regression/cbmc/array-constraint/test_json: un-KNOWNBUG, fix expectations

[tautschnig]

test_json.desc was added as KNOWNBUG in 2020 (commit ecb0a5d) asserting an aspirational JSON shape that cbmc never produced. Two flaws:

1. The exit code assertion '^EXIT=0$' did not match cbmc's actual exit. main.c contains 'assert(a[index] == 1)' with a non-deterministic 'index', which fails verification — cbmc exits with 10. (The two sibling tests, test.desc and test_xml.desc, exercise '--show-array- constraints' without '--json-ui' / with '--xml-ui'; cbmc rejects those combinations and exits 1, which they correctly assert.)

2. The regex asserted list-shaped JSON values, e.g. '"arrayWith": [.*]', but the implementation has always emitted scalar counts: '"arrayWith": 2'. The test was therefore unmatchable on day one.

Fix both: assert '^EXIT=10$' and rewrite the regex to match scalar counts ('\d+'). Drop the KNOWNBUG tag so the JSON contract for '--show-array-constraints' is now pinned by an actually-running test.

The test only applies to the default SAT backend: under '--cprover-smt2' or '--incremental-smt2-solver z3' cbmc bypasses the array theory entirely and emits no 'arrayConstraints' JSON block (and '--cprover-smt2' returns a different exit code). Tag the test 'broken-cprover-smt-backend no-new-smt' so it is skipped under those profiles, matching the convention used by other arrayst-dependent tests such as Array_operations2 / Bitfields1 / Computed-Goto1.

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[Copilot]

Pull request overview

This PR corrects the array-constraint JSON regression test so it matches CBMC’s actual behavior and can run as a normal CORE test (instead of an unmatchable KNOWNBUG), while being skipped under SMT-backend profiles where the output/exit code differs.

Changes:

• Remove KNOWNBUG and add solver-profile skip tags (broken-cprover-smt-backend, broken-z3-smt-backend, no-new-smt).
• Update expected exit code from 0 to 10 (verification failure).
• Fix the expected JSON shape to match scalar counts (e.g., "arrayWith": \d+) instead of list values.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.61%. Comparing base (79f0f3a) to head (0402bc0).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #9018      +/-   ##
===========================================
+ Coverage    80.59%   80.61%   +0.01%     
===========================================
  Files         1711     1711              
  Lines       189454   189454              
  Branches        73       73              
===========================================
+ Hits        152694   152727      +33     
+ Misses       36760    36727      -33     

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