confusing-minuses.qdoc

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// Copyright (C) 2025 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
\ingroup qmllint-warnings-and-errors
 
\title Confusing minuses
\brief [confusing-minuses] Confusing minuses.
 
\qmllintwarningcategory confusing-minuses
 
\section1 Confusing minuses
 
\section2 What happened?
JavaScript code uses a combination of operators written with '-' in a confusing
way. The neighboring '-' operators may be difficult to distinguish. This can be
made worse by unconventional spacing.
 
\section2 Why is that bad?
It makes the code more difficult to read and may cause confusion.
 
\section2 Example
\qml
import QtQuick
 
Item {
    function f(a: int, b: int) {
        let x = a-- - b
        let y = a - -b
        let z = a - --b
        return x + y + z
    }
}
\endqml
To fix this warning, rewrite the code so that it doesn't contain similar '-'
operators next to each other. Simplify expressions where possible. Remove
redundant unary operators and spacing, and use parentheses to isolate
subexpressions.
 
Be mindful that these operators may perform coercions. An expression like
\c{a - -b} may not be equivalent to \c{a + b} depending on the type of b.
\qml
import QtQuick
 
Item {
    function f(a: int, b: int) {
        let x = (a--) - b
        let y = a + b
        let z = a - b + 1
        return x + y + z
    }
}
\endqml
*/