[flang-commits] [flang] [flang][doc] Added remark about array element references in data clauses. (PR #72332)

[Slava Zakharin via flang-commits]

https://github.com/vzakhari created https://github.com/llvm/llvm-project/pull/72332

…ses.

>From 4c81a3ed191558414c2a8d395c965329f7600061 Mon Sep 17 00:00:00 2001
From: Slava Zakharin <szakharin at nvidia.com>
Date: Tue, 14 Nov 2023 16:56:25 -0800
Subject: [PATCH] [flang][doc] Added remark about array element references in
 data clauses.

---
 flang/docs/OpenACC.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/flang/docs/OpenACC.md b/flang/docs/OpenACC.md
index 4c36a38f8bf5731..9be6ee2ff4e7832 100644
--- a/flang/docs/OpenACC.md
+++ b/flang/docs/OpenACC.md
@@ -25,3 +25,10 @@ local:
   logical expression.
 * `!$acc routine` directive can be placed at the top level. 
 * `!$acc cache` directive accepts scalar variable.
+
+## Remarks about incompatibilities with other implementations
+* Array element references in the data clauses are equivalent to array sections
+  consisting of this single element, i.e. `copyin(a[n])` is equivalent to
+  `copyin(a[n:n])`.  Some other implementations have treated it as
+  `copyin(a[:n])`, which does not correspond to OpenACC spec – Flang does not
+  support this interpretation of an array element reference.