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https://issues.apache.org/jira/browse/GROOVY-12715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18139850#comment-18139850
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ASF GitHub Bot commented on GROOVY-12715:
-----------------------------------------
codeconsole opened a new pull request, #3248:
URL: https://github.com/apache/groovy/pull/3248
`await` and `async` have their own alternatives in the `expression` rule
(`awaitExprAlt`, `asyncClosureExprAlt`), but the operand of a cast is parsed by
`castOperandExpression`, which listed only another cast, a `postfixExpression`
and the unary operators. After a cast the two words therefore fell back to
being identifiers: `(BigDecimal) await(price)` was a call to a method named
`await` with one argument and `(Awaitable<Integer>) async { 7 }` a call to a
method named `async` with a closure. At script level that is a
`MissingMethodException`; inside an async task the failure is swallowed by the
task nobody awaits, and the code awaiting the task's result hangs (the issue
has the three reproducers; the parenthesised forms `(int) (await t)` and
`-(await t)` were fine).
`castOperandExpression` gains the two alternatives, with the same labels;
the rule declares `baseContext = expression`, so they produce the same contexts
and `AstBuilder.visitAwaitExprAlt` and `visitAsyncClosureExprAlt` apply
unchanged.
Tests: `AsyncAwaitTest` gains a cast applied to `await` with one and with
several arguments, the same inside an async task that binds a
`DataflowVariable` (the shape that hung), and a cast applied to an async
closure. On JDK 21 `AsyncAwaitTest` (277 tests) and `ParserPositiveSyntaxTest`
pass; `ParserNegativeSyntaxTest` shows only the two failures master has since
GEP-19 landed (#3247 fixes those).
Found by the eval harness of a Groovy-for-agents project: Claude Opus 5.5
wrote the cast form in every statically typed answer to a dataflow task, and
each run timed out. Candidate for `GROOVY_6_0_X` as well.
> A cast applied to await or to an async closure is parsed as a call to a
> method named await or async
> ---------------------------------------------------------------------------------------------------
>
> Key: GROOVY-12715
> URL: https://issues.apache.org/jira/browse/GROOVY-12715
> Project: Groovy
> Issue Type: Bug
> Components: parser-antlr4
> Affects Versions: 6.0.0
> Environment: Groovy 6.0.0 binary distribution and master 7379c5720d;
> BellSoft JDK 21.0.12; macOS 15 arm64
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> {{await}} and {{async}} are contextual keywords with their own alternatives
> in the {{expression}} rule of the grammar ({{awaitExprAlt}},
> {{asyncClosureExprAlt}}), but the operand of a cast is parsed by
> {{castOperandExpression}}, which lists only another cast, a
> {{postfixExpression}} and the unary operators. So after a cast the two words
> fall back to being identifiers, and {{(BigDecimal) await(price)}} is a call
> to a method named {{await}} with one argument, {{(Awaitable<Integer>) async {
> 7 }}} a call to a method named {{async}} with a closure. At script level that
> is a {{MissingMethodException}}; inside an async task the exception is
> swallowed by the task nobody awaits, and the code awaiting the task's result
> hangs.
> On 6.0.0 and master (JDK 21):
> {code:groovy}
> def t = async { 7 }
> Integer a = (Integer) await t // MissingMethodException: No
> signature of method: await for class: Script1 ...
> (groovy.concurrent.Awaitable)
> {code}
> {code:groovy}
> import groovy.concurrent.Awaitable
> Awaitable<Integer> t = (Awaitable<Integer>) async { 7 } //
> MissingMethodException: ... async ... (Script1$_run_closure1)
> {code}
> {code:groovy}
> import groovy.concurrent.DataflowVariable
> DataflowVariable<BigDecimal> price = new DataflowVariable<BigDecimal>()
> DataflowVariable<Integer> quantity = new DataflowVariable<Integer>()
> DataflowVariable<BigDecimal> total = new DataflowVariable<BigDecimal>()
> async {
> BigDecimal unitPrice = (BigDecimal) await(price) // parsed as
> this.await(price): the task fails
> Integer count = (Integer) await(quantity)
> total << unitPrice * count
> }
> async { quantity << 4 }
> async { price << 2.50 }
> println await(total) // hangs: total is
> never bound
> {code}
> The parenthesised forms {{(int) (await t)}} and {{-(await t)}} work, as do
> {{BigDecimal b = await(price)}} and {{await(price) as BigDecimal}}. Found
> because Claude Opus 5.5 wrote the cast form in every answer of an eval task
> under static typing; the script then timed out.
> Suggested fix: add the {{asyncClosureExprAlt}} and {{awaitExprAlt}}
> alternatives to {{castOperandExpression}} (it uses {{options { baseContext =
> expression; }}}, so the same labels reuse the same contexts and
> {{AstBuilder.visitAwaitExprAlt}} and {{visitAsyncClosureExprAlt}} apply
> unchanged). Pull request to follow.
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