*converter: query extension and MIME only for data/file imageconverters.

Otherwise magnum-imageconverter --info-converter /
magnum-sceneconverter --info-image-converter crashes if asked on e.g.
StbResizeImageConverter.

src/Magnum/Trade/Implementation/converterUtilities.h

@@ -135,10 +135,17 @@ void printImageConverterInfo(const Debug::Flags useColor, const Trade::AbstractI
 
     Debug d{useColor|Debug::Flag::NoNewlineAtTheEnd};
 
-    if(const Containers::String extension = converter.extension())
-        d << Debug::boldColor(Debug::Color::Default) << "File extension:" << Debug::resetColor << extension << Debug::newline;
-    if(const Containers::String mimeType = converter.mimeType())
-        d << Debug::boldColor(Debug::Color::Default) << "MIME type:" << Debug::resetColor << mimeType << Debug::newline;
+    if(converter.features() & (ImageConverterFeature::Convert1DToFile|
+                               ImageConverterFeature::Convert2DToFile|
+                               ImageConverterFeature::Convert3DToFile|
+                               ImageConverterFeature::ConvertCompressed1DToFile|
+                               ImageConverterFeature::ConvertCompressed2DToFile|
+                               ImageConverterFeature::ConvertCompressed3DToFile)) {
+        if(const Containers::String extension = converter.extension())
+            d << Debug::boldColor(Debug::Color::Default) << "File extension:" << Debug::resetColor << extension << Debug::newline;
+        if(const Containers::String mimeType = converter.mimeType())
+            d << Debug::boldColor(Debug::Color::Default) << "MIME type:" << Debug::resetColor << mimeType << Debug::newline;
+    }
 
     printPluginConfigurationInfo(useColor, converter);
 }

src/Magnum/Trade/Test/ImageConverterImplementationTest.cpp

@@ -27,6 +27,7 @@
 #include <Corrade/Containers/StringStl.h> /** @todo remove once Debug is stream-free */
 #include <Corrade/TestSuite/Tester.h>
 #include <Corrade/TestSuite/Compare/StringToFile.h>
+#include <Corrade/TestSuite/Compare/String.h>
 #include <Corrade/Utility/Configuration.h>
 #include <Corrade/Utility/DebugStl.h> /** @todo remove once Debug is stream-free */
 #include <Corrade/Utility/Path.h>
@@ -48,6 +49,7 @@ struct ImageConverterImplementationTest: TestSuite::Tester {
     void importerInfo();
     void converterInfo();
     void converterInfoExtensionMimeType();
+    void converterInfoExtensionMimeTypeNoFileConversion();
 
     void info();
     void infoError();
@@ -66,6 +68,7 @@ ImageConverterImplementationTest::ImageConverterImplementationTest() {
               &ImageConverterImplementationTest::importerInfo,
               &ImageConverterImplementationTest::converterInfo,
               &ImageConverterImplementationTest::converterInfoExtensionMimeType,
+              &ImageConverterImplementationTest::converterInfoExtensionMimeTypeNoFileConversion,
 
               &ImageConverterImplementationTest::info,
               &ImageConverterImplementationTest::infoError});
@@ -364,6 +367,36 @@ void ImageConverterImplementationTest::converterInfoExtensionMimeType() {
         "  something=is there\n");
 }
 
+void ImageConverterImplementationTest::converterInfoExtensionMimeTypeNoFileConversion() {
+    PluginManager::Manager<Trade::AbstractImageConverter> converterManager{MAGNUM_PLUGINS_IMAGECONVERTER_INSTALL_DIR};
+
+    /* Check if the required plugin can be loaded. Catches also ABI and
+       interface mismatch errors. */
+    if(!(converterManager.load("StbResizeImageConverter") & PluginManager::LoadState::Loaded))
+        CORRADE_SKIP("StbResizeImageConverter plugin can't be loaded.");
+
+    Containers::Pointer<Trade::AbstractImageConverter> converter = converterManager.instantiate("StbResizeImageConverter");
+
+    /* Print to visually verify coloring */
+    {
+        Debug{} << "======================== visual color verification start =======================";
+        Implementation::printImageConverterInfo(Debug::isTty() ? Debug::Flags{} : Debug::Flag::DisableColors, *converter);
+        Debug{} << "======================== visual color verification end =========================";
+    }
+
+    std::ostringstream out;
+    Debug redirectOutput{&out};
+    Implementation::printImageConverterInfo(Debug::Flag::DisableColors, *converter);
+    CORRADE_COMPARE_AS(out.str(),
+        "Plugin name: StbResizeImageConverter\n"
+        "Features:\n"
+        "  Convert2D\n"
+        "  Convert3D\n"
+        "Configuration:\n"
+        "  # Target width and height",
+        TestSuite::Compare::StringHasPrefix);
+}
+
 void ImageConverterImplementationTest::info() {
     struct Importer: Trade::AbstractImporter {
         Trade::ImporterFeatures doFeatures() const override { return {}; }