From 7c7dd45554ef8f2a2cb4a140d02343e01d1c2223 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 6 Feb 2019 20:46:16 -0800
Subject: [PATCH 01/43] Properly handle SyntaxErrors in Python source files.

SyntaxErrors in the target module will rise normally, while SyntaxErrors in dependencies will be added to badmodules. This includes a new regression test.
---
 Lib/modulefinder.py           |  3 +++
 Lib/test/test_modulefinder.py | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 10320a74d94249..ab8d2aa28849b3 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -323,6 +323,9 @@ def _safe_import_hook(self, name, caller, fromlist, level=-1):
         except ImportError as msg:
             self.msg(2, "ImportError:", str(msg))
             self._add_badmodule(name, caller)
+        except SyntaxError as msg:
+            self.msg(2, "SyntaxError:", str(msg))
+            self._add_badmodule(name, caller)
         else:
             if fromlist:
                 for sub in fromlist:
diff --git a/Lib/test/test_modulefinder.py b/Lib/test/test_modulefinder.py
index e4df2a90d4a4d0..73156bde21d14b 100644
--- a/Lib/test/test_modulefinder.py
+++ b/Lib/test/test_modulefinder.py
@@ -218,6 +218,19 @@ def foo(): pass
     ""
 ]
 
+syntax_error_test = [
+    "a.module",
+    ["a", "a.module", "b"],
+    ["b.module"], [],
+    """\
+a/__init__.py
+a/module.py
+                                import b.module
+b/__init__.py
+b/module.py
+                                ?  # SyntaxError: invalid syntax
+"""]
+
 
 def open_file(path):
     dirname = os.path.dirname(path)
@@ -299,6 +312,9 @@ def test_relative_imports_3(self):
     def test_relative_imports_4(self):
         self._do_test(relative_import_test_4)
 
+    def test_syntax_error(self):
+        self._do_test(syntax_error_test)
+
     def test_bytecode(self):
         base_path = os.path.join(TEST_DIR, 'a')
         source_path = base_path + importlib.machinery.SOURCE_SUFFIXES[0]

From 8f98ca6df2987ff7a14611479917c486acf3279c Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 6 Feb 2019 21:13:04 -0800
Subject: [PATCH 02/43] Fix name collision bug.

This fixes an issue where a "fromlist" import with the same name as a previously failed import would be incorrectly added to badmodules. This includes a new regression test.
---
 Lib/modulefinder.py           |  6 +++---
 Lib/test/test_modulefinder.py | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index ab8d2aa28849b3..39fc9f4a2f471f 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -329,14 +329,14 @@ def _safe_import_hook(self, name, caller, fromlist, level=-1):
         else:
             if fromlist:
                 for sub in fromlist:
-                    if sub in self.badmodules:
-                        self._add_badmodule(sub, caller)
+                    fullname = name + "." + sub
+                    if fullname in self.badmodules:
+                        self._add_badmodule(fullname, caller)
                         continue
                     try:
                         self.import_hook(name, caller, [sub], level=level)
                     except ImportError as msg:
                         self.msg(2, "ImportError:", str(msg))
-                        fullname = name + "." + sub
                         self._add_badmodule(fullname, caller)
 
     def scan_opcodes(self, co):
diff --git a/Lib/test/test_modulefinder.py b/Lib/test/test_modulefinder.py
index 73156bde21d14b..ebd96e1c8a2dd0 100644
--- a/Lib/test/test_modulefinder.py
+++ b/Lib/test/test_modulefinder.py
@@ -232,6 +232,20 @@ def foo(): pass
 """]
 
 
+same_name_as_bad_test = [
+    "a.module",
+    ["a", "a.module", "b", "b.c"],
+    ["c"], [],
+    """\
+a/__init__.py
+a/module.py
+                                import c
+                                from b import c
+b/__init__.py
+b/c.py
+"""]
+
+
 def open_file(path):
     dirname = os.path.dirname(path)
     try:
@@ -315,6 +329,9 @@ def test_relative_imports_4(self):
     def test_syntax_error(self):
         self._do_test(syntax_error_test)
 
+    def test_same_name_as_bad(self):
+        self._do_test(same_name_as_bad_test)
+
     def test_bytecode(self):
         base_path = os.path.join(TEST_DIR, 'a')
         source_path = base_path + importlib.machinery.SOURCE_SUFFIXES[0]

From c00c4b6cd72c062300df9f2a4583b44b76399676 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 6 Feb 2019 20:49:47 -0800
Subject: [PATCH 03/43] Replace mutable default values.

Bound empty lists have been replaced with the "if param is None" idiom.
---
 Lib/modulefinder.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 39fc9f4a2f471f..3d0ec442a5aa20 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -69,7 +69,7 @@ def __repr__(self):
 
 class ModuleFinder:
 
-    def __init__(self, path=None, debug=0, excludes=[], replace_paths=[]):
+    def __init__(self, path=None, debug=0, excludes=None, replace_paths=None):
         if path is None:
             path = sys.path
         self.path = path
@@ -77,8 +77,8 @@ def __init__(self, path=None, debug=0, excludes=[], replace_paths=[]):
         self.badmodules = {}
         self.debug = debug
         self.indent = 0
-        self.excludes = excludes
-        self.replace_paths = replace_paths
+        self.excludes = excludes if excludes is not None else []
+        self.replace_paths = replace_paths if replace_paths is not None else []
         self.processed_paths = []   # Used in debugging only
 
     def msg(self, level, str, *args):

From 94e38d42cd391d731c9c6b8bc96b7f2f01c2ef1d Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 6 Feb 2019 20:43:12 -0800
Subject: [PATCH 04/43] Replace deprecated imp usage.

