DiagnosticsError codes
M0004 declared and not used
Go rejects local variables that are never read.
example $ marmot build . error[M0004]: declared and not used: count --> ./main.go:4:2 | 4 | count := len(xs) // never read | ^^^^^ declared here but never used | help: assign the value to `_` | 4 - count := len(xs) // never read 4 + _ = len(xs) // never read | error[M0002]: undefined: xs --> ./main.go:4:15 | 4 | count := len(xs) // never read | ^^ not declared in this scope error: build failed with 2 errors 1 error can be fixed automatically: run `marmot fix` for more about an error, run `marmot explain M0002`
The program that produced it
package main
func main() {
count := len(xs) // never read
}
Assigning to a variable does not count as a use.
The mistake and the fix
count := len(xs) // never read// remove it, or use it:
count := len(xs)
fmt.Println(count) The fix
Use the variable, remove it, or assign the value to _.
See also all error codes and marmot explain.