From 4724959ee63e5e050fb9d7f30de9a62ee2760f1b Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Tue, 4 Jul 2023 18:11:45 +0200
Subject: [PATCH] GDALBufferHasOnlyNoData() / GTiff SPARSE_OK=YES: recognize
 negative floating point 0 as 0 (fixes #8025)

---
 gcore/rasterio.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gcore/rasterio.cpp b/gcore/rasterio.cpp
index 928d76daf949..0943ccf950a9 100644
--- a/gcore/rasterio.cpp
+++ b/gcore/rasterio.cpp
@@ -5110,7 +5110,10 @@ bool GDALBufferHasOnlyNoData(const void *pBuffer, double dfNoDataValue,
 #else
     typedef std::uint32_t WordType;
 #endif
-    if (dfNoDataValue == 0.0 && nWidth == nLineStride)
+    if (dfNoDataValue == 0.0 && nWidth == nLineStride &&
+        // Do not use this optimized code path for floating point numbers,
+        // as it can't detect negative zero.
+        nSampleFormat != GSF_FLOATING_POINT)
     {
         const GByte *pabyBuffer = static_cast<const GByte *>(pBuffer);
         const size_t nSize =