Identical Operands

ID

swift.identical_operands

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

Swift

Tags

reliability, suspicious

Description

Reports an equality (==, !=, ===, !==) or relational (<, ⇐, >, >=) binary expression whose left and right operands have identical source text. x == x is always true (except NaN); x < x is always false — almost always a typo.

if x == x { ... }              // FLAW
return s != s                  // FLAW
if a < a { ... }               // FLAW

if x == y { ... }              // OK
if x.isNaN { ... }             // OK — explicit NaN check

Rationale

The only legitimate use of x != x is detecting NaN — and Swift has isNaN for that. Every other identical-operand comparison is dead code, usually copy-paste from a more complex expression that lost its second variable.

Remediation

Replace with the intended comparison:

// If you wanted to compare with a different variable:
if x == y { ... }

// If you wanted a NaN check:
if x.isNaN { ... }

References