Merge pull request #212939 from amjoseph-nixpkgs/pr/isStatic

meta: replace predicates with pattern over elaborated platform

lib/meta.nix

@@ -76,20 +76,19 @@ rec {
 
        1. (legacy) a system string.
 
-       2. (modern) a pattern for the platform `parsed` field.
+       2. (modern) a pattern for the entire platform structure (see `lib.systems.inspect.platformPatterns`).
 
-       3. (functional) a predicate function returning a boolean.
+       3. (modern) a pattern for the platform `parsed` field (see `lib.systems.inspect.patterns`).
 
      We can inject these into a pattern for the whole of a structured platform,
      and then match that.
   */
-  platformMatch = platform: elem:
-    if builtins.isFunction elem
-    then elem platform
-    else let
+  platformMatch = platform: elem: let
       pattern =
         if builtins.isString elem
         then { system = elem; }
+        else if elem?parsed
+        then elem
         else { parsed = elem; };
     in lib.matchAttrs pattern platform;
 

lib/systems/inspect.nix

@@ -7,6 +7,7 @@ let abis_ = abis; in
 let abis = lib.mapAttrs (_: abi: builtins.removeAttrs abi [ "assertions" ]) abis_; in
 
 rec {
+  # these patterns are to be matched against {host,build,target}Platform.parsed
   patterns = rec {
     isi686         = { cpu = cpuTypes.i686; };
     isx86_32       = { cpu = { family = "x86"; bits = 32; }; };
@@ -90,4 +91,13 @@ rec {
     else matchAttrs patterns;
 
   predicates = mapAttrs (_: matchAnyAttrs) patterns;
+
+  # these patterns are to be matched against the entire
+  # {host,build,target}Platform structure; they include a `parsed={}` marker so
+  # that `lib.meta.availableOn` can distinguish them from the patterns which
+  # apply only to the `parsed` field.
+
+  platformPatterns = mapAttrs (_: p: { parsed = {}; } // p) {
+    isStatic = { isStatic = true; };
+  };
 }

pkgs/os-specific/linux/systemd/default.nix

@@ -714,7 +714,7 @@ stdenv.mkDerivation {
     description = "A system and service manager for Linux";
     license = licenses.lgpl21Plus;
     platforms = platforms.linux;
-    badPlatforms = [ (plat: plat.isStatic) ];
+    badPlatforms = [ lib.systems.inspect.platformPatterns.isStatic ];
     # https://github.com/systemd/systemd/issues/20600#issuecomment-912338965
     broken = stdenv.hostPlatform.isStatic;
     priority = 10;

pkgs/stdenv/generic/check-meta.nix

@@ -271,7 +271,7 @@ let
     sourceProvenance = listOf lib.types.attrs;
     maintainers = listOf (attrsOf anything); # TODO use the maintainer type from lib/tests/maintainer-module.nix
     priority = int;
-    platforms = listOf (oneOf [ str (attrsOf anything) (functionTo bool) ]);   # see lib.meta.platformMatch
+    platforms = listOf (either str (attrsOf anything));   # see lib.meta.platformMatch
     hydraPlatforms = listOf str;
     broken = bool;
     unfree = bool;