From 96a17b1683fb1bd5b49abff2e4e661084268e672 Mon Sep 17 00:00:00 2001
From: Anthony Sottile <asottile@umich.edu>
Date: Fri, 11 Sep 2020 16:44:24 -0700
Subject: [PATCH] Fix INTERNALERROR when accessing locals / globals with faulty
 `exec`

---
 changelog/7742.bugfix.rst    |  1 +
 src/_pytest/_code/code.py    | 16 +++++++++++++---
 testing/code/test_excinfo.py | 13 +++++++++++++
 3 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 changelog/7742.bugfix.rst

diff --git a/changelog/7742.bugfix.rst b/changelog/7742.bugfix.rst
new file mode 100644
index 00000000000..95277ee8908
--- /dev/null
+++ b/changelog/7742.bugfix.rst
@@ -0,0 +1 @@
+Fix INTERNALERROR when accessing locals / globals with faulty ``exec``.
diff --git a/src/_pytest/_code/code.py b/src/_pytest/_code/code.py
index 12d39306a69..98aea8c11ec 100644
--- a/src/_pytest/_code/code.py
+++ b/src/_pytest/_code/code.py
@@ -246,10 +246,20 @@ def ishidden(self) -> bool:
 
         Mostly for internal use.
         """
-        f = self.frame
-        tbh = f.f_locals.get(
-            "__tracebackhide__", f.f_globals.get("__tracebackhide__", False)
+        tbh = (
+            False
         )  # type: Union[bool, Callable[[Optional[ExceptionInfo[BaseException]]], bool]]
+        for maybe_ns_dct in (self.frame.f_locals, self.frame.f_globals):
+            # in normal cases, f_locals and f_globals are dictionaries
+            # however via `exec(...)` / `eval(...)` they can be other types
+            # (even incorrect types!).
+            # as such, we suppress all exceptions while accessing __tracebackhide__
+            try:
+                tbh = maybe_ns_dct["__tracebackhide__"]
+            except Exception:
+                pass
+            else:
+                break
         if tbh and callable(tbh):
             return tbh(None if self._excinfo is None else self._excinfo())
         return tbh
diff --git a/testing/code/test_excinfo.py b/testing/code/test_excinfo.py
index 4dfd6f5cc95..5754977ddc7 100644
--- a/testing/code/test_excinfo.py
+++ b/testing/code/test_excinfo.py
@@ -1352,6 +1352,19 @@ def unreraise():
         )
         assert out == expected_out
 
+    def test_exec_type_error_filter(self, importasmod):
+        """See #7742"""
+        mod = importasmod(
+            """\
+            def f():
+                exec("a = 1", {}, [])
+            """
+        )
+        with pytest.raises(TypeError) as excinfo:
+            mod.f()
+        # previously crashed with `AttributeError: list has no attribute get`
+        excinfo.traceback.filter()
+
 
 @pytest.mark.parametrize("style", ["short", "long"])
 @pytest.mark.parametrize("encoding", [None, "utf8", "utf16"])