From f9170a84f6eb6a162c800c39c17d3b34eff87dda Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <xokdvium@proton.me>
Date: Sun, 15 Jun 2025 16:51:44 +0000
Subject: [PATCH] tests/functional/lang: Add sort stability test for lists
 langer than 16 elements

libstdc++'s std::stable_sort and new builtins.sort implementation
special-case ranges with length less than or equal to 16 and delegate
to insertionsort.

Having a larger e2e test would allow catching sort stability issues
at functional level as well.
---
 tests/functional/lang/eval-okay-sort.exp |  2 +-
 tests/functional/lang/eval-okay-sort.nix | 74 ++++++++++++++++++++++++
 2 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/tests/functional/lang/eval-okay-sort.exp b/tests/functional/lang/eval-okay-sort.exp
index 899119e20..fcb3b2224 100644
--- a/tests/functional/lang/eval-okay-sort.exp
+++ b/tests/functional/lang/eval-okay-sort.exp
@@ -1 +1 @@
-[ [ 42 77 147 249 483 526 ] [ 526 483 249 147 77 42 ] [ "bar" "fnord" "foo" "xyzzy" ] [ { key = 1; value = "foo"; } { key = 1; value = "fnord"; } { key = 2; value = "bar"; } ] [ [ ] [ ] [ 1 ] [ 1 4 ] [ 1 5 ] [ 1 6 ] [ 2 ] [ 2 3 ] [ 3 ] [ 3 ] ] ]
+[ [ 42 77 147 249 483 526 ] [ 526 483 249 147 77 42 ] [ "bar" "fnord" "foo" "xyzzy" ] [ { key = 1; value = "foo"; } { key = 1; value = "fnord"; } { key = 2; value = "bar"; } ] [ { key = 1; value = "foo"; } { key = 1; value = "foo2"; } { key = 1; value = "foo3"; } { key = 1; value = "foo4"; } { key = 1; value = "foo5"; } { key = 1; value = "foo6"; } { key = 1; value = "foo7"; } { key = 1; value = "foo8"; } { key = 2; value = "bar"; } { key = 2; value = "bar2"; } { key = 2; value = "bar3"; } { key = 2; value = "bar4"; } { key = 2; value = "bar5"; } { key = 3; value = "baz"; } { key = 3; value = "baz2"; } { key = 3; value = "baz3"; } { key = 3; value = "baz4"; } { key = 4; value = "biz1"; } ] [ [ ] [ ] [ 1 ] [ 1 4 ] [ 1 5 ] [ 1 6 ] [ 2 ] [ 2 3 ] [ 3 ] [ 3 ] ] ]
diff --git a/tests/functional/lang/eval-okay-sort.nix b/tests/functional/lang/eval-okay-sort.nix
index 412bda4a0..7a3b7f71b 100644
--- a/tests/functional/lang/eval-okay-sort.nix
+++ b/tests/functional/lang/eval-okay-sort.nix
@@ -37,6 +37,80 @@ with builtins;
       value = "fnord";
     }
   ])
+  (sort (x: y: x.key < y.key) [
+    {
+      key = 1;
+      value = "foo";
+    }
+    {
+      key = 2;
+      value = "bar";
+    }
+    {
+      key = 1;
+      value = "foo2";
+    }
+    {
+      key = 2;
+      value = "bar2";
+    }
+    {
+      key = 2;
+      value = "bar3";
+    }
+    {
+      key = 2;
+      value = "bar4";
+    }
+    {
+      key = 1;
+      value = "foo3";
+    }
+    {
+      key = 3;
+      value = "baz";
+    }
+    {
+      key = 3;
+      value = "baz2";
+    }
+    {
+      key = 1;
+      value = "foo4";
+    }
+    {
+      key = 3;
+      value = "baz3";
+    }
+    {
+      key = 1;
+      value = "foo5";
+    }
+    {
+      key = 1;
+      value = "foo6";
+    }
+    {
+      key = 2;
+      value = "bar5";
+    }
+    {
+      key = 3;
+      value = "baz4";
+    }
+    {
+      key = 1;
+      value = "foo7";
+    }
+    {
+      key = 4;
+      value = "biz1";
+    }
+    {
+      key = 1;
+      value = "foo8";
+    }
+  ])
   (sort lessThan [
     [
       1