From 7d4f510f26444923741ab9554d1402f040978f62 Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Wed, 18 Oct 2023 21:46:54 +0100
Subject: [PATCH 1/8] home-environment: add home.sessionSearchVariables

This commit introduces `home.sessionSearchVariables` option, that is
created to be a "generic" version of `home.sessionPath` for any
environment variables that is similar to PATH (e.g.: MANPATH). This
allows composition of those variables between multiple modules, avoiding
issues like this one:

https://github.com/nix-community/home-manager/pull/4579/files#r1364374048

This commit also reimplements `home.sessionPath` as terms of
`home.sessionSearchVariables`, to reduce code duplication and show that
the code is correct.
---
 modules/home-environment.nix                  | 34 +++++++++++++++++--
 tests/modules/home-environment/default.nix    |  3 +-
 .../session-search-variables.nix              | 15 ++++++++
 3 files changed, 48 insertions(+), 4 deletions(-)
 create mode 100644 tests/modules/home-environment/session-search-variables.nix

diff --git a/modules/home-environment.nix b/modules/home-environment.nix
index 87046460..69d04a12 100644
--- a/modules/home-environment.nix
+++ b/modules/home-environment.nix
@@ -319,6 +319,28 @@ in
       '';
     };
 
+    home.sessionSearchVariables = mkOption {
+      default = { };
+      type = with types; attrsOf (listOf str);
+      example = {
+        MANPATH = [
+          "$HOME/.npm-packages/man"
+          "\${xdg.configHome}/.local/share/man"
+        ];
+      };
+      description = ''
+        Extra directories to add to arbitrary PATH-like environment
+        variables (e.g.: {env}`MANPATH`). The values will be concatenated
+        by `:`.
+
+        These directories are added to the environment variable in a
+        double-quoted context, so expressions like `$HOME` are
+        expanded by the shell. However, since expressions like `~` or
+        `*` are escaped, they will end up in the environment
+        verbatim.
+      '';
+    };
+
     home.sessionVariablesExtra = mkOption {
       type = types.lines;
       default = "";
@@ -555,11 +577,17 @@ in
         export __HM_SESS_VARS_SOURCED=1
 
         ${config.lib.shell.exportAll cfg.sessionVariables}
-      '' + lib.optionalString (cfg.sessionPath != [ ]) ''
-        export PATH="$PATH''${PATH:+:}${concatStringsSep ":" cfg.sessionPath}"
-      '' + cfg.sessionVariablesExtra;
+      '' + concatStringsSep "\n"
+        (mapAttrsToList
+          (env: values: ''
+            export ${env}="''$${env}''${${env}:+:}${concatStringsSep ":" values}"'')
+          cfg.sessionSearchVariables)
+        + cfg.sessionVariablesExtra;
     };
 
+    home.sessionSearchVariables.PATH =
+      mkIf (cfg.sessionPath != [ ]) cfg.sessionPath;
+
     home.packages = [ config.home.sessionVariablesPackage ];
 
     # A dummy entry acting as a boundary between the activation
diff --git a/tests/modules/home-environment/default.nix b/tests/modules/home-environment/default.nix
index e76e248a..c38ad5ce 100644
--- a/tests/modules/home-environment/default.nix
+++ b/tests/modules/home-environment/default.nix
@@ -1,4 +1,5 @@
 {
-  home-session-variables = ./session-variables.nix;
   home-session-path = ./session-path.nix;
+  home-session-search-variables = ./session-search-variables.nix;
+  home-session-variables = ./session-variables.nix;
 }
diff --git a/tests/modules/home-environment/session-search-variables.nix b/tests/modules/home-environment/session-search-variables.nix
new file mode 100644
index 00000000..c260e6fe
--- /dev/null
+++ b/tests/modules/home-environment/session-search-variables.nix
@@ -0,0 +1,15 @@
+{ config, lib, pkgs, ... }:
+
+{
+  imports = [
+    ({ ... }: { config.home.sessionSearchVariables.TEST = [ "foo" ]; })
+    ({ ... }: { config.home.sessionSearchVariables.TEST = [ "bar" "baz" ]; })
+  ];
+
+  nmt.script = ''
+    hmSessVars=home-path/etc/profile.d/hm-session-vars.sh
+    assertFileExists $hmSessVars
+    assertFileContains $hmSessVars \
+      'export TEST="$TEST''${TEST:+:}bar:baz:foo"'
+  '';
+}

