Remove static initializers for `RegisterLegacyCommand`

This moves the "legacy"/"nix2" commands under a new `src/legacy/`
directory, instead of being scattered around in a bunch of different
directories.

A new `liblegacy` build target is defined, and the `nix` binary is
linked against it.

Then, `RegisterLegacyCommand` is replaced with `LegacyCommand::add`
calls in functions like `registerNixCollectGarbage()`. These
registration functions are called explicitly in `src/nix/main.cc`.

See: https://git.lix.systems/lix-project/lix/issues/359

Change-Id: Id450ffc3f793374907599cfcc121863b792aac1a

1 files changed, 14 insertions, 0 deletions

diff --git a/src/legacy/user-env.hh b/src/legacy/user-env.hh
new file mode 100644
index 000000000..af45d2d85
--- /dev/null
+++ b/src/legacy/user-env.hh
@@ -0,0 +1,14 @@
+#pragma once
+///@file
+
+#include "get-drvs.hh"
+
+namespace nix {
+
+DrvInfos queryInstalled(EvalState & state, const Path & userEnv);
+
+bool createUserEnv(EvalState & state, DrvInfos & elems,
+    const Path & profile, bool keepDerivations,
+    const std::string & lockToken);
+
+}