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https://jira.codehaus.org/browse/MNG-5777?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=364322#comment-364322
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Robert Scholte commented on MNG-5777:
-------------------------------------
Together with [~hboutemy] we came to the conclusion that making requiments
{{Comparable}} doesn't seem to be the right approach. The version-part is easy
to compare, but if 2 tools have the same version, you need to compare other
requirements like {{vendor}}. In a string-based comparison you'll always get
IBM before Oracle or Sun and that's not always the intention.
It actually means, that your definition of requirements for choosing the right
tool is incomplete. We need to think of a way to add additional requirements,
e.g. {noformat}-Dtoolchain[jdk].vendor=apache{noformat}
> Matching of toolchains against version ranges depends on their order of
> declaration
> -----------------------------------------------------------------------------------
>
> Key: MNG-5777
> URL: https://jira.codehaus.org/browse/MNG-5777
> Project: Maven
> Issue Type: Bug
> Components: Toolchains
> Affects Versions: 3.2.5
> Environment: Apache Maven 3.2.5
> (12a6b3acb947671f09b81f49094c53f426d8cea1; 2014-12-14T17:29:23+00:00)
> Java version: 1.8.0_31, vendor: Oracle Corporation
> Default locale: en_GB, platform encoding: Cp1251
> OS name: "windows 7", version: "6.1", arch: "amd64", family: "dos"
> Reporter: Sergei Ivanov
> Attachments: toolchains-test.zip
>
>
> If multiple toolchains of the same type match the requested version range,
> then the first toolchain in {{toolchains.xml}} is selected. This is because
> the first matching toolchain wins unconditionally, and there is no way nor
> means to resolve ties. Please see the attached example.
> {noformat}
> mvn validate -t toolchains1.xml
> [INFO] --- maven-toolchains-plugin:1.1:toolchain (default-toolchain) @
> toolchains-test ---
> [INFO] Required toolchain: jdk [ version='[1.7,)' ]
> [INFO] Found matching toolchain for type jdk: JDK[C:/Java/jdk1.8.0_31_x64]
> mvn validate -t toolchains2.xml
> [INFO] --- maven-toolchains-plugin:1.1:toolchain (default-toolchain) @
> toolchains-test ---
> [INFO] Required toolchain: jdk [ version='[1.7,)' ]
> [INFO] Found matching toolchain for type jdk: JDK[C:/Java/jdk1.7.0_76_x64]
> {noformat}
> I think that a {{RequirementsMatcher}} may need two additional features:
> # order (or priority), so that e.g. a match against 'id' key takes precedence
> over a match against 'vendor' key. This is specific to the toolchain type and
> can be provided by toolchain factory at the time of reading the toolchain
> definition.
> # comparison for the matched values with the same key, so that e.g. two
> versions matching the same version range can be compared. We may need some
> sort of hinting or pluggable strategy here, so that e.g. either the lowest
> version in the range is preferred, or the highest.
> Then instead of picking the first matching toolchain, Maven would collect all
> matching toolchains, and then sift through them using the comparison criteria
> above. If that still results in a tie, then it would either abort the
> execution, or pick the first toolchain and proceed with it.
> @Robert Scholte: I saw you've made a lot of changes in the area recently, and
> maybe you have already considered possible solutions for this particular
> problem.
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