Use guaranteed binary and source compatibility between releases of Scalafmt (#260)

* Use guaranteed binary and source compatibility between releases of Scalafmt

* Update CHANGE.md

Author: joan38

lib/src/main/java/com/diffplug/spotless/scala/ScalaFmtStep.java

@@ -92,34 +92,34 @@ FormatterFunc createFormat() throws Exception {
 
 				Class<?> optionCls = classLoader.loadClass("scala.Option");
 				Class<?> configCls = classLoader.loadClass("org.scalafmt.config.Config");
+				Class<?> scalafmtCls = classLoader.loadClass("org.scalafmt.Scalafmt");
 
 				Object either;
 
 				try {
-					// scalafmt >= v0.7.0-RC1
-					Method fromHocon = configCls.getMethod("fromHoconString", String.class, optionCls);
-					Object fromHoconEmptyPath = configCls.getMethod("fromHoconString$default$2").invoke(null);
+					// scalafmt >= 1.6.0
+					Method parseHoconConfig = scalafmtCls.getMethod("parseHoconConfig", String.class);
 
 					String configStr = new String(Files.readAllBytes(file.toPath()), StandardCharsets.UTF_8);
 
-					Object configured = fromHocon.invoke(null, configStr, fromHoconEmptyPath);
+					Object configured = parseHoconConfig.invoke(null, configStr);
 					either = invokeNoArg(configured, "toEither");
 				} catch (NoSuchMethodException e) {
-					// In case of a NoSuchMethodException try old configuration API
-					// scalafmt <= v0.6.8
-					Method fromHocon = configCls.getMethod("fromHocon", String.class, optionCls);
-					Object fromHoconEmptyPath = configCls.getMethod("fromHocon$default$2").invoke(null);
+					// scalafmt >= v0.7.0-RC1 && scalafmt < 1.6.0
+					Method fromHocon = configCls.getMethod("fromHoconString", String.class, optionCls);
+					Object fromHoconEmptyPath = configCls.getMethod("fromHoconString$default$2").invoke(null);
 
 					String configStr = new String(Files.readAllBytes(file.toPath()), StandardCharsets.UTF_8);
-					either = fromHocon.invoke(null, configStr, fromHoconEmptyPath);
+
+					Object configured = fromHocon.invoke(null, configStr, fromHoconEmptyPath);
+					either = invokeNoArg(configured, "toEither");
 				}
 
 				config = invokeNoArg(invokeNoArg(either, "right"), "get");
 			}
 			return input -> {
 				Object resultInsideFormatted = formatMethod.invoke(null, input, config, emptyRange);
-				String result = (String) formattedGet.invoke(resultInsideFormatted);
-				return result;
+				return (String) formattedGet.invoke(resultInsideFormatted);
 			};
 		}
 	}

plugin-gradle/CHANGES.md

@@ -5,6 +5,7 @@
 * Updated default groovy-eclipse from 4.6.3 to 4.8.0 ([#244](https://github.com/diffplug/spotless/pull/244)). New version allows to ignore internal formatter errors/warnings.
 * Updated default eclipse-jdt from 4.7.2 to 4.7.3a ([#263](https://github.com/diffplug/spotless/issues/263)). New version fixes a bug preventing Java code formatting within JavaDoc comments ([#191](https://github.com/diffplug/spotless/issues/191)).
 * Eclipse formatter versions decoupled from Spotless formatter step implementations to allow independent updates of M2 based Eclipse dependencies. ([#253](https://github.com/diffplug/spotless/pull/253))
+* Use guaranteed binary and source compatibility between releases of Scalafmt. ([#260](https://github.com/diffplug/spotless/pull/260))
 
 ### Version 3.13.0 - June 1st 2018 ([javadoc](https://diffplug.github.io/spotless/javadoc/spotless-plugin-gradle/3.13.0/), [jcenter](https://bintray.com/diffplug/opensource/spotless-plugin-gradle/3.13.0))