Pulicize clippy_utils::ty::ty_from_hir_ty

And use it in the next commit to avoid ICE.

Author: tesuji

clippy_lints/src/zero_sized_map_values.rs

@@ -1,10 +1,9 @@
 use clippy_utils::diagnostics::span_lint_and_help;
-use clippy_utils::ty::{is_normalizable, is_type_diagnostic_item};
+use clippy_utils::ty::{is_normalizable, is_type_diagnostic_item, ty_from_hir_ty};
 use rustc_hir::{self as hir, AmbigArg, HirId, ItemKind, Node};
-use rustc_hir_analysis::lower_ty;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::layout::LayoutOf as _;
-use rustc_middle::ty::{self, Ty, TypeVisitableExt};
+use rustc_middle::ty::{self, TypeVisitableExt};
 use rustc_session::declare_lint_pass;
 use rustc_span::sym;
 
@@ -82,15 +81,3 @@ fn in_trait_impl(cx: &LateContext<'_>, hir_id: HirId) -> bool {
     }
     false
 }
-
-fn ty_from_hir_ty<'tcx>(cx: &LateContext<'tcx>, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
-    cx.maybe_typeck_results()
-        .and_then(|results| {
-            if results.hir_owner == hir_ty.hir_id.owner {
-                results.node_type_opt(hir_ty.hir_id)
-            } else {
-                None
-            }
-        })
-        .unwrap_or_else(|| lower_ty(cx.tcx, hir_ty))
-}

clippy_utils/src/lib.rs

@@ -39,6 +39,7 @@ extern crate rustc_data_structures;
 extern crate rustc_driver;
 extern crate rustc_errors;
 extern crate rustc_hir;
+extern crate rustc_hir_analysis;
 extern crate rustc_hir_typeck;
 extern crate rustc_index;
 extern crate rustc_infer;

clippy_utils/src/ty/mod.rs

@@ -10,6 +10,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::{Expr, FnDecl, LangItem, TyKind};
+use rustc_hir_analysis::lower_ty;
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::LateContext;
 use rustc_middle::mir::ConstValue;
@@ -36,6 +37,19 @@ use crate::{def_path_def_ids, match_def_path, path_res};
 mod type_certainty;
 pub use type_certainty::expr_type_is_certain;
 
+/// Lower a [`hir::Ty`] to a [`rustc_middle::Ty`].
+pub fn ty_from_hir_ty<'tcx>(cx: &LateContext<'tcx>, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
+    cx.maybe_typeck_results()
+        .and_then(|results| {
+            if results.hir_owner == hir_ty.hir_id.owner {
+                results.node_type_opt(hir_ty.hir_id)
+            } else {
+                None
+            }
+        })
+        .unwrap_or_else(|| lower_ty(cx.tcx, hir_ty))
+}
+
 /// Checks if the given type implements copy.
 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
     cx.type_is_copy_modulo_regions(ty)