getEnv(): Return std::optional

This allows distinguishing between an empty value and no value.

4 files changed, 5 insertions, 5 deletions

diff --git a/src/nix/command.cc b/src/nix/command.cc
index 97c2fcf1c..724f03e5d 100644
--- a/src/nix/command.cc
+++ b/src/nix/command.cc
@@ -156,7 +156,7 @@ void StorePathCommand::run(ref<Store> store)
 
 Strings editorFor(const Pos & pos)
 {
-    auto editor = getEnv("EDITOR", "cat");
+    auto editor = getEnv("EDITOR").value_or("cat");
     auto args = tokenizeString<Strings>(editor);
     if (pos.line > 0 && (
         editor.find("emacs") != std::string::npos ||
diff --git a/src/nix/doctor.cc b/src/nix/doctor.cc
index 795236c5f..481c93b45 100644
--- a/src/nix/doctor.cc
+++ b/src/nix/doctor.cc
@@ -68,7 +68,7 @@ struct CmdDoctor : StoreCommand
     {
         PathSet dirs;
 
-        for (auto & dir : tokenizeString<Strings>(getEnv("PATH"), ":"))
+        for (auto & dir : tokenizeString<Strings>(getEnv("PATH").value_or(""), ":"))
             if (pathExists(dir + "/nix-env"))
                 dirs.insert(dirOf(canonPath(dir + "/nix-env", true)));
 
@@ -87,7 +87,7 @@ struct CmdDoctor : StoreCommand
     {
         PathSet dirs;
 
-        for (auto & dir : tokenizeString<Strings>(getEnv("PATH"), ":")) {
+        for (auto & dir : tokenizeString<Strings>(getEnv("PATH").value_or(""), ":")) {
             Path profileDir = dirOf(dir);
             try {
                 Path userEnv = canonPath(profileDir, true);
diff --git a/src/nix/run.cc b/src/nix/run.cc
index 90b76d666..fd4f92282 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -128,7 +128,7 @@ struct CmdRun : InstallablesCommand
         std::queue<Path> todo;
         for (auto & path : outPaths) todo.push(path);
 
-        auto unixPath = tokenizeString<Strings>(getEnv("PATH"), ":");
+        auto unixPath = tokenizeString<Strings>(getEnv("PATH").value_or(""), ":");
 
         while (!todo.empty()) {
             Path path = todo.front();
diff --git a/src/nix/upgrade-nix.cc b/src/nix/upgrade-nix.cc
index 35c44a70c..6c9e37d04 100644
--- a/src/nix/upgrade-nix.cc
+++ b/src/nix/upgrade-nix.cc
@@ -106,7 +106,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand
     {
         Path where;
 
-        for (auto & dir : tokenizeString<Strings>(getEnv("PATH"), ":"))
+        for (auto & dir : tokenizeString<Strings>(getEnv("PATH").value_or(""), ":"))
             if (pathExists(dir + "/nix-env")) {
                 where = dir;
                 break;