python · AWhetter · Jul 3, 2020
diff --git a/Lib/lib2to3/fixes/fix_dict.py b/Lib/lib2to3/fixes/fix_dict.py
@@ -65,6 +65,8 @@ def transform(self, node, results):
        head = [n.clone() for n in head]
        tail = [n.clone() for n in tail]
        special = not tail and self.in_special_context(node, isiter)
+        if special and not (isiter or isview):
+            return None
        args = head + [pytree.Node(syms.trailer,
                                   [Dot(),
                                    Name(method_name,

diff --git a/Lib/lib2to3/fixes/fix_except.py b/Lib/lib2to3/fixes/fix_except.py
@@ -50,10 +50,12 @@ def transform(self, node, results):
        tail = [n.clone() for n in results["tail"]]

        try_cleanup = [ch.clone() for ch in results["cleanup"]]
+        changed = False
        for except_clause, e_suite in find_excepts(try_cleanup):
            if len(except_clause.children) == 4:
                (E, comma, N) = except_clause.children[1:4]
                comma.replace(Name("as", prefix=" "))
+                changed = True

                if N.type != token.NAME:
                    # Generate a new N for the except clause
@@ -88,6 +90,9 @@ def transform(self, node, results):
                    # not so much.
                    N.prefix = " "

+        if not changed:
+            return None
+
        #TODO(cwinter) fix this when children becomes a smart list
        children = [c.clone() for c in node.children[:3]] + try_cleanup + tail
        return pytree.Node(node.type, children)
diff --git a/Lib/lib2to3/fixes/fix_isinstance.py b/Lib/lib2to3/fixes/fix_isinstance.py
@@ -32,8 +32,10 @@ def transform(self, node, results):
        args = testlist.children
        new_args = []
        iterator = enumerate(args)
+        changed = False
        for idx, arg in iterator:
            if arg.type == token.NAME and arg.value in names_inserted:
+                changed = True
                if idx < len(args) - 1 and args[idx + 1].type == token.COMMA:
                    next(iterator)
                    continue
@@ -42,11 +44,13 @@ def transform(self, node, results):
                if arg.type == token.NAME:
                    names_inserted.add(arg.value)
        if new_args and new_args[-1].type == token.COMMA:
+            changed = True
            del new_args[-1]
-        if len(new_args) == 1:
-            atom = testlist.parent
+        atom = testlist.parent
+        if len(new_args) == 1 and new_args[0].prefix != atom.prefix:
+            changed = True
            new_args[0].prefix = atom.prefix
            atom.replace(new_args[0])
-        else:
+        if changed:
            args[:] = new_args
            node.changed()
diff --git a/Lib/lib2to3/fixes/fix_numliterals.py b/Lib/lib2to3/fixes/fix_numliterals.py
@@ -14,15 +14,24 @@ class FixNumliterals(fixer_base.BaseFix):

    _accept_type = token.NUMBER

+    def is_long(self, node):
+        return node.value[-1] in 'Ll'
+
+    def is_octal(self, node):
+        return (
+            node.value.startswith("0")
+            and node.value.isdigit()
+            and len(set(node.value)) > 1
+        )
+
    def match(self, node):
        # Override
-        return (node.value.startswith("0") or node.value[-1] in "Ll")
+        return self.is_long(node) or self.is_octal(node)

    def transform(self, node, results):
-        val = node.value
-        if val[-1] in 'Ll':
-            val = val[:-1]
-        elif val.startswith('0') and val.isdigit() and len(set(val)) > 1:
-            val = "0o" + val[1:]
+        if self.is_long(node):
+            return Number(node.value[:-1], prefix=node.prefix)
+        elif self.is_octal(node):
+            return Number("0o" + node.value[1:], prefix=node.prefix)

-        return Number(val, prefix=node.prefix)
+        return None
diff --git a/Lib/lib2to3/fixes/fix_raise.py b/Lib/lib2to3/fixes/fix_raise.py
@@ -37,6 +37,7 @@ class FixRaise(fixer_base.BaseFix):

    def transform(self, node, results):
        syms = self.syms
+        changed = False

        exc = results["exc"].clone()
        if exc.type == token.STRING:
@@ -56,8 +57,12 @@ def transform(self, node, results):
                # exc.children[1].children[0] is the first element of the tuple
                exc = exc.children[1].children[0].clone()
            exc.prefix = " "
+            changed = True

        if "val" not in results:
+            if not changed:
+                return None
+
            # One-argument raise
            new = pytree.Node(syms.raise_stmt, [Name("raise"), exc])
            new.prefix = node.prefix

