Why does file argument require quoting for space separated value?

[snicoll]

This is a follow-up of #2342.

I now understand that the value should be quoted so that it's not interpreted and all is well. However, I've noticed that quotes are also mandatory for file arguments.

I've pushed an updated test that showcases the failure I am experiencing.

I must be missing something but I thought the file arg could be an opportunity to provide one argument per line. As such, quoting isn't necessary as the end of the line is a good marker for the end of the argument value.

[remkop]

I still need to run your updated test, but I would expect that testWithSingleArgumentValueFromFileShouldBeQuoted passes and testWithSingleArgumentValueFromFile fails because of the missing quotes.

Picocli also supports a simplified format for @-files (argument files) where every line (except empty lines and comment lines) is interpreted as a single argument. Arguments containing whitespace do not need to be quoted, but it is not possible to have arguments with embedded newlines or to have empty string arguments without quotes.
See 3.9.3. Simplified Format
This may be what you are looking for.

[snicoll]

I still need to run your updated test, but I would expect that testWithSingleArgumentValueFromFileShouldBeQuoted passes and testWithSingleArgumentValueFromFile fails because of the missing quotes.

Yes, the two tests were meant to showcase that one works and one doesn't.

This may be what you are looking for.

I don't know if that was a guess. What I'd like is the tests as described to all pass...

I've tried your suggestion in snicoll@e9061fc and this fails with

picocli.CommandLine$UnmatchedArgumentException: Unknown options: '--compiler-arguments --parameters --source 21 --target 21 -nowarn', '--target my-file.jar'

	at picocli.CommandLine$Interpreter.validateConstraints(CommandLine.java:13668)
	at picocli.CommandLine$Interpreter.parse(CommandLine.java:13620)
	at picocli.CommandLine$Interpreter.parse(CommandLine.java:13565)
	at picocli.CommandLine$Interpreter.parse(CommandLine.java:13460)
	at picocli.CommandLine.parseArgs(CommandLine.java:1552)
	at picocli.Issue2342FileArg.testWithSingleArgumentValueFromFile(Issue2342FileArg.java:81)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

This format means that each item should be on its own line. I was hoping to keep the current arrangement, without the quoting and using the new line as the termination of the value. But maybe that's too specific?

[remkop]

I believe the argument file is in incorrect format. "Every line (except empty lines and comment lines) is interpreted as a single argument", so --compiler-argument should be on a separate line than the value.

I believe this should be the format of the argument file for testWithSingleArgumentValueFromFile:

# each option and option parameter is separated by a newline
--compiler-arguments
# the following line is a single parameter for the --compiler-arguments option
--parameters --source 21 --target 21 -nowarn
--target
my-file.jar

Hence the test code should be as follows:

// test code (testWithSingleArgumentValueFromFile)
try (PrintWriter out = new PrintWriter(Files.newBufferedWriter(argsFile))) {
  out.println("--compiler-arguments");
  // test that comment lines in the argument file are ignored
  out.println("# the following line is a single parameter for the --compiler-arguments option");
  out.println("--parameters --source 21 --target 21 -nowarn");
  out.println("--target");
  out.println("my-file.jar");
}

[snicoll]

Yes, I know. That's what I wrote at the end of the stacktrace:

This format means that each item should be on its own line. I was hoping to keep the current arrangement, without the quoting and using the new line as the termination of the value. But maybe that's too specific?

[remkop]

I am not convinced that it would be a good idea for picocli to provide yet another @-file format...