From 52ea78741bd45732b5478a64f316a42b5fbe4335 Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Wed, 18 Oct 2023 21:50:35 +0100
Subject: [PATCH 2/8] im/fcitx5: use home.sessionSearchVariables for
 QT_PLUGIN_PATH

---
 modules/i18n/input-method/fcitx5.nix | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/modules/i18n/input-method/fcitx5.nix b/modules/i18n/input-method/fcitx5.nix
index 3599fd2d..610df25f 100644
--- a/modules/i18n/input-method/fcitx5.nix
+++ b/modules/i18n/input-method/fcitx5.nix
@@ -23,13 +23,15 @@ in {
   config = mkIf (im.enabled == "fcitx5") {
     i18n.inputMethod.package = fcitx5Package;
 
-    home.sessionVariables = {
-      GLFW_IM_MODULE = "ibus"; # IME support in kitty
-      GTK_IM_MODULE = "fcitx";
-      QT_IM_MODULE = "fcitx";
-      XMODIFIERS = "@im=fcitx";
-      QT_PLUGIN_PATH =
-        "$QT_PLUGIN_PATH\${QT_PLUGIN_PATH:+:}${fcitx5Package}/${pkgs.qt6.qtbase.qtPluginPrefix}";
+    home = {
+      sessionVariables = {
+        GLFW_IM_MODULE = "ibus"; # IME support in kitty
+        GTK_IM_MODULE = "fcitx";
+        QT_IM_MODULE = "fcitx";
+        XMODIFIERS = "@im=fcitx";
+      };
+      sessionSearchVariables.QT_PLUGIN_PATH =
+        [ "${fcitx5Package}/${pkgs.qt6.qtbase.qtPluginPrefix}" ];
     };
 
     systemd.user.services.fcitx5-daemon = {

From f9b4b85ca393f03407d783b469c859b78f08b0df Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Wed, 18 Oct 2023 23:42:23 +0100
Subject: [PATCH 3/8] debug: use home.sessionSearchVariables for
 NIX_DEBUG_INFO_DIRS

---
 modules/misc/debug.nix | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/modules/misc/debug.nix b/modules/misc/debug.nix
index fc0d8946..908b9114 100644
--- a/modules/misc/debug.nix
+++ b/modules/misc/debug.nix
@@ -18,9 +18,8 @@ with lib;
   config = mkIf config.home.enableDebugInfo {
     home.extraOutputsToInstall = [ "debug" ];
 
-    home.sessionVariables = {
-      NIX_DEBUG_INFO_DIRS =
-        "$NIX_DEBUG_INFO_DIRS\${NIX_DEBUG_INFO_DIRS:+:}${config.home.profileDirectory}/lib/debug";
+    home.sessionSearchVariables = {
+      NIX_DEBUG_INFO_DIRS = [ "${config.home.profileDirectory}/lib/debug" ];
     };
   };
 }

From 5921a96caf482d10284e6412020be5ef8cc811ef Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Wed, 18 Oct 2023 23:59:16 +0100
Subject: [PATCH 4/8] home-cursor: use home.sessionSearchVariables for
 XCURSOR_PATH

---
 modules/config/home-cursor.nix | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/modules/config/home-cursor.nix b/modules/config/home-cursor.nix
index c696908d..89f5409d 100644
--- a/modules/config/home-cursor.nix
+++ b/modules/config/home-cursor.nix
@@ -136,16 +136,17 @@ in {
 
       home.packages = [ cfg.package defaultIndexThemePackage ];
 
