Intelligent fork or bootclasspath based on desired target JDK
-------------------------------------------------------------
Key: MCOMPILER-65
URL: http://jira.codehaus.org/browse/MCOMPILER-65
Project: Maven 2.x Compiler Plugin
Issue Type: Improvement
Reporter: David Smiley
I work with Maven on a few projects, some jdk 1.4, some jdk 1.5. The only way
to get a consistent compiled build is to fork the compiler so that a particular
jdk is used, it's not necessarily enough to set the "source" and "target"
params on the compiler plugin ( see http://madbean.com/2006/target14/ ) for an
explanation. I say not necessarily in part not just on the info in that
referred URL, but we really can't and shouldn't assume that maven itself is
using a particular jdk either. I think this is a big deal and I would guess
that the maven team would also think it's a big deal based on a cornerstone
philosophy of repeatable builds. -- Builds that shouldn't come with special
instructions to do some magic (like run maven in a certain VM or set certain
system properties).
This issue needs to be more prominently displayed in the maven documentation,
both for the plugin and most certainly this FAQ entry:
http://maven.apache.org/general.html#Compiling-J2SE-5 -- if only it were that
simple.
I have an idea for a solution that involves only forking when necessary and if
not that possibly setting the bootclasspath. The idea is to avoid forking, and
to avoid setting bootclasspath if neither are necessary. And of course the
result is a compiler configuration that can and should be as simple as setting
the "target" param to get a repeatable build no matter what JDK maven is
running under.
1. Standardize on the system property names for the java homes, i.e.
JAVA_1_4_HOME JAVA_1_5_HOME etc. Furthermore... this *should* be set in the
user's settings.xml. Yes this means installation requires another step but I
see no way around that unless maven were to try and figure out these based on
operating-specific logic.
2. Based on the "source" and "target" parameters, determine wether (a) Maven's
current VM can be used as-is without setting bootclasspath for javac (b)
Maven's current VM can be used but needs to set the bootclasspath for javac, or
(c) fork and use an external javac. If (a) can be chosen then the standardized
property names don't need to be consulted. In (b) the java home is needed for
the bootclasspath, and in (c) to fork javac. Also, ensure that the choice of
a,b,c is somehow displayed in the maven output so the developer knows.
Implementation note: I noticed that the maven compiler plugin uses Ant heavily
to do its job. In light of that, implementing this feature might instead
involve enhancing the ant side to have this feature and then making minor
changes on the maven side to accommodate them.
--
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators:
http://jira.codehaus.org/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
