Merge remote-tracking branch 'hubertp/issue/5554' into develop

3 files changed, 7 insertions, 6 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
index afe0b42167..d7b4171c65 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
@@ -726,7 +726,6 @@ trait ContextErrors {
         // we have to set the type of tree to ErrorType only in the very last
         // fallback action that is done in the inference (tracking it manually is error prone).
         // This avoids entering infinite loop in doTypeApply.
-        // TODO: maybe we should do the same thing with inferExprAlternative.
         if (implicitly[Context].reportErrors) setError(tree)
       }
 
@@ -736,6 +735,8 @@ trait ContextErrors {
           "argument types " + argtpes.mkString("(", ",", ")") +
          (if (pt == WildcardType) "" else " and expected result type " + pt)
         val (pos, msg) = ambiguousErrorMsgPos(tree.pos, pre, best, firstCompeting, msg0)
+        // discover last attempt in a similar way as for NoBestMethodAlternativeError
+        if (implicitly[Context].ambiguousErrors) setError(tree)
         issueAmbiguousTypeError(pre, best, firstCompeting, AmbiguousTypeError(tree, pos, msg))
       }
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 90e07023bb..261cc18d26 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -319,6 +319,7 @@ trait Contexts { self: Analyzer =>
     }
 
     def issueAmbiguousError(pre: Type, sym1: Symbol, sym2: Symbol, err: AbsTypeError) {
+      if (settings.debug.value) println("issue ambiguous error: " + err.errMsg)
       if (ambiguousErrors) {
         if (!pre.isErroneous && !sym1.isErroneous && !sym2.isErroneous)
           unitError(err.errPos, err.errMsg)
@@ -327,6 +328,7 @@ trait Contexts { self: Analyzer =>
     }
 
     def issueAmbiguousError(err: AbsTypeError) {
+      if (settings.debug.value) println("issue ambiguous error: " + err.errMsg)
       if (ambiguousErrors)
         unitError(err.errPos, addDiagString(err.errMsg))
       else if (bufferErrors) { buffer += err }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index 896d8c711d..cea5858915 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -1493,14 +1493,12 @@ trait Infer {
             if (improves(alt, best)) alt else best)
           val competing = applicable.dropWhile(alt => best == alt || improves(best, alt))
           if (best == NoSymbol) {
-            if (pt == WildcardType)
-              NoBestMethodAlternativeError(tree, argtpes, pt)
-            else
-              inferMethodAlternative(tree, undetparams, argtpes, WildcardType)
+            if (pt == WildcardType) NoBestMethodAlternativeError(tree, argtpes, pt)
+            else inferMethodAlternative(tree, undetparams, argtpes, WildcardType)
           } else if (!competing.isEmpty) {
             if (!(argtpes exists (_.isErroneous)) && !pt.isErroneous)
               AmbiguousMethodAlternativeError(tree, pre, best, competing.head, argtpes, pt)
-            setError(tree)
+            else setError(tree)
             ()
           } else {
 //            checkNotShadowed(tree.pos, pre, best, applicable)