忽略输出的golang nil指针分配-（*）（nil）[重复]

Question

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• What does an underscore and interface name after keyword var mean? 2 answers

while going through this tutorial on writing FUSE filesystems in go, I came across this cryptic assignment:

var _ fs.Node = (*Dir)(nil)

Can someone explain the mechanics of this syntax, and how does it fit in the context in which it is declared? As I understand the outcome of the assignment is actually ignored (and what does the right hand expression even result in? a nil Dir pointer?)

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Answer 1

This makes the compiler check if type *Dir fulfills fs.Node interface.

Take a nil pointer, make it a *Dir pointer and assign it to an unnamed variable of interface type fs.Node. Since we never use this variable, we have to make it unnamed.