feat: support managing submodules via inputs.self

Provides sepcial handling for inputs.self. If submodule is set to true,
will re-call getFlake as if the original reference was set. The intended
behavior is for CLI management of the paramenter overriddes any
direct flake.nix settings.

src/libexpr/flake/flake.cc

@@ -104,6 +104,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
  auto sUrl = state.symbols.create("url");
  auto sFlake = state.symbols.create("flake");
  auto sFollows = state.symbols.create("follows");
+ auto sSubmodules = state.symbols.create("submodules");
 
  fetchers::Attrs attrs;
  std::optional<std::string> url;
@@ -117,6 +118,9 @@ static FlakeInput parseFlakeInput(EvalState & state,
  } else if (attr.name == sFlake) {
  expectType(state, nBool, *attr.value, attr.pos);
  input.isFlake = attr.value->boolean;
+ } else if (attr.name == sSubmodules) {
+ expectType(state, nBool, *attr.value, attr.pos);
+ input.hasSubmodules = attr.value->boolean;
  } else if (attr.name == sInputs) {
  input.overrides = parseFlakeInputs(state, attr.value, attr.pos, baseDir, lockRootPath);
  } else if (attr.name == sFollows) {
@@ -229,8 +233,17 @@ static Flake getFlake(
 
  auto sInputs = state.symbols.create("inputs");
 
- if (auto inputs = vInfo.attrs->get(sInputs))
+ if (auto inputs = vInfo.attrs->get(sInputs)){
  flake.inputs = parseFlakeInputs(state, inputs->value, inputs->pos, flakeDir, lockRootPath);
+ if (originalRef.input.attrs.count("submodules") == 0) {
+ if (auto self = flake.inputs.find("self") ; self != flake.inputs.end() && self->second.hasSubmodules) {
+ auto newRef = originalRef;
+ newRef.input.attrs["submodules"] = nix::Explicit<bool>{true};
+ warn("Using Git submodules due to input.self.submodule value");
+ return getFlake(state,newRef,allowLookup,flakeCache,lockRootPath);
+ }
+ }
+ }
 
  auto sOutputs = state.symbols.create("outputs");
 
@@ -405,6 +418,7 @@ LockedFlake lockFlake(
  necessary (i.e. if they're new or the flakeref changed
  from what's in the lock file). */
  for (auto & [id, input2] : flakeInputs) {
+ if (id == "self") continue;
  auto inputPath(inputPathPrefix);
  inputPath.push_back(id);
  auto inputPathS = printInputPath(inputPath);

src/libexpr/flake/flake.hh

@@ -41,6 +41,7 @@ typedef std::map<FlakeId, FlakeInput> FlakeInputs;
 struct FlakeInput
 {
  std::optional<FlakeRef> ref;
+ bool hasSubmodules = false;
  bool isFlake = true; // true = process flake to get outputs, false = (fetched) static source path
  std::optional<InputPath> follows;
  FlakeInputs overrides;