Trade: fix unused variable warning when building with CORRADE_NO_ASSERT.

src/Magnum/Trade/MaterialData.cpp

@@ -366,7 +366,9 @@ UnsignedInt MaterialData::layerFactorTexture(const UnsignedInt layer) const {
 }
 
 UnsignedInt MaterialData::layerFactorTexture(const Containers::StringView layer) const {
+    #ifndef CORRADE_NO_ASSERT
     const UnsignedInt layerId = layerFor(layer);
+    #endif
     CORRADE_ASSERT(layerId != ~UnsignedInt{},
         "Trade::MaterialData::layerFactorTexture(): layer" << layer << "not found", {});
     /* Not delegating into layerFactorTexture() in order to have layer name
@@ -389,7 +391,9 @@ MaterialTextureSwizzle MaterialData::layerFactorTextureSwizzle(const UnsignedInt
 }
 
 MaterialTextureSwizzle MaterialData::layerFactorTextureSwizzle(const Containers::StringView layer) const {
+    #ifndef CORRADE_NO_ASSERT
     const UnsignedInt layerId = layerFor(layer);
+    #endif
     CORRADE_ASSERT(layerId != ~UnsignedInt{},
         "Trade::MaterialData::layerFactorTextureSwizzle(): layer" << layer << "not found", {});
     CORRADE_ASSERT(hasAttribute(layerId, MaterialAttribute::LayerFactorTexture),

src/Magnum/Trade/MaterialData.h

@@ -2721,7 +2721,9 @@ template<class T> T MaterialData::attribute(const UnsignedInt layer, const Unsig
     #ifdef CORRADE_GRACEFUL_ASSERT
     if(!value) return {};
     #endif
+    #ifndef CORRADE_NO_ASSERT
     const Trade::MaterialAttributeData& data = _data[layerOffset(layer) + id];
+    #endif
     CORRADE_ASSERT(Implementation::MaterialAttributeTypeFor<T>::type() == data._data.type,
         "Trade::MaterialData::attribute(): improper type requested for" << (data._data.data + 1) << "of" << data._data.type, {});
     return *reinterpret_cast<const T*>(value);