+      home.sessionVariables = {
+        XCURSOR_SIZE = mkDefault cfg.size;
+        XCURSOR_THEME = mkDefault cfg.name;
+      };
+
       # Set directory to look for cursors in, needed for some applications
       # that are unable to find cursors otherwise. See:
       # https://github.com/nix-community/home-manager/issues/2812
       # https://wiki.archlinux.org/title/Cursor_themes#Environment_variable
-      home.sessionVariables = {
-        XCURSOR_PATH = mkDefault ("$XCURSOR_PATH\${XCURSOR_PATH:+:}"
-          + "${config.home.profileDirectory}/share/icons");
-        XCURSOR_SIZE = mkDefault cfg.size;
-        XCURSOR_THEME = mkDefault cfg.name;
-      };
+      home.sessionSearchVariables.XCURSOR_PATH =
+        [ "${config.home.profileDirectory}/share/icons" ];
 
       # Add symlink of cursor icon directory to $HOME/.icons, needed for
       # backwards compatibility with some applications. See:

From 1e030277ba0196ea0a8d88a3af81a1191c16e197 Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Thu, 19 Oct 2023 00:01:00 +0100
Subject: [PATCH 5/8] targets/generic-linux: use home.sessionSearchVariables
 for XCURSOR_PATH

---
 modules/targets/generic-linux.nix | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/modules/targets/generic-linux.nix b/modules/targets/generic-linux.nix
index b5a07d5f..d6a045b4 100644
--- a/modules/targets/generic-linux.nix
+++ b/modules/targets/generic-linux.nix
@@ -48,12 +48,8 @@ in {
     # We need to append system-wide FHS directories due to the default prefix
     # resolving to the Nix store.
     # https://github.com/nix-community/home-manager/pull/2891#issuecomment-1101064521
-    home.sessionVariables = {
-      XCURSOR_PATH = "$XCURSOR_PATH\${XCURSOR_PATH:+:}" + concatStringsSep ":" [
-        "${config.home.profileDirectory}/share/icons"
-        "/usr/share/icons"
-        "/usr/share/pixmaps"
-      ];
+    home.sessionSearchVariables = {
+      XCURSOR_PATH = [ "/usr/share/icons" "/usr/share/pixmaps" ];
     };
 
     home.sessionVariablesExtra = ''

From 664086fa4c9eb05bbd986cc4d6f41325efa1491b Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Thu, 19 Oct 2023 01:02:01 +0100
Subject: [PATCH 6/8] lib/shell: add appendToVar function

---
 modules/home-environment.nix | 5 +++--
 modules/lib/shell.nix        | 8 ++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/modules/home-environment.nix b/modules/home-environment.nix
index 69d04a12..3533ea2c 100644
--- a/modules/home-environment.nix
+++ b/modules/home-environment.nix
@@ -579,8 +579,9 @@ in
         ${config.lib.shell.exportAll cfg.sessionVariables}
       '' + concatStringsSep "\n"
         (mapAttrsToList
-          (env: values: ''
-            export ${env}="''$${env}''${${env}:+:}${concatStringsSep ":" values}"'')
+          (env: values: config.lib.shell.export
+            env
+            (config.lib.shell.appendToVar ":" env values))
           cfg.sessionSearchVariables)
         + cfg.sessionVariablesExtra;
     };
diff --git a/modules/lib/shell.nix b/modules/lib/shell.nix
index 5e5743f5..cdcfdefa 100644
--- a/modules/lib/shell.nix
+++ b/modules/lib/shell.nix
@@ -1,6 +1,14 @@
 { lib }:
 
 rec {
+  # Produces a Bourne shell like statement that appends new values to
+  # an possibly existing variable, using sep(ator).
+  # Example:
+  #   appendToVar ":" "PATH" [ "$HOME/bin" "$HOME/.local/bin" ]
+  #   => "$PATH\${PATH:+:}$HOME/bin:$HOME/.local/bin"
+  appendToVar = sep: n: v:
+    "\$${n}\${${n}:+${sep}}${lib.concatStringsSep sep v}";
+
   # Produces a Bourne shell like variable export statement.
   export = n: v: ''export ${n}="${toString v}"'';
 

