From 8d0fcbe9b2b714db2f34d202353547c840f26eec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Batuhan=20Ta=C5=9Fkaya?= <batuhanosmantaskaya@gmail.com>
Date: Wed, 22 Apr 2020 01:07:26 +0300
Subject: [PATCH 1/2] bpo-38870: Don't start generated output with newlines

---
 Lib/ast.py               | 14 ++++++++++----
 Lib/test/test_unparse.py | 12 +++++-------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/Lib/ast.py b/Lib/ast.py
index 401af5647a240ce..ff0fe6cc5452c5d 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -669,10 +669,16 @@ def items_view(self, traverser, items):
         else:
             self.interleave(lambda: self.write(", "), traverser, items)
 
+    def newline(self):
+        """Adds a newline if it isn't the start of generated source"""
+        if self._source:
+            self.write("\n")
+
     def fill(self, text=""):
         """Indent a piece of text and append it, according to the current
         indentation level"""
-        self.write("\n" + "    " * self._indent + text)
+        self.newline()
+        self.write("    " * self._indent + text)
 
     def write(self, text):
         """Append a piece of text"""
@@ -916,7 +922,7 @@ def visit_ExceptHandler(self, node):
             self.traverse(node.body)
 
     def visit_ClassDef(self, node):
-        self.write("\n")
+        self.newline()
         for deco in node.decorator_list:
             self.fill("@")
             self.traverse(deco)
@@ -946,7 +952,7 @@ def visit_AsyncFunctionDef(self, node):
         self._function_helper(node, "async def")
 
     def _function_helper(self, node, fill_suffix):
-        self.write("\n")
+        self.newline()
         for deco in node.decorator_list:
             self.fill("@")
             self.traverse(deco)
@@ -1043,7 +1049,7 @@ def _fstring_FormattedValue(self, node, write):
         write("{")
         unparser = type(self)()
         unparser.set_precedence(_Precedence.TEST.next(), node.value)
-        expr = unparser.visit(node.value).rstrip("\n")
+        expr = unparser.visit(node.value)
         if expr.startswith("{"):
             write(" ")  # Separate pair of opening brackets as "{ {"
         write(expr)
diff --git a/Lib/test/test_unparse.py b/Lib/test/test_unparse.py
index d4089a3fc1cdf8f..2be44b246aa697b 100644
--- a/Lib/test/test_unparse.py
+++ b/Lib/test/test_unparse.py
@@ -128,19 +128,17 @@ def check_ast_roundtrip(self, code1, **kwargs):
     def check_invalid(self, node, raises=ValueError):
         self.assertRaises(raises, ast.unparse, node)
 
-    def get_source(self, code1, code2=None, strip=True):
+    def get_source(self, code1, code2=None):
         code2 = code2 or code1
         code1 = ast.unparse(ast.parse(code1))
-        if strip:
-            code1 = code1.strip()
         return code1, code2
 
-    def check_src_roundtrip(self, code1, code2=None, strip=True):
-        code1, code2 = self.get_source(code1, code2, strip)
+    def check_src_roundtrip(self, code1, code2=None):
+        code1, code2 = self.get_source(code1, code2)
         self.assertEqual(code2, code1)
 
-    def check_src_dont_roundtrip(self, code1, code2=None, strip=True):
-        code1, code2 = self.get_source(code1, code2, strip)
+    def check_src_dont_roundtrip(self, code1, code2=None):
+        code1, code2 = self.get_source(code1, code2)
         self.assertNotEqual(code2, code1)
 
 class UnparseTestCase(ASTTestCase):

From 3c67ff7907ec19ae5ad6d11af46a9ac1d6a5ea37 Mon Sep 17 00:00:00 2001
From: Batuhan Taskaya <batuhanosmantaskaya@gmail.com>
Date: Sun, 3 May 2020 17:35:31 +0300
Subject: [PATCH 2/2] Rename newline to maybe_newline

---
 Lib/ast.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Lib/ast.py b/Lib/ast.py
index ff0fe6cc5452c5d..5c68c4a66e1dd06 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -669,7 +669,7 @@ def items_view(self, traverser, items):
         else:
             self.interleave(lambda: self.write(", "), traverser, items)
 
-    def newline(self):
+    def maybe_newline(self):
         """Adds a newline if it isn't the start of generated source"""
         if self._source:
             self.write("\n")
@@ -677,7 +677,7 @@ def newline(self):
     def fill(self, text=""):
         """Indent a piece of text and append it, according to the current
         indentation level"""
-        self.newline()
+        self.maybe_newline()
         self.write("    " * self._indent + text)
 
     def write(self, text):
@@ -922,7 +922,7 @@ def visit_ExceptHandler(self, node):
             self.traverse(node.body)
 
     def visit_ClassDef(self, node):
-        self.newline()
+        self.maybe_newline()
         for deco in node.decorator_list:
             self.fill("@")
             self.traverse(deco)
@@ -952,7 +952,7 @@ def visit_AsyncFunctionDef(self, node):
         self._function_helper(node, "async def")
 
     def _function_helper(self, node, fill_suffix):
-        self.newline()
+        self.maybe_newline()
         for deco in node.decorator_list:
             self.fill("@")
             self.traverse(deco)