Add test for tuple struct field generation in search index

Author: GuillaumeGomez

src/test/rustdoc/no-unit-struct-field.rs

@@ -0,0 +1,18 @@
+// This test ensures that the tuple struct fields are not generated in the
+// search index.
+
+// @!hasraw search-index.js '"0"'
+// @!hasraw search-index.js '"1"'
+// @hasraw search-index.js '"foo_a"'
+// @hasraw search-index.js '"bar_a"'
+
+pub struct Bar(pub u32, pub u8);
+pub struct Foo {
+    pub foo_a: u8,
+}
+pub enum Enum {
+    Foo(u8),
+    Bar {
+        bar_a: u8,
+    },
+}