When compiling libgit2 with -DDEPRECATE_HARD, we add a preprocessor definition `GIT_DEPRECATE_HARD` which causes the "git2/deprecated.h" header to be empty. As a result, no function declarations are made available to callers, but the implementations are still available to link against. This has the problem that function declarations also aren't visible to the implementations, meaning that the symbol's visibility will not be set up correctly. As a result, the resulting library may not expose those deprecated symbols at all on some platforms and thus cause linking errors. Fix the issue by conditionally compiling deprecated functions, only. While it becomes impossible to link against such a library in case one uses deprecated functions, distributors of libgit2 aren't expected to pass -DDEPRECATE_HARD anyway. Instead, users of libgit2 should manually define GIT_DEPRECATE_HARD to hide deprecated functions. Using "real" hard deprecation still makes sense in the context of CI to test we don't use deprecated symbols ourselves and in case a dependant uses libgit2 in a vendored way and knows it won't ever use any of the deprecated symbols anyway.
Our file utils functions all have a "futils" prefix, e.g. `git_futils_touch`. One would thus naturally guess that their definitions and implementation would live in files "futils.h" and "futils.c", respectively, but in fact they live in "fileops.h". Rename the files to match expectations.
In libgit2 nomenclature, when we need to verb a direct object, we name a function `git_directobject_verb`. Thus, if we need to init an options structure named `git_foo_options`, then the name of the function that does that should be `git_foo_options_init`. The previous names of `git_foo_init_options` is close - it _sounds_ as if it's initializing the options of a `foo`, but in fact `git_foo_options` is its own noun that should be respected. Deprecate the old names; they'll now call directly to the new ones.
Move to the `git_error` name in the internal API for error-related functions.
Next to including several files, our "common.h" header also declares various macros which are then used throughout the project. As such, we have to make sure to always include this file first in all implementation files. Otherwise, we might encounter problems or even silent behavioural differences due to macros or defines not being defined as they should be. So in fact, our header and implementation files should make sure to always include "common.h" first. This commit does so by establishing a common include pattern. Header files inside of "src" will now always include "common.h" as its first other file, separated by a newline from all the other includes to make it stand out as special. There are two cases for the implementation files. If they do have a matching header file, they will always include this one first, leading to "common.h" being transitively included as first file. If they do not have a matching header file, they instead include "common.h" as first file themselves. This fixes the outlined problems and will become our standard practice for header and source files inside of the "src/" from now on.
The recent introduction of the commondir variable of a repository requires callers to distinguish whether their files are part of the dot-git directory or the common directory shared between multpile worktrees. In order to take the burden from callers and unify knowledge on which files reside where, the `git_repository_item_path` function has been introduced which encapsulate this knowledge. Modify most existing callers of `git_repository_path` to use `git_repository_item_path` instead, thus making them implicitly aware of the common directory.