when executing 'mvn dependency:tree -pl=phoenix-core'. It shows that we depends on both antlr-3.5.jar and antlr-2.7.7.jar.
[INFO] +- org.antlr:antlr:jar:3.5:compile
[INFO] | - org.antlr:ST4:jar:4.0.7:compile
[INFO] +- org.antlr:antlr-runtime:jar:3.5:compile
[INFO] | - org.antlr:stringtemplate:jar:3.2.1:compile
[INFO] | - antlr:antlr:jar:2.7.7:compile
Moreover, in the final jar file phoenix-4.6.0-HBase-1.1-client.jar, it contains both antlr 3.5 and 2.7.7 too. Fortunately they have different package name and will not cause unexpected problems. So it does not have any negative effects, but it is a existed problem.
It seems that it is a known issue and has not been solved and never will be for antlr 3. I don't know whether it still exists in antlr 4.
I searched the source code and generated source code and i cannot find explicit import for classes in antlr-*.jar, but only antlr-runtime instead. Is antlr 3.5 necessary for phoenix?
I did the following things:
1. remove antlr 3.5 dependency from pom
2. add exclusion of stringtemplate for antlr-runtime (so it will not have the transit dependency of antlr 2.7.7)
Then, both antlr 3.5 and antlr 2.7.7 disappeared. After that, all IT/UTs passed. Everything seems to be fine.
Moreover, I added java parameter '-verbose:class' for sqlline.py and see which antlr class is loaded. The result shows that only classes in antlr-runtime had been loaded, not any in antlr 3.5/2.7.7.
So, I think it might be safe to remove dependency of antlr 3.5 and exclude stringtemplate from antlr-runtime.