From 9fb85d9921fd5876372900ccc0933851d6e262bf Mon Sep 17 00:00:00 2001
From: Jan Marvin Garbuszus <jan.garbuszus@rub.de>
Date: Mon, 23 Dec 2024 18:02:31 +0100
Subject: [PATCH] [write] allow shared formulas without A1 cell reference

---
 NEWS.md                        | 9 +++++++++
 R/write.R                      | 2 +-
 tests/testthat/test-formulas.R | 7 +++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/NEWS.md b/NEWS.md
index 7860cf42c..8807869e5 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,12 @@
+# openxlsx2 (development version)
+
+## Fixes
+
+* Formulas that do not have a `A1` cell reference to increase, are now shareable too. `wb_add_formula(x = "1", dims = "A1:A2", shared = TRUE)`
+
+
+***************************************************************************
+
 # openxlsx2 1.12
 
 ## New features
diff --git a/R/write.R b/R/write.R
index 489d5f20d..51bff5d9d 100644
--- a/R/write.R
+++ b/R/write.R
@@ -520,7 +520,7 @@ write_data2 <- function(
     cc$f_t              <- "shared"
     cc[1, "f_ref"]      <- dims
     cc[2:nrow(cc), "f"] <- ""
-    cc$f_si             <- max(int_si) + 1L
+    cc$f_si             <- max(int_si, -1L) + 1L
   }
 
   if (is.null(wb$worksheets[[sheetno]]$sheet_data$cc)) {
diff --git a/tests/testthat/test-formulas.R b/tests/testthat/test-formulas.R
index 4274d2d18..85c9cc424 100644
--- a/tests/testthat/test-formulas.R
+++ b/tests/testthat/test-formulas.R
@@ -187,6 +187,13 @@ test_that("writing shared formulas works", {
   got <- unique(cc$f_si)
   expect_equal(exp, got)
 
+  wb <- wb_workbook()$add_worksheet()
+  wb$add_formula(x = "1", dims = "A1:B1", shared = TRUE)
+
+  exp <- "shared"
+  got <- unique(wb$worksheets[[1]]$sheet_data$cc$f_t)
+  expect_equal(exp, got)
+
 })
 
 test_that("increase formula dims if required", {