Constants imported from imp have been moved to private module-level constants, and ModuleFinder.find_module has been refactored to use importlib. Other than an improvement on how frozen builtin imports are reported (as the frozen imports they are, rather than the stdlib modules they *may* have originated from), these changes maintain complete compatibility with past versions... including odd behavior for returning relative (below current directory, but not a C extension) vs. absolute (above current directory, or a C extension) paths.
---
 Lib/modulefinder.py | 85 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 75 insertions(+), 10 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 3d0ec442a5aa20..a46a07a567caf1 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -2,15 +2,14 @@
 
 import dis
 import importlib._bootstrap_external
+import importlib.util
 import importlib.machinery
 import marshal
 import os
 import sys
 import types
 import warnings
-with warnings.catch_warnings():
-    warnings.simplefilter('ignore', DeprecationWarning)
-    import imp
+
 
 LOAD_CONST = dis.opmap['LOAD_CONST']
 IMPORT_NAME = dis.opmap['IMPORT_NAME']
@@ -19,6 +18,16 @@
 STORE_OPS = STORE_NAME, STORE_GLOBAL
 EXTENDED_ARG = dis.EXTENDED_ARG
 
+# Old imp constants:
+
+_SEARCH_ERROR = 0
+_PY_SOURCE = 1
+_PY_COMPILED = 2
+_C_EXTENSION = 3
+_PKG_DIRECTORY = 5
+_C_BUILTIN = 6
+_PY_FROZEN = 7
+
 # Modulefinder does a good job at simulating Python's, but it can not
 # handle __path__ modifications packages make at runtime.  Therefore there
 # is a mechanism whereby you can register extra paths in this map for a
@@ -105,14 +114,14 @@ def msgout(self, *args):
     def run_script(self, pathname):
         self.msg(2, "run_script", pathname)
         with open(pathname) as fp:
-            stuff = ("", "r", imp.PY_SOURCE)
+            stuff = ("", "r", _PY_SOURCE)
             self.load_module('__main__', fp, pathname, stuff)
 
     def load_file(self, pathname):
         dir, name = os.path.split(pathname)
         name, ext = os.path.splitext(name)
         with open(pathname) as fp:
-            stuff = (ext, "r", imp.PY_SOURCE)
+            stuff = (ext, "r", _PY_SOURCE)
             self.load_module(name, fp, pathname, stuff)
 
     def import_hook(self, name, caller=None, fromlist=None, level=-1):
@@ -279,13 +288,13 @@ def import_module(self, partname, fqname, parent):
     def load_module(self, fqname, fp, pathname, file_info):
         suffix, mode, type = file_info
         self.msgin(2, "load_module", fqname, fp and "fp", pathname)
-        if type == imp.PKG_DIRECTORY:
+        if type == _PKG_DIRECTORY:
             m = self.load_package(fqname, pathname)
             self.msgout(2, "load_module ->", m)
             return m
-        if type == imp.PY_SOURCE:
+        if type == _PY_SOURCE:
             co = compile(fp.read()+'\n', pathname, 'exec')
-        elif type == imp.PY_COMPILED:
+        elif type == _PY_COMPILED:
             try:
                 data = fp.read()
                 importlib._bootstrap_external._classify_pyc(data, fqname, {})
@@ -448,10 +457,66 @@ def find_module(self, name, path, parent=None):
 
         if path is None:
             if name in sys.builtin_module_names:
-                return (None, None, ("", "", imp.C_BUILTIN))
+                return (None, None, ("", "", _C_BUILTIN))
 
             path = self.path
-        return imp.find_module(name, path)
+
+        old_path = sys.path
+
+        try:
+
+            sys.path = path + old_path
+
+            try:
+                spec = importlib.util.find_spec(fullname)
+            except ImportError:
+                spec = importlib.util.find_spec(name)
+
+        finally:
+
+            sys.path = old_path
+
+        if spec is None:
+            raise ImportError("No module named {name!r}".format(name=name), name=name)
+
+        if isinstance(spec.loader, type):
+
+            if issubclass(spec.loader, importlib.machinery.BuiltinImporter):
+                return None, None, ("", "", _C_BUILTIN)
+                
+            if issubclass(spec.loader, importlib.machinery.FrozenImporter):
+                return None, None, ("", "", _PY_FROZEN)
+
+        file_path = spec.origin
+
+        if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
+            file_path = os.path.relpath(file_path)
+
+        base, suffix = os.path.splitext(file_path)
+        
+        if suffix in importlib.machinery.EXTENSION_SUFFIXES:
+            file_path = os.path.abspath(file_path)
+            kind = _C_EXTENSION
+            mode = "rb"
+
+        elif suffix in importlib.machinery.SOURCE_SUFFIXES:
+            
+            if name != "__init__" and os.path.basename(base) == "__init__":
+                return (None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY))
+
+            kind = _PY_SOURCE
+            mode = "r"
+
+        elif suffix in importlib.machinery.BYTECODE_SUFFIXES:
+            kind = _PY_COMPILED
+            mode = "rb"
+
+        else:
+            return None, None, ("", "", _SEARCH_ERROR)  # Should never happen.
+
+        file = open(file_path, mode)
+
+        return file, file_path, (suffix, mode, kind)
 
     def report(self):
         """Print a report to stdout, listing the found modules with their

From 9bda94b717767ec00b084b579a6b5d3fb3750e18 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Thu, 7 Feb 2019 19:34:14 -0800
Subject: [PATCH 05/43] Fixed whitespace.

Whoops.
---
 Lib/modulefinder.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index a46a07a567caf1..dec03e7ee13737 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -483,7 +483,7 @@ def find_module(self, name, path, parent=None):
 
             if issubclass(spec.loader, importlib.machinery.BuiltinImporter):
                 return None, None, ("", "", _C_BUILTIN)
-                
+
             if issubclass(spec.loader, importlib.machinery.FrozenImporter):
                 return None, None, ("", "", _PY_FROZEN)
 
@@ -493,14 +493,14 @@ def find_module(self, name, path, parent=None):
             file_path = os.path.relpath(file_path)
 
         base, suffix = os.path.splitext(file_path)
-        
+
         if suffix in importlib.machinery.EXTENSION_SUFFIXES:
             file_path = os.path.abspath(file_path)
             kind = _C_EXTENSION
             mode = "rb"
 
         elif suffix in importlib.machinery.SOURCE_SUFFIXES:
-            
+
             if name != "__init__" and os.path.basename(base) == "__init__":
                 return (None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY))
 

From c366485fc348671e7577553ca3ec2b68c559be8a Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Thu, 7 Feb 2019 20:13:38 -0800
Subject: [PATCH 06/43] Handle differing drives on Windows.

Specifically, when checking whether the returned path should be relative or absolute.
---
 Lib/modulefinder.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index dec03e7ee13737..87ae230f6e24ca 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -489,8 +489,13 @@ def find_module(self, name, path, parent=None):
 
         file_path = spec.origin
 
-        if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
-            file_path = os.path.relpath(file_path)
+        try:
+            
+            if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
+                file_path = os.path.relpath(file_path)
+
+        except ValueError:
+            pass
 
         base, suffix = os.path.splitext(file_path)
 

From dc9180d35491b986252534ee91ae35e117463488 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Thu, 7 Feb 2019 20:14:23 -0800
Subject: [PATCH 07/43] Again, fixed whitespace.

