max_tree_depth: lower it for clangarm64 on Windows

Just as in b64d78ad02ca (max_tree_depth: lower it for MSVC to avoid
stack overflows, 2023-11-01), I encountered the same problem with the
clang builds on Windows/ARM64.

The symptom is an exit code 127 when t6700 tries to verify that `git
archive big` fails.

This exit code is reserved on Unix/Linux to mean "command not found".
Unfortunately in this case, it is the fall-back chosen by
Cygwin's `pinfo::status_exit()` method when encountering
the NSTATUS `STATUS_STACK_OVERFLOW`, see
https://github.com/cygwin/cygwin/blob/cygwin-3.6.1/winsup/cygwin/pinfo.cc#L171

I verified manually that the stack overflow always happens somewhere
around tree depth 1403, therefore 1280 should be a safe bound in these
instances.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/environment.c b/environment.c
index 9e4c7781be049aea5186f527df9ab906c3c81fea..d948bb3c7059cc49c619ce2dca87a8345eacb697 100644 (file)
--- a/environment.c
+++ b/environment.c
@@ -82,6 +82,16 @@ int max_allowed_tree_depth =
         * the stack overflow can occur.
         */
        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.
+        */
+       1280;
 #else
        2048;
 #endif