diff --git a/Lib/lib2to3/fixes/fix_unicode.py b/Lib/lib2to3/fixes/fix_unicode.py
@@ -36,7 +36,7 @@ def transform(self, node, results):
            if val[0] in 'uU':
                val = val[1:]
            if val == node.value:
-                return node
+                return
            new = node.clone()
            new.value = val
            return new
diff --git a/Lib/lib2to3/fixes/fix_ws_comma.py b/Lib/lib2to3/fixes/fix_ws_comma.py
@@ -24,16 +24,19 @@ class FixWsComma(fixer_base.BaseFix):
    def transform(self, node, results):
        new = node.clone()
        comma = False
+        changed = False
        for child in new.children:
            if child in self.SEPS:
                prefix = child.prefix
                if prefix.isspace() and "\n" not in prefix:
                    child.prefix = ""
+                    changed = True
                comma = True
            else:
                if comma:
                    prefix = child.prefix
                    if not prefix:
                        child.prefix = " "
+                        changed = True
                comma = False
-        return new
+        return new if changed else None
diff --git a/Lib/lib2to3/tests/test_fixers.py b/Lib/lib2to3/tests/test_fixers.py
@@ -48,7 +48,8 @@ def warns_unchanged(self, before, message):
        self.warns(before, before, message, unchanged=True)

    def unchanged(self, before, ignore_warnings=False):
-        self._check(before, before)
+        tree = self._check(before, before)
+        self.assertFalse(tree.was_changed)
        if not ignore_warnings:
            self.assertEqual(self.fixer_log, [])

@@ -955,6 +956,10 @@ def test_tuple_exc_2(self):
        a = """raise E1(V)"""
        self.check(b, a)

+    def test_unchanged(self):
+        a = """raise E1(V)"""
+        self.unchanged(a)
+
    # These should produce a warning

    def test_string_exc(self):
@@ -2776,6 +2781,10 @@ def test_unchanged_int(self):
    def test_unchanged_float(self):
        s = """5.0"""
        self.unchanged(s)
+        s = """0.1"""
+        self.unchanged(s)
+        s = """000"""
+        self.unchanged(s)

    def test_unchanged_octal(self):
        s = """0o755"""
@@ -2895,18 +2904,15 @@ def test_native_literal_escape_u(self):
        a = r"""'\\\\u20ac\\U0001d121\\u20ac'"""
        self.check(b, a)

-        b = r"""r'\\\u20ac\U0001d121\\u20ac'"""
        a = r"""r'\\\u20ac\U0001d121\\u20ac'"""
-        self.check(b, a)
+        self.unchanged(a)

    def test_bytes_literal_escape_u(self):
-        b = r"""b'\\\u20ac\U0001d121\\u20ac'"""
        a = r"""b'\\\u20ac\U0001d121\\u20ac'"""
-        self.check(b, a)
+        self.unchanged(a)

-        b = r"""br'\\\u20ac\U0001d121\\u20ac'"""
        a = r"""br'\\\u20ac\U0001d121\\u20ac'"""
-        self.check(b, a)
+        self.unchanged(a)

    def test_unicode_literal_escape_u(self):
        b = r"""u'\\\u20ac\U0001d121\\u20ac'"""
@@ -2919,13 +2925,15 @@ def test_unicode_literal_escape_u(self):

    def test_native_unicode_literal_escape_u(self):
        f = 'from __future__ import unicode_literals\n'
-        b = f + r"""'\\\u20ac\U0001d121\\u20ac'"""
        a = f + r"""'\\\u20ac\U0001d121\\u20ac'"""
-        self.check(b, a)
+        self.unchanged(a)

-        b = f + r"""r'\\\u20ac\U0001d121\\u20ac'"""
        a = f + r"""r'\\\u20ac\U0001d121\\u20ac'"""
-        self.check(b, a)
+        self.unchanged(a)
+
+    def test_unchanged(self):
+        a = """'h'"""
+        self.unchanged(a)


 class Test_filter(FixerTestCase):

diff --git a/Misc/NEWS.d/next/Library/2020-07-03-10-45-39.bpo-41110.GId8oe.rst b/Misc/NEWS.d/next/Library/2020-07-03-10-45-39.bpo-41110.GId8oe.rst
@@ -0,0 +1 @@
+Fixed lib2to3 reporting some unchanged files as needing modification.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fixed lib2to3 reporting some unchanged files as needing modification.