From 190dc23f7063787e145b1cf1c061259829681504 Mon Sep 17 00:00:00 2001
From: Eugene Yokota <eed3si9n@gmail.com>
Date: Wed, 11 Apr 2018 01:31:38 -0400
Subject: [PATCH] Fixes linter that detects missing .value

Fixes #4079

#3216 introduced a linter that checks against missing `.value`, but the tree only checked for `Ident`. This doesn't work because in reality the symbols of build.sbt are transformed to `$somehash.npmInstallTask` where `somehash` is the wrapper object we create. Similarly for the built-in keys, they are presented as `sbt.Keys.compile`.

With this change unused task will fail to load the build with the following message:

```
/sbt-4079/build.sbt:26: error: The key `compile` is not being invoked inside the task definition.

Problem: Keys missing `.value` are not initialized and their dependency is not registered.

Solution: Replace `compile` by `compile.value` or remove it if unused.

  compile
  ^
/sbt-4079/build.sbt:27: error: The key `npmInstallTask` is not being invoked inside the task definition.

Problem: Keys missing `.value` are not initialized and their dependency is not registered.

Solution: Replace `npmInstallTask` by `npmInstallTask.value` or remove it if unused.

  npmInstallTask
  ^
```
---
 .../main/scala/sbt/std/TaskLinterDSL.scala    | 20 ++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/main-settings/src/main/scala/sbt/std/TaskLinterDSL.scala b/main-settings/src/main/scala/sbt/std/TaskLinterDSL.scala
index a328cee70..1c47216fa 100644
--- a/main-settings/src/main/scala/sbt/std/TaskLinterDSL.scala
+++ b/main-settings/src/main/scala/sbt/std/TaskLinterDSL.scala
@@ -27,6 +27,7 @@ abstract class BaseTaskLinterDSL extends LinterDSL {
       private val taskKeyType = typeOf[sbt.TaskKey[_]]
       private val settingKeyType = typeOf[sbt.SettingKey[_]]
       private val inputKeyType = typeOf[sbt.InputKey[_]]
+      private val initializeType = typeOf[sbt.Def.Initialize[_]]
       private val uncheckedWrappers = MutableSet.empty[Tree]
       var insideIf: Boolean = false
       var insideAnon: Boolean = false
@@ -57,7 +58,7 @@ abstract class BaseTaskLinterDSL extends LinterDSL {
       }
 
       @inline def isKey(tpe: Type): Boolean =
-        tpe <:< taskKeyType || tpe <:< settingKeyType || tpe <:< inputKeyType
+        tpe <:< initializeType || tpe <:< taskKeyType || tpe <:< settingKeyType || tpe <:< inputKeyType
 
       def detectAndErrorOnKeyMissingValue(i: Ident): Unit = {
         if (isKey(i.tpe)) {
@@ -66,6 +67,13 @@ abstract class BaseTaskLinterDSL extends LinterDSL {
         } else ()
       }
 
+      def detectAndErrorOnKeyMissingValue(s: Select): Unit = {
+        if (isKey(s.tpe)) {
+          val keyName = s.name.decodedName.toString
+          ctx.error(s.pos, TaskLinterDSLFeedback.missingValueForKey(keyName))
+        } else ()
+      }
+
       override def traverse(tree: ctx.universe.Tree): Unit = {
         tree match {
           case ap @ Apply(TypeApply(Select(_, nme), tpe :: Nil), qual :: Nil) =>
@@ -118,11 +126,13 @@ abstract class BaseTaskLinterDSL extends LinterDSL {
                 // TODO: Consider using unused names analysis to be able to report on more cases
                 case ValDef(_, valName, _, rhs) if valName == termNames.WILDCARD =>
                   rhs match {
-                    case i: Ident => detectAndErrorOnKeyMissingValue(i)
-                    case _        => ()
+                    case i: Ident  => detectAndErrorOnKeyMissingValue(i)
+                    case s: Select => detectAndErrorOnKeyMissingValue(s)
+                    case _         => ()
                   }
-                case i: Ident => detectAndErrorOnKeyMissingValue(i)
-                case _        => ()
+                case i: Ident  => detectAndErrorOnKeyMissingValue(i)
+                case s: Select => detectAndErrorOnKeyMissingValue(s)
+                case t         => ()
               }
             }
             traverseTrees(stmts)