Merge branch 'master' into HEAD

* master:
  SI-7469 Remove @deprecated scala.util.logging
  SI-3943 Test case for already-fixed Java interop bug
  Fix formatting for couple of docs in the compiler
  SI-7476 Add documentation to GenericTraversableTemplate
  SI-7469 Remove @deprecated scala.util.parsing.ast
  SI-7469 Remove @deprecated MurmurHash elements
  SI-7469 Remove deprecated elements in s.u.parsing.combinator
  SI-7469 Make @deprecated elems in scala.concurrent private[scala]
  removes duplication in inferImplicitValue
  SI-7047 fixes silent for c.inferImplicitXXX
  SI-7167 implicit macros decide what is divergence
  macroExpandAll is now triggered in all invocations of typed
  SI-5923 instantiates targs in deferred macro applications
  SI-6406 Restore deprecated API
  SI-6039 Harden against irrelevant filesystem details
  Limit unnecessary calls to Type#toString.
  fix typo in comment
  SI-7432 add testcases
  SI-7432 Range.min should throw NoSuchElementException on empty range
  AbstractFile.getDirectory does not return null when outDir is "."

Conflicts:
	src/compiler/scala/tools/nsc/typechecker/Typers.scala

1 files changed, 24 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Macros.scala b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
index 31cc8bd93c..2cd2f9380b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Macros.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
@@ -396,7 +396,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
             case Fallback(fallback) =>
               typed1Expr(fallback)
             case Delayed(delayed) =>
-              delayed
+              typer.instantiate(delayed, EXPRmode, WildcardType)
             case Skipped(skipped) =>
               skipped
             case Failure(failure) =>
@@ -780,6 +780,29 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
           expanded2
         }
       }
+      override def onDelayed(delayed: Tree) = {
+        // If we've been delayed (i.e. bailed out of the expansion because of undetermined type params present in the expandee),
+        // then there are two possible situations we're in:
+        // 1) We're in POLYmode, when the typer tests the waters wrt type inference
+        // (e.g. as in typedArgToPoly in doTypedApply).
+        // 2) We're out of POLYmode, which means that the typer is out of tricks to infer our type
+        // (e.g. if we're an argument to a function call, then this means that no previous argument lists
+        // can determine our type variables for us).
+        //
+        // Situation #1 is okay for us, since there's no pressure. In POLYmode we're just verifying that
+        // there's nothing outrageously wrong with our undetermined type params (from what I understand!).
+        //
+        // Situation #2 requires measures to be taken. If we're in it, then noone's going to help us infer
+        // the undetermined type params. Therefore we need to do something ourselves or otherwise this
+        // expandee will forever remaing not expanded (see SI-5692). A traditional way out of this conundrum
+        // is to call `instantiate` and let the inferencer try to find the way out. It works for simple cases,
+        // but sometimes, if the inferencer lacks information, it will be forced to approximate. This prevents
+        // an important class of macros, fundep materializers, from working, which I perceive is a problem we need to solve.
+        // For details see SI-7470.
+        val shouldInstantiate = typer.context.undetparams.nonEmpty && !mode.inPolyMode
+        if (shouldInstantiate) typer.instantiatePossiblyExpectingUnit(delayed, mode, pt)
+        else delayed
+      }
     }
     expander(expandee)
   }