Make self attrs overridable

src/libfetchers/git.cc

@@ -253,10 +253,6 @@ struct GitInputScheme : InputScheme
             url.query.insert_or_assign("ref", *ref);
         if (getShallowAttr(input))
             url.query.insert_or_assign("shallow", "1");
-        if (getLfsAttr(input))
-            url.query.insert_or_assign("lfs", "1");
-        if (getSubmodulesAttr(input))
-            url.query.insert_or_assign("submodules", "1");
         if (maybeGetBoolAttr(input.attrs, "exportIgnore").value_or(false))
             url.query.insert_or_assign("exportIgnore", "1");
         if (maybeGetBoolAttr(input.attrs, "verifyCommit").value_or(false))
@@ -267,6 +263,11 @@ struct GitInputScheme : InputScheme
             url.query.insert_or_assign("publicKey", publicKeys.at(0).key);
         } else if (publicKeys.size() > 1)
             url.query.insert_or_assign("publicKeys", publicKeys_to_string(publicKeys));
+        // These are allowed as self attrs, the explicit false is important
+        if (auto lfs = maybeGetBoolAttr(input.attrs, "lfs"))
+            url.query.insert_or_assign("lfs", *lfs ? "1" : "0");
+        if (auto submodules = maybeGetBoolAttr(input.attrs, "submodules"))
+            url.query.insert_or_assign("submodules", *submodules ? "1" : "0");
         return url;
     }
 
@@ -884,8 +885,14 @@ struct GitInputScheme : InputScheme
     std::optional<std::string> getFingerprint(ref<Store> store, const Input & input) const override
     {
         auto makeFingerprint = [&](const Hash & rev) {
-            return rev.gitRev() + (getSubmodulesAttr(input) ? ";s" : "") + (getExportIgnoreAttr(input) ? ";e" : "")
-                   + (getLfsAttr(input) ? ";l" : "");
+            std::string modifiers = "";
+            if (getExportIgnoreAttr(input))
+                modifiers += ";e";
+            if (auto lfs = maybeGetBoolAttr(input.attrs, "lfs"))
+                modifiers += *lfs ? ";l1" : ";l0";
+            if (auto submodules = maybeGetBoolAttr(input.attrs, "submodules"))
+                modifiers += *submodules ? ";s1" : ";s0";
+            return rev.gitRev() + modifiers;
         };
 
         if (auto rev = input.getRev())

src/libflake/flake.cc

@@ -325,7 +325,7 @@ static FlakeRef applySelfAttrs(const FlakeRef & ref, const Flake & flake)
     for (auto & attr : flake.selfAttrs) {
         if (!allowedAttrs.contains(attr.first))
             throw Error("flake 'self' attribute '%s' is not supported", attr.first);
-        newRef.input.attrs.insert_or_assign(attr.first, attr.second);
+        newRef.input.attrs.try_emplace(attr.first, attr.second);
     }
 
     return newRef;

tests/nixos/fetch-git/test-cases/lfs/default.nix

@@ -209,6 +209,7 @@
       # memorize the revision
       self_lfs_rev = client.succeed(f"{repo.git} rev-parse HEAD").strip()
 
+      # Check that LFS is now enabled by default
       with TemporaryDirectory() as tempdir:
         client.succeed(f"mkdir -p {tempdir}")
         client.succeed(f"""
@@ -223,7 +224,24 @@
           nix eval --debug --raw {tempdir}#.outPath
         """)
 
-    client.succeed(f"cmp {repo.path}/beeg {fetched_self_lfs}/beeg >&2")
+      client.succeed(f"cmp {repo.path}/beeg {fetched_self_lfs}/beeg >&2")
+
+      # Check that we can disable LFS enabled by default
+      with TemporaryDirectory() as tempdir:
+        client.succeed(f"mkdir -p {tempdir}")
+        client.succeed(f"""
+          printf '{{
+            inputs.foo = {{
+              url = "git+{repo.remote}?ref=main&rev={self_lfs_rev}&lfs=0";
+            }};
+            outputs = {{ foo, self }}: {{ inherit (foo) outPath; }};
+          }}' >{tempdir}/flake.nix
+        """)
+        fetched_self_nolfs = client.succeed(f"""
+          nix eval --debug --raw {tempdir}#.outPath
+        """)
+
+      client.succeed(f"! cmp {fetched_self_lfs}/beeg {fetched_self_nolfs}/beeg >&2")
 
 
     with subtest("Ensure fetching with SSH generates the same output"):