Merge remote-tracking branch 'origin/2.10.2' into pr/merge

* origin/2.10.2:
  SI-7532 Fix regression in Java inner classfile reader
  SI-7517 Fix higher kinded type inference regression
  SI-7516 Revert "SI-7234 Make named args play nice w. depmet types"
  SI-7486 Regressions in implicit search.
  SI-7509 Avoid crasher as erronous args flow through NamesDefaults

4 files changed, 23 insertions, 30 deletions

diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
index da117540b4..47a8b1f947 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
@@ -44,8 +44,6 @@ abstract class ClassfileParser {
 
   def srcfile = srcfile0
 
-  private def currentIsTopLevel = !(currentClass.decodedName containsChar '$')
-
   private object unpickler extends scala.reflect.internal.pickling.UnPickler {
     val global: ClassfileParser.this.global.type = ClassfileParser.this.global
   }
@@ -515,8 +513,10 @@ abstract class ClassfileParser {
       }
     }
 
-    val c = if (currentIsTopLevel) pool.getClassSymbol(nameIdx) else clazz
-    if (currentIsTopLevel) {
+    val isTopLevel = !(currentClass containsChar '$') // Java class name; *don't* try to to use Scala name decoding (SI-7532)
+
+    val c = if (isTopLevel) pool.getClassSymbol(nameIdx) else clazz
+    if (isTopLevel) {
       if (c != clazz) {
         if ((clazz eq NoSymbol) && (c ne NoSymbol)) clazz = c
         else mismatchError(c)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index ef87a32c1d..35a4461ccc 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -997,22 +997,11 @@ trait Implicits {
             if (settings.Xdivergence211.value) DivergingImplicitExpansionError(tree, pt, DivergentImplicitRecovery.sym)(context)
             else throw DivergentImplicit
           }
-          else if (invalidImplicits.nonEmpty) {
-            val sym = invalidImplicits.head
-            // We don't even dare look if errors are being buffered
-            // !sym.hasFlag(LOCKED) is a hail mary between SI-2206 and SI-7486
-            def isSensibleAddendum = !sym.hasFlag(LOCKED) && (pt match {
-              case Function1(_, out) => out <:< sym.tpe.finalResultType
-              case _                 => pt <:< sym.tpe.finalResultType
-            })
-            // Don't pitch in with this theory unless it looks plausible that the
-            // implicit would have helped
+
+          if (invalidImplicits.nonEmpty)
             setAddendum(pos, () =>
-              if (isSensibleAddendum)
-                s"\n Note: implicit $sym is not applicable here because it comes after the application point and it lacks an explicit result type"
-              else ""
+              s"\n Note: implicit ${invalidImplicits.head} is not applicable here because it comes after the application point and it lacks an explicit result type"
             )
-          }
         }
 
         best
diff --git a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
index f3736f1519..d54f894c62 100644
--- a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
@@ -284,11 +284,13 @@ trait NamesDefaults { self: Analyzer =>
               case Typed(expr, Ident(tpnme.WILDCARD_STAR)) => expr.tpe
               case _                                       => seqType(arg.tpe)
             }
-            else
-              // Note stabilizing can lead to a non-conformant argument when existentials are involved, e.g. neg/t3507-old.scala, hence the filter.
-              // We have to deconst or types inferred from literal arguments will be Constant(_), e.g. pos/z1730.scala.
-              gen.stableTypeFor(arg).filter(_ <:< paramTpe).getOrElse(arg.tpe).deconst
-          )
+            else {
+              // TODO In 83c9c764b, we tried to a stable type here to fix SI-7234. But the resulting TypeTree over a
+              //      singleton type without an original TypeTree fails to retypecheck after a resetLocalAttrs (SI-7516),
+              //      which is important for (at least) macros.
+              arg.tpe
+            }
+          ).widen // have to widen or types inferred from literal defaults will be singletons
           val s = context.owner.newValue(unit.freshTermName("x$"), arg.pos) setInfo (
             if (byName) functionType(Nil, argTpe) else argTpe
           )
@@ -333,9 +335,12 @@ trait NamesDefaults { self: Analyzer =>
           // type the application without names; put the arguments in definition-site order
           val typedApp = doTypedApply(tree, funOnly, reorderArgs(namelessArgs, argPos), mode, pt)
           typedApp match {
-            // Extract the typed arguments, restore the call-site evaluation order (using
-            // ValDef's in the block), change the arguments to these local values.
-            case Apply(expr, typedArgs) if !(typedApp :: typedArgs).exists(_.isErrorTyped) => // bail out with erroneous args, see SI-7238
+            case Apply(expr, typedArgs) if (typedApp :: typedArgs).exists(_.isErrorTyped) =>
+              setError(tree) // bail out with and erroneous Apply *or* erroneous arguments, see SI-7238, SI-7509
+            case Apply(expr, typedArgs) =>
+              // Extract the typed arguments, restore the call-site evaluation order (using
+              // ValDef's in the block), change the arguments to these local values.
+
               // typedArgs: definition-site order
               val formals = formalTypes(expr.tpe.paramTypes, typedArgs.length, removeByName = false, removeRepeated = false)
               // valDefs: call-site order
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index fc3f5de77f..26d8234278 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -3226,10 +3226,9 @@ trait Types extends api.Types { self: SymbolTable =>
           sameLength(typeArgs, tp.typeArgs) && {
             val lhs = if (isLowerBound) tp.typeArgs else typeArgs
             val rhs = if (isLowerBound) typeArgs else tp.typeArgs
-            // this is a higher-kinded type var with same arity as tp.
-            // side effect: adds the type constructor itself as a bound
-            addBound(tp.typeConstructor)
-            isSubArgs(lhs, rhs, params, AnyDepth)
+            // This is a higher-kinded type var with same arity as tp.
+            // If so (see SI-7517), side effect: adds the type constructor itself as a bound.
+            isSubArgs(lhs, rhs, params, AnyDepth) && { addBound(tp.typeConstructor); true }
           }
         }
         // The type with which we can successfully unify can be hidden