From dedfaa384408b266c461fea45fee936989bb151b Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Thu, 15 Oct 2020 12:21:38 +0200
Subject: [PATCH] Cleanup alloc advice

---
 docs/dev/style.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/docs/dev/style.md b/docs/dev/style.md
index 435de63e3bd..20f1b6253e7 100644
--- a/docs/dev/style.md
+++ b/docs/dev/style.md
@@ -248,6 +248,8 @@ fn frbonicate(f: impl AsRef<Path>) {
 
 # Premature Pessimization
 
+## Avoid Allocations
+
 Avoid writing code which is slower than it needs to be.
 Don't allocate a `Vec` where an iterator would do, don't allocate strings needlessly.
 
@@ -267,6 +269,8 @@ if words.len() != 2 {
 }
 ```
 
+## Push Allocations to the Call Site
+
 If allocation is inevitable, let the caller allocate the resource:
 
 ```rust
@@ -282,6 +286,9 @@ fn frobnicate(s: &str) {
 }
 ```
 
+This is better because it reveals the costs.
+It is also more efficient when the caller already owns the allocation.
+
 ## Collection types
 
 Prefer `rustc_hash::FxHashMap` and `rustc_hash::FxHashSet` instead of the ones in `std::collections`.