none
               }
             }
-        }
+        },
+        index: none
     }
 }
 

src/rustdoc/rustdoc.rs

@@ -57,7 +57,8 @@ fn test_run_passes() {
                     name: doc.topmod.name() + "two"
                     with doc.topmod.item
                 },
-                items: []
+                items: [],
+                index: none
             }
         }
     }
@@ -71,7 +72,8 @@ fn test_run_passes() {
                     name: doc.topmod.name() + "three"
                     with doc.topmod.item
                 },
-                items: []
+                items: [],
+                index: none
             }
         }
     }