Move some functions into clippy_utils::ty

Author: smoelius

clippy_lints/src/lib.rs

@@ -41,7 +41,6 @@ extern crate rustc_hir;
 extern crate rustc_hir_analysis;
 extern crate rustc_hir_pretty;
 extern crate rustc_hir_typeck;
-extern crate rustc_index;
 extern crate rustc_infer;
 extern crate rustc_lexer;
 extern crate rustc_lint;

clippy_lints/src/methods/unnecessary_to_owned.rs

@@ -4,7 +4,10 @@ use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::res::MaybeDef;
 use clippy_utils::source::{SpanRangeExt, snippet};
-use clippy_utils::ty::{get_iterator_item_ty, implements_trait, is_copy, peel_and_count_ty_refs};
+use clippy_utils::ty::{
+    get_callee_generic_args_and_args, get_iterator_item_ty, implements_trait, is_copy, is_to_string_on_string_like,
+    peel_and_count_ty_refs,
+};
 use clippy_utils::visitors::find_all_ret_expressions;
 use clippy_utils::{fn_def_id, get_parent_expr, is_expr_temporary_value, return_ty, sym};
 use rustc_errors::Applicability;
@@ -16,7 +19,7 @@ use rustc_lint::LateContext;
 use rustc_middle::mir::Mutability;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, OverloadedDeref};
 use rustc_middle::ty::{
-    self, ClauseKind, GenericArg, GenericArgKind, GenericArgsRef, ParamTy, ProjectionPredicate, TraitPredicate, Ty,
+    self, ClauseKind, GenericArg, GenericArgKind, ParamTy, ProjectionPredicate, TraitPredicate, Ty,
 };
 use rustc_span::Symbol;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
@@ -441,33 +444,6 @@ fn skip_addr_of_ancestors<'tcx>(
     None
 }
 
-/// Checks whether an expression is a function or method call and, if so, returns its `DefId`,
-/// `GenericArgs`, and arguments.
-fn get_callee_generic_args_and_args<'tcx>(
-    cx: &LateContext<'tcx>,
-    expr: &'tcx Expr<'tcx>,
-) -> Option<(
-    DefId,
-    GenericArgsRef<'tcx>,
-    Option<&'tcx Expr<'tcx>>,
-    &'tcx [Expr<'tcx>],
-)> {
-    if let ExprKind::Call(callee, args) = expr.kind
-        && let callee_ty = cx.typeck_results().expr_ty(callee)
-        && let ty::FnDef(callee_def_id, _) = callee_ty.kind()
-    {
-        let generic_args = cx.typeck_results().node_args(callee.hir_id);
-        return Some((*callee_def_id, generic_args, None, args));
-    }
-    if let ExprKind::MethodCall(_, recv, args, _) = expr.kind
-        && let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
-    {
-        let generic_args = cx.typeck_results().node_args(expr.hir_id);
-        return Some((method_def_id, generic_args, Some(recv), args));
-    }
-    None
-}
-
 /// Returns the `TraitPredicate`s and `ProjectionPredicate`s for a function's input type.
 fn get_input_traits_and_projections<'tcx>(
     cx: &LateContext<'tcx>,
@@ -626,40 +602,14 @@ fn is_to_owned_like<'a>(
 ) -> bool {
     is_cow_into_owned(cx, method_name, method_parent_id)
         || (method_name != sym::to_string && is_clone_like(cx, method_name, method_parent_id))
-        || is_to_string_on_string_like(cx, call_expr, method_name, method_parent_id)
+        || is_to_string_on_string_like(cx, call_expr, method_parent_id)
 }
 
 /// Returns true if the named method is `Cow::into_owned`.
 fn is_cow_into_owned(cx: &LateContext<'_>, method_name: Symbol, method_parent_id: DefId) -> bool {
     method_name == sym::into_owned && method_parent_id.opt_impl_ty(cx).is_diag_item(cx, sym::Cow)
 }
 
-/// Returns true if the named method is `ToString::to_string` and it's called on a type that
-/// is string-like i.e. implements `AsRef<str>` or `Deref<Target = str>`.
-fn is_to_string_on_string_like<'a>(
-    cx: &LateContext<'_>,
-    call_expr: &'a Expr<'a>,
-    method_name: Symbol,
-    method_parent_id: DefId,
-) -> bool {
-    if method_name != sym::to_string || !method_parent_id.is_diag_item(cx, sym::ToString) {
-        return false;
-    }
-
-    if let Some(args) = cx.typeck_results().node_args_opt(call_expr.hir_id)
-        && let [generic_arg] = args.as_slice()
-        && let GenericArgKind::Type(ty) = generic_arg.kind()
-        && let Some(deref_trait_id) = cx.tcx.get_diagnostic_item(sym::Deref)
-        && let Some(as_ref_trait_id) = cx.tcx.get_diagnostic_item(sym::AsRef)
-        && (cx.get_associated_type(ty, deref_trait_id, sym::Target) == Some(cx.tcx.types.str_)
-            || implements_trait(cx, ty, as_ref_trait_id, &[cx.tcx.types.str_.into()]))
-    {
-        true
-    } else {
-        false
-    }
-}
-
 fn std_map_key<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
     match ty.kind() {
         ty::Adt(adt, args)