From b92fc9cb3133673f284ccdef76446673bd81c7a8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adrien=20Verg=C3=A9?= <adrienverge@gmail.com>
Date: Tue, 4 Apr 2023 18:44:26 +0200
Subject: [PATCH] colons: Prevent error when space before is mandatory
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In the rare case when the key before `:` is an alias (e.g. `{*x : 4}`),
the space before `:` is required (although this requirement is not
enforced by PyYAML), the reason being that a colon can be part of an
anchor name. Consequently, this commit adapts the `colons` rule to avoid
failures when this happens.

See this comment from Tina Müller for more details:
https://github.com/adrienverge/yamllint/pull/550#discussion_r1155297373
---
 tests/rules/test_colons.py | 16 ++++++++++++++++
 yamllint/rules/colons.py   |  4 +++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/tests/rules/test_colons.py b/tests/rules/test_colons.py
index 98f92c5a..5467c8be 100644
--- a/tests/rules/test_colons.py
+++ b/tests/rules/test_colons.py
@@ -256,3 +256,19 @@ def test_both_before_and_after(self):
                    '  property: {a: 1, b:  2, c : 3}\n', conf,
                    problem1=(3, 11), problem2=(4, 4),
                    problem3=(8, 23), problem4=(8, 28))
+
+    # Although accepted by PyYAML, `{*x: 4}` is not valid YAML: it should be
+    # noted `{*x : 4}`. The reason is that a colon can be part of an anchor
+    # name. See commit message for more details.
+    def test_with_alias_as_key(self):
+        conf = 'colons: {max-spaces-before: 0, max-spaces-after: 1}'
+        self.check('---\n'
+                   '- anchor: &a key\n'
+                   '- *a: 42\n'
+                   '- {*a: 42}\n'
+                   '- *a : 42\n'
+                   '- {*a : 42}\n'
+                   '- *a  : 42\n'
+                   '- {*a  : 42}\n',
+                   conf,
+                   problem1=(7, 6), problem2=(8, 7))
diff --git a/yamllint/rules/colons.py b/yamllint/rules/colons.py
index 486746fa..7390e51b 100644
--- a/yamllint/rules/colons.py
+++ b/yamllint/rules/colons.py
@@ -92,7 +92,9 @@
 
 
 def check(conf, token, prev, next, nextnext, context):
-    if isinstance(token, yaml.ValueToken):
+    if isinstance(token, yaml.ValueToken) and not (
+            isinstance(prev, yaml.AliasToken) and
+            token.start_mark.pointer - prev.end_mark.pointer == 1):
         problem = spaces_before(token, prev, next,
                                 max=conf['max-spaces-before'],
                                 max_desc='too many spaces before colon')