Derrick Stolee via GitGitGadget wrote:

From: Derrick Stolee <redacted>

Several builtins depend on being able to disable the replace references
so we actually operate on each object individually. These currently do
so by directly mutating the 'read_replace_refs' global.

A future change will move this global into a different place, so it will
be necessary to change all of these lines. However, we can simplify that
transition by abstracting the purpose of these global assignments with a
method call.

We will never scope this to an in-memory repository as we want to make
sure that we never use replace refs throughout the life of the process
if this method is called.

Although unfortunate (it would be nice to remove the global), this makes
sense. Disabling replace refs needs to be process-wide, and manually
propagating a repository setting to other repositories would be awkward
and prone to error.

All of my questions on this patch ("why were the 'disable_replace_refs()'
calls added later in the function than the original 'read_replace_refs =
0'?" and "why was '#include "environment.h"' added in 'repo-settings.c'?")
were asked [1] and answered [2] already. Beyond those two points, this patch
looks good!

[1] https://lore.kernel.org/git/CABPp-BFzA0yVecHK1DEGMpAhewm7oyqEim7BCw7-DTKpUzWnpw@mail.gmail.com/ (local)
[2] https://lore.kernel.org/git/ae89feda-0a76-29d7-14ce-662214414638@github.com/ (local)

+/*
+ * Some commands override config and environment settings for using
+ * replace references. Use this method to disable the setting and ensure
+ * those other settings will not override this choice. This applies
+ * globally to all in-process repositories.
+ */
+void disable_replace_refs(void);
+

Thanks for including the function documentation. It concisely explains the
purpose of 'disable_replace_refs()' and helps clarify how replace refs are
treated in Git. 

 #endif /* REPLACE_OBJECT_H */