Imported Language::Functional break subroutine is parsed as an operator

从 t/simple.t 第 77 行的 upstream 复现开始，并查看在两个后端上复现该问题的项目专项回归。跟踪导入的子程序名称与运算符重叠时它们是如何解析的，然后运行 JVM 和解释器测试。当 break { ... } $list 能在两个后端上完成解析并执行、真正的运算符仍能正常工作，且 upstream 的 97 项测试套件全部通过时，即表示完成。

Summary

Language::Functional 0.05 fails under PerlOnJava because its exported break function is parsed as a built-in operator instead of being resolved as the imported Perl subroutine.

Reproduction

The upstream test t/simple.t imports all functions from Language::Functional and calls:

use Language::Functional ':all';

ok(eval {show(break { shift() >= 4 } [1..6])},
   '[[1, 2, 3], [4, 5, 6]]');

Language::Functional defines and exports break as a normal Perl subroutine with prototype (&$).

Expected result

System Perl passes the complete upstream suite:

• 2 test files
• 97 tests
• t/simple.t passes all 96 tests

Actual result

The archived CPAN run fails during compilation at t/simple.t line 77, before the planned assertions execute:

JVM backend:

Operator "break" doesn't have a defined JVM descriptor at t/simple.t line 77, near ""

Interpreter backend:

Unsupported operator: break at t/simple.t line 77, near ""

The focused test reproduces this failure on both backends. The failure is recorded under target label InfiniteList, but the failing distribution is Language::Functional 0.05.

Likely root cause

PerlOnJava reserves or dispatches break as an operator before considering the imported subroutine installed by use Language::Functional ':all'. Standard Perl resolves this source form to the imported function, including its (&$) prototype and block argument.

This is a parser/symbol-resolution compatibility defect involving imported subroutines whose names overlap with built-in or feature-related operators. It is pure Perl and does not involve XS code, native libraries, or external services.

Acceptance criteria

• An imported subroutine named break can be called in the upstream form break { ... } $list on both JVM and interpreter backends.
• Language::Functional 0.05 passes all 97 upstream tests without modifying its tests.
• Add focused project-owned regression coverage for an imported subroutine shadowing or overriding a built-in/feature-related operator name.
• Preserve genuine operator behavior when no overriding subroutine is imported.
• Preserve prototype-aware parsing of the block argument.

Evidence

• CPAN run: 20260918-141920-96054
• Distribution: Language-Functional-0.05
• Failing test: t/simple.t line 77, break { shift() >= 4 } [1..6]
• System Perl: PASS, 2 files / 97 tests
• PerlOnJava: FAIL before assertions in t/simple.t
• JVM and interpreter: focused failure reproduced

Related issues

• #19 tracks imported Time::HiRes::time failing to override the built-in time operator. It is closed and concerns a different operator, but the import-vs-core-operator resolution problem is related.
• #1257 tracks symbol-resolution collisions between imported constants and lexical declarations. It is open and related to preserving Perl namespaces and imported symbol identity, but it does not cover operator-shaped subroutine calls.

This issue should be coordinated with those efforts while retaining Language::Functional as independent regression coverage.