Whoops.
---
 Lib/modulefinder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 87ae230f6e24ca..82b2620be3507a 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -490,7 +490,7 @@ def find_module(self, name, path, parent=None):
         file_path = spec.origin
 
         try:
-            
+
             if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
                 file_path = os.path.relpath(file_path)
 

From faf2902d056058a214ef5e0c01892856970d2519 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <blurb-it[bot]@users.noreply.github.com>
Date: Fri, 8 Feb 2019 04:46:59 +0000
Subject: [PATCH 08/43] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst b/Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst
new file mode 100644
index 00000000000000..c9df83b480c0ca
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst
@@ -0,0 +1,2 @@
+:mod:`modulefinder` has been refactored to use the non-deprecated :mod:`importlib`. Additionally, several long-standing bugs have been fixed.
+Patch by Brandt Bucher.
\ No newline at end of file

From a1db2ecc3c515a2a2e8fcaa85c58c823790eb1e8 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Thu, 7 Feb 2019 21:44:11 -0800
Subject: [PATCH 09/43] Fix relative imports.

Hopefully, this will help the failing tests on Windows.
---
 Lib/modulefinder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 82b2620be3507a..93d8ed1840f128 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -468,7 +468,7 @@ def find_module(self, name, path, parent=None):
             sys.path = path + old_path
 
             try:
-                spec = importlib.util.find_spec(fullname)
+                spec = importlib.util.find_spec(fullname, parent)
             except ImportError:
                 spec = importlib.util.find_spec(name)
 

From bd73fa5f44c8745378dff1b2c31af36bd95e8fbe Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Fri, 8 Feb 2019 20:15:20 -0800
Subject: [PATCH 10/43] Fix import side-effects.

importlib.util.find_spec(fullname, parent), where fullname contains a dot, results in the parent module being imported. This fix ensures that children are correctly located while also avoiding import side-effects by temporarily clearing sys.modules and modifying sys.path. Now, neither a dotted name nor parent are required.
---
 Lib/modulefinder.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 93d8ed1840f128..8a87cc7db95c93 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -462,19 +462,19 @@ def find_module(self, name, path, parent=None):
             path = self.path
 
         old_path = sys.path
+        old_modules = sys.modules
 
         try:
 
             sys.path = path + old_path
+            sys.modules = {}
 
-            try:
-                spec = importlib.util.find_spec(fullname, parent)
-            except ImportError:
-                spec = importlib.util.find_spec(name)
+            spec = importlib.util.find_spec(name)
 
         finally:
 
             sys.path = old_path
+            sys.modules = old_modules
 
         if spec is None:
             raise ImportError("No module named {name!r}".format(name=name), name=name)

From 210edadff9bbeb0c54e747f2ec15d940381b4e24 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Fri, 8 Feb 2019 21:12:32 -0800
Subject: [PATCH 11/43] Wait for sys.path to update.

I have a hunch the failing tests are due to a race condition in how sys.path updates. Sleep a bit here to see.
---
 Lib/modulefinder.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 8a87cc7db95c93..43d1bd812d8d78 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -7,6 +7,7 @@
 import marshal
 import os
 import sys
+import time
 import types
 import warnings
 
@@ -469,6 +470,7 @@ def find_module(self, name, path, parent=None):
             sys.path = path + old_path
             sys.modules = {}
 
+            time.sleep(0.000001)
             spec = importlib.util.find_spec(name)
 
         finally:

From 3a9dd35e48241e6b98502f7c8589cbdfd01d5a52 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Fri, 8 Feb 2019 21:32:09 -0800
Subject: [PATCH 12/43] Bump sleep time.

More test are passing, which supports my theory.
---
 Lib/modulefinder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 43d1bd812d8d78..21a63aeeed480c 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -470,7 +470,7 @@ def find_module(self, name, path, parent=None):
             sys.path = path + old_path
             sys.modules = {}
 
-            time.sleep(0.000001)
+            time.sleep(0.00001)
             spec = importlib.util.find_spec(name)
 
         finally:

From 2763440a3e8a829ead794e2ac82654bdb269d1e6 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Fri, 8 Feb 2019 22:16:18 -0800
Subject: [PATCH 13/43] WIP: Replace sleep with busy wait.

*crosses fingers*
---
 Lib/modulefinder.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 21a63aeeed480c..29688c7b741cd4 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -7,7 +7,6 @@
 import marshal
 import os
 import sys
-import time
 import types
 import warnings
 
@@ -470,7 +469,7 @@ def find_module(self, name, path, parent=None):
             sys.path = path + old_path
             sys.modules = {}
 
-            time.sleep(0.00001)
+            [i for i in range(10000)]  # XXX: Busy wait.
             spec = importlib.util.find_spec(name)
 
         finally:

From f9939bf4168a32f234981efb90371bfcbebb7ff3 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Fri, 8 Feb 2019 22:39:24 -0800
Subject: [PATCH 14/43] Remove busy wait.

I guess that wasn't the issue...
---
 Lib/modulefinder.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 29688c7b741cd4..8a87cc7db95c93 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -469,7 +469,6 @@ def find_module(self, name, path, parent=None):
             sys.path = path + old_path
             sys.modules = {}
 
-            [i for i in range(10000)]  # XXX: Busy wait.
             spec = importlib.util.find_spec(name)
 
         finally:

From ddb8752ce66d733b56e8aa09128fc7781a5159ff Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sat, 9 Feb 2019 08:24:23 -0800
Subject: [PATCH 15/43] Remove NEWS entry.

This will be replaced with several more specific entries detailing the various bug fixes.
---
 .../next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst       | 2 --
 1 file changed, 2 deletions(-)
 delete mode 100644 Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst b/Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst
deleted file mode 100644
index c9df83b480c0ca..00000000000000
--- a/Misc/NEWS.d/next/Library/2019-02-08-04-46-58.bpo-35936.q2ArjU.rst
+++ /dev/null
@@ -1,2 +0,0 @@
-:mod:`modulefinder` has been refactored to use the non-deprecated :mod:`importlib`. Additionally, several long-standing bugs have been fixed.
-Patch by Brandt Bucher.
\ No newline at end of file

From 8d7f272c9e412354487089e360eda4bdb20730ac Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sat, 9 Feb 2019 10:55:22 -0800
Subject: [PATCH 16/43] Mutate sys.path in-place.

