SI-8841 report named arg / assignment ambiguity also in silent mode.

For local definitions (eg. in a block that is an argument of a method
call), the type completer may have a silent context. A CyclicReference
is then not thrown but transformed into a NormalTypeError. When
deciding if 'x = e' is an assignment or a named arg, we need to report
cyclic references, but not other type errors. In the above case, the
cyclic reference was not reported.

Also makes sure that warnings are printed after typing argument
expressions.

1 files changed, 16 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
index b6387fd56b..4f943fcd28 100644
--- a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
@@ -521,8 +521,22 @@ trait NamesDefaults { self: Analyzer =>
             WarnAfterNonSilentRecursiveInference(param, arg)(context)
           res
         } match {
-          case SilentResultValue(t)  => !t.isErroneous // #4041
-          case _        => false
+          case SilentResultValue(t)  =>
+            !t.isErroneous // #4041
+          case SilentTypeError(e: NormalTypeErrorFromCyclicReference) =>
+            // If we end up here, the CyclicReference was reported in a silent context. This can
+            // happen for local definitions, when the completer for a definition is created during
+            // type checking in silent mode. ContextErrors.TypeSigError catches that cyclic reference
+            // and transforms it into a NormalTypeErrorFromCyclicReference.
+            // The cycle needs to be reported, because the program cannot be typed: we don't know
+            // if we have an assignment or a named arg.
+            context.issue(e)
+            // 'err = true' is required because we're in a silent context
+            WarnAfterNonSilentRecursiveInference(param, arg)(context)
+            false
+          case _        =>
+            // We got a type error, so it cannot be an assignment (it doesn't type check as one).
+            false
         }
         catch {
           // `silent` only catches and returns TypeErrors which are not