Added support for code specific to 2.9 or 2.10

Maven is configure to add an extra source folder in sdt.core,
the one matching the scala version.

Added code to manage the missing InvalidCompanions class in 2.10

Fix #1001243

org.scala-ide.sdt.core/.classpath

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <classpath>
 	<classpathentry kind="src" output="target/classes" path="src"/>
+	<classpathentry kind="src" path="src-2.9"/>
 	<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER"/>
 	<classpathentry kind="con" path="org.scala-ide.sdt.launching.SCALA_COMPILER_CONTAINER"/>
 	<classpathentry kind="con" path="org.eclipse.pde.core.requiredPlugins"/>

org.scala-ide.sdt.core/pom.xml

@@ -83,6 +83,23 @@
           </execution>
         </executions>
       </plugin>
+      <!-- added source folder containing the code specific to the scala version -->
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>build-helper-maven-plugin</artifactId>
+        <version>1.7</version>
+        <executions>
+          <execution>
+            <phase>generate-sources</phase>
+            <goals><goal>add-source</goal></goals>
+            <configuration>
+              <sources>
+                <source>src-${scala.major.minor.version}</source>
+              </sources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 </project>

org.scala-ide.sdt.core/src-2.10/scala/tools/eclipse/SymbolsCompatibility.scala

@@ -0,0 +1,17 @@
+package scala.tools.eclipse
+
+import scala.reflect.internal.Symbols
+
+/**
+ * Trait used to keep 2.9-2.10 source compatibility
+ */
+trait SymbolsCompatibility { self: Symbols =>
+
+  /**
+   * This class as been removed in 2.10, but we need its real implementation in 2.9
+   */
+  case class InvalidCompanions(sym1: Symbol, sym2: Symbol) extends Throwable {
+
+  }
+
+}

org.scala-ide.sdt.core/src-2.9/scala/tools/eclipse/SymbolsCompatibility.scala

@@ -0,0 +1,10 @@
+package scala.tools.eclipse
+
+import scala.tools.nsc.symtab.Symbols
+
+/**
+ * Trait used to keep 2.9-2.10 source compatibility
+ */
+trait SymbolsCompatibility { self: Symbols =>
+
+}

org.scala-ide.sdt.core/src/scala/tools/eclipse/ScalaPresentationCompiler.scala

@@ -41,7 +41,8 @@ class ScalaPresentationCompiler(project: ScalaProject, settings: Settings)
   with JavaSig
   with JVMUtils
   with LocateSymbol
-  with HasLogger { self =>
+  with HasLogger
+  with SymbolsCompatibility { self =>
 
   def presentationReporter = reporter.asInstanceOf[ScalaPresentationCompiler.PresentationReporter]
   presentationReporter.compiler = this