SI-6379 adds MethodSymbol.exception

Following Simon’s request, this commit introduces a dedicated API
that can be used to acquire the list of exceptions thrown by a method,
abstracting away from whether it’s a Java or a Scala artifact.

5 files changed, 72 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/api/Symbols.scala b/src/reflect/scala/reflect/api/Symbols.scala
index 562129d893..6fff965de1 100644
--- a/src/reflect/scala/reflect/api/Symbols.scala
+++ b/src/reflect/scala/reflect/api/Symbols.scala
@@ -824,6 +824,14 @@ trait Symbols { self: Universe =>
      *  @group Method
      */
     def returnType: Type
+
+    /** Exceptions that this method is known to throw.
+     *  For Scala methods, the list is calculated from [[throws]] annotations present on a method.
+     *  For Java methods, the list is calculated from `throws` clauses attached to the method and stored in bytecode.
+     *
+     *  @group Method
+     */
+    def exceptions: List[Symbol]
   }
 
   /** The API of module symbols.
diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index f2b3d52c6f..dae9eba878 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -2817,6 +2817,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
         }
       loop(info)
     }
+
+    override def exceptions = annotations flatMap ThrownException.unapply
   }
   implicit val MethodSymbolTag = ClassTag[MethodSymbol](classOf[MethodSymbol])
 
diff --git a/test/files/run/t6379.check b/test/files/run/t6379.check
new file mode 100644
index 0000000000..3e5dfec623
--- /dev/null
+++ b/test/files/run/t6379.check
@@ -0,0 +1,14 @@
+compile-time
+uninitialized close: List(class IOException)
+initialized close: List(class IOException)
+uninitialized productElement: List(class IndexOutOfBoundsException)
+initialized productElement: List(class IndexOutOfBoundsException)
+uninitialized read: List(class IOException)
+initialized read: List(class IOException)
+runtime
+uninitialized close: List(class IOException)
+initialized close: List(class IOException)
+uninitialized productElement: List(class IndexOutOfBoundsException)
+initialized productElement: List(class IndexOutOfBoundsException)
+uninitialized read: List(class IOException)
+initialized read: List(class IOException)
diff --git a/test/files/run/t6379/Macros_1.scala b/test/files/run/t6379/Macros_1.scala
new file mode 100644
index 0000000000..a866438f7d
--- /dev/null
+++ b/test/files/run/t6379/Macros_1.scala
@@ -0,0 +1,26 @@
+import scala.reflect.macros.whitebox._
+import scala.language.experimental.macros
+import java.io._
+
+object Macros {
+  def impl(c: Context) = {
+    var messages = List[String]()
+    def println(msg: String) = messages :+= msg
+
+    import c.universe._
+    def test(sym: MethodSymbol): Unit = {
+      println(s"uninitialized ${sym.name}: ${sym.exceptions}")
+      sym.typeSignature
+      println(s"initialized ${sym.name}: ${sym.exceptions}")
+    }
+
+    println("compile-time")
+    test(typeOf[Closeable].declaration(TermName("close")).asMethod)
+    test(typeOf[Product1[_]].declaration(TermName("productElement")).asMethod)
+    test(c.mirror.staticClass("Reader").typeSignature.declaration(TermName("read")).asMethod)
+
+    q"..${messages.map(msg => q"println($msg)")}"
+  }
+
+  def foo: Any = macro impl
+}
\ No newline at end of file
diff --git a/test/files/run/t6379/Test_2.scala b/test/files/run/t6379/Test_2.scala
new file mode 100644
index 0000000000..af4ec7c6d0
--- /dev/null
+++ b/test/files/run/t6379/Test_2.scala
@@ -0,0 +1,22 @@
+import java.io._
+import scala.reflect.runtime.universe._
+
+class Reader(fname: String) {
+  private val in = new BufferedReader(new FileReader(fname))
+  @throws[IOException]("if the file doesn't exist")
+  def read() = in.read()
+}
+
+object Test extends App {
+  def test(sym: MethodSymbol): Unit = {
+    println(s"uninitialized ${sym.name}: ${sym.exceptions}")
+    sym.typeSignature
+    println(s"initialized ${sym.name}: ${sym.exceptions}")
+  }
+
+  Macros.foo
+  println("runtime")
+  test(typeOf[Closeable].declaration(TermName("close")).asMethod)
+  test(typeOf[Product1[_]].declaration(TermName("productElement")).asMethod)
+  test(typeOf[Reader].declaration(TermName("read")).asMethod)
+}