SI-8675 Avoid unreported error after second try using implicit view

This is specific to situations in which we first typecheck an
application `qual.m(arg)` against the method `m` directly provided
by `qual`, and then fall back to `implicitView(qual).m(arg)`.

Regressed in SI-3971 / 7fa77af, in which error reports were moved
to the innermost `Apply`, and the check for `errorInResult` was
accordingly changed to recurse through `Apply` trees.

Before that change, we did not fall back to using a view. After the
change, we do try a view. We retypecheck the arguments under the
`retyping` mode (see `tryTypedArgs`), but this doesn't seem to
be enough to avoid leaking the error typed nested trees from the
first try.

Here's an example from the enclosed test case:

    a.update(0, x[A]({new isString(true)}))
                                   `-- error typed

    refArrayOps(a).update(0, x[A]({new isString(true)}))
                             `                  `-- error type persists
                              `-- this tree is retypecked by tryTypedArgs

This commit changes `onError` to only proceed with the second
try if the retyped argument trees are error free.

1 files changed, 11 insertions, 0 deletions

diff --git a/test/files/neg/t8675.check b/test/files/neg/t8675.check
new file mode 100644
index 0000000000..4e44fba918
--- /dev/null
+++ b/test/files/neg/t8675.check
@@ -0,0 +1,11 @@
+t8675.scala:13: error: type mismatch;
+ found   : Boolean(true)
+ required: String
+    a.update(0, x[A]({new isString(true)})) // !!! allowed
+                                   ^
+t8675.scala:22: error: type mismatch;
+ found   : Boolean(true)
+ required: String
+    new X().m(x[A]({new isString(true)})) // !!! allowed
+                                 ^
+two errors found