Avoid looking regex crate up multiple times

Author: GnomedDev

clippy_lints/src/regex.rs

@@ -3,7 +3,7 @@ use std::fmt::Display;
 use clippy_utils::consts::{ConstEvalCtxt, Constant};
 use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
 use clippy_utils::source::SpanRangeExt;
-use clippy_utils::{def_path_def_ids, path_def_id, paths};
+use clippy_utils::{def_path_res_with_base, find_crates, path_def_id, paths};
 use rustc_ast::ast::{LitKind, StrStyle};
 use rustc_hir::def_id::DefIdMap;
 use rustc_hir::{BorrowKind, Expr, ExprKind};
@@ -75,11 +75,14 @@ impl<'tcx> LateLintPass<'tcx> for Regex {
         // We don't use `match_def_path` here because that relies on matching the exact path, which changed
         // between regex 1.8 and 1.9
         //
-        // `def_path_def_ids` will resolve through re-exports but is relatively heavy, so we only perform
-        // the operation once and store the results
-        let mut resolve = |path, kind| {
-            for id in def_path_def_ids(cx.tcx, path) {
-                self.definitions.insert(id, kind);
+        // `def_path_res_with_base` will resolve through re-exports but is relatively heavy, so we only
+        // perform the operation once and store the results
+        let regex_crates = find_crates(cx.tcx, sym!(regex));
+        let mut resolve = |path: &[&str], kind: RegexKind| {
+            for res in def_path_res_with_base(cx.tcx, regex_crates.clone(), &path[1..]) {
+                if let Some(id) = res.opt_def_id() {
+                    self.definitions.insert(id, kind);
+                }
             }
         };