Improved builtin inference for ``tuple``, ``set``, ``frozenset``, ``list`` and ``dict``

We were properly inferring these callables *only* if they had consts as
values, but that is not the case most of the time. Instead we try to infer
the values that their arguments can be and use them instead of assuming
Const nodes all the time.

Close PyCQA/pylint#2841

1 files changed, 11 insertions, 4 deletions

diff --git a/astroid/node_classes.py b/astroid/node_classes.py
index 204d8023..449470d0 100644
--- a/astroid/node_classes.py
+++ b/astroid/node_classes.py
@@ -48,6 +48,10 @@ BUILTINS = builtins_mod.__name__
 MANAGER = manager.AstroidManager()
 
 
+def _is_const(value):
+    return isinstance(value, tuple(CONST_CLS))
+
+
 @decorators.raise_if_nothing_inferred
 def unpack_infer(stmt, context=None):
     """recursively generate nodes inferred by the given statement.
@@ -1017,7 +1021,7 @@ class _BaseContainer(
         self.elts = elts
 
     @classmethod
-    def from_constants(cls, elts=None):
+    def from_elements(cls, elts=None):
         """Create a node of this type from the given list of elements.
 
         :param elts: The list of elements that the node should contain.
@@ -1030,7 +1034,7 @@ class _BaseContainer(
         if elts is None:
             node.elts = []
         else:
-            node.elts = [const_factory(e) for e in elts]
+            node.elts = [const_factory(e) if _is_const(e) else e for e in elts]
         return node
 
     def itered(self):
@@ -2728,7 +2732,7 @@ class Dict(NodeNG, bases.Instance):
         self.items = items
 
     @classmethod
-    def from_constants(cls, items=None):
+    def from_elements(cls, items=None):
         """Create a :class:`Dict` of constants from a live dictionary.
 
         :param items: The items to store in the node.
@@ -2742,7 +2746,10 @@ class Dict(NodeNG, bases.Instance):
             node.items = []
         else:
             node.items = [
-                (const_factory(k), const_factory(v)) for k, v in items.items()
+                (const_factory(k), const_factory(v) if _is_const(v) else v)
+                for k, v in items.items()
+                # The keys need to be constants
+                if _is_const(k)
             ]
         return node