Issue inliner warnings for callsites that cannot be inlined

Issue precise warnings when the inliner fails to inline or analyze a
callsite. Inline failures may have various causes, for example because
some class cannot be found on the classpath when building the call
graph. So we need to store problems that happen early in the optimizer
(when building the necessary data structures, call graph, ClassBTypes)
to be able to report them later in case the inliner accesses the
related data.

We use Either to store these warning messages. The commit introduces
an implicit class `RightBiasedEither` to make Either easier to use for
error propagation. This would be subsumed by a biased either in the
standard library (or could use a Validation).

The `info` of each ClassBType is now an Either. There are two cases
where the info is not available:
  - The type info should be parsed from a classfile, but the class
    cannot be found on the classpath
  - SI-9111, the type of a Java source originating class symbol cannot
    be completed

This means that the operations on ClassBType that query the info now
return an Either, too.

Each Callsite in the call graph now stores the source position of the
call instruction. Since the call graph is built after code generation,
we build a map from invocation nodes to positions during code gen and
query it when building the call graph.

The new inliner can report a large number of precise warnings when a
callsite cannot be inlined, or if the inlining metadata cannot be
computed precisely, for example due to a missing classfile.

The new -Yopt-warnings multi-choice option allows configuring inliner
warnings.

By default (no option provided), a one-line summary is issued in case
there were callsites annotated @inline that could not be inlined.

12 files changed, 21 insertions, 9 deletions

diff --git a/test/files/run/colltest1.scala b/test/files/run/colltest1.scala
index e0ec378585..de8780a050 100644
--- a/test/files/run/colltest1.scala
+++ b/test/files/run/colltest1.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warnings; re-run with -Yinline-warnings for details
+ * filter: inliner warnings; re-run with
  */
 import scala.collection._
 import scala.language.postfixOps
diff --git a/test/files/run/compiler-asSeenFrom.scala b/test/files/run/compiler-asSeenFrom.scala
index 677dd40ddc..a60c2e8925 100644
--- a/test/files/run/compiler-asSeenFrom.scala
+++ b/test/files/run/compiler-asSeenFrom.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warning; re-run with -Yinline-warnings for details
+ * filter: inliner warning; re-run with
  */
 import scala.tools.nsc._
 import scala.tools.partest.DirectTest
diff --git a/test/files/run/existentials-in-compiler.scala b/test/files/run/existentials-in-compiler.scala
index dfc7048b31..e516eddf95 100644
--- a/test/files/run/existentials-in-compiler.scala
+++ b/test/files/run/existentials-in-compiler.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warnings; re-run with -Yinline-warnings for details
+ * filter: inliner warnings; re-run with
  */
 import scala.tools.nsc._
 import scala.tools.partest.CompilerTest
diff --git a/test/files/run/is-valid-num.scala b/test/files/run/is-valid-num.scala
index 4ab2fac8dd..156121cab5 100644
--- a/test/files/run/is-valid-num.scala
+++ b/test/files/run/is-valid-num.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warnings; re-run with -Yinline-warnings for details
+ * filter: inliner warnings; re-run with
  */
 object Test {
   def x = BigInt("10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000")
diff --git a/test/files/run/iterator-from.scala b/test/files/run/iterator-from.scala
index e2ca5864ea..e7ba1aeb28 100644
--- a/test/files/run/iterator-from.scala
+++ b/test/files/run/iterator-from.scala
@@ -1,5 +1,5 @@
 /* This file tests iteratorFrom, keysIteratorFrom, and valueIteratorFrom on various sorted sets and maps
- * filter: inliner warnings; re-run with -Yinline-warnings for details
+ * filter: inliner warnings; re-run with
  */
 
 import scala.util.{Random => R}
diff --git a/test/files/run/mapConserve.scala b/test/files/run/mapConserve.scala
index f52af3b9f4..c17754283a 100644
--- a/test/files/run/mapConserve.scala
+++ b/test/files/run/mapConserve.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warnings; re-run with -Yinline-warnings for details
+ * filter: inliner warnings; re-run with
  */
 import scala.annotation.tailrec
 import scala.collection.mutable.ListBuffer
diff --git a/test/files/run/pc-conversions.scala b/test/files/run/pc-conversions.scala
index 5fecac9d94..d4ae305aa7 100644
--- a/test/files/run/pc-conversions.scala
+++ b/test/files/run/pc-conversions.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warning; re-run with -Yinline-warnings for details
+ * filter: inliner warning; re-run with
  */
 
 import collection._
diff --git a/test/files/run/stringinterpolation_macro-run.scala b/test/files/run/stringinterpolation_macro-run.scala
index e18375d521..ae7c0e5d7a 100644
--- a/test/files/run/stringinterpolation_macro-run.scala
+++ b/test/files/run/stringinterpolation_macro-run.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warnings; re-run with -Yinline-warnings for details
+ * filter: inliner warnings; re-run with
  */
 object Test extends App {
 
diff --git a/test/files/run/synchronized.check b/test/files/run/synchronized.check
index eab191b4ed..9add05ea0c 100644
--- a/test/files/run/synchronized.check
+++ b/test/files/run/synchronized.check
@@ -1,4 +1,8 @@
+#partest !-Ybackend:GenBCode
 warning: there were 14 inliner warnings; re-run with -Yinline-warnings for details
+#partest -Ybackend:GenBCode
+warning: there were 14 inliner warnings; re-run with -Yopt-warnings for details
+#partest
     .|.               c1.f1:     OK
     .|.               c1.fi:     OK
     .|...             c1.fv:     OK
diff --git a/test/files/run/t7096.scala b/test/files/run/t7096.scala
index 872562dd4d..f723d70abe 100644
--- a/test/files/run/t7096.scala
+++ b/test/files/run/t7096.scala
@@ -1,5 +1,5 @@
 /*
- * filter: inliner warning; re-run with -Yinline-warnings for details
+ * filter: inliner warning; re-run with
  */
 import scala.tools.partest._
 import scala.tools.nsc._
diff --git a/test/files/run/t7582.check b/test/files/run/t7582.check
index cd951d8d4f..2a11210000 100644
--- a/test/files/run/t7582.check
+++ b/test/files/run/t7582.check
@@ -1,2 +1,6 @@
+#partest !-Ybackend:GenBCode
 warning: there was one inliner warning; re-run with -Yinline-warnings for details
+#partest -Ybackend:GenBCode
+warning: there was one inliner warning; re-run with -Yopt-warnings for details
+#partest
 2
diff --git a/test/files/run/t7582b.check b/test/files/run/t7582b.check
index cd951d8d4f..2a11210000 100644
--- a/test/files/run/t7582b.check
+++ b/test/files/run/t7582b.check
@@ -1,2 +1,6 @@
+#partest !-Ybackend:GenBCode
 warning: there was one inliner warning; re-run with -Yinline-warnings for details
+#partest -Ybackend:GenBCode
+warning: there was one inliner warning; re-run with -Yopt-warnings for details
+#partest
 2