Uppercase digits in hex literals (#530)

diff --git a/README.md b/README.md
index 244f60d776c06df92ac15f02bc3dc4ecf43471f6..a23cb61f359bcf1a8d8924baad676bfd6e578800 100644 (file)
--- a/README.md
+++ b/README.md
@@ -374,7 +374,8 @@ an adoption helper, avoid using this for new projects.
 
 ### Numeric literals
 
-*Black* standardizes most numeric literals to use lowercase letters: `0xab`
+*Black* standardizes most numeric literals to use lowercase letters for the
+syntactic parts and uppercase letters for the digits themselves: `0xAB`
 instead of `0XAB` and `1e10` instead of `1E10`. Python 2 long literals are
 styled as `2L` instead of `2l` to avoid confusion between `l` and `1`. In
 Python 3.6+, *Black* adds underscores to long numeric literals to aid

diff --git a/black.py b/black.py
index f2c450c33876a615472e5d28ec641cc1a4ccfb83..522474123092e46c6d3d3bf26b7fe0211141d634 100644 (file)
--- a/black.py
+++ b/black.py
@@ -2542,9 +2542,13 @@ def normalize_numeric_literal(leaf: Leaf, allow_underscores: bool) -> None:
     in Python 2 long literals), and long number literals are split using underscores.
     """
     text = leaf.value.lower()
-    if text.startswith(("0o", "0x", "0b")):
-        # Leave octal, hex, and binary literals alone.
+    if text.startswith(("0o", "0b")):
+        # Leave octal and binary literals alone.
         pass
+    elif text.startswith("0x"):
+        # Change hex literals to upper case.
+        before, after = text[:2], text[2:]
+        text = f"{before}{after.upper()}"
     elif "e" in text:
         before, after = text.split("e")
         sign = ""

diff --git a/tests/data/numeric_literals.py b/tests/data/numeric_literals.py
index b812ebfa82429f7c7a47da12c41633d139f8c4e6..9a49dfa32c91ce254df25b7b33a6d98affabb24c 100644 (file)
--- a/tests/data/numeric_literals.py
+++ b/tests/data/numeric_literals.py
@@ -34,7 +34,7 @@ x = 123_456_789.123_456_789e123_456_789
 x = 123_456_789e123_456_789
 x = 123_456_789j
 x = 123_456_789.123_456_789j
-x = 0xb1acc
+x = 0xB1ACC
 x = 0b1011
 x = 0o777
 x = 0.000_000_006

diff --git a/tests/data/numeric_literals_py2.py b/tests/data/numeric_literals_py2.py
index d2db7b0ccc474f785c6eb515c3ae8ad29e9f02f4..8f85c43f2653cf009c772522cb281bad9e73ba25 100644 (file)
--- a/tests/data/numeric_literals_py2.py
+++ b/tests/data/numeric_literals_py2.py
@@ -3,6 +3,7 @@
 x = 123456789L
 x = 123456789l
 x = 123456789
+x = 0xb1acc
 
 # output
 
@@ -12,3 +13,4 @@ x = 123456789
 x = 123456789L
 x = 123456789L
 x = 123456789
+x = 0xB1ACC