ArrayFilterDropsZero

warning native off by default

Group: Probable bugs

Detect builtin array_filter with its callback omitted or explicitly null, when the effective entries of a literal array contain integer zero or string zero and another nonempty scalar value. Later entries replacing the same key determine the effective value.

Example

<?php
array_filter([0, 2]);

Reported:

• line 2: Preserve zero values with an explicit filter predicate.

Detection

• Report builtin array_filter with its callback omitted or explicitly null, when the effective entries of a literal array contain integer zero or string zero and another nonempty scalar value. Later entries replacing the same key determine the effective value.
• 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 infer intent from an unknown input array; an explicit non-null predicate suppresses the report. An explicit null callback retains PHP’s default filtering behavior.
• 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

Use an explicit predicate preserving valid zero values. No automatic fix: the rejected-value policy 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": {
    "ArrayFilterDropsZero": {
      "enabled": true
    }
  }
}

Suppress

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

// @custos-ignore ArrayFilterDropsZero