<!DOCTYPE qhelp PUBLIC

"-//Semmle//qhelp//EN"

"qhelp.dtd">

<qhelp>

<overview>

<p>

Assigning a variable to itself typically indicates a mistake such as a missing qualifier or a

misspelled variable name.

</p>

</overview>

<recommendation>

<p>

Carefully inspect the assignment to check for misspellings or missing qualifiers.

</p>

</recommendation>

<example>

<p>

In the example below, the struct type <code>Rect</code> has two setter methods

<code>setWidth</code> and <code>setHeight</code> that are meant to be used to update the

<code>width</code> and <code>height</code> fields, respectively:

</p>

<sample src="SelfAssignment.go" />

<p>

Note, however, that in <code>setHeight</code> the programmer forgot to qualify the left-hand side

of the assignment with the receiver variable <code>r</code>, so the method performs a useless

assignment of the <code>width</code> parameter to itself and leaves the <code>width</code>

field unchanged.

</p>

<p>

To fix this issue, insert a qualifier:

</p>

<sample src="SelfAssignmentGood.go" />

</example>

<references>

<li>The Go Programming Language Specification: <a href="https://golang.org/ref/spec#Assignments">Assignments</a>.</li>

</references>

</qhelp>