6 files changed, 58 insertions, 2 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 166bb2d18c..dd4f13fd7b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -1197,6 +1197,18 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
       case _ =>
     }
 
+    // SI-6276 warn for `def foo = foo` or `val bar: X = bar`, which come up more frequently than you might think.
+    def checkInfiniteLoop(valOrDef: ValOrDefDef) {
+      val trivialInifiniteLoop = (
+        !valOrDef.isErroneous
+     && !valOrDef.symbol.isValueParameter
+     && valOrDef.symbol.paramss.isEmpty
+     && valOrDef.rhs.hasSymbolWhich(_.accessedOrSelf == valOrDef.symbol)
+      )
+      if (trivialInifiniteLoop)
+        unit.warning(valOrDef.rhs.pos, s"${valOrDef.symbol.fullLocationString} does nothing other than call itself recursively")
+    }
+
 // Transformation ------------------------------------------------------------
 
     /* Convert a reference to a case factory of type `tpe` to a new of the class it produces. */
@@ -1640,6 +1652,7 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
 
           case ValDef(_, _, _, _) | DefDef(_, _, _, _, _, _) =>
             checkDeprecatedOvers(tree)
+            checkInfiniteLoop(tree.asInstanceOf[ValOrDefDef])
             if (settings.warnNullaryUnit.value)
               checkNullaryMethodReturnType(sym)
             if (settings.warnInaccessible.value) {
diff --git a/test/files/neg/override.check b/test/files/neg/override.check
index fc152cb3b1..8be98bf4d0 100644
--- a/test/files/neg/override.check
+++ b/test/files/neg/override.check
@@ -1,5 +1,5 @@
 override.scala:9: error: overriding type T in trait A with bounds >: Int <: Int;
  type T in trait B with bounds >: String <: String has incompatible type
-  lazy val x : A with B = x
+  lazy val x : A with B = {println(""); x}
                ^
 one error found
diff --git a/test/files/neg/override.scala b/test/files/neg/override.scala
index 3e589b52e3..7975516061 100755
--- a/test/files/neg/override.scala
+++ b/test/files/neg/override.scala
@@ -6,7 +6,7 @@ trait X {
 
 trait Y extends X {
   trait B { type T >: String <: String }
-  lazy val x : A with B = x
+  lazy val x : A with B = {println(""); x}
   n = "foo"
 }
 
diff --git a/test/files/neg/t6276.check b/test/files/neg/t6276.check
new file mode 100644
index 0000000000..8bd92cf293
--- /dev/null
+++ b/test/files/neg/t6276.check
@@ -0,0 +1,13 @@
+t6276.scala:4: error: method a does nothing other than call itself recursively
+      def a: Any = a // warn
+                   ^
+t6276.scala:5: error: value b does nothing other than call itself recursively
+      val b: Any = b // warn
+                   ^
+t6276.scala:10: error: method a does nothing other than call itself recursively
+      def a: Any = a // warn
+                   ^
+t6276.scala:19: error: method a does nothing other than call itself recursively
+      def a = a // warn
+              ^
+four errors found
diff --git a/test/files/neg/t6276.flags b/test/files/neg/t6276.flags
new file mode 100644
index 0000000000..85d8eb2ba2
--- /dev/null
+++ b/test/files/neg/t6276.flags
@@ -0,0 +1 @@
+-Xfatal-warnings
diff --git a/test/files/neg/t6276.scala b/test/files/neg/t6276.scala
new file mode 100644
index 0000000000..8333618964
--- /dev/null
+++ b/test/files/neg/t6276.scala
@@ -0,0 +1,29 @@
+object Test {
+  def foo(a: Int, b: Int, c: Int) {
+    new {
+      def a: Any = a // warn
+      val b: Any = b // warn
+    }
+
+    def method {
+      // method local
+      def a: Any = a // warn
+    }
+
+    trait T {
+      def a: Any
+    }
+
+    new T {
+      // inherited return type
+      def a = a // warn
+    }
+
+    // no warnings below
+    new {
+      def a: Any = {println(""); a}
+      val b: Any = {println(""); b}
+      def c(i: Int): Any = c(i - 0)
+    }
+  }
+}