-target: jvm-1.5 seems to generate calls to isEmpty on java.lang.String, which doesn't exist in JDK 1.5

[scabug]

Someone complained that ScalaTest 1.6.1 was not working on JDK 1.5. Their exception was:

Exception in thread "main" java.lang.NoSuchMethodError:
java.lang.String.isEmpty()Z
at org.scalatest.NodeFamily$.getTestName(NodeFamily.scala:99)

I double checked and the ant file that generated it does say target="jvm-1.5" inside every scalac element. I also checked and isEmpty was added to java.lang.String in JDK 1.6.

I tried this with just scalac 2.9.0 (Sorry I don't have 2.9.0-1 to try it on), and I got the same problem. I used the source file Simple.scala:

class Simple {
println("hi".isEmpty())
}

I compiled it with:

scalac -target:jvm-1.5 Simple.scala

When I do a javap -v Simple, I see the call to java.lang.String.isEmpty:

public Simple();
Code:
Stack=2, Locals=1, Args_size=1
0: aload_0
1: invokespecial #10; //Method java/lang/Object."":()V
4: getstatic #16; //Field scala/Predef$.MODULE$:Lscala/Predef$;
7: ldc #18; //String hi
9: invokevirtual #24; //Method java/lang/String.isEmpty:()Z
12: invokestatic #30; //Method scala/runtime/BoxesRunTime.boxToBoolean:(Z)Ljava/lang/Boolean;
15: invokevirtual #34; //Method scala/Predef$.println:(Ljava/lang/Object;)V
18: return
LineNumberTable:
line 2: 0
line 3: 4

[scabug]

Imported From: https://issues.scala-lang.org/browse/SUGGEST-5?orig=1
Reporter: @bvenners
Attachments:

• Simple.class (created on Jun 16, 2011 12:59:18 AM UTC, 730 bytes)
• Simple.scala (created on Jun 16, 2011 12:59:18 AM UTC, 44 bytes)

[scabug]

@paulp said:
target=1.5 refers to what version of bytecode to generate. It doesn't deal with this.

http://scala-programming-language.1934581.n4.nabble.com/Targetting-different-JVMs-was-scala-internals-First-candidate-for-2-8-0-beta-tt2006918.html

[scabug]

@SethTisue said:
if you want to compile on Java 6 but target Java 5, you also need to use -javabootclasspath to point to the Java 5 standard library.
(if you're on Mac OS X you don't have it and you have to grab it first from somewhere else.)