Subject: Re: [PATCH 01/10] environment: move access to core.maxTreeDepth into repo settings

From: Patrick Steinhardt <[email-masked]>
Date: Mon, 12 Jan 2026 10:21:40 +0100

On Fri, Jan 09, 2026 at 10:30:12PM +0100, René Scharfe wrote:
> diff --git a/git-compat-util.h b/git-compat-util.h
> index b0673d1a450..bebcf9f698c 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -578,6 +578,30 @@ static inline bool strip_suffix(const char *str, const char *suffix,
>  #define DEFAULT_PACKED_GIT_LIMIT \
>  	((1024L * 1024L) * (size_t)(sizeof(void*) >= 8 ? (32 * 1024L * 1024L) : 256))
>  
> +#ifdef _MSC_VER
> +  /*
> +   * When traversing into too-deep trees, Visual C-compiled Git seems to
> +   * run into some internal stack overflow detection in the
> +   * `RtlpAllocateHeap()` function that is called from within
> +   * `git_inflate_init()`'s call tree. The following value seems to be
> +   * low enough to avoid that by letting Git exit with an error before
> +   * the stack overflow can occur.
> +   */
> +#define DEFAULT_MAX_ALLOWED_TREE_DEPTH 512
> +#elif defined(GIT_WINDOWS_NATIVE) && defined(__clang__) && defined(__aarch64__)
> +  /*
> +   * Similar to Visual C, it seems that on Windows/ARM64 the clang-based
> +   * builds have a smaller stack space available. When running out of
> +   * that stack space, a `STATUS_STACK_OVERFLOW` is produced. When the
> +   * Git command was run from an MSYS2 Bash, this unfortunately results
> +   * in an exit code 127. Let's prevent that by lowering the maximal
> +   * tree depth; This value seems to be low enough.
> +   */
> +#define DEFAULT_MAX_ALLOWED_TREE_DEPTH 1280
> +#else
> +#define DEFAULT_MAX_ALLOWED_TREE_DEPTH 2048
> +#endif
> +
>  int git_open_cloexec(const char *name, int flags);
>  #define git_open(name) git_open_cloexec(name, O_RDONLY)
>  

Why is this new constant defined in "git-compat-util.h"? That feels way
too global for my taste for a value that should ultimately only be
required by "repo-settings.c". Is there a reason why it's not declared
in "repo-settings.h"?

I think we could even get away with declaring it in "repo-settings.c".
The expectation is that the settings need to be prepared anyway, so we
can simply set up the default when parsing the config.

Patrick