Remove support for '::' spec for dependency groups

The `pip` parsing for `--group` already uses a single colon for this
information. Rather than introducing a second format here, to match other
`pip-compile` behaviors, stick to only one format for this information.

Author: sirosen

piptools/_internal/_cli/_param_types.py

@@ -7,7 +7,7 @@
 
 class DependencyGroupParamType(click.ParamType):
     def get_metavar(self, param: click.Parameter) -> str:
-        return "[pyproject-path::]groupname"
+        return "[pyproject-path:]groupname"
 
     def convert(
         self, value: str, param: click.Parameter | None, ctx: click.Context | None

piptools/_internal/_cli/_parsed_param_types.py

@@ -14,14 +14,10 @@ class ParsedDependencyGroupParam:
 
     ``:`` cannot appear in dependency group names, so this is a safe and simple parse.
 
-    If the path portion ends in ":", then the ":" is removed, effectively resulting in
-    a split on "::" when that is used.
-
     The following conversions are expected::
 
         'foo' -> ('pyproject.toml', 'foo')
         'foo/pyproject.toml:bar' -> ('foo/pyproject.toml', 'bar')
-        'foo/pyproject.toml::bar' -> ('foo/pyproject.toml', 'bar')
     """
 
     def __init__(self, value: str) -> None:
@@ -31,9 +27,6 @@ def __init__(self, value: str) -> None:
         if not sep:
             path = "pyproject.toml"
         else:
-            # strip a rightmost ":" if one was present
-            if path.endswith(":"):
-                path = path[:-1]
             # check for 'pyproject.toml' filenames using pathlib
             if pathlib.PurePath(path).name != "pyproject.toml":
                 msg = "group paths use 'pyproject.toml' filenames"

tests/test_cli_compile.py

@@ -1570,27 +1570,20 @@ def __exit__(self, *args, **kwargs):
         """)
 
 
-@pytest.mark.parametrize(
-    "groupspec",
-    ("mygroup", "pyproject.toml:mygroup", "pyproject.toml::mygroup"),
-)
+@pytest.mark.parametrize("groupspec", ("mygroup", "pyproject.toml:mygroup"))
 def test_dependency_group_resolution(pip_conf, runner, tmpdir_cwd, groupspec):
     """
     Test compile requirements from pyproject.toml [dependency-groups].
     """
     pyproj = tmpdir_cwd / "pyproject.toml"
-    pyproj.write_text(
-        dedent(
-            """\
+    pyproj.write_text(dedent("""\
             [project]
             name = "foo"
             version = "1.0"
 
             [dependency-groups]
             mygroup = ["small-fake-a==0.1"]
-            """
-        )
-    )
+            """))
 
     out = runner.invoke(
         cli,
@@ -1606,12 +1599,10 @@ def test_dependency_group_resolution(pip_conf, runner, tmpdir_cwd, groupspec):
     )
     assert out.exit_code == 0, out.stderr
 
-    assert out.stdout == dedent(
-        f"""\
+    assert out.stdout == dedent(f"""\
         small-fake-a==0.1
             # via --group '{groupspec}'
-        """
-    )
+        """)
 
 
 @pytest.mark.parametrize(