From 45a7012fd969ad97fcbcdd4af2530875e37663b7 Mon Sep 17 00:00:00 2001
From: Owen Sanchez <pengowen816@gmail.com>
Date: Mon, 6 Feb 2017 12:25:38 -0700
Subject: [PATCH] Search directly for the largest and smallest variants instead
 of sorting

---
 clippy_lints/src/large_enum_variant.rs | 29 +++++++++++++++-----------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/clippy_lints/src/large_enum_variant.rs b/clippy_lints/src/large_enum_variant.rs
index 1363183cb81..050362dede0 100644
--- a/clippy_lints/src/large_enum_variant.rs
+++ b/clippy_lints/src/large_enum_variant.rs
@@ -51,10 +51,10 @@ fn check_item(&mut self, cx: &LateContext, item: &Item) {
             let ty = cx.tcx.item_type(did);
             let adt = ty.ty_adt_def().expect("already checked whether this is an enum");
 
-            let mut sizes = Vec::new();
-            let mut variants = Vec::new();
+            let mut smallest_variant: Option<(_, _)> = None;
+            let mut largest_variant: Option<(_, _)> = None;
 
-            for variant in &adt.variants {
+            for (i, variant) in adt.variants.iter().enumerate() {
                 let data_layout = TargetDataLayout::parse(cx.sess());
                 cx.tcx.infer_ctxt((), Reveal::All).enter(|infcx| {
                     let size: u64 = variant.fields
@@ -72,18 +72,13 @@ fn check_item(&mut self, cx: &LateContext, item: &Item) {
                         })
                         .sum();
 
-                    sizes.push(size);
-                    variants.push(variant);
+                    let grouped = (size, (i, variant));
+
+                    update_if(&mut smallest_variant, grouped, |a, b| b.0 <= a.0);
+                    update_if(&mut largest_variant, grouped, |a, b| b.0 >= a.0);
                 });
             }
 
-            let mut grouped = sizes.into_iter().zip(variants.into_iter().enumerate()).collect::<Vec<_>>();
-
-            grouped.sort_by_key(|g| g.0);
-
-            let smallest_variant = grouped.first();
-            let largest_variant = grouped.last();
-
             if let (Some(smallest), Some(largest)) = (smallest_variant, largest_variant) {
                 let difference = largest.0 - smallest.0;
 
@@ -118,3 +113,13 @@ fn check_item(&mut self, cx: &LateContext, item: &Item) {
         }
     }
 }
+
+fn update_if<T, F>(old: &mut Option<T>, new: T, f: F) where F: Fn(&T, &T) -> bool {
+    if let Some(ref mut val) = *old {
+        if f(val, &new) {
+            *val = new;
+        }
+    } else {
+        *old = Some(new);
+    }
+}
-- 
2.44.0