Copy the Option before applying property values in handleProperties

[farkhalit]

DefaultParser.handleProperties calls processValue on the Option instance owned by the caller's Options rather than on a copy, so a value that arrives through the defaults Properties is written into the shared Option and stays there after the parse. Reuse that same Options for a second parse and the isValuesEmpty guard silently serves the first parse's value instead of the second one's, and the value remains readable through options.getOption(...). Parser.processProperties has the same write-through and also puts the shared Option on the CommandLine, so a later parse rewrites what an earlier CommandLine returns.

Both property paths now clone before storing the value, which is what the argv paths already do in handleOption and processArgs. The new test in AbstractParserTestCase fails for DefaultParser, BasicParser, GnuParser and PosixParser without the change.

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[Copilot]

Pull request overview

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Fixes property-based parsing so that option values from Properties are applied to a cloned Option rather than mutating the caller-owned Options, preventing value “write-through” across parses and threads.

Changes:

• Clone Option instances in both property-processing paths before applying processValue() / adding to CommandLine.
• Add a regression test ensuring reusing the same Options across parses doesn’t leak values into earlier CommandLines or into Options.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/test/java/org/apache/commons/cli/AbstractParserTestCase.java	Adds regression test covering Options reuse across property-based parses.
src/main/java/org/apache/commons/cli/Parser.java	Clones options in processProperties before setting values / adding to CommandLine.
src/main/java/org/apache/commons/cli/DefaultParser.java	Clones options in handleProperties before setting values / passing to handleOption.

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[farkhalit]

Done here too, same restructure: the continue happens first so no clone is made for a skipped flag.

[farkhalit]

Good point, fixed. The no-arg skip check now runs against opt before the clone, so a flag whose value isn't yes/true/1 never allocates a copy.

[garydgregory]

@farkhalit
Please review the Copilot comments.

[farkhalit]

Reviewed both Copilot notes, they're fair. Pushed a commit that moves the no-arg skip check ahead of the clone in both paths, so a flag whose property value isn't yes/true/1 no longer allocates a copy. Behavior is unchanged and the parser tests stay green.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

Suppressed comments (1)

src/main/java/org/apache/commons/cli/DefaultParser.java:531

• handleProperties clones opt into copy, sets the property value on it, then passes it to handleOption, which clones again. This creates an extra allocation per property option and makes the flow harder to follow. Consider adding the already-cloned, already-populated copy directly to cmd (after checkRequiredArgs() / updateRequiredOptions(copy)) instead of calling handleOption(copy).

                final Option copy = (Option) opt.clone();
                if (copy.hasArg() && copy.isValuesEmpty()) {
                    copy.processValue(stripLeadingAndTrailingQuotesDefaultOff(value));
                }
                handleOption(copy);

[garydgregory]

@farkhalit
I'm looking at our User's Guide which describes a three-stage usage pattern, and it now seems to me this PR invents a requirement for the library. I am converting the PR to draft for now.

[farkhalit]

Fair point on the guide: it only describes define, parse, interrogate, and nothing in it promises parsing from several threads, so I've taken the concurrency angle out of the description. The case I'd stand on is narrower: parsing more than once with the same Options, and the library already treats that as supported. CLI-71 (Parser.parse clears option values "in case it's been used before"), CLI-156 ("required options are properly checked if an Options instance is used twice") and CLI-183 (groups reused for several parsings) were all fixed for exactly that, testReuseOptionsTwice covers it in the suite, DefaultParser.parse resets the group selection on every call, and handleOption clones for the same reason. The properties path is the one place left that still writes into the caller's Options, so with DefaultParser a second parse quietly returns the first parse's property value. That's the gap the new test pins down.

Two updates on the branch: merged current master to clear the conflict, and took the suppressed Copilot note, so handleProperties now just sets the value on the copy handleOption already makes, the same idiom the argv paths use, with no extra clone. If you'd still rather keep Options single-use, I'm fine closing this.

I also corrected the checklist in the description: the AI box should have been ticked. Claude was used to help find and prepare this change.