问题
The documention for git_treebuilder_insert seems to imply that it doesn't care whether the object being inserted is valid:
No attempt is being made to ensure that the provided oid points to an existing git object in the object database, nor that the attributes make sense regarding the type of the pointed at object.
However, when actually using the library to create tree objects, if I try to write an entry with an invalid oid, this function returns failure. As reference, here's the code:
if (filemode != GIT_FILEMODE_COMMIT &&
!git_object__is_valid(bld->repo, id, otype_from_mode(filemode)))
return tree_error("Failed to insert entry; invalid object specified", filename);
What is the intended behavior, the code or the documentation?
回答1:
The documentation is outdated; the code behaves as expected. The change to validate object pointers was made in order to:
Allow library users to make assumptions about the safety of their projects. It is generally an error to create something that dangles and points to an object that does not exist.
Improve consistency between creating references and creating objects. Now they both validate that the thing(s) they're pointing to exist, by default.
If you do not want this behavior, you can disable it, by calling:
git_libgit2_opts(GIT_OPT_ENABLE_STRICT_OBJECT_CREATION, 0);
来源：https://stackoverflow.com/questions/48037132/why-does-git-treebuilder-insert-fail-for-invalid-objects