GdPaletteIndexDecodedAsRgb

warning native on by default

Group: Probable bugs

Identify a color id from imagecolorallocate on a proven imagecreate palette image used in packed RGB extraction with rightshift8/16 and mask255. imagecreatetruecolor, imagepalettetotruecolor and imagecolorsforindex exclude.

Detection

• Report a color id from imagecolorallocate on a proven imagecreate palette image used in packed RGB extraction with rightshift8/16 and mask255. imagecreatetruecolor, imagepalettetotruecolor and imagecolorsforindex exclude.
• Resolve builtin functions, classes, constants and methods, including imports and supported named arguments. Follow only bounded local facts within one lexical scope. Receiver and argument provenance must establish the specific API contract; variable names and comments never prove intent.
• Report one finding per violating operation. A reachable path, unchanged value identity and applicable API behavior are required. Intervening mutation, unknown calls involving tracked values, escaped aliases or exhausted analysis budgets invalidate proof.

Exceptions (no report)

• Exclude unresolved required symbols, user-defined lookalikes, incomplete syntax, unknown required values and unsupported versions.
• Any imagepalettetotruecolor call on the same image located between its creation and the allocation removes the palette proof, even when the call sits in a branch or loop and does not run on every path: the image may be truecolor there and the shift is then valid. A conversion of another image, one preceding a new imagecreate assignment, or one following the allocation (the id is already a palette index) does not exclude.
• The index and its image must each be the one value every path to the shift agrees on. When another assignment reaches the shift or the allocation on some path (a packed colour, an index allocated on another image, a truecolor image), or a loop replaces either after the shift, nothing is reported, whichever assignment is written first: the shift may be valid there.
• Both @custos-ignore GdPaletteIndexDecodedAsRgb and @noinspection GdPaletteIndexDecodedAsRgb suppress this native rule.

Fix

None. A repair requires a semantic decision or application error-handling policy.

PHP versions

Available in PHP 5.3–8.5 where the referenced API exists. Do not apply extension contracts when the resolved API is unavailable. Gate syntax and version-specific behavior to the configured target.

Configure

In custos.json:

{
  "rules": {
    "GdPaletteIndexDecodedAsRgb": {
      "enabled": false
    }
  }
}

Suppress

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

// @custos-ignore GdPaletteIndexDecodedAsRgb