From 4ebb118f5f3763e2162ee5318898558ea126f725 Mon Sep 17 00:00:00 2001
From: wisp3rwind <17089248+wisp3rwind@users.noreply.github.com>
Date: Thu, 30 May 2019 10:47:17 +0200
Subject: [PATCH 1/2] functemplate: Adapt ast syntax to PEP570 changes on
 python3.8

---
 beets/util/functemplate.py | 46 +++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/beets/util/functemplate.py b/beets/util/functemplate.py
index 5d9900f0b..79dcb9ad4 100644
--- a/beets/util/functemplate.py
+++ b/beets/util/functemplate.py
@@ -118,30 +118,36 @@ def compile_func(arg_names, statements, name='_the_func', debug=False):
     bytecode of the compiled function.
     """
     if six.PY2:
-        func_def = ast.FunctionDef(
-            name=name.encode('utf-8'),
-            args=ast.arguments(
-                args=[ast.Name(n, ast.Param()) for n in arg_names],
-                vararg=None,
-                kwarg=None,
-                defaults=[ex_literal(None) for _ in arg_names],
-            ),
-            body=statements,
-            decorator_list=[],
+        name = name.encode('utf-8')
+        args = ast.arguments(
+            args=[ast.Name(n, ast.Param()) for n in arg_names],
+            vararg=None,
+            kwarg=None,
+            defaults=[ex_literal(None) for _ in arg_names],
+        )
+    elif sys.version_info >= (3, 8):
+        args = ast.arguments(
+            args=[ast.arg(arg=n, annotation=None) for n in arg_names],
+            posonlyargs=[],
+            kwonlyargs=[],
+            kw_defaults=[],
+            defaults=[ex_literal(None) for _ in arg_names],
         )
     else:
-        func_def = ast.FunctionDef(
-            name=name,
-            args=ast.arguments(
-                args=[ast.arg(arg=n, annotation=None) for n in arg_names],
-                kwonlyargs=[],
-                kw_defaults=[],
-                defaults=[ex_literal(None) for _ in arg_names],
-            ),
-            body=statements,
-            decorator_list=[],
+        args = ast.arguments(
+            args=[ast.arg(arg=n, annotation=None) for n in arg_names],
+            kwonlyargs=[],
+            kw_defaults=[],
+            defaults=[ex_literal(None) for _ in arg_names],
         )
 
+    func_def = ast.FunctionDef(
+        name=name,
+        args=args,
+        body=statements,
+        decorator_list=[],
+    )
+
     # The ast.Module signature changed in 3.8 to accept a list of types to
     # ignore.
     if sys.version_info >= (3, 8):

From ade1df52a2ae06d8cd0e704327ac0a6ae2d16746 Mon Sep 17 00:00:00 2001
From: Adrian Sampson <adrian@radbox.org>
Date: Thu, 30 May 2019 18:14:40 -0400
Subject: [PATCH 2/2] Use "feature detection" for 3.8 compat (#3278)

---
 beets/util/functemplate.py | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/beets/util/functemplate.py b/beets/util/functemplate.py
index 79dcb9ad4..af22b7908 100644
--- a/beets/util/functemplate.py
+++ b/beets/util/functemplate.py
@@ -125,21 +125,16 @@ def compile_func(arg_names, statements, name='_the_func', debug=False):
             kwarg=None,
             defaults=[ex_literal(None) for _ in arg_names],
         )
-    elif sys.version_info >= (3, 8):
-        args = ast.arguments(
-            args=[ast.arg(arg=n, annotation=None) for n in arg_names],
-            posonlyargs=[],
-            kwonlyargs=[],
-            kw_defaults=[],
-            defaults=[ex_literal(None) for _ in arg_names],
-        )
     else:
-        args = ast.arguments(
-            args=[ast.arg(arg=n, annotation=None) for n in arg_names],
-            kwonlyargs=[],
-            kw_defaults=[],
-            defaults=[ex_literal(None) for _ in arg_names],
-        )
+        args_fields = {
+            'args': [ast.arg(arg=n, annotation=None) for n in arg_names],
+            'kwonlyargs': [],
+            'kw_defaults': [],
+            'defaults': [ex_literal(None) for _ in arg_names],
+        }
+        if 'posonlyargs' in ast.arguments._fields:  # Added in Python 3.8.
+            args_fields['posonlyargs'] = []
+        args = ast.arguments(**args_fields)
 
     func_def = ast.FunctionDef(
         name=name,