fetchgit: allow disabling cone mode for sparse checkouts, fix test

doc/builders/fetchers.chapter.md

@@ -91,7 +91,7 @@ Used with Git. Expects `url` to a Git repo, `rev`, and `sha256`. `rev` in this c
 
 Additionally, the following optional arguments can be given: `fetchSubmodules = true` makes `fetchgit` also fetch the submodules of a repository. If `deepClone` is set to true, the entire repository is cloned as opposing to just creating a shallow clone. `deepClone = true` also implies `leaveDotGit = true` which means that the `.git` directory of the clone won't be removed after checkout.
 
-If only parts of the repository are needed, `sparseCheckout` can be used. This will prevent git from fetching unnecessary blobs from server, see [git sparse-checkout](https://git-scm.com/docs/git-sparse-checkout) and [git clone --filter](https://git-scm.com/docs/git-clone#Documentation/git-clone.txt---filterltfilter-specgt) for more information:
+If only parts of the repository are needed, `sparseCheckout` can be used. This will prevent git from fetching unnecessary blobs from server, see [git sparse-checkout](https://git-scm.com/docs/git-sparse-checkout) for more information:
 
 ```nix
 { stdenv, fetchgit }:
@@ -101,8 +101,8 @@ stdenv.mkDerivation {
   src = fetchgit {
     url = "https://...";
     sparseCheckout = ''
-      path/to/be/included
-      another/path
+      directory/to/be/included
+      another/directory
     '';
     sha256 = "0000000000000000000000000000000000000000000000000000";
   };

nixos/doc/manual/from_md/release-notes/rl-2211.section.xml

@@ -251,6 +251,18 @@
           <literal>(with foo; isPower &amp;&amp; is32bit &amp;&amp; isBigEndian)</literal>.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          The <literal>fetchgit</literal> fetcher now uses
+          <link xlink:href="https://www.git-scm.com/docs/git-sparse-checkout/2.37.0#_internalscone_mode_handling">cone
+          mode</link> by default for sparse checkouts.
+          <link xlink:href="https://www.git-scm.com/docs/git-sparse-checkout/2.37.0#_internalsnon_cone_problems">Non-cone
+          mode</link> can be enabled by passing
+          <literal>nonConeMode = true</literal>, but note that non-cone
+          mode is deprecated and this option may be removed alongside a
+          future Git update without notice.
+        </para>
+      </listitem>
       <listitem>
         <para>
           <literal>bsp-layout</literal> no longer uses the command

nixos/doc/manual/release-notes/rl-2211.section.md

@@ -97,6 +97,8 @@ In addition to numerous new and upgraded packages, this release has the followin
 
 - The `isPowerPC` predicate, found on `platform` attrsets (`hostPlatform`, `buildPlatform`, `targetPlatform`, etc) has been removed in order to reduce confusion.  The predicate was was defined such that it matches only the 32-bit big-endian members of the POWER/PowerPC family, despite having a name which would imply a broader set of systems.  If you were using this predicate, you can replace `foo.isPowerPC` with `(with foo; isPower && is32bit && isBigEndian)`.
 
+- The `fetchgit` fetcher now uses [cone mode](https://www.git-scm.com/docs/git-sparse-checkout/2.37.0#_internalscone_mode_handling) by default for sparse checkouts. [Non-cone mode](https://www.git-scm.com/docs/git-sparse-checkout/2.37.0#_internalsnon_cone_problems) can be enabled by passing `nonConeMode = true`, but note that non-cone mode is deprecated and this option may be removed alongside a future Git update without notice.
+
 - `bsp-layout` no longer uses the command `cycle` to switch to other window layouts, as it got replaced by the commands `previous` and `next`.
 
 - The Barco ClickShare driver/client package `pkgs.clickshare-csc1` and the option `programs.clickshare-csc1.enable` have been removed,

pkgs/build-support/fetchgit/builder.sh

@@ -12,6 +12,7 @@ $SHELL $fetcher --builder --url "$url" --out "$out" --rev "$rev" \
   ${deepClone:+--deepClone} \
   ${fetchSubmodules:+--fetch-submodules} \
   ${sparseCheckout:+--sparse-checkout "$sparseCheckout"} \
+  ${nonConeMode:+--non-cone-mode} \
   ${branchName:+--branch-name "$branchName"}
 
 runHook postFetch

pkgs/build-support/fetchgit/default.nix

@@ -16,6 +16,7 @@ in
 , fetchSubmodules ? true, deepClone ? false
 , branchName ? null
 , sparseCheckout ? ""
+, nonConeMode ? false
 , name ? urlToName url rev
 , # Shell code executed after the file has been fetched
   # successfully. This can do things like check or transform the file.
@@ -54,6 +55,7 @@ in
 */
 
 assert deepClone -> leaveDotGit;
+assert nonConeMode -> (sparseCheckout != "");
 
 if md5 != "" then
   throw "fetchgit does not support md5 anymore, please use sha256"
@@ -77,7 +79,7 @@ stdenvNoCC.mkDerivation {
   else
     lib.fakeSha256;
 
-  inherit url rev leaveDotGit fetchLFS fetchSubmodules deepClone branchName sparseCheckout postFetch;
+  inherit url rev leaveDotGit fetchLFS fetchSubmodules deepClone branchName sparseCheckout nonConeMode postFetch;
 
   postHook = if netrcPhase == null then null else ''
     ${netrcPhase}

pkgs/build-support/fetchgit/nix-prefetch-git

@@ -49,6 +49,7 @@ Options:
       --hash h        Expected hash.
       --branch-name   Branch name to check out into
       --sparse-checkout Only fetch and checkout part of the repository.
+      --non-cone-mode Use non-cone mode for sparse checkouts.
       --deepClone     Clone the entire repository.
       --no-deepClone  Make a shallow clone of just the required ref.
       --leave-dotGit  Keep the .git directories.
@@ -77,6 +78,7 @@ for arg; do
             --branch-name) argfun=set_branchName;;
             --deepClone) deepClone=true;;
             --sparse-checkout) argfun=set_sparseCheckout;;
+            --non-cone-mode) nonConeMode=true;;
             --quiet) QUIET=true;;
             --no-deepClone) deepClone=;;
             --leave-dotGit) leaveDotGit=true;;
@@ -116,7 +118,7 @@ init_remote(){
     clean_git remote add origin "$url"
     if [ -n "$sparseCheckout" ]; then
         git config remote.origin.partialclonefilter "blob:none"
-        echo "$sparseCheckout" | git sparse-checkout set --stdin
+        echo "$sparseCheckout" | git sparse-checkout set --stdin ${nonConeMode:+--no-cone}
     fi
     ( [ -n "$http_proxy" ] && clean_git config http.proxy "$http_proxy" ) || true
 }

pkgs/build-support/fetchgit/tests.nix

@@ -16,6 +16,18 @@
       src
       tests
     '';
+    sha256 = "sha256-g1PHGTWgAcd/+sXHo1o6AjVWCvC6HiocOfMbMh873LQ=";
+  };
+
+  sparseCheckoutNonConeMode = testers.invalidateFetcherByDrvHash fetchgit {
+    name = "nix-source";
+    url = "https://github.com/NixOS/nix";
+    rev = "9d9dbe6ed05854e03811c361a3380e09183f4f4a";
+    sparseCheckout = ''
+      src
+      tests
+    '';
+    nonConeMode = true;
     sha256 = "sha256-FknO6C/PSnMPfhUqObD4vsW4PhkwdmPa9blNzcNvJQ4=";
   };
 }