fix: Correctly resolve packages from preferences.packages.version (#33)

Before this, a value that does not correspond to an attribute under a
package alias' `versions` would make it default to the latest as defined
by `lib.packages.getLatest`, which isn't a silver bullt: it choose
"bash5.2.15-bootstrap" for instance instead of stage1-passthrough (and I
don;t think we have an easy fix for that).

Given values like `"1.2.3"` makes little sense in
`config.preferences.packages.version` (because it's a package-set-wide
preference), this means it was hardly ever useful.

before:

```console
❯ nix eval -f tidepool --apply 't:
  t.extend {modules = [{config.preferences.packages.version = "latest";}];}
  |> (t: t.config.lib.packages.resolve t.config.packages.foundation.bash)
  |> (p: p.version)'
"5.2.15-bootstrap"
❯ nix eval -f tidepool --apply 't:
  t.extend {modules = [{config.preferences.packages.version = "stable";}];}
  |> (t: t.config.lib.packages.resolve t.config.packages.foundation.bash)
  |> (p: p.version)'
"5.2.15-bootstrap"
```

after:

```console
❯ nix eval -f tidepool --apply 't:
  t.extend {modules = [{config.preferences.packages.version = "latest";}];}
  |> (t: t.config.lib.packages.resolve t.config.packages.foundation.bash)
  |> (p: p.version)'
"5.2.15-stage1-passthrough"
❯ nix eval -f tidepool --apply 't:
  t.extend {modules = [{config.preferences.packages.version = "stable";}];}
  |> (t: t.config.lib.packages.resolve t.config.packages.foundation.bash)
  |> (p: p.version)'
"5.2.15-bootstrap"
```

Co-authored-by: austreelis <git@swhaele.net>
Reviewed-on: auxolotl/labs#33
Reviewed-by: Ruby Iris Juric <ruby+auxolotl@srxl.me>
Co-authored-by: Austreelis <austreelis@noreply.git.auxolotl.org>
Co-committed-by: Austreelis <austreelis@noreply.git.auxolotl.org>

tidepool/npins/sources.json

@@ -8,9 +8,9 @@
       },
       "branch": "main",
       "submodules": false,
-      "revision": "ec6ba877756d3b898c75bdf8f75faff671fb3dbb",
+      "revision": "f39cac8caec87b3d93bd2f941bcf8768dc46d912",
       "url": null,
-      "hash": "sha256-wCnUEFuFu1YKo2iE/kZeEpg3G8sCWeijuHXHTctKpJQ="
+      "hash": "sha256-LgdIew95Y3PBTTj8vV70gbWIyMPf3Fl30cM2WPWylNk="
     },
     "lib": {
       "type": "Git",

tidepool/src/lib/packages.nix

@@ -243,11 +243,22 @@ in
         in
         outputs;
 
+      WELL_KNOWN_ALIASES = [
+        # NOTE: When adding a version alias here, update lib.types.alias and lib.types.platforms' alias sub-option
+        "stable"
+        "latest"
+      ];
+
       resolve =
         alias:
-        if alias ? versions then
-          alias.versions.${config.preferences.packages.version}
-            or (alias.versions.${lib.packages.getLatest alias})
+        let
+          prefered = config.preferences.packages.version;
+          isWellKnown = builtins.elem prefered lib.packages.WELL_KNOWN_ALIASES;
+        in
+        if isWellKnown && alias ? ${prefered} then
+          alias.${prefered}
+        else if alias ? versions then
+          alias.versions.${prefered} or (alias.versions.${lib.packages.getLatest alias})
         else
           alias;
 

tidepool/src/lib/types.nix

@@ -13,19 +13,18 @@ in
             { config }:
             {
               options = {
-                name = {
-                  full = lib.options.create {
-                    description = "The full name of the license.";
-                    type = lib.types.string;
-                  };
 
-                  short = lib.options.create {
-                    description = "The short name of the license.";
-                    type = lib.types.string;
-                  };
+                name = lib.options.create {
+                  description = "The short name of the license.";
+                  type = lib.types.string;
                 };
 
-                spdx = lib.options.create {
+                fullName = lib.options.create {
+                  description = "The full name of the license.";
+                  type = lib.types.string;
+                };
+
+                spdxId = lib.options.create {
                   description = "The SPDX identifier for the license.";
                   type = lib.types.nullish lib.types.string;
                   default.value = null;
@@ -33,7 +32,11 @@ in
 
                 url = lib.options.create {
                   description = "The URL for the license.";
-                  type = lib.types.nullish lib.types.string;
+                  type = lib.types.string;
+                  default = {
+                    text = "spdx.org entry, if `spdxId` is set, `null` otherwise";
+                    value = if config.spdxId == null then null else "https://spdx.org/licenses/${config.spdxId}.html";
+                  };
                 };
 
                 free = lib.options.create {
@@ -304,6 +307,7 @@ in
               type = lib.types.artifact;
               default.value = null;
             };
+            # NOTE: When adding a version alias here, update lib.packages.WELL_KNOWN_ALIASES
             versions = lib.options.create {
               description = "Available versions of the artifact.";
               type = lib.types.attrs.of lib.types.artifact;
@@ -398,6 +402,8 @@ in
                 if config.versions == { } then null else config.versions.${lib.packages.getLatest config};
             };
 
+            # NOTE: When adding a version alias here, update lib.packages.WELL_KNOWN_ALIASES
+
             versions = lib.options.create {
               description = "Available versions of the package.";
               type = lib.types.attrs.of lib.types.package;

tidepool/src/packages/default.nix

@@ -37,10 +37,7 @@ in
     preferences.packages = {
       version = lib.options.create {
         description = "The preferred package version when using aliases.";
-        type = lib.types.enum [
-          "latest"
-          "stable"
-        ];
+        type = lib.types.enum lib.packages.WELL_KNOWN_ALIASES;
         default.value = "latest";
       };