fix Properties out-of-bounds check

+testcase

Author: wjakob

include/mitsuba/core/properties.h

@@ -181,12 +181,22 @@ class MI_EXPORT_LIB Properties {
 
         // Perform a range check just in case
         if constexpr (std::is_integral_v<T2> && !std::is_same_v<T2, bool>) {
-            constexpr T2 min = (T2) std::numeric_limits<T>::min(),
-                         max = (T2) std::numeric_limits<T>::max();
-
-            if (value < min || value > max)
+            constexpr T min_t = std::numeric_limits<T>::min(),
+                        max_t = std::numeric_limits<T>::max();
+            bool out_of_bounds = false;
+
+            if constexpr (std::is_unsigned_v<T>) {
+                if constexpr (max_t <= (T) std::numeric_limits<T2>::max())
+                    out_of_bounds = value > (T2) max_t;
+                if (value < 0)
+                    out_of_bounds = true;
+            } else {
+                out_of_bounds = value < (T2) min_t || value > (T2) max_t;
+            }
+
+            if (out_of_bounds)
                 Throw("Property \"%s\": value %lld is out of bounds, must be "
-                      "in the range [%lld, %lld]", name, value, min, max);
+                      "in the range [%lld, %lld]", name, value, min_t, max_t);
         }
 
         if constexpr (std::is_same_v<T2, ref<Object>>) {
@@ -243,12 +253,23 @@ class MI_EXPORT_LIB Properties {
 
         // Perform a range check just in case
         if constexpr (std::is_integral_v<T2> && !std::is_same_v<T2, bool>) {
-            constexpr T2 min = (T2) std::numeric_limits<T>::min(),
-                         max = (T2) std::numeric_limits<T>::max();
+            constexpr T min_t = std::numeric_limits<T>::min();
+            constexpr T max_t = std::numeric_limits<T>::max();
+
+            bool out_of_bounds = false;
+
+            if constexpr (std::is_unsigned_v<T>) {
+                if constexpr (max_t <= (T) std::numeric_limits<T2>::max())
+                    out_of_bounds = value > (T2) max_t;
+                if (value < 0)
+                    out_of_bounds = true;
+            } else {
+                out_of_bounds = value < (T2) min_t || value > (T2) max_t;
+            }
 
-            if (value < min || value > max)
+            if (out_of_bounds)
                 Throw("Property \"%s\": value %lld is out of bounds, must be "
-                      "in the range [%lld, %lld]", name, value, min, max);
+                      "in the range [%lld, %lld]", name, value, (T2) min_t, (T2) max_t);
         }
 
         if constexpr (std::is_same_v<T2, ref<Object>>) {

src/core/tests/test_properties.py

@@ -355,3 +355,7 @@ def test17_dictionary_like_interface(variant_scalar_rgb):
         assert 'remove_property() is deprecated' in str(w[2].message)
 
 
+def test18_range(variant_scalar_rgb):
+    with pytest.raises(RuntimeError, match=r'Property "bsdf_samples": value -3 is out of bounds, must be in the range \[0, -1\]'):
+        mi.load_dict({'type': 'direct', 'bsdf_samples': -3})
+    mi.load_dict({'type': 'direct', 'bsdf_samples': 10})