Odd errors for named stdout output

[njspix]

Bug report

Expected behavior and actual behavior

Expected behavior: I should either be able to name a stdout output, or not
Actual: I can name a stdout output as long as it is part of a tuple, even if it's the only entry in the tuple

Steps to reproduce the problem

process sayHello {
    input:
        val number

    output:
        path("*.txt"), emit: test1
        tuple stdout, emit: test2

    script:
    """
        echo "Hello ${number}" | tee test_${number}.txt
    """
}

workflow {
    test = Channel.of(1, 2, 3)

    sayHello(test)
    sayHello.out.test2.view()
}

This runs sucessfully but produces a warning:
WARN: Output tuple must define at least two elements -- Check process sayHello

On the other hand, this will not run:

process sayHello {
    input:
        val number

    output:
        path("*.txt"), emit: test1
        stdout, emit: test2

    script:
    """
        echo "Hello ${number}" | tee test_${number}.txt
    """
}

workflow {
    test = Channel.of(1, 2, 3)

    sayHello(test)
    sayHello.out.test2.view()
}

Error:

ERROR ~ Script compilation error
- file : /varidata/research/projects/laird/nathan/projects/tmp/test.nf
- cause: Unexpected input: '{' @ line 1, column 18.
   process sayHello {

Environment

• Nextflow version: 24.10.3.5933
• Java version: openjdk 21-internal 2023-09-19
• Operating system: Linux submit003 5.14.0-427.42.1.el9_4.x86_64 A process that define only an input of type 'each' never stops #1 SMP PREEMPT_DYNAMIC Thu Oct 31 14:01:51 UTC 2024 x86_64 GNU/Linux
• Bash version: GNU bash, version 5.1.8(1)-release (x86_64-redhat-linux-gnu)

Additional context

Not sure if this a bug or a feature request. Thanks!

[bentsherman]

You can think of stdout like a function call. Because there is no positional argument like there is for val or path, you don't need the comma before the emit option.

Also, I plopped this code into the VS Code extension (now with built-in language server) and it gave a better error message:

The language server uses a more strict parser that will be integrated into Nextflow itself in the future, so you'll get the better error either way. Hope this clears things up

[njspix]

Thanks so much for clarifying! Is this noted anywhere in the docs?

[bentsherman]

I think there is a note about it somewhere, don't remember