Better error reporting regarding main methods.

Now notices most things which look like main methods and says
something useful if they aren't usable as entry points.
Closes SI-4749.

1 files changed, 28 insertions, 0 deletions

diff --git a/test/files/neg/t4749.check b/test/files/neg/t4749.check
new file mode 100644
index 0000000000..93ad3935fa
--- /dev/null
+++ b/test/files/neg/t4749.check
@@ -0,0 +1,28 @@
+t4749.scala:2: error: Fail1 has a main method with parameter type Array[String], but bippy.Fail1 will not be a runnable program.
+  Reason: main method must have exact signature (Array[String])Unit
+  object Fail1 {
+         ^
+t4749.scala:6: error: Fail2 has a main method with parameter type Array[String], but bippy.Fail2 will not be a runnable program.
+  Reason: main methods cannot be generic.
+  object Fail2 {
+         ^
+t4749.scala:13: error: Fail3 has a main method with parameter type Array[String], but bippy.Fail3 will not be a runnable program.
+  Reason: main methods cannot refer to type parameters or abstract types.
+  object Fail3 extends Bippy[Unit] { }
+         ^
+t4749.scala:16: error: Fail4 has a main method with parameter type Array[String], but bippy.Fail4 will not be a runnable program.
+  Reason: companion is a trait, which means no static forwarder can be generated.
+
+  object Fail4 {
+         ^
+t4749.scala:21: error: Fail5 has a main method with parameter type Array[String], but bippy.Fail5 will not be a runnable program.
+  Reason: companion contains its own main method, which means no static forwarder can be generated.
+
+  object Fail5 extends Fail5 { }    
+         ^
+t4749.scala:26: error: Fail6 has a main method with parameter type Array[String], but bippy.Fail6 will not be a runnable program.
+  Reason: companion contains its own main method (implementation restriction: no main is allowed, regardless of signature), which means no static forwarder can be generated.
+
+  object Fail6 {
+         ^
+6 errors found