Merge pull request #15488 from dotty-staging/fix-15459

Fix #15459: Display uninitialized fields in promotion error
scala · Jun 21, 2022 · 7f1ae28 · 7f1ae28
2 parents 9e3953d + 227616c
commit 7f1ae28
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Showing 7 changed files with 59 additions and 19 deletions.
diff --git a/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala b/compiler/src/dotty/tools/dotc/transform/init/Semantic.scala
@@ -1006,6 +1006,19 @@ object Semantic:
       }
     }
 
+    def nonInitFields(): Contextual[List[Symbol]] =
+      val obj = ref.objekt
+      ref.klass.baseClasses.flatMap { klass =>
+        if klass.hasSource then
+          klass.info.decls.filter { member =>
+            !member.isOneOf(Flags.Method | Flags.Lazy | Flags.Deferred)
+            && !member.isType
+            && !obj.hasField(member)
+          }
+        else
+          Nil
+      }
+
   end extension
 
   extension (thisRef: ThisRef)
@@ -1032,8 +1045,12 @@ object Semantic:
           reporter.report(PromoteError(msg, trace.toVector))
 
         case thisRef: ThisRef =>
-          if !thisRef.tryPromoteCurrentObject() then
-            reporter.report(PromoteError(msg, trace.toVector))
+          val emptyFields = thisRef.nonInitFields()
+          if emptyFields.isEmpty then
+            promoted.promoteCurrent(thisRef)
+          else
+            val fields = "Non initialized field(s): " + emptyFields.map(_.show).mkString(", ") + "."
+            reporter.report(PromoteError(msg + "\n" + fields, trace.toVector))
 
         case warm: Warm =>
           if !promoted.contains(warm) then

diff --git a/tests/init/neg/closureLeak.check b/tests/init/neg/closureLeak.check
@@ -8,6 +8,7 @@
    |               ^^^^^^^^^^^^^^^^^
    |
    |  Promoting the value to fully initialized failed due to the following problem:
-   |  Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak. Calling trace:
+   |  Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak.
+   |  Non initialized field(s): value p. Calling trace:
    |  -> l.foreach(a => a.addX(this)) // error	[ closureLeak.scala:11 ]
    |                           ^^^^
diff --git a/tests/init/neg/default-this.check b/tests/init/neg/default-this.check
@@ -1,12 +1,13 @@
 -- Error: tests/init/neg/default-this.scala:9:8 ------------------------------------------------------------------------
 9 |        compare() // error
   |        ^^^^^^^
-  |    Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak. Calling trace:
-  |    -> class B extends A {	[ default-this.scala:6 ]
-  |       ^
-  |    -> val result = updateThenCompare(5)	[ default-this.scala:11 ]
-  |                    ^^^^^^^^^^^^^^^^^^^^
-  |    -> def updateThenCompare(c: Int): Boolean = {	[ default-this.scala:7 ]
-  |       ^
-  |    -> compare() // error	[ default-this.scala:9 ]
-  |       ^^^^^^^
+  |        Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak.
+  |        Non initialized field(s): value result. Calling trace:
+  |        -> class B extends A {	[ default-this.scala:6 ]
+  |           ^
+  |        -> val result = updateThenCompare(5)	[ default-this.scala:11 ]
+  |                        ^^^^^^^^^^^^^^^^^^^^
+  |        -> def updateThenCompare(c: Int): Boolean = {	[ default-this.scala:7 ]
+  |           ^
+  |        -> compare() // error	[ default-this.scala:9 ]
+  |           ^^^^^^^
diff --git a/tests/init/neg/i15459.check b/tests/init/neg/i15459.check
@@ -0,0 +1,11 @@
+-- Error: tests/init/neg/i15459.scala:3:10 -----------------------------------------------------------------------------
+3 |  println(this)  // error
+  |          ^^^^
+  |          Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak.
+  |          Non initialized field(s): value b. Calling trace:
+  |          -> class Sub extends Sup:	[ i15459.scala:5 ]
+  |             ^
+  |          -> class Sup:	[ i15459.scala:1 ]
+  |             ^
+  |          -> println(this)  // error	[ i15459.scala:3 ]
+  |                     ^^^^
diff --git a/tests/init/neg/i15459.scala b/tests/init/neg/i15459.scala
@@ -0,0 +1,8 @@
+class Sup:
+  val a = 10
+  println(this)  // error
+
+class Sub extends Sup:
+  val b = 20
+
+  override def toString() = "a = " + a + ", b = " + b
diff --git a/tests/init/neg/inlined-method.check b/tests/init/neg/inlined-method.check
@@ -1,10 +1,11 @@
 -- Error: tests/init/neg/inlined-method.scala:8:45 ---------------------------------------------------------------------
 8 |    scala.runtime.Scala3RunTime.assertFailed(message) // error
   |                                             ^^^^^^^
-  |    Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak. Calling trace:
-  |    -> class InlineError {	[ inlined-method.scala:1 ]
-  |       ^
-  |    -> Assertion.failAssert(this)	[ inlined-method.scala:2 ]
-  |       ^^^^^^^^^^^^^^^^^^^^^^^^^^
-  |    -> scala.runtime.Scala3RunTime.assertFailed(message) // error	[ inlined-method.scala:8 ]
-  |                                                ^^^^^^^
+  |                   Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak.
+  |                   Non initialized field(s): value v. Calling trace:
+  |                   -> class InlineError {	[ inlined-method.scala:1 ]
+  |                      ^
+  |                   -> Assertion.failAssert(this)	[ inlined-method.scala:2 ]
+  |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
+  |                   -> scala.runtime.Scala3RunTime.assertFailed(message) // error	[ inlined-method.scala:8 ]
+  |                                                               ^^^^^^^
diff --git a/tests/init/neg/promotion-loop.check b/tests/init/neg/promotion-loop.check
@@ -9,3 +9,4 @@
    |
    |  Promoting the value to fully initialized failed due to the following problem:
    |  Cannot prove that the field val outer is fully initialized.
+   |  Non initialized field(s): value n.