basename() fails on required variable

[aofarrel]

Made a new ticket for this since it's a new issue. basename() does not work on optional values, but sometimes it seems to think things that aren't optional are optional.

This passes miniwdl and Cromwell, ie, is expected behavior:

version 1.0

task T {
	input {
		File? tsv_file_input
		String tsv_arg = if defined(tsv_file_input) then basename(select_first([tsv_file_input, "/path/to/file.txt"])) else ""
	}

	command <<<
		echo ~{tsv_arg}
	>>>

}

workflow W {
	input {
		File? tsv_file_input
	}

	call T {
		input:
			tsv_file_input = tsv_file_input
	}
}

This passes miniwdl, but fails Cromwell, even though it really ought to pass both:

version 1.0

task T {
	input {
		File? tsv_file_input
		String foo = select_first([tsv_file_input, "/path/to/file.txt"])
		String tsv_arg = if defined(tsv_file_input) then basename(foo) else ""
	}

	command <<<
		echo ~{tsv_arg}
	>>>

}

workflow W {
	input {
		File? tsv_file_input
	}

	call T {
		input:
			tsv_file_input = tsv_file_input
	}
}

Cromwell's error is:

14:27:13.383 [main] ERROR io.dockstore.client.cli.ArgumentUtility - Problem parsing WDL file: Failed to process task definition 'T' (reason 1 of 1): Failed to process expression 'select_first([tsv_arg, if defined(tsv_file_input) then basename(foo) else ""])' (reason 1 of 1): Invalid parameter 'IdentifierLookup(foo)'. Expected 'File' but got 'String?' 14:27:13.385 [main] ERROR io.dockstore.client.cli.ArgumentUtility - wdl.draft3.parser.WdlParser$SyntaxError: Failed to process task definition 'T' (reason 1 of 1): Failed to process expression 'select_first([tsv_arg, if defined(tsv_file_input) then basename(foo) else ""])' (reason 1 of 1): Invalid parameter 'IdentifierLookup(foo)'. Expected 'File' but got 'String?'

Originally posted by @aofarrel in https://github.com/broadinstitute/cromwell/issues/6840#issuecomment-1245982086