panic while handling some //line directives about gofumpt

[flimzy]

Similar panic in the stdlib on this file, although this one appears to be intentionally "broken" (not sure if that means gofumpt should actually panic, though):

$ gofumpt -w test/dwarf/linedirectives.go 
panic: invalid line number 289 (should be < 83) [recovered]
        panic: invalid line number 289 (should be < 83)

goroutine 19 [running]:
golang.org/x/tools/go/ast/astutil.Apply.func1()
        /home/jonhall/go/pkg/mod/golang.org/x/[email protected]/go/ast/astutil/rewrite.go:48 +0xab
panic({0x66f1e0?, 0xc0001143d0?})
        /usr/local/go/src/runtime/panic.go:914 +0x21f
go/token.(*File).MergeLine(0xc000134480, 0xc000112a48?)
        /usr/local/go/src/go/token/position.go:152 +0x1c8
mvdan.cc/gofumpt/format.(*fumpter).removeLines(...)
        /home/jonhall/src/gofumpt/format/format.go:249
mvdan.cc/gofumpt/format.(*fumpter).removeLinesBetween(0xc0001320a0, 0xc00015c200?, 0x5b8?)
        /home/jonhall/src/gofumpt/format/format.go:257 +0x13f
mvdan.cc/gofumpt/format.(*fumpter).applyPre(0xc0001320a0, 0xc0001344f0)
        /home/jonhall/src/gofumpt/format/format.go:545 +0x7b2
mvdan.cc/gofumpt/format.File.func1(0xc0001344f0)
        /home/jonhall/src/gofumpt/format/format.go:109 +0x34
golang.org/x/tools/go/ast/astutil.(*application).apply(0xc0001344e0, {0x724050?, 0xc00011a420?}, {0x6bf529?, 0x0?}, 0x0?, {0x723998?, 0xc00011a3f0?})
        /home/jonhall/go/pkg/mod/golang.org/x/[email protected]/go/ast/astutil/rewrite.go:199 +0x1aa
golang.org/x/tools/go/ast/astutil.(*application).apply(0xc0001344e0, {0x724078?, 0xc0001520a0?}, {0x6bf95e?, 0x40d1da?}, 0x14?, {0x724050?, 0xc00011a420?})
        /home/jonhall/go/pkg/mod/golang.org/x/[email protected]/go/ast/astutil/rewrite.go:429 +0x225d
golang.org/x/tools/go/ast/astutil.(*application).applyList(0xc0001344e0, {0x724078?, 0xc0001520a0}, {0x6bf95e, 0x5})
        /home/jonhall/go/pkg/mod/golang.org/x/[email protected]/go/ast/astutil/rewrite.go:484 +0xa5
golang.org/x/tools/go/ast/astutil.(*application).apply(0xc0001344e0, {0x7242d8?, 0xc0001143a0?}, {0x6bf699?, 0x697fe0?}, 0x6b7040?, {0x724078?, 0xc0001520a0?})
        /home/jonhall/go/pkg/mod/golang.org/x/[email protected]/go/ast/astutil/rewrite.go:435 +0x230e
golang.org/x/tools/go/ast/astutil.Apply({0x724078?, 0xc0001520a0}, 0xc000128b58, 0xc000128b70)
        /home/jonhall/go/pkg/mod/golang.org/x/[email protected]/go/ast/astutil/rewrite.go:53 +0x152
mvdan.cc/gofumpt/format.File(0xc000116080, 0xc0001520a0, {{0x6bf2e6, 0x2}, {0x0, 0x0}, 0x0})
        /home/jonhall/src/gofumpt/format/format.go:157 +0x2d7
main.processFile({0x7ffd6c1f2e83, 0x1c}, {0x725828, 0xc0000964e0}, {0x0?, 0x0?}, 0x0?, 0x1)
        /home/jonhall/src/gofumpt/gofmt.go:313 +0x308
main.gofmtMain.func3(0x0?)
        /home/jonhall/src/gofumpt/gofmt.go:508 +0x34
main.(*sequencer).Add.func2()
        /home/jonhall/src/gofumpt/gofmt.go:191 +0x42
created by main.(*sequencer).Add in goroutine 1
        /home/jonhall/src/gofumpt/gofmt.go:190 +0x1ae

[mvdan]

Thanks for spotting - I've never liked those line directives to be honest. They are definitely an obstacle for a formatter.