Subject: Re: [PATCH 1/3] do full type check in COPY_ARRAY and MOVE_ARRAY

From: Junio C Hamano <[email-masked]>
Date: Sun, 01 Jan 2023 12:59:43 +0900

Junio C Hamano <[email-masked]> writes:

> ...  I think what you ideally want to enforce is that
> typeof(dst) is exactly typeof(src), or typeof(src) sans constness
> (i.e. you can populate non-const array from a const template)?

IOW, I am wondering if something like this is an improvement.

 git-compat-util.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git c/git-compat-util.h w/git-compat-util.h
index a76d0526f7..be435615f0 100644
--- c/git-compat-util.h
+++ w/git-compat-util.h
@@ -97,8 +97,13 @@ struct strbuf;
 # define BARF_UNLESS_AN_ARRAY(arr)						\
 	BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(__typeof__(arr), \
 							   __typeof__(&(arr)[0])))
+# define ARRAYS_COPYABLE_OR_ZERO(src,dst) \
+	(BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(__typeof__(src), \
+							    __typeof__(dst))) + \
+			      (0 ? *(dst) = *(src) : 0))
 #else
 # define BARF_UNLESS_AN_ARRAY(arr) 0
+# define ARRAYS_COPYABLE_OR_ZERO(src,dst) (0 ? *(dst) = *(src) : 0))
 #endif
 /*
  * ARRAY_SIZE - get the number of elements in a visible array