cafkafk/nixpkgs
cafkafk/nixpkgs
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 2

lib/system: move toLosslessStringMaybe into lib/tests

Browse source 
toLosslessStringMaybe is not used by anything other than lib/tests,
so it can be private to that file.

I don't think this function was terribly well thought-through.  If
people start using it, we will become permanently dependent on the
ability to test platforms for equality.  It also makes the
elaboration process more fragile, because it encourages code outside
of nixpkgs to become sensitive to the minute details of how
elaboration happens.
This commit is contained in:
Adam Joseph 2023-06-22 00:18:31 -07:00
parent 66ee7de717
commit 00a749a3a6
2 changed files with 18 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
lib/systems/default.nix
View file

@ -27,21 +27,6 @@ rec {
let removeFunctions = a: lib.filterAttrs (_: v: !builtins.isFunction v) a;
in a: b: removeFunctions a == removeFunctions b;
/*
Try to convert an elaborated system back to a simple string. If not possible,
return null. So we have the property:
sys: _valid_ sys ->
sys == elaborate (toLosslessStringMaybe sys)
NOTE: This property is not guaranteed when `sys` was elaborated by a different
version of Nixpkgs.
*/
toLosslessStringMaybe = sys:
if lib.isString sys then sys
else if equals sys (elaborate sys.system) then sys.system
else null;
/* List of all Nix system doubles the nixpkgs flake will expose the package set
for. All systems listed here must be supported by nixpkgs as `localSystem`.

20
lib/tests/systems.nix
View file

@ -9,6 +9,22 @@ let
expr = lib.sort lib.lessThan x;
expected = lib.sort lib.lessThan y;
};
/*
Try to convert an elaborated system back to a simple string. If not possible,
return null. So we have the property:
sys: _valid_ sys ->
sys == elaborate (toLosslessStringMaybe sys)
NOTE: This property is not guaranteed when `sys` was elaborated by a different
version of Nixpkgs.
*/
toLosslessStringMaybe = sys:
if lib.isString sys then sys
else if lib.systems.equals sys (lib.systems.elaborate sys.system) then sys.system
else null;
in
lib.runTests (
# We assert that the new algorithmic way of generating these lists matches the
@ -55,11 +71,11 @@ lib.runTests (
};
test_toLosslessStringMaybe_example_x86_64-linux = {
expr = lib.systems.toLosslessStringMaybe (lib.systems.elaborate "x86_64-linux");
expr = toLosslessStringMaybe (lib.systems.elaborate "x86_64-linux");
expected = "x86_64-linux";
};
test_toLosslessStringMaybe_fail = {
expr = lib.systems.toLosslessStringMaybe (lib.systems.elaborate "x86_64-linux" // { something = "extra"; });
expr = toLosslessStringMaybe (lib.systems.elaborate "x86_64-linux" // { something = "extra"; });
expected = null;
};
}