Revert iter raises checks

This reverts commit e938580257.

Revert "improve error msg and test"

This reverts commit c0cf822ca1.

Revert "error msg"

This reverts commit ec1053cc16.

Revert "changelog"

This reverts commit d2dc8a70b5.

Revert "simplify code / take out user-gen typeerror case"

This reverts commit b9cb87d862.

changelog/7966.bugfix.rst

@@ -1 +0,0 @@
-Assertion rewrite mechanism now gives a seperate, more detailed error message from failures within __iter__.

src/_pytest/assertion/util.py

@@ -134,13 +134,6 @@ def isiterable(obj: Any) -> bool:
         return not istext(obj)
     except TypeError:
         return False
-    except Exception as e:
-        raise ValueError(
-            [
-                f"pytest_assertion plugin: unexpected exception {e!r} while testing object {obj!r}",
-                ", probably from __iter__",
-            ]
-        )
 
 
 def has_default_eq(
@@ -202,14 +195,7 @@ def assertrepr_compare(
                 explanation = _notin_text(left, right, verbose)
     except outcomes.Exit:
         raise
-    except Exception as e:
-        if (
-            isinstance(e, ValueError)
-            and (len(e.args) == 1)
-            and ("__iter__" in str(e.args[0]))
-        ):
-            explanation = e.args[0]
-        else:
+    except Exception:
         explanation = [
             "(pytest_assertion plugin: representation of details failed: {}.".format(
                 _pytest._code.ExceptionInfo.from_current()._getreprcrash()

testing/test_assertrewrite.py

@@ -689,7 +689,7 @@ class TestAssertionRewrite:
         def f() -> None:
             class A:
                 def __iter__(self):
-                    raise ValueError()
+                    raise TypeError("user message")
 
                 def __eq__(self, o: object) -> bool:
                     return self is o
@@ -698,7 +698,7 @@ class TestAssertionRewrite:
 
         msg = getmsg(f)
         assert msg is not None
-        assert "__iter__" in msg and "__repr__" not in msg
+        assert "Unexpected exception" in msg
 
     def test_formatchar(self) -> None:
         def f() -> None: