__builtins__ and int are not defined

[diamond-lizard]

When I run mypy against this test program ("foo.py"):

def gcd(a: int, b: int) -> int:
  while b:
    a, b = b, a % b
  return a

print(gcd( 'x', 15 ))

I get this error:

foo.py: error: Name '__builtins__' is not defined
foo.py:1: error: Name 'int' is not defined
foo.py:1: error: Cannot find module named 'builtins'
foo.py:1: note: (Perhaps setting MYPYPATH or using the "--ignore-missing-imports" flag would help)
foo.py:1: error: INTERNAL ERROR -- please report a bug at https://github.com/python/mypy/issues version: 0.521
Traceback (most recent call last):
  File "/home/me/.local/bin/mypy", line 11, in <module>
    sys.exit(console_entry())
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/__main__.py", line 7, in console_entry
    main(None)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/main.py", line 50, in main
    res = type_check_only(sources, bin_dir, options)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/main.py", line 97, in type_check_only
    options=options)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/build.py", line 196, in build
    graph = dispatch(sources, manager)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/build.py", line 1801, in dispatch
    process_graph(graph, manager)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/build.py", line 2044, in process_graph
    process_stale_scc(graph, scc, manager)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/build.py", line 2139, in process_stale_scc
    graph[id].semantic_analysis()
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/build.py", line 1696, in semantic_analysis
    self.manager.semantic_analyzer.visit_file(self.tree, self.xpath, self.options, patches)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/semanal.py", line 295, in visit_file
    self.accept(d)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/semanal.py", line 3645, in accept
    node.accept(self)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/nodes.py", line 565, in accept
    return visitor.visit_func_def(self)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/semanal.py", line 418, in visit_func_def
    self.analyze_function(defn)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/semanal.py", line 598, in analyze_function
    defn.type = self.type_analyzer().visit_callable_type(defn.type, nested=False)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/typeanal.py", line 333, in visit_callable_type
    fallback=t.fallback or self.named_type('builtins.function'),
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/typeanal.py", line 545, in named_type
    node = self.lookup_fqn_func(fully_qualified_name)
  File "/home/me/.local/lib64/python3.4/site-packages/mypy/semanal.py", line 3491, in lookup_fully_qualified
    n = self.modules[parts[0]]
KeyError: 'builtins'
foo.py:1: note: use --pdb to drop into pdb

I'm using python 3.4.5 under gentoo linux amd64. I had installed mypy using "pip3 install --user mypy" and my version of pip3 is "pip 9.0.1 from /usr/lib64/python3.4/site-packages (python 3.4)".

This was from a fresh install of mypy, but I then tried "pip3 install --user --upgrade mypy" which installed typing-3.6.2 but I still got the same error.

[ethanhs]

Hi! This is usually a problem related to a broken installation. Could you paste (perhaps in a gist?) the output of calling mypy with the verbose flag -v (this should help us debug the issue). This will tell us where mypy is looking for typeshed, which it likely did not find correctly.

[gvanrossum]

I'd guess that the 'lib64' in the path might have confused mypy in its search to find typeshed. I recall some recent fix for that, but I don't recall whether it made it into mypy 0.521.

…

On Thu, Aug 24, 2017 at 1:42 AM, Ethan Smith ***@***.***> wrote: Hi! This is usually a problem related to a broken installation. Could you paste (perhaps in a gist?) the output of calling mypy with the verbose flag -v (this should help us debug the issue). This will tell us where mypy is looking for typeshed, which it likely did not find correctly. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#3867 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACwrMiqc9HkWn4bWJyW_CnjvNgkitaChks5sbTdhgaJpZM4PBBgr> .

-- --Guido van Rossum (python.org/~guido)

[diamond-lizard]

Here is the output of "mypy -v --show-traceback foo.py"

[gvanrossum]

Can you try with the the latest master?

…

On Aug 24, 2017 8:28 AM, "diamond-lizard" ***@***.***> wrote: Here <https://gist.github.com/diamond-lizard/a343dfcaf5c79750fe1e469392924d37> is the output of "mypy -v --show-traceback foo.py" — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3867 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACwrMknLGlyVILrgYT8BenURBu5yIt0cks5sbZangaJpZM4PBBgr> .

[diamond-lizard]

Apologies for the ignorant question, but how would I install the latest master?

I tried "pip3 install --user --upgrade mypy" and got:

Requirement already up-to-date: mypy in ./.local/lib64/python3.4/site-packages
Requirement already up-to-date: typing>=3.5.3; python_version < "3.5" in ./.local/lib64/python3.4/site-packages (from mypy)
Requirement already up-to-date: typed-ast<1.1.0,>=1.0.4 in ./.local/lib64/python3.4/site-packages (from mypy)

... and then got the same error when I ran mypy against foo.py

[diamond-lizard]

Nevermind. I figured it out:

git clone https://github.com/python/mypy.git
cd mypy
git submodule update --init typeshed
pip3 install --user --upgrade .

And now "mypy foo.py" seems to work:

foo.py:6: error: Argument 1 to "gcd" has incompatible type "str"; expected "int"

Thanks for your help!

[ethanhs]

#3758 fixed this, it seems it was merged right around 0.521, and probably was missed.

[ilevkivskyi]

Nevermind. I figured it out:

git clone https://github.com/python/mypy.git
cd mypy
git submodule update --init typeshed
pip3 install --user --upgrade .

@gvanrossum @ethanhs
What do you think about an explicit recommendation in README to try master if one thinks there is a bug in PyPI version? Also the relevant section of the docs on installing from source is missing the typeshed submodule update step.

[gvanrossum]

Oh, the "install from source" section definitely needs to be fixed.

But "try from master" is more easily done through a GitHub URL:

pip3 -U install git+https://github.com/python/mypy.git

It's probably a good idea to add a hint about trying that first if you think you've found a bug -- it's a common occurrence.