Return to the main menu if a shader compilation fails

src/client/clientlauncher.cpp

@@ -277,6 +277,10 @@ bool ClientLauncher::run(GameStartData &start_data, const Settings &cmd_args)
 			error_message = gettext("Connection error (timed out?)");
 			errorstream << error_message << std::endl;
 		}
+		catch (ShaderException &e) {
+			error_message = e.what();
+			errorstream << error_message << std::endl;
+		}
 
 #ifdef NDEBUG
 		catch (std::exception &e) {

src/client/shader.cpp

@@ -322,6 +322,44 @@ class MainShaderConstantSetterFactory : public IShaderConstantSetterFactory
 };
 
 
+namespace {
+	class IrrlichtErrorCapturer : public IEventReceiver
+	{
+		std::string &m_output;
+		IEventReceiver *m_old_recv;
+
+	public:
+		IrrlichtErrorCapturer(std::string &output):
+			m_output{output}
+		{
+			IrrlichtDevice *device{RenderingEngine::get_raw_device()};
+			m_old_recv = device->getEventReceiver();
+			device->setEventReceiver(this);
+		}
+
+		~IrrlichtErrorCapturer()
+		{
+			IrrlichtDevice *device{RenderingEngine::get_raw_device()};
+			device->setEventReceiver(m_old_recv);
+		}
+
+		IrrlichtErrorCapturer(const IrrlichtErrorCapturer&) = delete;
+		IrrlichtErrorCapturer &operator=(const IrrlichtErrorCapturer&) = delete;
+
+		virtual bool OnEvent(const SEvent &event)
+		{
+			if (event.EventType == EET_LOG_TEXT_EVENT &&
+					event.LogEvent.Level == ELL_ERROR) {
+				// Log messages from Irrlicht are *usually* not
+				// newline-terminated.
+				m_output.append(event.LogEvent.Text).append("\n");
+				return true;
+			}
+			return m_old_recv->OnEvent(event);
+		}
+	};
+}
+
 /*
 	ShaderSource
 */
@@ -588,8 +626,8 @@ ShaderInfo ShaderSource::generateShader(const std::string &name,
 
 	video::IVideoDriver *driver = RenderingEngine::get_video_driver();
 	if (!driver->queryFeature(video::EVDF_ARB_GLSL)) {
-		errorstream << "Shaders are enabled but GLSL is not supported by the driver\n";
-		return shaderinfo;
+		throw ShaderException("Shaders are enabled but GLSL is not supported "
+			"by the driver");
 	}
 	video::IGPUProgrammingServices *gpu = driver->getGPUProgrammingServices();
 
@@ -777,11 +815,16 @@ ShaderInfo ShaderSource::generateShader(const std::string &name,
 
 	irr_ptr<ShaderCallback> cb{new ShaderCallback(m_setter_factories)};
 	infostream<<"Compiling high level shaders for "<<name<<std::endl;
-	s32 shadermat = gpu->addHighLevelShaderMaterial(
-		vertex_shader.c_str(), nullptr, video::EVST_VS_1_1,
-		fragment_shader.c_str(), nullptr, video::EPST_PS_1_1,
-		geometry_shader_ptr, nullptr, video::EGST_GS_4_0, scene::EPT_TRIANGLES, scene::EPT_TRIANGLES, 0,
-		cb.get(), shaderinfo.base_material,  1);
+	std::string shader_compilation_errors{""};
+	s32 shadermat;
+	{
+		IrrlichtErrorCapturer capturer{shader_compilation_errors};
+		shadermat = gpu->addHighLevelShaderMaterial(
+			vertex_shader.c_str(), nullptr, video::EVST_VS_1_1,
+			fragment_shader.c_str(), nullptr, video::EPST_PS_1_1,
+			geometry_shader_ptr, nullptr, video::EGST_GS_4_0, scene::EPT_TRIANGLES, scene::EPT_TRIANGLES, 0,
+			cb.get(), shaderinfo.base_material,  1);
+	}
 	if (shadermat == -1) {
 		errorstream<<"generate_shader(): "
 				"failed to generate \""<<name<<"\", "
@@ -790,7 +833,13 @@ ShaderInfo ShaderSource::generateShader(const std::string &name,
 		dumpShaderProgram(warningstream, "Vertex", vertex_shader);
 		dumpShaderProgram(warningstream, "Fragment", fragment_shader);
 		dumpShaderProgram(warningstream, "Geometry", geometry_shader);
-		return shaderinfo;
+		throw ShaderException(
+			"Failed to compile the \"" + name + "\" shader.\n" +
+			shader_compilation_errors +
+			"Check debug.txt for details.");
+	} else if (!shader_compilation_errors.empty()) {
+		// Don't suppress any error messages.
+		errorstream << shader_compilation_errors;
 	}
 
 	// Apply the newly created material type

src/exceptions.h

@@ -92,6 +92,11 @@ class PrngException : public BaseException {
 	PrngException(const std::string &s): BaseException(s) {}
 };
 
+class ShaderException : public BaseException {
+public:
+	ShaderException(const std::string &s): BaseException(s) {}
+};
+
 class ModError : public BaseException {
 public:
 	ModError(const std::string &s): BaseException(s) {}