From 0b25ac41ee8754cecfacfbbb311ed008e5670260 Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Thu, 19 Oct 2023 13:02:18 +0100
Subject: [PATCH 7/8] home-environment: prepend instead of append

---
 modules/home-environment.nix                           | 10 +++++-----
 modules/lib/shell.nix                                  | 10 +++++-----
 tests/modules/home-environment/session-path.nix        |  2 +-
 .../home-environment/session-search-variables.nix      |  2 +-
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/modules/home-environment.nix b/modules/home-environment.nix
index 3533ea2c..8f40eae3 100644
--- a/modules/home-environment.nix
+++ b/modules/home-environment.nix
@@ -309,7 +309,7 @@ in
         ".git/safe/../../bin"
       ];
       description = ''
-        Extra directories to add to {env}`PATH`.
+        Extra directories to be prepend to {env}`PATH`.
 
         These directories are added to the {env}`PATH` variable in a
         double-quoted context, so expressions like `$HOME` are
@@ -329,9 +329,9 @@ in
         ];
       };
       description = ''
-        Extra directories to add to arbitrary PATH-like environment
-        variables (e.g.: {env}`MANPATH`). The values will be concatenated
-        by `:`.
+        Extra directories to be prepend to arbitrary PATH-like
+        environment variables (e.g.: {env}`MANPATH`). The values
+        will be concatenated by `:`.
 
         These directories are added to the environment variable in a
         double-quoted context, so expressions like `$HOME` are
@@ -581,7 +581,7 @@ in
         (mapAttrsToList
           (env: values: config.lib.shell.export
             env
-            (config.lib.shell.appendToVar ":" env values))
+            (config.lib.shell.prependToVar ":" env values))
           cfg.sessionSearchVariables)
         + cfg.sessionVariablesExtra;
     };
diff --git a/modules/lib/shell.nix b/modules/lib/shell.nix
index cdcfdefa..c6113d0f 100644
--- a/modules/lib/shell.nix
+++ b/modules/lib/shell.nix
@@ -1,13 +1,13 @@
 { lib }:
 
 rec {
-  # Produces a Bourne shell like statement that appends new values to
+  # Produces a Bourne shell like statement that prepend new values to
   # an possibly existing variable, using sep(ator).
   # Example:
-  #   appendToVar ":" "PATH" [ "$HOME/bin" "$HOME/.local/bin" ]
-  #   => "$PATH\${PATH:+:}$HOME/bin:$HOME/.local/bin"
-  appendToVar = sep: n: v:
-    "\$${n}\${${n}:+${sep}}${lib.concatStringsSep sep v}";
+  #   prependToVar ":" "PATH" [ "$HOME/bin" "$HOME/.local/bin" ]
+  #   => "$HOME/bin:$HOME/.local/bin:${PATH:+:}\$PATH"
+  prependToVar = sep: n: v:
+    "${lib.concatStringsSep sep v}\${${n}:+${sep}}\$${n}";
 
   # Produces a Bourne shell like variable export statement.
   export = n: v: ''export ${n}="${toString v}"'';
diff --git a/tests/modules/home-environment/session-path.nix b/tests/modules/home-environment/session-path.nix
index 57cfeced..55c4084a 100644
--- a/tests/modules/home-environment/session-path.nix
+++ b/tests/modules/home-environment/session-path.nix
@@ -10,6 +10,6 @@
     hmSessVars=home-path/etc/profile.d/hm-session-vars.sh
     assertFileExists $hmSessVars
     assertFileContains $hmSessVars \
-      'export PATH="$PATH''${PATH:+:}bar:baz:foo"'
+      'export PATH="bar:baz:foo''${PATH:+:}$PATH"'
   '';
 }
diff --git a/tests/modules/home-environment/session-search-variables.nix b/tests/modules/home-environment/session-search-variables.nix
index c260e6fe..66dcb034 100644
--- a/tests/modules/home-environment/session-search-variables.nix
+++ b/tests/modules/home-environment/session-search-variables.nix
@@ -10,6 +10,6 @@
     hmSessVars=home-path/etc/profile.d/hm-session-vars.sh
     assertFileExists $hmSessVars
     assertFileContains $hmSessVars \
-      'export TEST="$TEST''${TEST:+:}bar:baz:foo"'
+      'export TEST="bar:baz:foo''${TEST:+:}$TEST"'
   '';
 }

