gdalbuildvrt: Emit warning on invalid value for -vrtnodata

apps/gdalbuildvrt_lib.cpp

@@ -436,6 +436,21 @@ static CPLString GetProjectionName(const char *pszProjection)
 /*                           AnalyseRaster()                            */
 /************************************************************************/
 
+static void checkNoDataValues(const std::vector<BandProperty> &asProperties)
+{
+    for (const auto &oProps : asProperties)
+    {
+        if (oProps.bHasNoData && GDALDataTypeIsInteger(oProps.dataType) &&
+            !GDALIsValueExactAs(oProps.noDataValue, oProps.dataType))
+        {
+            CPLError(CE_Warning, CPLE_NotSupported,
+                     "Band data type of %s cannot represent the specified "
+                     "NoData value of %g",
+                     GDALGetDataTypeName(oProps.dataType), oProps.noDataValue);
+        }
+    }
+}
+
 std::string VRTBuilder::AnalyseRaster(GDALDatasetH hDS,
                                       DatasetProperty *psDatasetProperties)
 {
@@ -965,6 +980,8 @@ std::string VRTBuilder::AnalyseRaster(GDALDatasetH hDS,
         }
     }
 
+    checkNoDataValues(asBandProperties);
+
     return "";
 }
 

autotest/pymod/gdaltest.py

@@ -2095,3 +2095,31 @@ def vsi_open(path, mode="r"):
 def vrt_has_open_support():
     drv = gdal.GetDriverByName("VRT")
     return drv is not None and drv.GetMetadataItem(gdal.DMD_OPENOPTIONLIST) is not None
+
+
+###############################################################################
+# Check that an error or warning is raised
+
+
+@contextlib.contextmanager
+def error_raised(type, match=""):
+
+    err_levels = {
+        gdal.CE_Debug: "CE_Debug",
+        gdal.CE_Failure: "CE_Failure",
+        gdal.CE_Fatal: "CE_Fatal",
+        gdal.CE_None: "CE_None",
+        gdal.CE_Warning: "CE_Warning",
+    }
+
+    errors = []
+
+    def handler(lvl, no, msg):
+        errors.append({"level": lvl, "number": no, "message": msg})
+
+    with error_handler(handler):
+        yield
+
+    assert any(
+        [err["level"] == type and match in err["message"] for err in errors]
+    ), f'Did not receive an error of type {err_levels[type]} matching "{match}"'

autotest/utilities/test_gdalbuildvrt_lib.py

@@ -900,3 +900,26 @@ def test_gdalbuildvrt_lib_nodataMaxMaskThreshold_rgb_mask(tmp_vsimem):
     assert struct.unpack(
         "f" * 3, vrt_ds.GetRasterBand(1).ReadRaster(buf_type=gdal.GDT_Float32)
     ) == pytest.approx((1.0, 1.001, 2.0))
+
+
+###############################################################################
+
+
+@pytest.mark.parametrize(
+    "dtype,nodata",
+    [
+        (gdal.GDT_Byte, float("nan")),
+        (gdal.GDT_UInt16, -1),
+    ],
+)
+def test_gdalbuildvrt_lib_nodata_invalid(tmp_vsimem, dtype, nodata):
+
+    drv = gdal.GetDriverByName("GTiff")
+    with drv.Create(tmp_vsimem / "in.tif", 1, 1, eType=dtype) as ds:
+        ds.GetRasterBand(1).Fill(1)
+        ds.SetGeoTransform((0, 1, 0, 1, 0, -1))
+
+    with gdaltest.error_raised(
+        gdal.CE_Warning, "cannot represent the specified NoData value"
+    ):
+        gdal.BuildVRT("", [tmp_vsimem / "in.tif"], VRTNodata=nodata)