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cmd/go2go: unexpected type parameter panic in translator #39953

Closed griesemer closed 4 years ago

griesemer commented 4 years ago

Extracted from #39758: The following program

package main

type top(type T, T2) struct {
    p *parent(T, T2)
}

type parent(type T, T2) struct {
    (child(T, T2))
}

type child(type T, T2) struct {
    T2
}

func (d *top(T, T2)) foo() *T {
    // panic: internal error: receiver type parameter inference failed
    // t, _ := d.p.foo() 

    // panic: -: unexpected type string character '₇' in "T₇"
    t, _ := d.p.child.foo()
    return t
}

func (rb *child(T, T2)) foo() (*T, bool) {
    return nil, true
}

func main() {
    var _ top(int, int)
}

type-checks ok but the translator reports

$ go tool go2go run main.go2 
panic: unexpected type parameter

goroutine 1 [running]:
go/go2go.(*translator).typeToAST(0xc0001a5678, 0x12e40a0, 0xc00012ae80, 0xc00011d6e0, 0xc0001a4c78)
    /Users/gri/go/src/go/go2go/types.go:596 +0x1725
go/go2go.(*translator).typeListToASTList(0xc0001a5678, 0xc00011cf80, 0x2, 0x2, 0x0, 0x0, 0xc0001241f8, 0xc0001a4b68, 0x1003598, 0x12570c0)
    /Users/gri/go/src/go/go2go/rewrite.go:1175 +0xe5
go/go2go.(*translator).lookupInstantiatedType(0xc0001a5678, 0xc0001366c0, 0x0, 0x0, 0x0)
    /Users/gri/go/src/go/go2go/rewrite.go:1095 +0x2b6
go/go2go.(*translator).translateSelectorExpr(0xc0001a5678, 0xc00011c780)
    /Users/gri/go/src/go/go2go/rewrite.go:804 +0x5b1
go/go2go.(*translator).translateExpr(0xc0001a5678, 0xc00011c780)
    /Users/gri/go/src/go/go2go/rewrite.go:666 +0x4ba
go/go2go.(*translator).translateSelectorExpr(0xc0001a5678, 0xc00012a800)
    /Users/gri/go/src/go/go2go/rewrite.go:756 +0x71
go/go2go.(*translator).translateExpr(0xc0001a5678, 0xc00012a800)
    /Users/gri/go/src/go/go2go/rewrite.go:666 +0x4ba
go/go2go.(*translator).translateExpr(0xc0001a5678, 0xc0001046c0)
    /Users/gri/go/src/go/go2go/rewrite.go:685 +0x385
go/go2go.(*translator).translateExprList(0xc0001a5678, 0xc0001046c0, 0x1, 0x1)
    /Users/gri/go/src/go/go2go/rewrite.go:852 +0x46
go/go2go.(*translator).translateStmt(0xc0001a5678, 0xc00011c7e0)
    /Users/gri/go/src/go/go2go/rewrite.go:583 +0x29d
go/go2go.(*translator).translateBlockStmt(0xc0001a5678, 0xc000106de0)
    /Users/gri/go/src/go/go2go/rewrite.go:544 +0x57
go/go2go.(*translator).translateFuncDecl(0xc0001a5678, 0xc00011d5b0)
    /Users/gri/go/src/go/go2go/rewrite.go:534 +0xc5
go/go2go.(*translator).translate(0xc0001a5678, 0xc000140280)
    /Users/gri/go/src/go/go2go/rewrite.go:461 +0x391
go/go2go.rewriteAST(0xc00012a240, 0xc000126360, 0x0, 0x0, 0xc000101770, 0xc000140280, 0x2583701, 0xc00012a5c0, 0x14197e0)
    /Users/gri/go/src/go/go2go/rewrite.go:257 +0xe5
go/go2go.rewriteFile(0xc00017a0a0, 0x43, 0xc00012a240, 0xc000126360, 0x0, 0x0, 0xc000101770, 0xc00017a230, 0x4c, 0xc000140280, ...)
    /Users/gri/go/src/go/go2go/rewrite.go:221 +0xb8
go/go2go.rewriteFilesInPath(0xc000126360, 0x0, 0x0, 0xc00017a0a0, 0x43, 0xc000104480, 0x1, 0x1, 0x0, 0x0, ...)
    /Users/gri/go/src/go/go2go/go2go.go:114 +0xc5c
go/go2go.rewriteToPkgs(0xc000126360, 0x0, 0x0, 0xc00017a0a0, 0x43, 0xc0001061a0, 0xc00017a0a0, 0x43, 0x7ffeefbffa96, 0x8)
    /Users/gri/go/src/go/go2go/go2go.go:46 +0x165
go/go2go.Rewrite(...)
    /Users/gri/go/src/go/go2go/go2go.go:30
main.translate(0xc000126360, 0xc00017a0a0, 0x43)
    /Users/gri/go/src/cmd/go2go/translate.go:15 +0x47
main.main()
    /Users/gri/go/src/cmd/go2go/main.go:54 +0xb25
gopherbot commented 4 years ago

Change https://golang.org/cl/240522 mentions this issue: [dev.go2go] go/go2go: instantiate embedded field when needed

ianlancetaylor commented 4 years ago

Thanks, fixed on dev.go2go branch.