Some effort to minimize flake dependencies

For example, if the top-level flake depends on
"nixpkgs/release-19.03", and one of its dependencies depends on
"nixpkgs", then the latter will be mapped to "nixpkgs/release-19.03",
rather than whatever the default branch of "nixpkgs" is. Thus you get
only one "nixpkgs" dependency rather than two.

This currently only works in a breadth-first way, so the other way
around (i.e. if the top-level flake depends on "nixpkgs", and a
dependency depends on "nixpkgs/release-19.03") still results in two
"nixpkgs" dependencies.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index 4ce326c0b..4930d03ce 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -255,6 +255,23 @@ FlakeRef FlakeRef::baseRef() const // Removes the ref and rev from a FlakeRef.
     return result;
 }
 
+bool FlakeRef::contains(const FlakeRef & other) const
+{
+    if (!(data == other.data))
+        return false;
+
+    if (ref && ref != other.ref)
+        return false;
+
+    if (rev && rev != other.rev)
+        return false;
+
+    if (subdir != other.subdir)
+        return false;
+
+    return true;
+}
+
 std::optional<FlakeRef> parseFlakeRef(
     const std::string & uri, bool allowRelative)
 {