ArrayFlipDuplicateValueLoss

warning native off by default

Group: Probable bugs

Detect array_flip of a literal array with two statically equal string or integer values after PHP key conversion.

Example

<?php
array_flip(["a"=>"red","b"=>"red"]);

Reported:

• line 2: Preserve every key associated with this duplicate value.

Detection

• Report array_flip of a literal array with two statically equal string or integer values after PHP key conversion.
• Resolve builtin calls and named arguments before checking the contract. Project-local callees are considered only when their bodies or immutable summaries establish the required facts. The default is disabled; enable only when the stated intent matches the application.
• For flow-dependent conditions, require a reachable source-to-use path with no intervening invalidation. Unknown calls, ambiguous aliases or recursion cannot establish definite facts. When the proof is inconclusive, nothing is reported.

Exceptions (no report)

• Do not report unknown values or distinct values; exclude non-key values handled by ArrayFlipInvalidValueType.
• Unresolved targets, incomplete required facts, suppressed findings and PHP versions lacking the referenced API or language feature produce no report. User declarations shadowing builtin names are not builtin contracts.

Fix

No automatic fix: the desired grouping representation is unknown.

PHP versions

Apply only on PHP versions supporting the referenced APIs and syntax (within PHP 5.3–8.5). Builtin behavior and argument contracts follow the configured PHP version. Extension-specific calls require resolved extension API symbols; do not treat same-named application functions as extension calls.

Options

None. Enable or disable this rule through normal rule configuration.

Configure

In custos.json:

{
  "rules": {
    "ArrayFlipDuplicateValueLoss": {
      "enabled": true
    }
  }
}

Suppress

Before the statement or declaration (or the first statement of the file):

// @custos-ignore ArrayFlipDuplicateValueLoss