Use VK_LOADER_DEBUG if settings stderr_log is empty

If a loader settings file was present, the logging settings of the file
were used irregardless of whether the settings file actually specified.

The loader will now check to see if the settings stderr_log value is at
least non-zero before deciding to skip a message, allowing for the
VK_LOADER_DEBUG filter to be applied in case if it is zero.

Author: charles-lunarg

loader/log.c

@@ -143,9 +143,11 @@ void loader_log(const struct loader_instance *inst, VkFlags msg_type, int32_t ms
 
     // Always log to stderr if this is a fatal error
     if (0 == (msg_type & VULKAN_LOADER_FATAL_ERROR_BIT)) {
-        // Exit early if the current instance settings do not ask for logging to stderr
-        if (inst && inst->settings.settings_active && 0 == (msg_type & inst->settings.debug_level)) {
-            return;
+        if (inst && inst->settings.settings_active && inst->settings.debug_level > 0) {
+            // Exit early if the current instance settings have some debugging options but do match the current msg_type
+            if (0 == (msg_type & inst->settings.debug_level)) {
+                return;
+            }
             // Check the global settings and if that doesn't say to skip, check the environment variable
         } else if (0 == (msg_type & g_loader_debug)) {
             return;

tests/loader_settings_tests.cpp

@@ -2243,6 +2243,61 @@ TEST(SettingsFile, StderrLog_NoOutput) {
     }
 }
 
+// Settings can say which filters to use - make sure the lack of this filter works correctly with VK_LOADER_DEBUG
+TEST(SettingsFile, NoStderr_log_but_VK_LOADER_DEBUG) {
+    FrameworkEnvironment env{FrameworkSettings{}.set_log_filter("all")};
+    env.add_icd(TestICDDetails(TEST_ICD_PATH_VERSION_2)).add_physical_device({});
+
+    const char* explicit_layer_name = "Regular_TestLayer1";
+
+    env.add_explicit_layer(TestLayerDetails{
+        ManifestLayer{}.add_layer(
+            ManifestLayer::LayerDescription{}.set_name(explicit_layer_name).set_lib_path(TEST_LAYER_PATH_EXPORT_VERSION_2)),
+        "explicit_test_layer1.json"});
+
+    env.update_loader_settings(env.loader_settings.set_file_format_version({1, 0, 0}).add_app_specific_setting(
+        AppSpecificSettings{}
+            .add_layer_configuration(LoaderSettingsLayerConfiguration{}
+                                         .set_name(explicit_layer_name)
+                                         .set_path(env.get_shimmed_layer_manifest_path())
+                                         .set_control("auto"))
+            .add_layer_configuration(
+                LoaderSettingsLayerConfiguration{}.set_name("VK_LAYER_missing").set_path("/road/to/nowhere").set_control("auto"))));
+    env.loader_settings.app_specific_settings.at(0).stderr_log = {};
+    env.update_loader_settings(env.loader_settings);
+
+    std::string expected_output_verbose;
+    expected_output_verbose += "DEBUG:             Layer Configurations count = 2\n";
+    expected_output_verbose += "DEBUG:             ---- Layer Configuration [0] ----\n";
+    expected_output_verbose += std::string("DEBUG:             Name: ") + explicit_layer_name + "\n";
+    expected_output_verbose += "DEBUG:             Path: " + env.get_shimmed_layer_manifest_path().string() + "\n";
+    expected_output_verbose += "DEBUG:             Control: auto\n";
+    expected_output_verbose += "DEBUG:             ---- Layer Configuration [1] ----\n";
+    expected_output_verbose += "DEBUG:             Name: VK_LAYER_missing\n";
+    expected_output_verbose += "DEBUG:             Path: /road/to/nowhere\n";
+    expected_output_verbose += "DEBUG:             Control: auto\n";
+    expected_output_verbose += "DEBUG:             ---------------------------------\n";
+
+    std::string expected_output_info = std::string("INFO:              ") + get_settings_location_log_message(env) + "\n";
+
+    std::string expected_output_warning =
+        "WARNING:           Layer name Regular_TestLayer1 does not conform to naming standard (Policy #LLP_LAYER_3)\n";
+
+    std::string expected_output_error = "ERROR:             loader_get_json: Failed to open JSON file /road/to/nowhere\n";
+
+    env.platform_shim->clear_logs();
+    {
+        InstWrapper inst{env.vulkan_functions};
+        inst.CheckCreate();
+        EXPECT_TRUE(env.platform_shim->find_in_log(expected_output_verbose));
+        EXPECT_TRUE(env.platform_shim->find_in_log(expected_output_info));
+        EXPECT_TRUE(env.platform_shim->find_in_log(expected_output_warning));
+        EXPECT_TRUE(env.platform_shim->find_in_log(expected_output_error));
+
+        auto active_layer_props = inst.GetActiveLayers(inst.GetPhysDev(), 0);
+        EXPECT_TRUE(active_layer_props.size() == 0);
+    }
+}
 TEST(SettingsFile, ManyLayersEnabledInManyWays) {
     FrameworkEnvironment env{};
     env.add_icd(TestICDDetails(TEST_ICD_PATH_VERSION_2)).add_physical_device({});