Perhaps there is some underlying reference issue with straight-up sys.path replacement. Once again, fingers crossed!
---
 Lib/modulefinder.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 8a87cc7db95c93..39ebe96b309552 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -461,19 +461,19 @@ def find_module(self, name, path, parent=None):
 
             path = self.path
 
-        old_path = sys.path
+        old_path = sys.path[:]
         old_modules = sys.modules
 
         try:
 
-            sys.path = path + old_path
+            sys.path[:0] = path
             sys.modules = {}
 
             spec = importlib.util.find_spec(name)
 
         finally:
 
-            sys.path = old_path
+            sys.path[:] = old_path
             sys.modules = old_modules
 
         if spec is None:

From 1a594f0ceba5175c8fb3df1c428b3a883691edbe Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sat, 9 Feb 2019 11:23:00 -0800
Subject: [PATCH 17/43] Enter RLock during import search.

Perhaps test threads are stomping on each others' sys.path?
---
 Lib/modulefinder.py | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 39ebe96b309552..8c68bf32ce70d0 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -7,6 +7,7 @@
 import marshal
 import os
 import sys
+import threading
 import types
 import warnings
 
@@ -464,17 +465,19 @@ def find_module(self, name, path, parent=None):
         old_path = sys.path[:]
         old_modules = sys.modules
 
-        try:
+        with threading.RLock():
+
+            try:
 
-            sys.path[:0] = path
-            sys.modules = {}
+                sys.path[:0] = path
+                sys.modules = {}
 
-            spec = importlib.util.find_spec(name)
+                spec = importlib.util.find_spec(name)
 
-        finally:
+            finally:
 
-            sys.path[:] = old_path
-            sys.modules = old_modules
+                sys.path[:] = old_path
+                sys.modules = old_modules
 
         if spec is None:
             raise ImportError("No module named {name!r}".format(name=name), name=name)

From 6dabded23ab481ec2786530ecb6dc6e693dc6450 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sat, 9 Feb 2019 14:41:46 -0800
Subject: [PATCH 18/43] Try multiprocessing.RLock instead of threading.

These are processes, after all...
---
 Lib/modulefinder.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 8c68bf32ce70d0..ab69fc13ea6d37 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -5,9 +5,9 @@
 import importlib.util
 import importlib.machinery
 import marshal
+import multiprocessing
 import os
 import sys
-import threading
 import types
 import warnings
 
@@ -462,14 +462,14 @@ def find_module(self, name, path, parent=None):
 
             path = self.path
 
-        old_path = sys.path[:]
-        old_modules = sys.modules
+        with multiprocessing.RLock():
 
-        with threading.RLock():
+            old_path = sys.path[:]
+            old_modules = sys.modules
 
             try:
 
-                sys.path[:0] = path
+                sys.path[1:1] = path
                 sys.modules = {}
 
                 spec = importlib.util.find_spec(name)

From 7095d14cc86bdd3ad13601baecd8240af8bb50a6 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sat, 9 Feb 2019 15:29:21 -0800
Subject: [PATCH 19/43] Try a couple of possible fixes for failing lookups.

This is a longshot, but it's pretty much all I have left in terms of ideas.
---
 Lib/modulefinder.py | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index ab69fc13ea6d37..5f43be0612449a 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -462,22 +462,27 @@ def find_module(self, name, path, parent=None):
 
             path = self.path
 
-        with multiprocessing.RLock():
+        old_path = sys.path[:]
+        old_modules = sys.modules.copy()
+        old_path_importer_cache = sys.path_importer_cache.copy()
 
-            old_path = sys.path[:]
-            old_modules = sys.modules
+        try:
 
-            try:
+            sys._clear_type_cache()
 
-                sys.path[1:1] = path
-                sys.modules = {}
+            sys.path[:0] = path
+            sys.modules.clear()
+            sys.path_importer_cache.clear()
 
-                spec = importlib.util.find_spec(name)
+            sys._clear_type_cache()
 
-            finally:
+            spec = importlib.util.find_spec(name)
+
+        finally:
 
-                sys.path[:] = old_path
-                sys.modules = old_modules
+            sys.path[:] = old_path
+            sys.modules.update(old_modules)
+            sys.path_importer_cache.update(old_path_importer_cache)
 
         if spec is None:
             raise ImportError("No module named {name!r}".format(name=name), name=name)

From 1aea4af4622371ff24f7b6f9903768517aa9b815 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sat, 9 Feb 2019 15:56:25 -0800
Subject: [PATCH 20/43] Remove sys._clear_type_cache calls.

Is it a refleak issue?
---
 Lib/modulefinder.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 5f43be0612449a..776ab10b200877 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -468,14 +468,10 @@ def find_module(self, name, path, parent=None):
 
         try:
 
-            sys._clear_type_cache()
-
             sys.path[:0] = path
             sys.modules.clear()
             sys.path_importer_cache.clear()
 
-            sys._clear_type_cache()
-
             spec = importlib.util.find_spec(name)
 
         finally:

From 603481a8a067bab5303afb7ef4861d7adbc9e3d6 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <blurb-it[bot]@users.noreply.github.com>
Date: Sun, 10 Feb 2019 00:25:26 +0000
Subject: [PATCH 21/43] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst b/Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst
new file mode 100644
index 00000000000000..50596cf9e43f09
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst
@@ -0,0 +1,2 @@
+:mod:`modulefinder` no longer crashes when encountering syntax errors in followed imports.
+Patch by Brandt Bucher.
\ No newline at end of file

From f022f83fc5d042fa55eeb00bc341f05cb68510ff Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <blurb-it[bot]@users.noreply.github.com>
Date: Sun, 10 Feb 2019 00:47:14 +0000
Subject: [PATCH 22/43] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst b/Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst
new file mode 100644
index 00000000000000..a9bf8c9a636ccb
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst
@@ -0,0 +1,2 @@
+:mod:`modulefinder` correctly handles modules that have the same name as a bad package.
+Patch by Brandt Bucher.
\ No newline at end of file

From 2568d5acb7a6de6d09569634f8b060f8c48ae9d3 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <blurb-it[bot]@users.noreply.github.com>
Date: Sun, 10 Feb 2019 17:31:02 +0000
Subject: [PATCH 23/43] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst b/Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst
new file mode 100644
index 00000000000000..d96a18ab6e1bc2
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst
@@ -0,0 +1,2 @@
+:mod:`modulefinder` no longer uses the deprecated :mod:`imp` module.
+Patch by Brandt Bucher.
\ No newline at end of file

From bbae72e76ca723320363f517d24a0c56e81ad8cd Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 10 Feb 2019 09:53:59 -0800
Subject: [PATCH 24/43] Break out new code into standalone function.