From dbc1ebb0eb0463ecdc19817156088c785cd7c627 Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Tue, 21 Nov 2023 18:59:20 +0000
Subject: [PATCH 8/8] qt: use home.sessionSearchVariables

---
 modules/misc/qt.nix                           | 22 ++++++-------------
 .../modules/misc/qt/qt-platform-theme-gtk.nix |  1 -
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/modules/misc/qt.nix b/modules/misc/qt.nix
index f02bc186..18a90cb8 100644
--- a/modules/misc/qt.nix
+++ b/modules/misc/qt.nix
@@ -170,13 +170,10 @@ in {
       inherit (config.home) profileDirectory;
       qtVersions = with pkgs; [ qt5 qt6 ];
       makeQtPath = prefix:
-        lib.concatStringsSep ":"
         (map (qt: "${profileDirectory}/${qt.qtbase.${prefix}}") qtVersions);
     in {
-      QT_PLUGIN_PATH = "$QT_PLUGIN_PATH\${QT_PLUGIN_PATH:+:}"
-        + (makeQtPath "qtPluginPrefix");
-      QML2_IMPORT_PATH = "$QML2_IMPORT_PATH\${QML2_IMPORT_PATH:+:}"
-        + (makeQtPath "qtQmlPrefix");
+      QT_PLUGIN_PATH = makeQtPath "qtPluginPrefix";
+      QML2_IMPORT_PATH = makeQtPath "qtQmlPrefix";
     };
 
   in lib.mkIf cfg.enable {
@@ -194,19 +191,14 @@ in {
 
     home = {
       sessionVariables = envVars;
-      # home.sessionVariables does not support setting the same environment
-      # variable to different values.
-      # Since some other modules may set the QT_PLUGIN_PATH or QML2_IMPORT_PATH
-      # to their own value, e.g.: fcitx5, we avoid conflicts by setting
-      # the values in home.sessionVariablesExtra instead.
-      sessionVariablesExtra = ''
-        export QT_PLUGIN_PATH=${envVarsExtra.QT_PLUGIN_PATH}
-        export QML2_IMPORT_PATH=${envVarsExtra.QML2_IMPORT_PATH}
-      '';
+      sessionSearchVariables = envVarsExtra;
     };
 
     # Apply theming also to apps started by systemd.
-    systemd.user.sessionVariables = envVars // envVarsExtra;
+    systemd.user.sessionVariables = envVars // {
+      QT_PLUGIN_PATH = lib.concatStringsSep ":" envVarsExtra.QT_PLUGIN_PATH;
+      QML2_IMPORT_PATH = lib.concatStringsSep ":" envVarsExtra.QML2_IMPORT_PATH;
+    };
 
     home.packages = (lib.optionals (cfg.platformTheme != null)
       platformPackages.${cfg.platformTheme} or [ ])
diff --git a/tests/modules/misc/qt/qt-platform-theme-gtk.nix b/tests/modules/misc/qt/qt-platform-theme-gtk.nix
index 070c8020..b91496b5 100644
--- a/tests/modules/misc/qt/qt-platform-theme-gtk.nix
+++ b/tests/modules/misc/qt/qt-platform-theme-gtk.nix
@@ -6,7 +6,6 @@
       enable = true;
       platformTheme = "gtk";
     };
-    i18n.inputMethod.enabled = "fcitx5";
 
     nmt.script = ''
       assertFileRegex home-path/etc/profile.d/hm-session-vars.sh \