From Stephen Colebourne:

When trying to compile a module-info.java file, "weak" is rejected (I
assume not implemented yet). But, this is a report about the error
handling, which fails to recognise that this is a module-info file,
and thus outputs messages about missing class/interface/enum. Some
additional processing is needed to work out that the user was trying
to declare a module and got the syntax wrong:

> \apps\jdk-9-ea\bin\javac --module-source-path src -d mods src\myapp\
org\myapp\MyApp.java src\mylib\org\mylib\MyLib.java src\myapp\module-info.java s
rc\mylib\module-info.java

src\myapp\module-info.java:1: error: class, interface, or enum expected
weak module myapp {
^
src\myapp\module-info.java:3: error: class, interface, or enum expected
}
^
2 errors

Stephen