Merge pull request #4093 from matthewbauer/eval-system

Add eval-system option

(cherry picked from commit 071dbbee33af9f27338c3e53e4ea067dbfa14010)
Change-Id: Ia81358c8cfb60241da07a4d0e84b9ee62a18a53f

src/libexpr/eval-settings.cc

@@ -88,6 +88,12 @@ std::string EvalSettings::resolvePseudoUrl(std::string_view url)
         return std::string(url);
 }
 
+const std::string & EvalSettings::getCurrentSystem()
+{
+    const auto & evalSystem = currentSystem.get();
+    return evalSystem != "" ? evalSystem : settings.thisSystem.get();
+}
+
 EvalSettings evalSettings;
 
 static GlobalConfig::Register rEvalSettings(&evalSettings);