Error when adding package: EmptyConstraint instance has no attribute 'min'

• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: macOS 10.13.6
• Poetry version: 0.12.3
• Link of a Gist with the contents of your pyproject.toml file: https://gist.github.com/bi1yeu/41b2180afd838560daa0faf68e9c236b

Issue

Hi! This is my first time attempting to use poetry. I created a new empty project with this command:

$ poetry new example

Then, from within the example directory, I attempt to add the jupyter package:

$ poetry add jupyter
Using version ^1.0 for jupyter

Updating dependencies
Resolving dependencies... (4.0s)

[AttributeError]
EmptyConstraint instance has no attribute 'min'

add [-D|--dev] [--git GIT] [--path PATH] [-E|--extras EXTRAS] [--optional] [--python PYTHON] [--platform PLATFORM] [--allow-prereleases] [--dry-run] [--] <name> (<name>)...

Verbose output is contained within the gist linked above. I am able to add other packages without apparent error. Happy to provide additional info.

[glencairn]

I’m experiencing this same issue with Poetry 1.1.4 when trying to install certain packages. I was able to get around the issue following a similar approach that @bnoctis and @agilgur5 detailed above. However, for a more recent vendorized install, the file I had to modify was ~/.poetry/lib/poetry/_vendor/py3.8/poetry/core/packages/dependency.py (where python3.8 is my active interpreter).

Here’s a diff of the modifications I made, hopefully others find this useful:

diff --git a/tmp.py b/Users/user/.poetry/lib/poetry/_vendor/py3.8/poetry/core/packages/dependency.py
index e118794..6f97002 100644
--- a/tmp.py
+++ b/Users/user/.poetry/lib/poetry/_vendor/py3.8/poetry/core/packages/dependency.py
@@ -9,6 +9,7 @@ from poetry.core.semver import Version
 from poetry.core.semver import VersionConstraint
 from poetry.core.semver import VersionRange
 from poetry.core.semver import VersionUnion
+from poetry.core.semver import EmptyConstraint
 from poetry.core.semver import parse_constraint
 from poetry.core.version.markers import AnyMarker
 from poetry.core.version.markers import parse_marker
@@ -291,6 +292,8 @@ class Dependency(PackageSpecification):
                 name = "python_full_version"
 
             marker = '{} == "{}"'.format(name, constraint.text)
+        elif isinstance(constraint, EmptyConstraint):
+            marker = ''
         else:
             if constraint.min is not None:
                 min_name = name

---

System: MacOS Poetry: 1.1.4

[elicutler]

I had to edit ~/.poetry/lib/poetry/_vendor/py3.8/poetry/core/version/markers.py

from poetry.core.packages.constraints.empty_constraint import EmptyConstraint

and line 281 in the definition of validate(self, environment), added:

if isinstance(self._constraint, EmptyConstraint):
    return True