I've also added helpful documentation outlining the reasoning behind various design decisions.
---
 Lib/modulefinder.py | 147 ++++++++++++++++++++++++--------------------
 1 file changed, 82 insertions(+), 65 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 776ab10b200877..9b789a77d760dc 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -5,7 +5,6 @@
 import importlib.util
 import importlib.machinery
 import marshal
-import multiprocessing
 import os
 import sys
 import types
@@ -53,6 +52,87 @@ def ReplacePackage(oldname, newname):
     replacePackageMap[oldname] = newname
 
 
+def _find_module(name, path=None):
+    """`importlib`-only replacement for `imp.find_module`."""
+
+    # To correctly find the module on the given path,  we need to
+    # temporarily clear the import state of the program and modify sys.path.
+
+    sys_path = sys.path[:]
+    sys_modules = sys.modules.copy()
+    sys_path_importer_cache = sys.path_importer_cache.copy()
+
+    try:
+
+        sys.path[:0] = path
+        sys.modules.clear()
+        sys.path_importer_cache.clear()
+
+        # It is important that `name` not include any dots.
+        # Otherwise, the parent package could be actually imported.
+
+        spec = importlib.util.find_spec(name)
+
+    finally:
+
+        sys.path[:] = sys_path
+        sys.modules.update(sys_modules)
+        sys.path_importer_cache.update(sys_path_importer_cache)
+
+    if spec is None:
+        raise ImportError("No module named {name!r}".format(name=name), name=name)
+
+    if isinstance(spec.loader, type):  # Some special cases:
+
+        if issubclass(spec.loader, importlib.machinery.BuiltinImporter):
+            return None, None, ("", "", _C_BUILTIN)
+
+        if issubclass(spec.loader, importlib.machinery.FrozenImporter):
+            return None, None, ("", "", _PY_FROZEN)
+
+    file_path = spec.origin
+
+    try:
+
+        # `imp` behavior is s bit funny here:
+
+        # If the path is a descendant of the CWD, it is reported as a relative filepath
+        # ...unless it is an extension, in which case it will be absolute (see below)
+        # ...otherwise, it is fully resolved.
+
+        if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
+            file_path = os.path.relpath(file_path)  # imp has weird rules
+
+    except ValueError:
+        pass
+
+    base, suffix = os.path.splitext(file_path)
+
+    if suffix in importlib.machinery.EXTENSION_SUFFIXES:
+        file_path = os.path.abspath(file_path)
+        kind = _C_EXTENSION
+        mode = "rb"
+
+    elif suffix in importlib.machinery.SOURCE_SUFFIXES:
+
+        if name != "__init__" and os.path.basename(base) == "__init__":
+            return (None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY))
+
+        kind = _PY_SOURCE
+        mode = "r"
+
+    elif suffix in importlib.machinery.BYTECODE_SUFFIXES:
+        kind = _PY_COMPILED
+        mode = "rb"
+
+    else:  # Should never happen.
+        return None, None, ("", "", _SEARCH_ERROR)
+
+    file = open(file_path, mode)
+
+    return file, file_path, (suffix, mode, kind)
+
+
 class Module:
 
     def __init__(self, name, file=None, path=None):
@@ -462,70 +542,7 @@ def find_module(self, name, path, parent=None):
 
             path = self.path
 
-        old_path = sys.path[:]
-        old_modules = sys.modules.copy()
-        old_path_importer_cache = sys.path_importer_cache.copy()
-
-        try:
-
-            sys.path[:0] = path
-            sys.modules.clear()
-            sys.path_importer_cache.clear()
-
-            spec = importlib.util.find_spec(name)
-
-        finally:
-
-            sys.path[:] = old_path
-            sys.modules.update(old_modules)
-            sys.path_importer_cache.update(old_path_importer_cache)
-
-        if spec is None:
-            raise ImportError("No module named {name!r}".format(name=name), name=name)
-
-        if isinstance(spec.loader, type):
-
-            if issubclass(spec.loader, importlib.machinery.BuiltinImporter):
-                return None, None, ("", "", _C_BUILTIN)
-
-            if issubclass(spec.loader, importlib.machinery.FrozenImporter):
-                return None, None, ("", "", _PY_FROZEN)
-
-        file_path = spec.origin
-
-        try:
-
-            if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
-                file_path = os.path.relpath(file_path)
-
-        except ValueError:
-            pass
-
-        base, suffix = os.path.splitext(file_path)
-
-        if suffix in importlib.machinery.EXTENSION_SUFFIXES:
-            file_path = os.path.abspath(file_path)
-            kind = _C_EXTENSION
-            mode = "rb"
-
-        elif suffix in importlib.machinery.SOURCE_SUFFIXES:
-
-            if name != "__init__" and os.path.basename(base) == "__init__":
-                return (None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY))
-
-            kind = _PY_SOURCE
-            mode = "r"
-
-        elif suffix in importlib.machinery.BYTECODE_SUFFIXES:
-            kind = _PY_COMPILED
-            mode = "rb"
-
-        else:
-            return None, None, ("", "", _SEARCH_ERROR)  # Should never happen.
-
-        file = open(file_path, mode)
-
-        return file, file_path, (suffix, mode, kind)
+        return _find_module(name, path)
 
     def report(self):
         """Print a report to stdout, listing the found modules with their

From 68337928bcf288dfe6289b672d44ae75459a247e Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 10 Feb 2019 10:26:20 -0800
Subject: [PATCH 25/43] Don't modify import state in-place.

Changing references seems like a safer option and doesn't require extra copy operations.
---
 Lib/modulefinder.py | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 9b789a77d760dc..a2f916c2f0c2ba 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -58,15 +58,15 @@ def _find_module(name, path=None):
     # To correctly find the module on the given path,  we need to
     # temporarily clear the import state of the program and modify sys.path.
 
