From 4fec045073a9964996f41e13454334290e1b6ab0 Mon Sep 17 00:00:00 2001
From: Fabian Homborg <FHomborg@gmail.com>
Date: Thu, 7 Apr 2022 16:09:28 +0200
Subject: [PATCH] sort: Use a stable sort

This allows e.g. sorting first by dirname and then by basename.
---
 src/builtins/path.cpp  | 16 ++++++++++++----
 tests/checks/path.fish | 14 ++++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/builtins/path.cpp b/src/builtins/path.cpp
index af734a4f6..59b91fcfd 100644
--- a/src/builtins/path.cpp
+++ b/src/builtins/path.cpp
@@ -736,16 +736,24 @@ static int path_sort(parser_t &parser, io_streams_t &streams, int argc, const wc
             funced[arg] = func(arg);
         }
 
-        std::sort(list.begin(), list.end(),
+        // We use a stable sort here, and also explicit < and >,
+        // to avoid changing the order so you can chain calls.
+        std::stable_sort(list.begin(), list.end(),
                   [&](const wcstring &a, const wcstring &b) {
-                      return (wcsfilecmp_glob(funced[a].c_str(), funced[b].c_str()) < 0) != opts.invert;
+                      if (!opts.invert)
+                          return (wcsfilecmp_glob(funced[a].c_str(), funced[b].c_str()) < 0);
+                      else
+                          return (wcsfilecmp_glob(funced[a].c_str(), funced[b].c_str()) > 0);
                   });
     } else {
         // Without --what, we just sort by the entire path,
         // so we have no need to transform and such.
-        std::sort(list.begin(), list.end(),
+        std::stable_sort(list.begin(), list.end(),
                   [&](const wcstring &a, const wcstring &b) {
-                      return (wcsfilecmp_glob(a.c_str(), b.c_str()) < 0) != opts.invert;
+                      if (!opts.invert)
+                          return (wcsfilecmp_glob(a.c_str(), b.c_str()) < 0);
+                      else
+                          return (wcsfilecmp_glob(a.c_str(), b.c_str()) > 0);
                   });
     }
 
diff --git a/tests/checks/path.fish b/tests/checks/path.fish
index 426625fcc..7ba7f126e 100644
--- a/tests/checks/path.fish
+++ b/tests/checks/path.fish
@@ -141,3 +141,17 @@ string replace -r "^"(pwd -P | string escape --style=regex)'/' "" -- $path
 
 path resolve /banana//terracota/terracota/booooo/../pie
 # CHECK: /banana/terracota/terracota/pie
+
+path sort --what=basename {def,abc}/{456,123,789,abc,def,0} | path sort --what=dirname -v
+# CHECK: def/0
+# CHECK: def/123
+# CHECK: def/456
+# CHECK: def/789
+# CHECK: def/abc
+# CHECK: def/def
+# CHECK: abc/0
+# CHECK: abc/123
+# CHECK: abc/456
+# CHECK: abc/789
+# CHECK: abc/abc
+# CHECK: abc/def