GH-38709: [C++] Protect against PREALLOCATE preprocessor defined on m…

…acOS (#38760) ### Rationale for this change The macOS header `sys/vnode.h` defines `PREALLOCATE` as a preprocessor macro, which causes a conflict in `arrow/compute/kernel.h` where the same name is defined as an identifier. Other BSDs does not seem to define this macro. ### What changes are included in this PR? `#undef PREALLOCATE` on macOS and if defined. ### Are these changes tested? Somewhat, in a different context. ### Are there any user-facing changes? If some code specific to macOS actually uses the `PREALLOCATE` macro, then that code may have problems. However, it is unlikely that any user code would use this macro as it seems to be intended for internal use in the BSD kernel of macOS. * Closes: #38709 Lead-authored-by: Christian Holm Christensen <[email protected]> Co-authored-by: Sutou Kouhei <[email protected]> Signed-off-by: Sutou Kouhei <[email protected]>
apache · Nov 29, 2023 · 61a4a80 · 61a4a80
1 parent d662bef
commit 61a4a80
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/cpp/src/arrow/compute/kernel.h b/cpp/src/arrow/compute/kernel.h
@@ -38,6 +38,12 @@
 #include "arrow/util/macros.h"
 #include "arrow/util/visibility.h"
 
+// macOS defines PREALLOCATE as a preprocessor macro in the header sys/vnode.h.
+// No other BSD seems to do so. The name is used as an identifier in MemAllocation enum.
+#if defined(__APPLE__) && defined(PREALLOCATE)
+#undef PREALLOCATE
+#endif
+
 namespace arrow {
 namespace compute {