[PATCH] diffseq: pacify gcc -Wusless-cast

* lib/diffseq.h (OFFSET_MAX): Pacify when OFFSET is int.
---
 ChangeLog     | 5 +++++
 lib/diffseq.h | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 0611c6c7a1..80bca2cba3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2026-05-25  Paul Eggert  <[email protected]>
+
+	diffseq: pacify gcc -Wusless-cast
+	* lib/diffseq.h (OFFSET_MAX): Pacify when OFFSET is int.
+
 2026-05-25  Bruno Haible  <[email protected]>
 
 	trim tests: Enhance tests.
diff --git a/lib/diffseq.h b/lib/diffseq.h
index cf710a316f..73fa47b42e 100644
--- a/lib/diffseq.h
+++ b/lib/diffseq.h
@@ -82,10 +82,11 @@
  #error "Please include config.h first."
 #endif
 
-/* Maximum value of type OFFSET.  */
+/* Maximum value of type OFFSET.  The 1u pacifies -Wuseless-cast, and
+   unlike a compound literal can appear in an integer constant expression.  */
 #ifndef OFFSET_MAX
 # define OFFSET_MAX \
-   ((((OFFSET) 1 << (sizeof (OFFSET) * CHAR_BIT - 2)) - 1) * 2 + 1)
+   ((((OFFSET) 1u << (sizeof (OFFSET) * CHAR_BIT - 2)) - 1) * 2 + 1)
 #endif
 
 /* Default to no early abort.  */
-- 
2.54.0