scala runner puts . into class path implicitly

[scabug]

If you specify the class path using -cp, scala
will nonetheless use "." to get class files if they are there.
I have a simple test case with a JAR file with the results of compiling
two Scala files that print #1 when invoked. The #2 versions are the
same but print #2. If I execute "scala -cp " in the directory
with the compiled versions of the #2 files, it gets those rather than the
ones from the JAR files: . takes precedence over the class path.
I unset the CLASSPATH environment variable.

I suspected a java bug, but I have been unable to duplicate a Java only
situation. It may have something to do with the very large number of
JAR files passed to -Xbootclasspath/a in scala 2.9.1

Workaround: use the -nobootcp option.

See the following script.

pabst.cs 593 % cat Test.scala
object Test {
   var f : Foo = new Foo()
   def main(s : Array[String]) : Unit = { println("Test #2"); }
}
pabst.cs 594 % cat Foo.scala
class Foo() {
  { println("Foo #2"); }
}
pabst.cs 595 % ls
Foo.class    Foo.scala    Test$.class  Test.class   Test.scala
pabst.cs 596 % scala -cp ../src1/one.jar Test
Foo #2
Test #2
pabst.cs 597 % \rm *.class
pabst.cs 598 % scala -cp ../src1/one.jar Test
Foo #1
Test #1
pabst.cs 599 % java -version
java version "1.6.0_05"
Java(TM) SE Runtime Environment (build 1.6.0_05-b13)
Java HotSpot(TM) Server VM (build 10.0-b19, mixed mode)
pabst.cs 600 % scala -version
Scala code runner version 2.9.1.final -- Copyright 2002-2011, LAMP/EPFL
pabst.cs 601 % more ~/.profile
user=boyland
pabst.cs 602 % uname -a
SunOS pabst.cs.uwm.edu 5.10 Generic_141445-09 i86pc i386 i86pc
pabst.cs 603 % echo $CLASSPATH
CLASSPATH: Undefined variable
pabst.cs 604 % scalac *.scala
pabst.cs 605 % scala -cp ../src1/one.jar Test
Foo #2
Test #2
pabst.cs 606 % scala -nobootcp -cp ../src1/one.jar Test
Foo #1
Test #1

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-5528?orig=1
Reporter: John Tang Boyland (john.boyland)
Affected Versions: 2.9.1

[scabug]

@djspiewak said:
Reproduced locally with 2.9.1 and with an oldish build of 2.10. Note that there are a couple steps not given in the bug report. Namely, creating the one.jar with the modified files. In any case, the bug is clear.

[scabug]

John Tang Boyland (john.boyland) said:
Reproduced on MacOSX 10 SnowLeopard.
The bug does not exist in scala 2.7.7

[scabug]

@paulp said:
That was confusing. It is java sneaking up through the back door: by putting the scala libs on the bootclasspath, we end up not specifying a classpath to java at all, which proceeds to include ".", which we then propagate forward from java.class.path thinking the user set it.

[scabug]

@paulp said:
07ffa8d66d

[scabug]

John Tang Boyland (john.boyland) said:
Paul, thanks for the quick fix. Can you describe the change you do, presumably in the "scala" command script?
That would make it easier for me to fix my current configuration.

[scabug]

@paulp said (edited on Feb 28, 2012 3:44:36 AM UTC):
Here's the diff:

-    echo "-Xbootclasspath/a:$TOOL_CLASSPATH"
+    echo "-Xbootclasspath/a:$TOOL_CLASSPATH -classpath \"\""

[scabug]

John Tang Boyland (john.boyland) said:
Thanks for the diff. It doesn't seem to apply to Scala 2.9.1. Here's a patch that seems to work for me:

*** scala       Mon Aug 29 11:44:19 2011
--- scala.fixed Tue Feb 28 14:18:48 2012
***************
*** 111,116 ****
--- 111,117 ----

  # default to the boot classpath for speed.
  CPSELECT="-Xbootclasspath/a:"
+ CPCLEAR="-classpath \"\""

  while [ $# -gt 0 ]; do
    case "$1" in
***************
*** 134,139 ****
--- 135,141 ----
        ;;
      -nobootcp)
        CPSELECT="-classpath "
+       CPCLEAR=""
        shift
        ;;
      *)
***************
*** 153,159 ****
  "${JAVACMD:=java}" \
    $JAVA_OPTS \
    "${java_args[@]}" \
!   ${CPSELECT}${TOOL_CLASSPATH} \
    -Dscala.usejavacp=true \
    -Dscala.home="$SCALA_HOME" \
    -Denv.emacs="$EMACS" \
--- 155,161 ----
  "${JAVACMD:=java}" \
    $JAVA_OPTS \
    "${java_args[@]}" \
!   ${CPSELECT}${TOOL_CLASSPATH} ${CPCLEAR}\
    -Dscala.usejavacp=true \
    -Dscala.home="$SCALA_HOME" \
    -Denv.emacs="$EMACS" \