SI-6923 Context now buffers warnings as well as errors

Code that was silently typed would not report warnings, even if it
returned a successful result.

This appeared in the following code which didn't show warnings even
with -Ywarn-adapted-args:

    def foo(a: Any) = a; foo(1, 2)

While the following would show the expected warning:

    def foo[A](a: Any) = a; foo(1, 2)

1 files changed, 9 insertions, 1 deletions

diff --git a/test/files/neg/names-defaults-neg.check b/test/files/neg/names-defaults-neg.check
index 6f9dc7d127..f6bd703e1f 100644
--- a/test/files/neg/names-defaults-neg.check
+++ b/test/files/neg/names-defaults-neg.check
@@ -134,9 +134,17 @@ names-defaults-neg.scala:144: error: variable definition needs type because 'x'
 names-defaults-neg.scala:147: error: variable definition needs type because 'x' is used as a named argument in its body.
   object t6 { var x = t.f(x = 1) }
                   ^
+names-defaults-neg.scala:147: warning: type-checking the invocation of method f checks if the named argument expression 'x = ...' is a valid assignment
+in the current scope. The resulting type inference error (see above) can be fixed by providing an explicit type in the local definition for x.
+  object t6 { var x = t.f(x = 1) }
+                            ^
 names-defaults-neg.scala:150: error: variable definition needs type because 'x' is used as a named argument in its body.
   class t9 { var x = t.f(x = 1) }
                  ^
+names-defaults-neg.scala:150: warning: type-checking the invocation of method f checks if the named argument expression 'x = ...' is a valid assignment
+in the current scope. The resulting type inference error (see above) can be fixed by providing an explicit type in the local definition for x.
+  class t9 { var x = t.f(x = 1) }
+                           ^
 names-defaults-neg.scala:164: error: variable definition needs type because 'x' is used as a named argument in its body.
   def u3 { var x = u.f(x = 1) }
                ^
@@ -156,5 +164,5 @@ in the current scope. The resulting type inference error (see above) can be fixe
 names-defaults-neg.scala:180: error: reference to x is ambiguous; it is both a method parameter and a variable in scope.
   class u18 { var x: Int = u.f(x = 1) }
                                  ^
-two warnings found
+four warnings found
 41 errors found