Look only in source trees in workspace/symbol

We were inspecting all trees on the classpath for every project, which
was not efficient and lead to duplicate results. This commit changes the
implementation so that the language server inspects only the source
trees of every project.

Author: Duhemm

language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala

@@ -470,7 +470,7 @@ class DottyLanguageServer extends LanguageServer
     drivers.values.toList.flatMap { driver =>
       implicit val ctx = driver.currentCtx
 
-      val trees = driver.allTrees
+      val trees = driver.sourceTreesContaining(query)
       val defs = Interactive.namedTrees(trees, nameSubstring = query)
       defs.flatMap(d => symbolInfo(d.tree.symbol, d.namePos, positionMapperFor(d.source)))
     }.asJava

language-server/test/dotty/tools/languageserver/SymbolTest.scala

@@ -39,4 +39,19 @@ class SymbolTest {
       .symbol("Foo", (m1 to m2).symInfo("Foo", SymbolKind.Module),
                      (m3 to m4).symInfo("Foo", SymbolKind.Class))
   }
+
+  @Test def multipleProjects0: Unit = {
+    val p0 = Project.withSources(
+      code"""class ${m1}Foo${m2}"""
+    )
+
+    val p1 = Project.dependingOn(p0).withSources(
+      code"""class ${m3}Bar${m4} extends Foo"""
+    )
+
+    withProjects(p0, p1)
+      .symbol("Foo", (m1 to m2).symInfo("Foo", SymbolKind.Class))
+
+
+  }
 }