SI-6896, spurious warning with overloaded main.

Make sure there's no legit main signature before issuing
any warnings about missing main methods.

3 files changed, 21 insertions, 11 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenJVMASM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenJVMASM.scala
index 49c0fa2757..540935fd57 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenJVMASM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenJVMASM.scala
@@ -78,17 +78,19 @@ trait GenJVMASM {
           failNoForwarder("companion is a trait")
         // Now either succeeed, or issue some additional warnings for things which look like
         // attempts to be java main methods.
-        else possibles exists { m =>
-          m.info match {
-            case PolyType(_, _) =>
-              fail("main methods cannot be generic.")
-            case MethodType(params, res) =>
-              if (res.typeSymbol :: params exists (_.isAbstractType))
-                fail("main methods cannot refer to type parameters or abstract types.", m.pos)
-              else
-                isJavaMainMethod(m) || fail("main method must have exact signature (Array[String])Unit", m.pos)
-            case tp =>
-              fail("don't know what this is: " + tp, m.pos)
+        else (possibles exists isJavaMainMethod) || {
+          possibles exists { m =>
+            m.info match {
+              case PolyType(_, _) =>
+                fail("main methods cannot be generic.")
+              case MethodType(params, res) =>
+                if (res.typeSymbol :: params exists (_.isAbstractType))
+                  fail("main methods cannot refer to type parameters or abstract types.", m.pos)
+                else
+                  isJavaMainMethod(m) || fail("main method must have exact signature (Array[String])Unit", m.pos)
+              case tp =>
+                fail("don't know what this is: " + tp, m.pos)
+            }
           }
         }
       }
diff --git a/test/files/pos/t6896.flags b/test/files/pos/t6896.flags
new file mode 100644
index 0000000000..85d8eb2ba2
--- /dev/null
+++ b/test/files/pos/t6896.flags
@@ -0,0 +1 @@
+-Xfatal-warnings
diff --git a/test/files/pos/t6896.scala b/test/files/pos/t6896.scala
new file mode 100644
index 0000000000..ab527a804a
--- /dev/null
+++ b/test/files/pos/t6896.scala
@@ -0,0 +1,7 @@
+object TooManyMains {
+  def main(args: Array[String]): Unit = {
+    println("Hello, World!")
+  }
+  def main(a: Int, b: Int) = ???
+  def main(s: String, n: String) = ???
+}