Fix the criteria to avoid always returning a placeholder

milli/src/search/criteria/asc_desc.rs

@@ -128,8 +128,11 @@ impl<'t> Criterion for AscDesc<'t> {
         loop {
             match (&mut self.query_tree, &mut self.candidates) {
                 (_, Allowed(candidates)) if candidates.is_empty() => {
-                    self.query_tree = None;
+                    return Ok(Some(CriterionResult {
-                    self.candidates = Candidates::default();
+                        query_tree: self.query_tree.take(),
+                        candidates: take(&mut self.candidates).into_inner(),
+                        bucket_candidates: take(&mut self.bucket_candidates),
+                    }));
                 },
                 (Some(qt), Allowed(candidates)) => {
                     let bucket_candidates = match self.parent {

milli/src/search/criteria/fetcher.rs

@@ -54,20 +54,26 @@ impl<'t> Criterion for Fetcher<'t> {
                 self.should_get_documents_ids, self.candidates,
             );
 
+            let should_get_documents_ids = take(&mut self.should_get_documents_ids);
             match &mut self.candidates {
-                Allowed(candidates) => if candidates.is_empty() {
+                Allowed(candidates) => {
-                    self.candidates = Candidates::default();
-                } else {
-                    self.should_get_documents_ids = false;
                     let candidates = take(&mut self.candidates).into_inner();
+                    let candidates = match &self.query_tree {
+                        Some(qt) if should_get_documents_ids => {
+                            let mut docids = resolve_query_tree(self.ctx, &qt, &mut HashMap::new())?;
+                            docids.intersect_with(&candidates);
+                            docids
+                        },
+                        _ => candidates,
+                    };
+
                     return Ok(Some(CriterionResult {
-                        query_tree: self.query_tree.clone(),
+                        query_tree: self.query_tree.take(),
                         candidates: candidates.clone(),
                         bucket_candidates: candidates,
                     }));
                 },
                 Forbidden(_) => {
-                    let should_get_documents_ids = take(&mut self.should_get_documents_ids);
                     match self.parent.as_mut() {
                         Some(parent) => {
                             match parent.next()? {

milli/src/search/criteria/proximity.rs

@@ -64,8 +64,11 @@ impl<'t> Criterion for Proximity<'t> {
 
             match (&mut self.query_tree, &mut self.candidates) {
                 (_, Allowed(candidates)) if candidates.is_empty() => {
-                    self.query_tree = None;
+                    return Ok(Some(CriterionResult {
-                    self.candidates = Candidates::default();
+                        query_tree: self.query_tree.take().map(|(_, qt)| qt),
+                        candidates: take(&mut self.candidates).into_inner(),
+                        bucket_candidates: take(&mut self.bucket_candidates),
+                    }));
                 },
                 (Some((max_prox, query_tree)), Allowed(candidates)) => {
                     if self.proximity as usize > *max_prox {

milli/src/search/criteria/typo.rs

@@ -64,8 +64,11 @@ impl<'t> Criterion for Typo<'t> {
 
             match (&mut self.query_tree, &mut self.candidates) {
                 (_, Allowed(candidates)) if candidates.is_empty() => {
-                    self.query_tree = None;
+                    return Ok(Some(CriterionResult {
-                    self.candidates = Candidates::default();
+                        query_tree: self.query_tree.take().map(|(_, qt)| qt),
+                        candidates: take(&mut self.candidates).into_inner(),
+                        bucket_candidates: take(&mut self.bucket_candidates),
+                    }));
                 },
                 (Some((max_typos, query_tree)), Allowed(candidates)) => {
                     if self.number_typos as usize > *max_typos {

milli/src/search/criteria/words.rs

@@ -56,9 +56,13 @@ impl<'t> Criterion for Words<'t> {
             debug!("Words at iteration {} ({:?})", self.query_trees.len(), self.candidates);
 
             match (self.query_trees.pop(), &mut self.candidates) {
-                (_, Allowed(candidates)) if candidates.is_empty() => {
+                (query_tree, Allowed(candidates)) if candidates.is_empty() => {
                     self.query_trees = Vec::new();
-                    self.candidates = Candidates::default();
+                    return Ok(Some(CriterionResult {
+                        query_tree,
+                        candidates: take(&mut self.candidates).into_inner(),
+                        bucket_candidates: take(&mut self.bucket_candidates),
+                    }));
                 },
                 (Some(qt), Allowed(candidates)) => {
                     let mut found_candidates = resolve_query_tree(self.ctx, &qt, &mut self.candidates_cache)?;