-    sys_path = sys.path[:]
-    sys_modules = sys.modules.copy()
-    sys_path_importer_cache = sys.path_importer_cache.copy()
+    sys_path = sys.path
+    sys_modules = sys.modules
+    sys_path_importer_cache = sys.path_importer_cache
 
     try:
 
-        sys.path[:0] = path
-        sys.modules.clear()
-        sys.path_importer_cache.clear()
+        sys.path = path + sys.path
+        sys.modules = {}
+        sys.path_importer_cache = {}
 
         # It is important that `name` not include any dots.
         # Otherwise, the parent package could be actually imported.
@@ -75,9 +75,9 @@ def _find_module(name, path=None):
 
     finally:
 
-        sys.path[:] = sys_path
-        sys.modules.update(sys_modules)
-        sys.path_importer_cache.update(sys_path_importer_cache)
+        sys.path = sys_path
+        sys.modules = sys_modules
+        sys.path_importer_cache = sys_path_importer_cache
 
     if spec is None:
         raise ImportError("No module named {name!r}".format(name=name), name=name)

From 0af9f08ad3c4e01aea073b675223d266f5da973f Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 10 Feb 2019 10:31:35 -0800
Subject: [PATCH 26/43] Reorder new import.

Minor. Keep our imports in ASCIIbetical order.
---
 Lib/modulefinder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index a2f916c2f0c2ba..ce317776afe45a 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -2,8 +2,8 @@
 
 import dis
 import importlib._bootstrap_external
-import importlib.util
 import importlib.machinery
+import importlib.util
 import marshal
 import os
 import sys

From 4bb452e7e2d3a09bb39b039fee708bcc7ac2746f Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Mon, 11 Feb 2019 07:34:00 -0800
Subject: [PATCH 27/43] Minor style stuff.

Remove a comment, change a docstring, and add an ACK.
---
 Lib/modulefinder.py | 4 ++--
 Misc/ACKS           | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index ce317776afe45a..cdcd7eea3f8a86 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -53,7 +53,7 @@ def ReplacePackage(oldname, newname):
 
 
 def _find_module(name, path=None):
-    """`importlib`-only replacement for `imp.find_module`."""
+    """An importlib reimplementation of imp.find_module (for our purposes)."""
 
     # To correctly find the module on the given path,  we need to
     # temporarily clear the import state of the program and modify sys.path.
@@ -101,7 +101,7 @@ def _find_module(name, path=None):
         # ...otherwise, it is fully resolved.
 
         if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
-            file_path = os.path.relpath(file_path)  # imp has weird rules
+            file_path = os.path.relpath(file_path)
 
     except ValueError:
         pass
diff --git a/Misc/ACKS b/Misc/ACKS
index 81b51f75199159..6aaab0fbdad1c9 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -222,6 +222,7 @@ Ian Bruntlett
 Floris Bruynooghe
 Matt Bryant
 Stan Bubrouski
+Brandt Bucher
 Colm Buckley
 Erik de Bueger
 Jan-Hein Bührman

From a9fd3c654f1f0097a8681d0bfb477e644d1420a9 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 13 Feb 2019 08:42:31 -0800
Subject: [PATCH 28/43] Replace importlib.util.find_spec with
 importlib.machinery.PathFinder.find_spec.

This swap avoids behavior changes and concurrency issues. The reverted changes will be proposed and reviewed separately. Thanks @ncoghlan!
---
 Lib/modulefinder.py | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index cdcd7eea3f8a86..470285ac6e1e58 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -3,7 +3,6 @@
 import dis
 import importlib._bootstrap_external
 import importlib.machinery
-import importlib.util
 import marshal
 import os
 import sys
@@ -55,29 +54,7 @@ def ReplacePackage(oldname, newname):
 def _find_module(name, path=None):
     """An importlib reimplementation of imp.find_module (for our purposes)."""
 
-    # To correctly find the module on the given path,  we need to
-    # temporarily clear the import state of the program and modify sys.path.
-
-    sys_path = sys.path
-    sys_modules = sys.modules
-    sys_path_importer_cache = sys.path_importer_cache
-
-    try:
-
-        sys.path = path + sys.path
-        sys.modules = {}
-        sys.path_importer_cache = {}
-
-        # It is important that `name` not include any dots.
-        # Otherwise, the parent package could be actually imported.
-
-        spec = importlib.util.find_spec(name)
-
-    finally:
-
-        sys.path = sys_path
-        sys.modules = sys_modules
-        sys.path_importer_cache = sys_path_importer_cache
+    spec = importlib.machinery.PathFinder.find_spec(name, path+sys.path)
 
     if spec is None:
         raise ImportError("No module named {name!r}".format(name=name), name=name)

From 826eef5440b93fd563351c30ca2aa50b705a09d5 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 13 Feb 2019 09:20:15 -0800
Subject: [PATCH 29/43] Invalidate caches before find_spec call.

It appears that we're still hitting some caches. This *should* help...
---
 Lib/modulefinder.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 470285ac6e1e58..fc4df2e4a0925f 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -54,6 +54,8 @@ def ReplacePackage(oldname, newname):
 def _find_module(name, path=None):
     """An importlib reimplementation of imp.find_module (for our purposes)."""
 
+    importlib.machinery.PathFinder.invalidate_caches()
+    
     spec = importlib.machinery.PathFinder.find_spec(name, path+sys.path)
 
     if spec is None:

From de22d673a71c1b48444b311c95862cd0d2159b49 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 13 Feb 2019 09:21:00 -0800
Subject: [PATCH 30/43] Fix whitespace.

Whoops.
---
 Lib/modulefinder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index fc4df2e4a0925f..a9cce548e48036 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -55,7 +55,7 @@ def _find_module(name, path=None):
     """An importlib reimplementation of imp.find_module (for our purposes)."""
 
     importlib.machinery.PathFinder.invalidate_caches()
-    
+
     spec = importlib.machinery.PathFinder.find_spec(name, path+sys.path)
 
     if spec is None:

From 4de4b3dc1c5fed4aeae253f05a7a1b8d594a5fe8 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 13 Feb 2019 10:55:45 -0800
Subject: [PATCH 31/43] Remove duplicate-bpo NEWS entries.

