Merge pull request scala#3268 from adriaanm/support-3021

Report error on code size overflow, log method name.

Author: adriaanm

src/asm/scala/tools/asm/MethodWriter.java

@@ -1853,7 +1853,12 @@ final int getSize() {
         int size = 8;
         if (code.length > 0) {
             if (code.length > 65536) {
-                throw new RuntimeException("Method code too large!");
+                String nameString = "";
+                int i = 0;
+                // find item that corresponds to the index of our name
+                while (i < cw.items.length && (cw.items[i] == null || cw.items[i].index != name)) i++;
+                if (cw.items[i] != null) nameString = cw.items[i].strVal1 +"'s ";
+                throw new RuntimeException("Method "+ nameString +"code too large!");
             }
             cw.newUTF8("Code");
             size += 18 + code.length + 8 * handlerCount;

src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala

@@ -450,17 +450,17 @@ abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM {
     }
 
     // -----------------------------------------------------------------------------------------
-    // utitilies useful when emitting plain, mirror, and beaninfo classes.
+    // utilities useful when emitting plain, mirror, and beaninfo classes.
     // -----------------------------------------------------------------------------------------
 
     def writeIfNotTooBig(label: String, jclassName: String, jclass: asm.ClassWriter, sym: Symbol) {
       try {
         val arr = jclass.toByteArray()
         bytecodeWriter.writeClass(label, jclassName, arr, sym)
       } catch {
-        case e: java.lang.RuntimeException if(e.getMessage() == "Class file too large!") =>
-          // TODO check where ASM throws the equivalent of CodeSizeTooBigException
-          log("Skipped class "+jclassName+" because it exceeds JVM limits (it's too big or has methods that are too long).")
+        case e: java.lang.RuntimeException if e != null && (e.getMessage contains "too large!") =>
+          reporter.error(sym.pos,
+            s"Could not write class $jclassName because it exceeds JVM code size limits. ${e.getMessage}")
       }
     }
 
@@ -1402,7 +1402,6 @@ abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM {
       addInnerClasses(clasz.symbol, jclass)
       jclass.visitEnd()
       writeIfNotTooBig("" + c.symbol.name, thisName, jclass, c.symbol)
-
     }
 
     /**

test/files/run/large_code.check

@@ -0,0 +1,3 @@
+newSource1.scala:1: error: Could not write class BigEnoughToFail because it exceeds JVM code size limits. Method tooLong's code too large!
+class BigEnoughToFail {
+      ^

test/files/run/large_code.scala

@@ -0,0 +1,24 @@
+import scala.tools.partest._
+import java.io.{Console => _, _}
+
+// a cold run of partest takes about 15s for this test on my laptop
+object Test extends DirectTest {
+  override def extraSettings: String = "-usejavacp -d " + testOutput.path
+
+  // test that we hit the code size limit and error out gracefully
+  // 5958 is the magic number (2^16/11 -- each `a(1,2,3,4,5,6)` is 11 bytes of bytecode)
+  override def code
+    = s"""
+      |class BigEnoughToFail {
+      |  def a(a: Int, b: Int, c: Int, d: Int, e: Int, f: Int): Unit = {}
+      |  def tooLong: Unit = {
+      |    ${(1 to 5958) map (_ => "a(1,2,3,4,5,6)") mkString(";")}
+      |  }
+      |}""".stripMargin.trim
+
+  override def show(): Unit = {
+    Console.withErr(System.out) {
+      compile()
+    }
+  }
+}