SI-5479 deprecate DelayedInit outside of App

DelayedInit's semantics are way too surprising.

For example, it delays initialization of fields,
so that fields on objects that extend `App`
(which `extends DelayedInit`) are not initialized
until the `main` method is called.

For more details and a proposed alternative,
see https://issues.scala-lang.org/browse/SI-4330?jql=labels%20%3D%20delayedinit%20AND%20resolution%20%3D%20unresolved.

Support for `App` will continue -- we'll special case it.

6 files changed, 10 insertions, 2 deletions

diff --git a/test/files/neg/delayed-init-ref.check b/test/files/neg/delayed-init-ref.check
index ce5b205832..63ed5843fc 100644
--- a/test/files/neg/delayed-init-ref.check
+++ b/test/files/neg/delayed-init-ref.check
@@ -4,9 +4,13 @@ delayed-init-ref.scala:17: warning: Selecting value vall from object O, which ex
 delayed-init-ref.scala:19: warning: Selecting value vall from object O, which extends scala.DelayedInit, is likely to yield an uninitialized value
   println(vall)       // warn
           ^
+delayed-init-ref.scala:28: warning: trait DelayedInit in package scala is deprecated: DelayedInit semantics can be surprising.
+(For details and a proposed alternative, see https://issues.scala-lang.org/browse/SI-4330?jql=labels%20%3D%20delayedinit%20AND%20resolution%20%3D%20unresolved. Support for `App` will continue.)
+trait Before extends DelayedInit {
+                     ^
 delayed-init-ref.scala:40: warning: Selecting value foo from trait UserContext, which extends scala.DelayedInit, is likely to yield an uninitialized value
     println({locally(()); this}.foo)  // warn (spurious, but we can't discriminate)
                                 ^
 error: No warnings can be incurred under -Xfatal-warnings.
-three warnings found
+four warnings found
 one error found
diff --git a/test/files/neg/delayed-init-ref.flags b/test/files/neg/delayed-init-ref.flags
index 7949c2afa2..88a3e4c676 100644
--- a/test/files/neg/delayed-init-ref.flags
+++ b/test/files/neg/delayed-init-ref.flags
@@ -1 +1 @@
--Xlint -Xfatal-warnings
+-deprecation -Xlint -Xfatal-warnings
diff --git a/test/files/run/delay-bad.check b/test/files/run/delay-bad.check
index 2ae88267c5..5d8c5fa1d4 100644
--- a/test/files/run/delay-bad.check
+++ b/test/files/run/delay-bad.check
@@ -4,6 +4,7 @@ delay-bad.scala:53: warning: a pure expression does nothing in statement positio
 delay-bad.scala:73: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
     f(new { val x = 5 } with E() { 5 })
                                    ^
+warning: there were 1 deprecation warning(s); re-run with -deprecation for details
 
 
 // new C { }
diff --git a/test/files/run/t4396.check b/test/files/run/t4396.check
index 58f4fc5138..a75e1f257f 100644
--- a/test/files/run/t4396.check
+++ b/test/files/run/t4396.check
@@ -1,3 +1,4 @@
+warning: there were 1 deprecation warning(s); re-run with -deprecation for details
 hallo
 constructor
 out:22
diff --git a/test/files/run/t4680.check b/test/files/run/t4680.check
index b2e5209dc5..512bfd4b54 100644
--- a/test/files/run/t4680.check
+++ b/test/files/run/t4680.check
@@ -4,6 +4,7 @@ t4680.scala:51: warning: a pure expression does nothing in statement position; y
 t4680.scala:69: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
     new { val x = 5 } with E() { 5 }
                                  ^
+warning: there were 1 deprecation warning(s); re-run with -deprecation for details
 
 
 // new C { }
diff --git a/test/files/run/t6481.check b/test/files/run/t6481.check
index 7ec29631b1..df40722242 100644
--- a/test/files/run/t6481.check
+++ b/test/files/run/t6481.check
@@ -1,3 +1,4 @@
+warning: there were 1 deprecation warning(s); re-run with -deprecation for details
 delayed init
 new foo(1, 2)
 delayed init