These will be replaced with new ones properly referencing their respective bpo issue numbers.
---
 .../next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst       | 2 --
 .../next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst       | 2 --
 2 files changed, 4 deletions(-)
 delete mode 100644 Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst
 delete mode 100644 Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst b/Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst
deleted file mode 100644
index 50596cf9e43f09..00000000000000
--- a/Misc/NEWS.d/next/Library/2019-02-10-00-25-25.bpo-35936.oKRkrD.rst
+++ /dev/null
@@ -1,2 +0,0 @@
-:mod:`modulefinder` no longer crashes when encountering syntax errors in followed imports.
-Patch by Brandt Bucher.
\ No newline at end of file
diff --git a/Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst b/Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst
deleted file mode 100644
index a9bf8c9a636ccb..00000000000000
--- a/Misc/NEWS.d/next/Library/2019-02-10-00-47-13.bpo-35936.UFhYLj.rst
+++ /dev/null
@@ -1,2 +0,0 @@
-:mod:`modulefinder` correctly handles modules that have the same name as a bad package.
-Patch by Brandt Bucher.
\ No newline at end of file

From 3085a62105684ecb94e337801612017a2d8e70bc Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <blurb-it[bot]@users.noreply.github.com>
Date: Wed, 13 Feb 2019 18:56:24 +0000
Subject: [PATCH 32/43] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2019-02-13-18-56-22.bpo-17396.oKRkrD.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-02-13-18-56-22.bpo-17396.oKRkrD.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-13-18-56-22.bpo-17396.oKRkrD.rst b/Misc/NEWS.d/next/Library/2019-02-13-18-56-22.bpo-17396.oKRkrD.rst
new file mode 100644
index 00000000000000..50596cf9e43f09
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-02-13-18-56-22.bpo-17396.oKRkrD.rst
@@ -0,0 +1,2 @@
+:mod:`modulefinder` no longer crashes when encountering syntax errors in followed imports.
+Patch by Brandt Bucher.
\ No newline at end of file

From 7b76e58faab6aba59abef84170d35dc3fed86214 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <blurb-it[bot]@users.noreply.github.com>
Date: Wed, 13 Feb 2019 18:56:28 +0000
Subject: [PATCH 33/43] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2019-02-13-18-56-27.bpo-35376.UFhYLj.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-02-13-18-56-27.bpo-35376.UFhYLj.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-13-18-56-27.bpo-35376.UFhYLj.rst b/Misc/NEWS.d/next/Library/2019-02-13-18-56-27.bpo-35376.UFhYLj.rst
new file mode 100644
index 00000000000000..a9bf8c9a636ccb
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-02-13-18-56-27.bpo-35376.UFhYLj.rst
@@ -0,0 +1,2 @@
+:mod:`modulefinder` correctly handles modules that have the same name as a bad package.
+Patch by Brandt Bucher.
\ No newline at end of file

From 744de0c7d451ac4880b612fad2445a4a1226d44b Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Wed, 13 Feb 2019 11:34:17 -0800
Subject: [PATCH 34/43] Empty commit.

This is to force a rebuild on the PR.

From 7371742d8661c6fc8dd2275d3e268fef3ed40d74 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sat, 16 Feb 2019 14:02:34 -0800
Subject: [PATCH 35/43] Remove NEWS entry.

This is going to have info about the mutable defaults added.
---
 .../next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst       | 2 --
 1 file changed, 2 deletions(-)
 delete mode 100644 Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst b/Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst
deleted file mode 100644
index d96a18ab6e1bc2..00000000000000
--- a/Misc/NEWS.d/next/Library/2019-02-10-17-31-00.bpo-35936.1af0OQ.rst
+++ /dev/null
@@ -1,2 +0,0 @@
-:mod:`modulefinder` no longer uses the deprecated :mod:`imp` module.
-Patch by Brandt Bucher.
\ No newline at end of file

From 540e819ffeb926ea7d69f8ae847b900a1f244032 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <blurb-it[bot]@users.noreply.github.com>
Date: Sat, 16 Feb 2019 22:19:33 +0000
Subject: [PATCH 36/43] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20b?=
 =?UTF-8?q?lurb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2019-02-16-22-19-32.bpo-35936.Ay5WtD.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-02-16-22-19-32.bpo-35936.Ay5WtD.rst

diff --git a/Misc/NEWS.d/next/Library/2019-02-16-22-19-32.bpo-35936.Ay5WtD.rst b/Misc/NEWS.d/next/Library/2019-02-16-22-19-32.bpo-35936.Ay5WtD.rst
new file mode 100644
index 00000000000000..55a028ec8349cd
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-02-16-22-19-32.bpo-35936.Ay5WtD.rst
@@ -0,0 +1,2 @@
+:mod:`modulefinder` no longer depends on the deprecated :mod:`imp` module, and the initializer for :class:`modulefinder.ModuleFinder` now has immutable default arguments.
+Patch by Brandt Bucher.
\ No newline at end of file

From d6f19a6777e46f50e115f31b3c5bfc7ce82dbb69 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 17 Feb 2019 07:36:00 -0800
Subject: [PATCH 37/43] Remove loader subclass checks.

Identity checking is sufficient here.
---
 Lib/modulefinder.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index a9cce548e48036..22502a14140ff7 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -61,13 +61,13 @@ def _find_module(name, path=None):
     if spec is None:
         raise ImportError("No module named {name!r}".format(name=name), name=name)
 
-    if isinstance(spec.loader, type):  # Some special cases:
+    # Some special cases:
 
-        if issubclass(spec.loader, importlib.machinery.BuiltinImporter):
-            return None, None, ("", "", _C_BUILTIN)
+    if spec.loader is importlib.machinery.BuiltinImporter:
+        return None, None, ("", "", _C_BUILTIN)
 
-        if issubclass(spec.loader, importlib.machinery.FrozenImporter):
-            return None, None, ("", "", _PY_FROZEN)
+    if spec.loader is importlib.machinery.FrozenImporter:
+        return None, None, ("", "", _PY_FROZEN)
 
     file_path = spec.origin
 

From 04fc93a2f744defcf5083025be75b8cc987be3b8 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 17 Feb 2019 07:42:06 -0800
Subject: [PATCH 38/43] Use spec.loader for package checking.

