Address dogfood ci failure

Author: waynr

clippy_lints/src/methods/mod.rs

@@ -25,10 +25,10 @@ use crate::utils::{
     snippet_with_applicability, snippet_with_macro_callsite, span_lint, span_lint_and_sugg, span_lint_and_then,
     span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth, SpanlessEq,
 };
+use crate::rustc_data_structures::fx::FxHashMap;
 use if_chain::if_chain;
 use matches::matches;
 use std::borrow::Cow;
-use std::collections::HashMap;
 use std::fmt;
 use std::iter;
 
@@ -1948,7 +1948,7 @@ fn lint_filter_map<'a, 'tcx>(
     filter_args: &'tcx [hir::Expr],
     map_args: &'tcx [hir::Expr],
 ) {
-    let mut responses: HashMap<String, &str> = HashMap::new();
+    let mut responses: FxHashMap<String, &str> = FxHashMap::default();
     responses.insert(
         "is_some".to_string(),
         "called `filter(p).map(q)` on an `Iterator<Option<_>>`. \