fix: improve turbofish jump-to-def handling

Handle turbofish syntax correctly in rustdoc jump-to-def links
and add regression tests covering type aliases.

src/librustdoc/html/highlight.rs

@@ -1001,8 +1001,8 @@ fn get_full_ident_path(&mut self) -> Option<usize> {
                 has_ident = true;
                 nb_items += 1;
             } else if nb > 0 && has_ident {
-                // Following `;` will be handled on its own.
-                break Some(nb_items - 1);
+                // Drop all the colons we just peeked (e.g. `Option::<T>` → keep `Option`).
+                break Some(nb_items - nb);
             } else if has_ident {
                 break Some(nb_items);
             } else {

tests/rustdoc-html/jump-to-def/turbofish.rs

@@ -0,0 +1,17 @@
+// This test ensures that turbofish (`::<...>`) does not prevent jump-to-definition
+// links from being generated.
+
+//@ compile-flags: -Zunstable-options --generate-link-to-definition
+
+#![crate_name = "foo"]
+
+//@ has 'src/foo/turbofish.rs.html'
+use std::marker::PhantomData;
+
+pub fn foo() {
+    // `PhantomData::<usize>` — `PhantomData` must be linked despite the turbofish.
+    type TheOne = PhantomData<()>;
+
+    //@ has - '//a[@href="#13"]' 'TheOne'
+    let _: TheOne::<usize> = PhantomData;
+}