Regression: markers which are not strings cause eval errors

[lf-]

Describe the issue

Regression in #1905 cc @jamesdbrock @Nebucatnetzer

With a lock file entry like:

[[package]]
name = "colorama"
version = "0.4.6"
description = "Cross-platform colored terminal text."
optional = false
python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,!=3.5.*,!=3.6.*,>=2.7"
groups = ["main", "dev"]
files = [
    {file = "colorama-0.4.6-py2.py3-none-any.whl", hash = "sha256:4f1d9991f5acc0ca119f9d443620b77f9d6b33703e51011c16baf57afb285fc6"},
    {file = "colorama-0.4.6.tar.gz", hash = "sha256:08695f5cb7ed6e0531a20572697297273c47b8cae5a63ffc6d6ed5c201be6e44"},
]
markers = {main = "platform_system == \"Windows\"", dev = "sys_platform == \"win32\""}

The markers will cause an evaluation error:

       … while calling the 'listToAttrs' builtin
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/default.nix:270:29:
          269|             # Null out any filtered packages, we don't want python.pkgs from nixpkgs
          270|             (_final: _prev: builtins.listToAttrs (builtins.map (x: { name = normalizePackageName x.name; value = nul
l; }) incompatible))
             |                             ^
          271|             # Create poetry2nix layer

       … while calling the 'map' builtin
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/default.nix:270:51:
          269|             # Null out any filtered packages, we don't want python.pkgs from nixpkgs
          270|             (_final: _prev: builtins.listToAttrs (builtins.map (x: { name = normalizePackageName x.name; value = nul
l; }) incompatible))
             |                                                   ^
          271|             # Create poetry2nix layer

       … while evaluating an expression to select 'wrong' on it
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/default.nix:193:22:
          192|       compatible = partitions.right;
          193|       incompatible = partitions.wrong;
             |                      ^
          194|

       … while calling the 'partition' builtin
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/default.nix:191:9:
          190|         in
          191|         lib.partition supportsPythonVersion poetryLock.package;
             |         ^
          192|       compatible = partitions.right;

       … while calling 'supportsPythonVersion'
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/default.nix:182:35:
          181|         let
          182|           supportsPythonVersion = pkgMeta:
             |                                   ^
          183|             if pkgMeta ? markers then

       … from call site
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/default.nix:188:17:
          187|                 in
          188|                 pyproject-nix.lib.pep508.evalMarkers pep508Env marker
             |                 ^
          189|               ) else true && poetryLib.checkPythonVersions pyVersion pkgMeta.python-versions;

       … while calling 'evalMarkers'
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:763:14:
          762|   evalMarkers =
          763|     environ: value:
             |              ^
          764|     (

       … while evaluating a branch condition
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:765:7:
          764|     (
          765|       if value.type == "compare" then
             |       ^
          766|         (

       … while evaluating an expression to select 'type' on it
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:765:10:
          764|     (
          765|       if value.type == "compare" then
             |          ^
          766|         (

       … from call site
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/default.nix:186:28:
          185|                 let
          186|                   marker = pyproject-nix.lib.pep508.parseMarkers pkgMeta.markers;
             |                            ^
          187|                 in

       … while calling anonymous lambda
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:250:5:
          249|     in
          250|     input:
             |     ^
          251|     if input == "" then

       … from call site
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:429:7:
          428|       in
          429|       reduceValue { } groupedTokens;
             |       ^
          430|

       … while calling 'reduceValue'
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:351:17:
          350|         reduceValue =
          351|           lhs': value:
             |                 ^
          352|           if isList value then

       … while evaluating a branch condition
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:352:11:
          351|           lhs': value:
          352|           if isList value then
             |           ^
          353|             (

       … while calling the 'isList' builtin
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:352:14:
          351|           lhs': value:
          352|           if isList value then
             |              ^
          353|             (

       … while evaluating a branch condition
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:347:25:
          346|         # We can completely avoid it if the input doesn't contain any grouped subexpressions.
          347|         groupedTokens = if any (token: token == "(") tokens then groupTokens [ ] 0 else tokens;
             |                         ^
          348|

       … while calling the 'any' builtin
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:347:28:
          346|         # We can completely avoid it if the input doesn't contain any grouped subexpressions.
          347|         groupedTokens = if any (token: token == "(") tokens then groupTokens [ ] 0 else tokens;
             |                            ^
          348|

       … while evaluating a branch condition
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:314:11:
          313|         tokens =
          314|           if tokens'.start == cmax && last != " " then tokens'.tokens ++ [ last ] else tokens'.tokens;
             |           ^
          315|

       … in the left operand of the AND (&&) operator
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:314:36:
          313|         tokens =
          314|           if tokens'.start == cmax && last != " " then tokens'.tokens ++ [ last ] else tokens'.tokens;
             |                                    ^
          315|

       … while evaluating an expression to select 'start' on it
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:314:14:
          313|         tokens =
          314|           if tokens'.start == cmax && last != " " then tokens'.tokens ++ [ last ] else tokens'.tokens;
             |              ^
          315|

       … while calling the 'foldl'' builtin
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:263:11:
          262|         tokens' =
          263|           foldl'
             |           ^
          264|             (acc: c: rec {

       … from call site
         at /nix/store/sc7ip1wzp6madcvjv82abx91a1fcrnfa-source/vendor/pyproject.nix/lib/pep508.nix:255:17:
          254|       let
          255|         chars = stringToCharacters input;
             |                 ^
          256|         cmax = (length chars) - 1;

       … while calling 'stringToCharacters'
         at /nix/store/8hzp2ran0rqixlk37rfdyq4jpnmf3b6a-source/lib/strings.nix:898:24:
          897|   */
          898|   stringToCharacters = s:
             |                        ^
          899|     genList (p: substring p 1 s) (stringLength s);

       … while calling the 'genList' builtin
         at /nix/store/8hzp2ran0rqixlk37rfdyq4jpnmf3b6a-source/lib/strings.nix:899:5:
          898|   stringToCharacters = s:
          899|     genList (p: substring p 1 s) (stringLength s);
             |     ^
          900|

       … while evaluating the second argument passed to builtins.genList

       … while calling the 'stringLength' builtin
         at /nix/store/8hzp2ran0rqixlk37rfdyq4jpnmf3b6a-source/lib/strings.nix:899:35:
          898|   stringToCharacters = s:
          899|     genList (p: substring p 1 s) (stringLength s);
             |                                   ^
          900|

       … while evaluating the argument passed to builtins.stringLength

       error: cannot coerce a set to a string: { dev = "sys_platform == \"win32\""; main = "platform_system == \"Windows\""; }

Additional context

default.nix/shell.nix/flake.nix:
Sorry, it is proprietary :( I can write up a reproducer later when I get time; either this is enough info to find it or I can write a reproducer in a few hours.

[Nebucatnetzer]

I wait for a response by @jamesdbrock if he has an idea to fix it, otherwise I'm going to revert the change.

[Nebucatnetzer]

I started the revert.
With the provided logs we should be able to test the changes in a more robust way and hopefully don't break anything with the next try.
#1910

[jamesdbrock]

Ok I will try again.

[jamesdbrock]

@lf- What did the pyproject.toml dependency declaration for colorama look like?