From c23a63a185104b4dc39fe53d82254059c5ff4727 Mon Sep 17 00:00:00 2001
From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Sat, 25 Nov 2017 00:05:57 +0100
Subject: [PATCH 1/3] Improved bad factory error handling

---
 flask/cli.py      | 10 ++++++++++
 tests/test_cli.py |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/flask/cli.py b/flask/cli.py
index 8bfb21f6..b9d56b05 100644
--- a/flask/cli.py
+++ b/flask/cli.py
@@ -33,6 +33,12 @@ except ImportError:
     dotenv = None
 
 
+def _called_with_wrong_args(factory, exc_info):
+    exc_type, exc_value, tb = exc_info
+    return exc_type is TypeError and \
+        str(exc_value).startswith('%s() takes' % factory.__name__)
+
+
 class NoAppException(click.UsageError):
     """Raised if an application cannot be found or loaded."""
 
@@ -75,6 +81,8 @@ def find_best_app(script_info, module):
                 if isinstance(app, Flask):
                     return app
             except TypeError:
+                if not _called_with_wrong_args(app_factory, sys.exc_info()):
+                    raise
                 raise NoAppException(
                     'Detected factory "{factory}" in module "{module}", but '
                     'could not call it without arguments. Use '
@@ -148,6 +156,8 @@ def find_app_by_string(script_info, module, app_name):
         try:
             app = call_factory(script_info, attr, args)
         except TypeError as e:
+            if not _called_with_wrong_args(attr, sys.exc_info()):
+                raise
             raise NoAppException(
                 '{e}\nThe factory "{app_name}" in module "{module}" could not '
                 'be called with the specified arguments.'.format(
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 811ef0c8..d530b093 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -144,6 +144,13 @@ def test_find_best_app(test_apps):
 
     pytest.raises(NoAppException, find_best_app, script_info, Module)
 
+    class Module:
+        @staticmethod
+        def create_app():
+            raise TypeError('bad bad factory!')
+
+    pytest.raises(TypeError, find_best_app, script_info, Module)
+
 
 @pytest.mark.parametrize('value,path,result', (
     ('test', cwd, 'test'),

From 1a2dc6f205003cd2307b33927b8628a3d97b7ce6 Mon Sep 17 00:00:00 2001
From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Sat, 25 Nov 2017 00:18:10 +0100
Subject: [PATCH 2/3] Fixed tests for python 3

---
 flask/cli.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/flask/cli.py b/flask/cli.py
index b9d56b05..0a556ddc 100644
--- a/flask/cli.py
+++ b/flask/cli.py
@@ -36,7 +36,9 @@ except ImportError:
 def _called_with_wrong_args(factory, exc_info):
     exc_type, exc_value, tb = exc_info
     return exc_type is TypeError and \
-        str(exc_value).startswith('%s() takes' % factory.__name__)
+        str(exc_value).startswith((
+            '%s() takes' % factory.__name__,
+            '%s() missing' % factory.__name__))
 
 
 class NoAppException(click.UsageError):

From 2cba0d77eef983b605bf2f5c85a9d02fe212eda0 Mon Sep 17 00:00:00 2001
From: David Lord <davidism@gmail.com>
Date: Sun, 28 Jan 2018 11:20:42 -0800
Subject: [PATCH 3/3] use traceback to detect call more reliably

---
 flask/cli.py | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/flask/cli.py b/flask/cli.py
index 0a556ddc..383fe459 100644
--- a/flask/cli.py
+++ b/flask/cli.py
@@ -33,14 +33,6 @@ except ImportError:
     dotenv = None
 
 
-def _called_with_wrong_args(factory, exc_info):
-    exc_type, exc_value, tb = exc_info
-    return exc_type is TypeError and \
-        str(exc_value).startswith((
-            '%s() takes' % factory.__name__,
-            '%s() missing' % factory.__name__))
-
-
 class NoAppException(click.UsageError):
     """Raised if an application cannot be found or loaded."""
 
@@ -83,7 +75,7 @@ def find_best_app(script_info, module):
                 if isinstance(app, Flask):
                     return app
             except TypeError:
-                if not _called_with_wrong_args(app_factory, sys.exc_info()):
+                if not _called_with_wrong_args(app_factory):
                     raise
                 raise NoAppException(
                     'Detected factory "{factory}" in module "{module}", but '
@@ -121,6 +113,30 @@ def call_factory(script_info, app_factory, arguments=()):
     return app_factory()
 
 
+def _called_with_wrong_args(factory):
+    """Check whether calling a function raised a ``TypeError`` because
+    the call failed or because something in the factory raised the
+    error.
+
+    :param factory: the factory function that was called
+    :return: true if the call failed
+    """
+    tb = sys.exc_info()[2]
+
+    try:
+        while tb is not None:
+            if tb.tb_frame.f_code is factory.__code__:
+                # in the factory, it was called successfully
+                return False
+
+            tb = tb.tb_next
+
+        # didn't reach the factory
+        return True
+    finally:
+        del tb
+
+
 def find_app_by_string(script_info, module, app_name):
     """Checks if the given string is a variable name or a function. If it is a
     function, it checks for specified arguments and whether it takes a
@@ -158,8 +174,9 @@ def find_app_by_string(script_info, module, app_name):
         try:
             app = call_factory(script_info, attr, args)
         except TypeError as e:
-            if not _called_with_wrong_args(attr, sys.exc_info()):
+            if not _called_with_wrong_args(attr):
                 raise
+
             raise NoAppException(
                 '{e}\nThe factory "{app_name}" in module "{module}" could not '
                 'be called with the specified arguments.'.format(