[MNG-6503] parent pom relative path regression after 3.3.9

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Duplicate
• Affects Version/s: 3.5.4, 3.6.0
• Environment: Windows 10, Java 8, fails with maven 3.5.4 and 3.6.0, works with 3.3.9
• Assignee: Robert Scholte
• Reporter: Marshall Schor
• Created: 01/Nov/18 17:17
• Updated: 26/Nov/18 19:44
• Resolved: 26/Nov/18 19:44

Description

Used to work in 3.3.9.  Failure to resolve parent-pom via relative-path in some cases.
 
A trivial example, with the folder structure and the poms. You
can see the failure by typing mvn help:effective-pom after cd'ing to the top
project's folder.

Here's the folder structure:

 mvntst <- top folder
    parent  <- subfolder having parent pom
    subproj <- subfolder having a sub project

The 3 folders have a pom.xml:

in mvntst folder (the top level folder)

<?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
 [http://maven.apache.org/xsd/maven-4.0.0.xsd]">
     <modelVersion>4.0.0</modelVersion>
     <groupId>mvntst</groupId>
     <artifactId>top</artifactId>
     <packaging>pom</packaging>
     <parent>
         <groupId>mvntst</groupId>
         <artifactId>parent</artifactId>
         <version>1.0.0</version>
         <relativePath>parent/pom.xml</relativePath>   <!-- works, finds the
 parent -->
     </parent>
     <modules>
       <module>subproj</module>
     </modules>
 </project>

in parent subfolder:

<?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
 [http://maven.apache.org/xsd/maven-4.0.0.xsd]">
     <modelVersion>4.0.0</modelVersion>
     <groupId>mvntst</groupId>
     <artifactId>parent</artifactId>
     <version>1.0.0</version>
     <packaging>pom</packaging>
 </project>

in subproj subfolder:

<?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
 [http://maven.apache.org/xsd/maven-4.0.0.xsd]">
     <modelVersion>4.0.0</modelVersion>
     <groupId>mvntst</groupId>
     <artifactId>subproj</artifactId>
     <parent>
         <groupId>mvntst</groupId>
         <artifactId>parent</artifactId>
         <version>1.0.0</version>
         <relativePath>../parent/pom.xml</relativePath>  <!-- fails -->  
     </parent>
 </project>

In doing various tests: if the top pom is missing its relative-path, you get an
expected

Non-resolvable parent POM for mvntst:top:[unknown-version]: Failure to find
 mvntst:parent:pom:1.0.0 ...

putting in the relative-path into the top fixes this, and results in finding the
parent for the top level.
If you don't have a <modules> section in the top level, the mvn
help:effective-pom works OK.

Putting in the <modules> section gives the error:

Non-resolvable parent POM for mvntst:subproj:[unknown-version]: Failure to find
 mvntst:parent:pom:1.0.0

Adding the <version> to the artifact IDs for the top and subproj doesn't help,
except to change the error message to include the version instead of
[unknown-version]

Issue Links

• duplicates: MNG-6261 Relative parent POM resolution failing in 3.5.0 with complex multimodule builds