Condition Always True

ID

php.condition_always_true

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

Php

Tags

reliability, suspicious-comparison

Description

Reports conditions whose result is fixed at parse time, so the guarded branch either always runs or never runs. The analysis is purely structural and covers three shapes:

  • a literal true / false used as an if (or elseif) guard;

  • a comparison of two literals, such as 5 > 3, 'a' == 'b' or 1 === 2, in an if / elseif / while / ternary condition;

  • a single condition that &&-joins two comparisons of the same expression in a mutually-exclusive way — equality to two different values ($x == 1 && $x == 2) or an impossible numeric range ($x > 5 && $x < 3).

The idiomatic infinite loop while (true) is not flagged, and comparing an expression with itself ($x == $x) is handled by a separate rule and deliberately excluded here.

Rationale

A condition that cannot vary is a paradox: the author clearly expected it to decide something, yet it always resolves the same way. Such conditions hide bugs — a misplaced constant, a typo (== where a variable was meant), or contradictory bounds that silently disable a branch. Surfacing them exposes dead branches and logic errors that tests rarely catch because the branch is taken (or skipped) unconditionally.

<?php
if (true) {                 // FLAW — literal guard, branch always runs
    doSomething();
}
if (5 > 3) {                // FLAW — two constants, always true
    doSomething();
}
if ($x == 1 && $x == 2) {   // FLAW — $x cannot equal both 1 and 2
    impossible();
}
if ($x > 5 && $x < 10) {    // OK — a valid range that depends on $x
    inRange();
}

Remediation

Decide what the condition was meant to test. Replace a stray literal with the real predicate, fix the operand that was meant to be a variable, or correct the contradictory bounds. If the branch is genuinely unconditional, remove the condition (or the dead branch) outright.

References