From 7a22d5567a3f1b96e4dedff025ca57260927fc57 Mon Sep 17 00:00:00 2001
From: Andrew Walbran <qwandor@google.com>
Date: Wed, 15 Mar 2023 08:06:35 +0000
Subject: [PATCH] Don't allocate in success case (#506)

`format!` was being called (and allocating a string) even in the success case.
---
 src/error-handling/error-contexts.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/error-handling/error-contexts.md b/src/error-handling/error-contexts.md
index bb676d39..50fb5948 100644
--- a/src/error-handling/error-contexts.md
+++ b/src/error-handling/error-contexts.md
@@ -12,7 +12,7 @@ use anyhow::{Context, Result, bail};
 fn read_username(path: &str) -> Result<String> {
     let mut username = String::with_capacity(100);
     fs::File::open(path)
-        .context(format!("Failed to open {path}"))?
+        .with_context(|| format!("Failed to open {path}"))?
         .read_to_string(&mut username)
         .context("Failed to read")?;
     if username.is_empty() {