This is more robust than using a string comparison with "__init__".
---
 Lib/modulefinder.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 22502a14140ff7..d49cfbcae84b70 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -85,7 +85,7 @@ def _find_module(name, path=None):
     except ValueError:
         pass
 
-    base, suffix = os.path.splitext(file_path)
+    _, suffix = os.path.splitext(file_path)
 
     if suffix in importlib.machinery.EXTENSION_SUFFIXES:
         file_path = os.path.abspath(file_path)
@@ -94,8 +94,8 @@ def _find_module(name, path=None):
 
     elif suffix in importlib.machinery.SOURCE_SUFFIXES:
 
-        if name != "__init__" and os.path.basename(base) == "__init__":
-            return (None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY))
+        if spec.loader.is_package(name):
+            return None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY)
 
         kind = _PY_SOURCE
         mode = "r"

From a506dc4e9b6a2b8792c741b31ce57563587b58c0 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 17 Feb 2019 08:08:56 -0800
Subject: [PATCH 39/43] Remove sys.path from path.

This isn't actually needed (or wanted) here.
---
 Lib/modulefinder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index d49cfbcae84b70..7511a237359f66 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -56,7 +56,7 @@ def _find_module(name, path=None):
 
     importlib.machinery.PathFinder.invalidate_caches()
 
-    spec = importlib.machinery.PathFinder.find_spec(name, path+sys.path)
+    spec = importlib.machinery.PathFinder.find_spec(name, path)
 
     if spec is None:
         raise ImportError("No module named {name!r}".format(name=name), name=name)

From d1fa6afb67aa7275e3ab43069d4e2db8befe7e4c Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 17 Feb 2019 08:31:35 -0800
Subject: [PATCH 40/43] Use loader type to classify imports.

This is probably a better idea than using the extension alone.
---
 Lib/modulefinder.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 7511a237359f66..8d4a1e9a1c9ef4 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -87,12 +87,12 @@ def _find_module(name, path=None):
 
     _, suffix = os.path.splitext(file_path)
 
-    if suffix in importlib.machinery.EXTENSION_SUFFIXES:
+    if isinstance(spec.loader, importlib.machinery.ExtensionFileLoader):
         file_path = os.path.abspath(file_path)
         kind = _C_EXTENSION
         mode = "rb"
 
-    elif suffix in importlib.machinery.SOURCE_SUFFIXES:
+    elif isinstance(spec.loader, importlib.machinery.SourceFileLoader):
 
         if spec.loader.is_package(name):
             return None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY)
@@ -100,7 +100,7 @@ def _find_module(name, path=None):
         kind = _PY_SOURCE
         mode = "r"
 
-    elif suffix in importlib.machinery.BYTECODE_SUFFIXES:
+    elif isinstance(spec.loader, importlib.machinery.SourcelessFileLoader):
         kind = _PY_COMPILED
         mode = "rb"
 

From 8840bc0d0522d652a9fc60109f188c9a57fa4f54 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 17 Feb 2019 08:33:30 -0800
Subject: [PATCH 41/43] Remove absolute/relative path formatting.

Interestingly, it looks like PathFinder does this for us! That's great, because it really cleans up this section a lot.
---
 Lib/modulefinder.py | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 8d4a1e9a1c9ef4..c3c872d5d94978 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -71,24 +71,9 @@ def _find_module(name, path=None):
 
     file_path = spec.origin
 
-    try:
-
-        # `imp` behavior is s bit funny here:
-
-        # If the path is a descendant of the CWD, it is reported as a relative filepath
-        # ...unless it is an extension, in which case it will be absolute (see below)
-        # ...otherwise, it is fully resolved.
-
-        if os.path.commonpath(map(os.path.abspath, (file_path, os.getcwd()))) == os.getcwd():
-            file_path = os.path.relpath(file_path)
-
-    except ValueError:
-        pass
-
     _, suffix = os.path.splitext(file_path)
 
     if isinstance(spec.loader, importlib.machinery.ExtensionFileLoader):
-        file_path = os.path.abspath(file_path)
         kind = _C_EXTENSION
         mode = "rb"
 

From 654461b3d45d735280ef57cdccb928c4236b50c5 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 17 Feb 2019 08:37:33 -0800
Subject: [PATCH 42/43] Reorder branching.

Hopefully we can get a tiny boost here by checking likely outcomes first.
---
 Lib/modulefinder.py | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index c3c872d5d94978..7b7435e41887ea 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -71,20 +71,17 @@ def _find_module(name, path=None):
 
     file_path = spec.origin
 
-    _, suffix = os.path.splitext(file_path)
-
-    if isinstance(spec.loader, importlib.machinery.ExtensionFileLoader):
-        kind = _C_EXTENSION
-        mode = "rb"
-
-    elif isinstance(spec.loader, importlib.machinery.SourceFileLoader):
-
-        if spec.loader.is_package(name):
-            return None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY)
+    if spec.loader.is_package(name):
+        return None, os.path.dirname(file_path), ("", "", _PKG_DIRECTORY)
 
+    if isinstance(spec.loader, importlib.machinery.SourceFileLoader):
         kind = _PY_SOURCE
         mode = "r"
 
+    elif isinstance(spec.loader, importlib.machinery.ExtensionFileLoader):
+        kind = _C_EXTENSION
+        mode = "rb"
+
     elif isinstance(spec.loader, importlib.machinery.SourcelessFileLoader):
         kind = _PY_COMPILED
         mode = "rb"
@@ -93,6 +90,7 @@ def _find_module(name, path=None):
         return None, None, ("", "", _SEARCH_ERROR)
 
     file = open(file_path, mode)
+    suffix = os.path.splitext(file_path)[-1]
 
     return file, file_path, (suffix, mode, kind)
 

From 9a732c13e07903e31f1008f6faa39232c4db5d6e Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@gmail.com>
Date: Sun, 17 Feb 2019 09:27:39 -0800
Subject: [PATCH 43/43] Add comments on cache invalidation.

This makes the unintuitive reasoning behind this call explicit.
---
 Lib/modulefinder.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 7b7435e41887ea..0061ef415ce322 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -54,6 +54,10 @@ def ReplacePackage(oldname, newname):
 def _find_module(name, path=None):
     """An importlib reimplementation of imp.find_module (for our purposes)."""
 
+    # It's necessary to clear the caches for our Finder first, in case any
+    # modules are being added/deleted/modified at runtime. In particular,
+    # test_modulefinder.py changes file tree contents in a cache-breaking way:
+
     importlib.machinery.PathFinder.invalidate_caches()
 
     spec = importlib.machinery.PathFinder.find_spec(name, path)