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scalac fails to compile its library when source files were reordered #7335

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scabug opened this issue Apr 5, 2013 · 9 comments
Closed

scalac fails to compile its library when source files were reordered #7335

scabug opened this issue Apr 5, 2013 · 9 comments
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@scabug
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@scabug scabug commented Apr 5, 2013

Scalac depends on order of given source files when compiling scala library. The build fails, if the sources are unordered but succeeds when sorted before.

scalac is the current "starr" compiler. Its Bundle-Version is "2.11.0-20121228-195556-b7840d6b41".

I found this issue, while doing some experiments of building scala with SBuild, a Scala based buildsystem (http://sbuild.tototec.de) instead of SABBUS (ant). I first used a version, were the source files are collected from the filesystem and are feeded to the compiler as-is (see attachment "scalac-args-unsorted"). I got the following error:

/home/lefou/work/tototec/sbuild/build-foreign-project-examples/scala.git/src/library/scala/Predef.scala:72: error: illegal cyclic reference involving object Predef
object Predef extends LowPriorityImplicits with DeprecatedPredef {
                      ^
one error found

Then, I sorted the source files alphabetically (see attachment "scalac-args-sorted"), and the error vanished.

Note, that I can not produce the same issue with SABBUS, as it always collects the source files alphabetically sorted.

@scabug
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@scabug scabug commented Apr 5, 2013

Imported From: https://issues.scala-lang.org/browse/SI-7335?orig=1
Reporter: Tobias Roeser (lefou)
Affected Versions: 2.11.0-M2
Attachments:

@scabug
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@scabug scabug commented Apr 6, 2013

@scabug
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@scabug scabug commented Apr 6, 2013

@retronym said:
I'm not able to reproduce:

% java -Xmx1G -cp lib/scala-library.jar:lib/scala-reflect.jar:lib/scala-compiler.jar:lib/forkjoin.jar -Dscala.usejavacp=true scala.tools.nsc.Main @args.txt
src/library/scala/SerialVersionUID.scala:15: warning: Implementation restriction: subclassing Classfile does not
make your annotation visible at runtime.  If that is what
you want, you must write the annotation class in Java.
class SerialVersionUID(value: Long) extends scala.annotation.ClassfileAnnotation
      ^
warning: there were 128 deprecation warnings; re-run with -deprecation for details
warning: there were 5 feature warnings; re-run with -feature for details
three warnings found

% java -Xmx1G -cp lib/scala-library.jar:lib/scala-reflect.jar:lib/scala-compiler.jar:lib/forkjoin.jar -Dscala.usejavacp=true scala.tools.nsc.Main -version
Scala compiler version 2.11.0-20121228-195556-b7840d6b41 -- Copyright 2002-2012, LAMP/EPFL

% head -n25 args.txt
-classpath
target/locker/library/classes:target/forkjoin.jar:/home/lefou/.m2/repository/org/apache/ant/ant/1.8.4/ant-1.8.4.jar:target/locker/library/classes
-d
target/locker/library/classes
-encoding
UTF-8
-target:jvm-1.6
src/library/scala/Function3.scala
src/library/scala/Console.scala
src/library/scala/Product9.scala
src/library/scala/PartialFunction.scala
src/library/scala/Symbol.scala
src/library/scala/Product1.scala
src/library/scala/StringContext.scala
src/library/scala/Product17.scala
src/library/scala/Short.scala
src/library/scala/Function14.scala
src/library/scala/Product18.scala
src/library/scala/Mutable.scala
src/library/scala/Product10.scala
src/library/scala/Product19.scala
src/library/scala/Product8.scala
src/library/scala/noinline.scala
src/library/scala/Boolean.scala
src/library/scala/Tuple3.scala

@scabug
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@scabug scabug commented Apr 6, 2013

@lrytz said:
I'm quite sure the reason you cannot reproduce it is that you're using "usejavacp". The error only happens if there is no scala library on the classpath (at all) - that's why there's a "sourcepath" argument.

@scabug
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@scabug scabug commented Apr 6, 2013

@retronym said (edited on Apr 6, 2013 9:31:08 PM UTC):
Gotcha. This fails:

rm -rf target/locker/library/classes/scala &&                \
> export LIB=build/pack/lib;                                   \
> java -Xmx1G -cp $LIB/scala-library.jar:$LIB/scala-reflect.jar:$LIB/scala-compiler.jar:$LIB/forkjoin.jar \
>   scala.tools.nsc.Main                                       \
>    -classpath lib/forkjoin.jar:target/locker/library/classes \
>    -sourcepath src/library                                   \
>    -d target/locker/library/classes                          \
>    src/library/scala/{Predef,LowPriorityImplicits}.scala
src/library/scala/Predef.scala:72: error: illegal cyclic reference involving object Predef
object Predef extends LowPriorityImplicits with DeprecatedPredef {
                      ^
one error found

@scabug
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@scabug scabug commented Apr 6, 2013

@retronym said:
It seems the correct fix here is to disable the automatic import or scala.Predef._ in LowPriorityImplicits.scala, either by modifying TreeInfo#noPredefImportForUnit, or by simply merging the contents of that file into Predef.scala.

I had thought that adding {import scala.Predef.{_ => _} at the top of LPI.scala would suffice, but I still hit the error.

@scabug
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@scabug scabug commented Apr 6, 2013

@retronym said:
The addition of DeprecatedPredef in Predef.scala has exposed some flakiness in noPredefImportForUnit / firstDefinesClassOrObject; Predef.scala now imports Predef._.

Assigning this ticket to myself, now i can see what's happening here.

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@scabug scabug commented Apr 7, 2013

@scabug
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@scabug scabug commented Apr 8, 2013

@scabug scabug closed this Apr 16, 2013
@scabug scabug added the has PR label Apr 7, 2017
@scabug scabug added this to the 2.11.0-M3 milestone Apr 7, 2017
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