This was first reported as an issue in the Ant project[1]. However, looking into it, it appears to be an issue in javac (Java 8 installation) command itself.

Consider the following arguments file (args.txt):

-d del#me

The del#me is a directory (within the current working dir). Run:

javac @args.txt Foo.java

(where Foo.java is any valid Java file). This throws the following error (only on Java 8):

javac: directory not found: del
Usage: javac <options> <source files>
use -help for a list of possible options

Now edit the args.txt to quote the argument value as follows:

-d "del#me"

and then run the javac command again:

javac @args.txt Foo.java

This time it passes without issues and generates the class file in the del#me directory.
This issue is reproducible only on Java 8 installation. More specifically I'm on:

javac -version
javac 1.8.0_172
(this is also reproducible on latest AdoptOpenJDK 8 version 1.8.0_265). I'm on a macOS.





[1] https://bz.apache.org/bugzilla/show_bug.cgi?id=64912