Remove deprecated support for passing str to Repository.merge()

Pass a Commit, Oid, or Reference object instead

Author: jdavid

CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# 1.20.0 (UNRELEASED)
 
 - Add riscv64 wheels
   [#1463](https://github.com/libgit2/pygit2/pull/1463)
@@ -8,6 +8,9 @@ Breaking changes:
 - Remove deprecated `pygit2.legacyenums` module and `GIT_*` constants,
   use `pygit2.enums` instead
 
+- Remove deprecated support for passing `str` to `Repository.merge(...)`,
+  pass a `Commit`, `Oid`, or `Reference` object instead
+
 
 # 1.19.3 (2026-06-13)
 

pygit2/repository.py

@@ -983,7 +983,7 @@ def merge_trees(
 
     def merge(
         self,
-        source: Reference | Commit | Oid | str,
+        source: Reference | Commit | Oid,
         favor: MergeFavor = MergeFavor.NORMAL,
         flags: MergeFlag = MergeFlag.FIND_RENAMES,
         file_flags: MergeFileFlag = MergeFileFlag.DEFAULT,
@@ -1003,8 +1003,6 @@ def merge(
             It is preferable to pass in a Reference, because this enriches the
             merge with additional information (for example, Repository.message will
             specify the name of the branch being merged).
-            Previous versions of pygit2 allowed passing in a partial commit
-            hash as a string; this is deprecated.
 
         favor
             An enums.MergeFavor constant specifying how to deal with file-level conflicts.
@@ -1026,15 +1024,7 @@ def merge(
             check_error(err)
         else:
             # Annotated commit from commit id
-            if isinstance(source, str):
-                # For backwards compatibility, parse a string as a partial commit hash
-                warnings.warn(
-                    'Passing str to Repository.merge is deprecated. '
-                    'Pass Commit, Oid, or a Reference (such as a Branch) instead.',
-                    DeprecationWarning,
-                )
-                oid = self[source].peel(Commit).id
-            elif isinstance(source, Commit):
+            if isinstance(source, Commit):
                 oid = source.id
             elif isinstance(source, Oid):
                 oid = source

test/test_merge.py

@@ -34,22 +34,12 @@
 from pygit2.enums import FileStatus, MergeAnalysis, MergeFavor, MergeFileFlag, MergeFlag
 
 
-@pytest.mark.parametrize('id', [None, 42])
-def test_merge_invalid_type(mergerepo: Repository, id: None | int) -> None:
+@pytest.mark.parametrize('id', [None, 42, '5ebeeebb320790caf276b9fc8b24546d63316533'])
+def test_merge_invalid_type(mergerepo: Repository, id: None | int | str) -> None:
     with pytest.raises(TypeError):
         mergerepo.merge(id)  # type:ignore
 
 
-# TODO: Once Repository.merge drops support for str arguments,
-#       add an extra parameter to test_merge_invalid_type above
-#       to make sure we cover legacy code.
-def test_merge_string_argument_deprecated(mergerepo: Repository) -> None:
-    branch_head_hex = '5ebeeebb320790caf276b9fc8b24546d63316533'
-
-    with pytest.warns(DeprecationWarning, match=r'Pass Commit.+instead'):
-        mergerepo.merge(branch_head_hex)
-
-
 def test_merge_analysis_uptodate(mergerepo: Repository) -> None:
     branch_head_hex = '5ebeeebb320790caf276b9fc8b24546d63316533'
     branch_id = mergerepo[branch_head_hex].id
@@ -91,15 +81,6 @@ def test_merge_no_fastforward_no_conflicts(mergerepo: Repository) -> None:
     assert {} == mergerepo.status()
 
 
-def test_merge_invalid_hex(mergerepo: Repository) -> None:
-    branch_head_hex = '12345678'
-    with (
-        pytest.raises(KeyError),
-        pytest.warns(DeprecationWarning, match=r'Pass Commit.+instead'),
-    ):
-        mergerepo.merge(branch_head_hex)
-
-
 def test_merge_already_something_in_index(mergerepo: Repository) -> None:
     branch_head_hex = '03490f16b15a09913edb3a067a3dc67fbb8d41f1'
     branch_oid = mergerepo[branch_head_hex].id