From ba87b08f8529e4d9f8c58d8c625152058ceadb75 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 22 Nov 2019 16:06:44 +0100
Subject: getEnv(): Return std::optional

This allows distinguishing between an empty value and no value.
---
 src/libstore/gc.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'src/libstore/gc.cc')

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 7d3da1cc8..842980fb7 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -870,11 +870,11 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
 void LocalStore::autoGC(bool sync)
 {
-    static auto fakeFreeSpaceFile = getEnv("_NIX_TEST_FREE_SPACE_FILE", "");
+    static auto fakeFreeSpaceFile = getEnv("_NIX_TEST_FREE_SPACE_FILE");
 
     auto getAvail = [this]() -> uint64_t {
-        if (!fakeFreeSpaceFile.empty())
-            return std::stoll(readFile(fakeFreeSpaceFile));
+        if (fakeFreeSpaceFile)
+            return std::stoll(readFile(*fakeFreeSpaceFile));
 
         struct statvfs st;
         if (statvfs(realStoreDir.c_str(), &st))
-- 
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