remove unnecessary find_map calls

Author: Jacherr

clippy_lints/src/types/vec_box.rs

@@ -1,7 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::last_path_segment;
 use clippy_utils::source::snippet;
-use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{self as hir, GenericArg, QPath, TyKind};
@@ -21,45 +20,37 @@ pub(super) fn check(
     box_size_threshold: u64,
 ) -> bool {
     if cx.tcx.is_diagnostic_item(sym::Vec, def_id) {
-        if_chain! {
+        if let Some(last) = last_path_segment(qpath).args
             // Get the _ part of Vec<_>
-            if let Some(last) = last_path_segment(qpath).args;
-            if let Some(ty) = last.args.iter().find_map(|arg| match arg {
-                GenericArg::Type(ty) => Some(ty),
-                _ => None,
-            });
+            && let Some(GenericArg::Type(ty)) = last.args.first()
             // ty is now _ at this point
-            if let TyKind::Path(ref ty_qpath) = ty.kind;
-            let res = cx.qpath_res(ty_qpath, ty.hir_id);
-            if let Some(def_id) = res.opt_def_id();
-            if Some(def_id) == cx.tcx.lang_items().owned_box();
+            && let TyKind::Path(ref ty_qpath) = ty.kind
+            && let res = cx.qpath_res(ty_qpath, ty.hir_id)
+            && let Some(def_id) = res.opt_def_id()
+            && Some(def_id) == cx.tcx.lang_items().owned_box()
             // At this point, we know ty is Box<T>, now get T
-            if let Some(last) = last_path_segment(ty_qpath).args;
-            if let Some(boxed_ty) = last.args.iter().find_map(|arg| match arg {
-                GenericArg::Type(ty) => Some(ty),
-                _ => None,
-            });
-            let ty_ty = hir_ty_to_ty(cx.tcx, boxed_ty);
-            if !ty_ty.has_escaping_bound_vars();
-            if ty_ty.is_sized(cx.tcx, cx.param_env);
-            if let Ok(ty_ty_size) = cx.layout_of(ty_ty).map(|l| l.size.bytes());
-            if ty_ty_size < box_size_threshold;
-            then {
-                span_lint_and_sugg(
-                    cx,
-                    VEC_BOX,
-                    hir_ty.span,
-                    "`Vec<T>` is already on the heap, the boxing is unnecessary",
-                    "try",
-                    format!("Vec<{}>", snippet(cx, boxed_ty.span, "..")),
-                    Applicability::MachineApplicable,
-                );
-                true
-            } else {
-                false
-            }
+            && let Some(last) = last_path_segment(ty_qpath).args
+            && let Some(GenericArg::Type(boxed_ty)) = last.args.first()
+            && let ty_ty = hir_ty_to_ty(cx.tcx, boxed_ty)
+            && !ty_ty.has_escaping_bound_vars()
+            && ty_ty.is_sized(cx.tcx, cx.param_env)
+            && let Ok(ty_ty_size) = cx.layout_of(ty_ty).map(|l| l.size.bytes())
+            && ty_ty_size < box_size_threshold
+        {
+            span_lint_and_sugg(
+                cx,
+                VEC_BOX,
+                hir_ty.span,
+                "`Vec<T>` is already on the heap, the boxing is unnecessary",
+                "try",
+                format!("Vec<{}>", snippet(cx, boxed_ty.span, "..")),
+                Applicability::MachineApplicable,
+            );
+            true
+        } else {
+            false
         }
     } else {
         false
     }
-}
+}