Merge pull request #5057 from dotty-staging/topic/go-to-def-named-args

Support go-to-definition on named arguments

Author: odersky

compiler/src/dotty/tools/dotc/interactive/Interactive.scala

@@ -39,10 +39,15 @@ object Interactive {
     else path.head.tpe
   }
 
-  /** The closest enclosing tree with a symbol containing position `pos`.
+  /** The closest enclosing tree with a symbol containing position `pos`, or the `EmptyTree`.
    */
   def enclosingTree(trees: List[SourceTree], pos: SourcePosition)(implicit ctx: Context): Tree =
-    pathTo(trees, pos).dropWhile(!_.symbol.exists).headOption.getOrElse(tpd.EmptyTree)
+    enclosingTree(pathTo(trees, pos))
+
+  /** The closes enclosing tree with a symbol, or the `EmptyTree`.
+   */
+  def enclosingTree(path: List[Tree])(implicit ctx: Context): Tree =
+    path.dropWhile(!_.symbol.exists).headOption.getOrElse(tpd.EmptyTree)
 
   /** The source symbol of the closest enclosing tree with a symbol containing position `pos`.
    *

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

@@ -248,8 +248,31 @@ class DottyLanguageServer extends LanguageServer
     implicit val ctx = driver.currentCtx
 
     val pos = sourcePosition(driver, uri, params.getPosition)
-    val enclTree = Interactive.enclosingTree(driver.openedTrees(uri), pos)
-    val sym = Interactive.sourceSymbol(enclTree.symbol)
+    val path = Interactive.pathTo(driver.openedTrees(uri), pos)
+    val enclTree = Interactive.enclosingTree(path)
+
+    val sym = {
+      val sym = path match {
+        // For a named arg, find the target `DefDef` and jump to the param
+        case NamedArg(name, _) :: Apply(fn, _) :: _ =>
+          val funSym = fn.symbol
+          if (funSym.name == StdNames.nme.copy
+            && funSym.is(Synthetic)
+            && funSym.owner.is(CaseClass)) {
+            funSym.owner.info.member(name).symbol
+          } else {
+            val classTree = funSym.topLevelClass.asClass.tree
+            tpd.defPath(funSym, classTree).lastOption.flatMap {
+              case DefDef(_, _, paramss, _, _) =>
+                paramss.flatten.find(_.name == name).map(_.symbol)
+            }.getOrElse(fn.symbol)
+          }
+
+        case _ =>
+          enclTree.symbol
+      }
+      Interactive.sourceSymbol(sym)
+    }
 
     if (sym == NoSymbol) Nil.asJava
     else {

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

@@ -3,6 +3,7 @@ package dotty.tools.languageserver
 import org.junit.Test
 
 import dotty.tools.languageserver.util.Code._
+import dotty.tools.languageserver.util.embedded.CodeMarker
 
 class DefinitionTest {
 
@@ -43,4 +44,85 @@ class DefinitionTest {
     ).definition(m3 to m4, List(m1 to m2))
   }
 
+  @Test def goToDefNamedArg: Unit = {
+    code"""object Foo {
+             def foo(${m1}x${m2}: Int) = ${m3}x${m4}
+             foo(${m5}x${m6} = 2)
+           }""".withSource
+      .definition(m1 to m2, List(m1 to m2))
+      .definition(m3 to m4, List(m1 to m2))
+      .definition(m5 to m6, List(m1 to m2))
+  }
+
+  @Test def goToDefNamedArgOverload: Unit = {
+    val m9 = new CodeMarker("m9")
+    val m10 = new CodeMarker("m10")
+    val m11 = new CodeMarker("m11")
+    val m12 = new CodeMarker("m12")
+    val m13 = new CodeMarker("m13")
+    val m14 = new CodeMarker("m14")
+
+    code"""object Foo {
+             def foo(${m1}x${m2}: String): String = ${m3}x${m4}
+             def foo(${m5}x${m6}: Int): String = foo(${m7}x${m8} = ${m9}x${m10}.toString)
+             foo(${m11}x${m12} = "a")
+             foo(${m13}x${m14} = 2)
+           }""".withSource
+      .definition(m1 to m2, List(m1 to m2))
+      .definition(m3 to m4, List(m1 to m2))
+      .definition(m5 to m6, List(m5 to m6))
+      .definition(m7 to m8, List(m1 to m2))
+      .definition(m9 to m10, List(m5 to m6))
+      .definition(m11 to m12, List(m1 to m2))
+      .definition(m13 to m14, List(m5 to m6))
+  }
+
+  @Test def goToConstructorNamedArg: Unit = {
+    withSources(
+      code"""class Foo(${m1}x${m2}: Int)""",
+      code"""class Bar extends Foo(${m3}x${m4} = 5)""",
+      code"""object Buzz { new Foo(${m5}x${m6} = 2) }"""
+    ) .definition(m1 to m2, List(m1 to m2))
+      .definition(m3 to m4, List(m1 to m2))
+      .definition(m5 to m6, List(m1 to m2))
+  }
+
+  @Test def goToConstructorNamedArgOverload: Unit = {
+    val m9 = new CodeMarker("m9")
+    val m10 = new CodeMarker("m10")
+    val m11 = new CodeMarker("m11")
+    val m12 = new CodeMarker("m12")
+
+    withSources(
+      code"""class Foo(${m1}x${m2}: String) {
+               def this(${m3}x${m4}: Int) = this(${m5}x${m6} = ${m7}x${m8}.toString)
+             }""",
+      code"""object Bar {
+               new Foo(${m9}x${m10} = 1)
+               new Foo(${m11}x${m12} = "a")
+             }"""
+    ) .definition(m1 to m2, List(m1 to m2))
+      .definition(m3 to m4, List(m3 to m4))
+      .definition(m5 to m6, List(m1 to m2))
+      .definition(m7 to m8, List(m3 to m4))
+      .definition(m9 to m10, List(m3 to m4))
+      .definition(m11 to m12, List(m1 to m2))
+  }
+
+  @Test def goToParamCopyMethod: Unit = {
+    val m9 = new CodeMarker("m9")
+    val m10 = new CodeMarker("m10")
+
+    withSources(
+      code"""case class Foo(${m1}x${m2}: Int, ${m3}y${m4}: String)""",
+      code"""object Bar {
+               Foo(0, "a").copy(${m5}x${m6} = 1, ${m7}y${m8} = "b")
+               Foo(2, "c").copy(${m9}y${m10} = "d")"""
+    ) .definition(m1 to m2, List(m1 to m2))
+      .definition(m3 to m4, List(m3 to m4))
+      .definition(m5 to m6, List(m1 to m2))
+      .definition(m7 to m8, List(m3 to m4))
+      .definition(m9 to m10, List(m3 to m4))
+  }
+
 }