rustdoc: avoid loading index when user says no

Author: notriddle

src/librustdoc/html/render/search_index.rs

@@ -24,6 +24,7 @@ use tracing::instrument;
 
 use crate::clean::types::{Function, Generics, ItemId, Type, WherePredicate};
 use crate::clean::{self, utils};
+use crate::config::ShouldMerge;
 use crate::error::Error;
 use crate::formats::cache::{Cache, OrphanImplItem};
 use crate::formats::item_type::ItemType;
@@ -722,11 +723,7 @@ impl SerializedSearchIndex {
                     },
                 ),
                 self.alias_pointers[id].and_then(|alias| {
-                    if self.names[alias].is_empty() {
-                        None
-                    } else {
-                        map.get(&alias).copied()
-                    }
+                    if self.names[alias].is_empty() { None } else { map.get(&alias).copied() }
                 }),
             );
         }
@@ -1254,6 +1251,7 @@ pub(crate) fn build_index(
     tcx: TyCtxt<'_>,
     doc_root: &Path,
     resource_suffix: &str,
+    should_merge: &ShouldMerge,
 ) -> Result<SerializedSearchIndex, Error> {
     let mut search_index = std::mem::take(&mut cache.search_index);
 
@@ -1304,7 +1302,11 @@ pub(crate) fn build_index(
     //
     // if there's already a search index, load it into memory and add the new entries to it
     // otherwise, do nothing
-    let mut serialized_index = SerializedSearchIndex::load(doc_root, resource_suffix)?;
+    let mut serialized_index = if should_merge.read_rendered_cci {
+        SerializedSearchIndex::load(doc_root, resource_suffix)?
+    } else {
+        SerializedSearchIndex::default()
+    };
 
     // The crate always goes first in this list
     let crate_name = krate.name(tcx);

src/librustdoc/html/render/write_shared.rs

@@ -66,8 +66,14 @@ pub(crate) fn write_shared(
     // Write shared runs within a flock; disable thread dispatching of IO temporarily.
     let _lock = try_err!(flock::Lock::new(&lock_file, true, true, true), &lock_file);
 
-    let search_index =
-        build_index(krate, &mut cx.shared.cache, tcx, &cx.dst, &cx.shared.resource_suffix)?;
+    let search_index = build_index(
+        krate,
+        &mut cx.shared.cache,
+        tcx,
+        &cx.dst,
+        &cx.shared.resource_suffix,
+        &opt.should_merge,
+    )?;
 
     let crate_name = krate.name(cx.tcx());
     let crate_name = crate_name.as_str(); // rand