Explicitly model all settings and fail on unrecognized ones

Previously, the Settings class allowed other code to query for string
properties, which led to a proliferation of code all over the place making
up new options without any sort of central registry of valid options. This
commit pulls all those options back into the central Settings class and
removes the public get() methods, to discourage future abuses like that.

Furthermore, because we know the full set of options ahead of time, we
now fail loudly if someone enters an unrecognized option, thus preventing
subtle typos. With some template fun, we could probably also dump the full
set of options (with documentation, defaults, etc.) to the command line,
but I'm not doing that yet here.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 0aabe66c5626..bb3b430c9ec1 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -146,7 +146,7 @@ static void opRealise(Strings opFlags, Strings opArgs)
         unknown = PathSet();
     }
 
-    if (settings.get("print-missing", true))
+    if (settings.printMissing)
         printMissing(ref<Store>(store), willBuild, willSubstitute, unknown, downloadSize, narSize);
 
     if (dryRun) return;