From de65e601655b8841a363865ee3d7acfd2c866d67 Mon Sep 17 00:00:00 2001
From: David Fisher <ddfisher@dropbox.com>
Date: Thu, 1 Dec 2016 15:13:25 -0800
Subject: [PATCH] Make string interpolation checking less unnecessarily
 permissive

---
 mypy/checkstrformat.py                | 8 +++-----
 test-data/unit/check-expressions.test | 7 +++++++
 test-data/unit/fixtures/python2.pyi   | 8 +++++++-
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/mypy/checkstrformat.py b/mypy/checkstrformat.py
index ddf69c264c4ca..fec7d251622f1 100644
--- a/mypy/checkstrformat.py
+++ b/mypy/checkstrformat.py
@@ -151,13 +151,11 @@ def check_simple_str_interpolation(self, specifiers: List[ConversionSpecifier],
 
     def check_mapping_str_interpolation(self, specifiers: List[ConversionSpecifier],
                                        replacements: Expression) -> None:
-        if (isinstance(replacements, DictExpr) and
-                all(isinstance(k, (StrExpr, BytesExpr))
-                    for k, v in replacements.items)):
+        if isinstance(replacements, DictExpr):
             mapping = {}  # type: Dict[str, Type]
             for k, v in replacements.items:
-                key_str = cast(StrExpr, k).value
-                mapping[key_str] = self.accept(v)
+                if isinstance(k, (StrExpr, BytesExpr, UnicodeExpr)):
+                    mapping[k.value] = self.accept(v)
 
             for specifier in specifiers:
                 if specifier.type == '%':
diff --git a/test-data/unit/check-expressions.test b/test-data/unit/check-expressions.test
index e6fbbf092c86b..3c0d56f58ff27 100644
--- a/test-data/unit/check-expressions.test
+++ b/test-data/unit/check-expressions.test
@@ -1083,9 +1083,16 @@ a = None # type: Any
 '%(a)d' % {'a': 1, 'b': 2, 'c': 3}
 '%(q)d' % {'a': 1, 'b': 2, 'c': 3}  # E: Key 'q' not found in mapping
 '%(a)d %%' % {'a': 1}
+'%(q)d' % {'a': 1, 'b': 2, 0: 3}  # E: Key 'q' not found in mapping
 
 [builtins fixtures/dict.pyi]
 
+[case testStringInterpolationMappingKeys_python2]
+'%(q)d' % {u'a': 1, 'b': 2, 'c': 3}  # E: Key 'q' not found in mapping
+'%(a)d' % {u'a': 1, 'b': 2, 'c': 3}
+
+[builtins_py2 fixtures/python2.pyi]
+
 [case testStringInterpolationMappingDictTypes]
 from typing import Any, Dict
 a = None # type: Any
diff --git a/test-data/unit/fixtures/python2.pyi b/test-data/unit/fixtures/python2.pyi
index 61e48be4510e7..dd60331f99c76 100644
--- a/test-data/unit/fixtures/python2.pyi
+++ b/test-data/unit/fixtures/python2.pyi
@@ -1,4 +1,4 @@
-from typing import Generic, Iterable, TypeVar
+from typing import Generic, Iterable, Mapping, TypeVar
 
 class object:
     def __init__(self) -> None: pass
@@ -9,10 +9,16 @@ class type:
 class function: pass
 
 class int: pass
+class float: pass
 class str: pass
 class unicode: pass
+class tuple: pass
 
 T = TypeVar('T')
 class list(Iterable[T], Generic[T]): pass
 
+KT = TypeVar('KT')
+VT = TypeVar('VT')
+class dict(Iterable[KT], Mapping[KT, VT], Generic[KT, VT]): pass
+
 # Definition of None is implicit