From 2ac41d7c67f0d7c31aa4c0702a5153750a1b8ed8 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Sun, 1 Sep 2024 13:42:28 +0200
Subject: [PATCH] GDALWarpResolveWorkingDataType(): ignore srcNoDataValue if it
 doesn't fit into the data type of the source band

---
 alg/gdalwarper.cpp        | 26 ++++++++++++++++++++++++++
 autotest/cpp/test_alg.cpp | 29 +++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/alg/gdalwarper.cpp b/alg/gdalwarper.cpp
index d061cadb8736..e44ea097db10 100644
--- a/alg/gdalwarper.cpp
+++ b/alg/gdalwarper.cpp
@@ -1533,6 +1533,32 @@ void CPL_STDCALL GDALWarpResolveWorkingDataType(GDALWarpOptions *psOptions)
 
     psOptions->eWorkingDataType = GDT_Byte;
 
+    // If none of the provided input nodata values can be represented in the
+    // data type of the corresponding source band, ignore them.
+    if (psOptions->hSrcDS && psOptions->padfSrcNoDataReal)
+    {
+        int nCountInvalidSrcNoDataReal = 0;
+        for (int iBand = 0; iBand < psOptions->nBandCount; iBand++)
+        {
+            GDALRasterBandH hSrcBand = GDALGetRasterBand(
+                psOptions->hSrcDS, psOptions->panSrcBands[iBand]);
+
+            if (hSrcBand &&
+                !GDALIsValueExactAs(psOptions->padfSrcNoDataReal[iBand],
+                                    GDALGetRasterDataType(hSrcBand)))
+            {
+                nCountInvalidSrcNoDataReal++;
+            }
+        }
+        if (nCountInvalidSrcNoDataReal == psOptions->nBandCount)
+        {
+            CPLFree(psOptions->padfSrcNoDataReal);
+            psOptions->padfSrcNoDataReal = nullptr;
+            CPLFree(psOptions->padfSrcNoDataImag);
+            psOptions->padfSrcNoDataImag = nullptr;
+        }
+    }
+
     for (int iBand = 0; iBand < psOptions->nBandCount; iBand++)
     {
         if (psOptions->hDstDS != nullptr)
diff --git a/autotest/cpp/test_alg.cpp b/autotest/cpp/test_alg.cpp
index d8c5d64a4b44..6d58a164164e 100644
--- a/autotest/cpp/test_alg.cpp
+++ b/autotest/cpp/test_alg.cpp
@@ -151,6 +151,35 @@ TEST_F(test_alg, GDALWarpResolveWorkingDataType_padfSrcNoDataReal)
     GDALDestroyWarpOptions(psOptions);
 }
 
+// GDALWarpResolveWorkingDataType: effect of padfSrcNoDataReal
+TEST_F(test_alg, GDALWarpResolveWorkingDataType_padfSrcNoDataReal_with_band)
+{
+    GDALDatasetUniquePtr poDS(GDALDriver::FromHandle(GDALGetDriverByName("MEM"))
+                                  ->Create("", 1, 1, 1, GDT_Byte, nullptr));
+    GDALWarpOptions *psOptions = GDALCreateWarpOptions();
+    psOptions->hSrcDS = GDALDataset::ToHandle(poDS.get());
+    psOptions->nBandCount = 1;
+    psOptions->panSrcBands =
+        static_cast<int *>(CPLMalloc(psOptions->nBandCount * sizeof(int)));
+    psOptions->panSrcBands[0] = 1;
+    psOptions->padfSrcNoDataReal =
+        static_cast<double *>(CPLMalloc(sizeof(double)));
+    psOptions->padfSrcNoDataReal[0] = 0.0;
+    GDALWarpResolveWorkingDataType(psOptions);
+    EXPECT_EQ(psOptions->eWorkingDataType, GDT_Byte);
+
+    psOptions->padfSrcNoDataReal[0] = -1.0;
+    GDALWarpResolveWorkingDataType(psOptions);
+    EXPECT_EQ(psOptions->eWorkingDataType, GDT_Byte);
+
+    psOptions->eWorkingDataType = GDT_Unknown;
+    psOptions->padfSrcNoDataReal[0] = 2.0;
+    GDALWarpResolveWorkingDataType(psOptions);
+    EXPECT_EQ(psOptions->eWorkingDataType, GDT_Byte);
+
+    GDALDestroyWarpOptions(psOptions);
+}
+
 // GDALWarpResolveWorkingDataType: effect of padfSrcNoDataImag
 TEST_F(test_alg, GDALWarpResolveWorkingDataType_padfSrcNoDataImag)
 {