Buggy environment variable substitution - the order should NOT matter!

In preparation of an upcoming development project I downloaded and installed the latest Maven version.
Then - as instructed - I defined me two environment variables:

Code:

M2=%M2_HOME%\bin
M2_HOME=C:\Program Files\Apache Software Foundation\apache-maven-3.6.0

But for some strange reason the former %-placeholder 'M2' is not processed, i.e. "set" just yields:

Code:

M2=%M2_HOME%\bin
M2_HOME=C:\Program Files\Apache Software Foundation\apache-maven-3.6.0

It seems that the order in which the env-var dialog stores these variables is important and if a former variable refers to one further down in the alphabetical list, then: bad luck!

To test that hypothesis I defined me:

Code:

TestX=%TestY%\test3
TestY=%TestZ%\test2
TestZ=%JAVA_HOME%\test1

and the result is:

Code:

TestX=%TestY%\test3
TestY=%TestZ%\test2
TestZ=C:\Program Files\Java\jdk-11.0\test1

:-(

This - dear MicroSoft guys - is BUGGY! Such substitutions should/needs to work regardless of the ordering of the environment variables names! Unbelievable, that nobody at MS ever noticed and fixed this!

I wouldn't consider this a bug at all.

In the example the variable M2 refers to the variable M2_HOME which is not defined until the next line. This is a forward reference. Forward references should not be assumed to work unless this is explicitly documented and I have never seen any documentation that states it is. Even if this was a bug, and I don't think it is, it could not be changed now. Doing so would likely have compatibility issues that override any potential benefits.