Indicate that a final newline was added in --diff (#1897) (#1897)

[etc/vim.git] / src / black / __init__.py

diff --git a/src/black/__init__.py b/src/black/__init__.py
index e398ed04f437cf0b8864059cc3943c5c24e14505..c1907d9b1f10dd47a19d30df5686d9885fda4fdb 100644 (file)
--- a/src/black/__init__.py
+++ b/src/black/__init__.py
@@ -1480,7 +1480,8 @@ class Line:
     comments: Dict[LeafID, List[Leaf]] = field(default_factory=dict)
     bracket_tracker: BracketTracker = field(default_factory=BracketTracker)
     inside_brackets: bool = False
-    should_explode: bool = False
+    should_split: bool = False
+    magic_trailing_comma: Optional[Leaf] = None
 
     def append(self, leaf: Leaf, preformatted: bool = False) -> None:
         """Add a new `leaf` to the end of the line.
@@ -1508,7 +1509,7 @@ class Line:
             self.bracket_tracker.mark(leaf)
             if self.mode.magic_trailing_comma:
                 if self.has_magic_trailing_comma(leaf):
-                    self.should_explode = True
+                    self.magic_trailing_comma = leaf
             elif self.has_magic_trailing_comma(leaf, ensure_removable=True):
                 self.remove_trailing_comma()
         if not self.append_comment(leaf):
@@ -1791,7 +1792,8 @@ class Line:
             mode=self.mode,
             depth=self.depth,
             inside_brackets=self.inside_brackets,
-            should_explode=self.should_explode,
+            should_split=self.should_split,
+            magic_trailing_comma=self.magic_trailing_comma,
         )
 
     def __str__(self) -> str:
@@ -2710,7 +2712,8 @@ def transform_line(
     transformers: List[Transformer]
     if (
         not line.contains_uncollapsable_type_comments()
-        and not line.should_explode
+        and not line.should_split
+        and not line.magic_trailing_comma
         and (
             is_line_short_enough(line, line_length=mode.line_length, line_str=line_str)
             or line.contains_unsplittable_type_ignore()
@@ -4384,7 +4387,8 @@ class StringParenWrapper(CustomSplitMapMixin, BaseStringSplitter):
             mode=line.mode,
             depth=line.depth + 1,
             inside_brackets=True,
-            should_explode=line.should_explode,
+            should_split=line.should_split,
+            magic_trailing_comma=line.magic_trailing_comma,
         )
         string_leaf = Leaf(token.STRING, string_value)
         insert_str_child(string_leaf)
@@ -5005,8 +5009,8 @@ def bracket_split_build_line(
         result.append(leaf, preformatted=True)
         for comment_after in original.comments_after(leaf):
             result.append(comment_after, preformatted=True)
-    if is_body and should_split(result, opening_bracket):
-        result.should_explode = True
+    if is_body and should_split_line(result, opening_bracket):
+        result.should_split = True
     return result
 
 
@@ -5810,7 +5814,7 @@ def ensure_visible(leaf: Leaf) -> None:
         leaf.value = ")"
 
 
-def should_split(line: Line, opening_bracket: Leaf) -> bool:
+def should_split_line(line: Line, opening_bracket: Leaf) -> bool:
     """Should `line` be immediately split with `delimiter_split()` after RHS?"""
 
     if not (opening_bracket.parent and opening_bracket.value in "[{("):
@@ -5946,7 +5950,7 @@ def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[Leaf
     """
 
     omit: Set[LeafID] = set()
-    if not line.should_explode:
+    if not line.magic_trailing_comma:
         yield omit
 
     length = 4 * line.depth
@@ -5968,8 +5972,7 @@ def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[Leaf
             elif leaf.type in CLOSING_BRACKETS:
                 prev = line.leaves[index - 1] if index > 0 else None
                 if (
-                    line.should_explode
-                    and prev
+                    prev
                     and prev.type == token.COMMA
                     and not is_one_tuple_between(
                         leaf.opening_bracket, leaf, line.leaves
@@ -5996,8 +5999,7 @@ def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[Leaf
                 yield omit
 
             if (
-                line.should_explode
-                and prev
+                prev
                 and prev.type == token.COMMA
                 and not is_one_tuple_between(leaf.opening_bracket, leaf, line.leaves)
             ):
@@ -6423,14 +6425,14 @@ def assert_stable(src: str, dst: str, mode: Mode) -> None:
 
 
 @mypyc_attr(patchable=True)
-def dump_to_file(*output: str) -> str:
+def dump_to_file(*output: str, ensure_final_newline: bool = True) -> str:
     """Dump `output` to a temporary file. Return path to the file."""
     with tempfile.NamedTemporaryFile(
         mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8"
     ) as f:
         for lines in output:
             f.write(lines)
-            if lines and lines[-1] != "\n":
+            if ensure_final_newline and lines and lines[-1] != "\n":
                 f.write("\n")
     return f.name
 
@@ -6448,11 +6450,20 @@ def diff(a: str, b: str, a_name: str, b_name: str) -> str:
     """Return a unified diff string between strings `a` and `b`."""
     import difflib
 
-    a_lines = [line + "\n" for line in a.splitlines()]
-    b_lines = [line + "\n" for line in b.splitlines()]
-    return "".join(
-        difflib.unified_diff(a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5)
-    )
+    a_lines = [line for line in a.splitlines(keepends=True)]
+    b_lines = [line for line in b.splitlines(keepends=True)]
+    diff_lines = []
+    for line in difflib.unified_diff(
+        a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5
+    ):
+        # Work around https://bugs.python.org/issue2142
+        # See https://www.gnu.org/software/diffutils/manual/html_node/Incomplete-Lines.html
+        if line[-1] == "\n":
+            diff_lines.append(line)
+        else:
+            diff_lines.append(line + "\n")
+            diff_lines.append("\\ No newline at end of file\n")
+    return "".join(diff_lines)
 
 
 def cancel(tasks: Iterable["asyncio.Task[Any]"]) -> None:
@@ -6629,7 +6640,7 @@ def can_omit_invisible_parens(
 
     penultimate = line.leaves[-2]
     last = line.leaves[-1]
-    if line.should_explode:
+    if line.magic_trailing_comma:
         try:
             penultimate, last = last_two_except(line.leaves, omit=omit_on_explode)
         except LookupError:
@@ -6656,7 +6667,7 @@ def can_omit_invisible_parens(
             # unnecessary.
             return True
 
-        if line.should_explode and penultimate.type == token.COMMA:
+        if line.magic_trailing_comma and penultimate.type == token.COMMA:
             # The rightmost non-omitted bracket pair is the one we want to explode on.
             return True