x/tools/gopls: refactor.extract.variable on multi-valued expression produces invalid code

[adonovan]

Gopls' extract logic does not correctly handle the case when an expression has multiple values:

Before:

func f(m map[string]int) {
    if v, ok := m[""]; ok { // <-- refactor.extract.variable on m[""]
        println(v)
    }
}

After:

func f(m map[string]int) {
    x := m[""]
    if v, ok := x; ok { // error: assignment mismatch
        println(v)
    }
}

[gopherbot]

Change https://go.dev/cl/631777 mentions this issue: gopls/internal/golang: refactor.extract.variable: allow all exprs

[gabyhelp]

Related Issues

• x/tools/gopls: refactor.extract.variable on RHS of const declaration produces invalid code #70562

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