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cmd/compile: unexported interface method declared in body of exported inlined function causes import error #14164

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albertjin opened this issue Jan 30, 2016 · 4 comments
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cmd/compile: unexported interface method declared in body of exported inlined function causes import error #14164

albertjin opened this issue Jan 30, 2016 · 4 comments
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Go1.6

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@albertjin
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Version: go1.6rc1/darwin

Note that go1.5.x does not have this issue. Maybe this is a new feature by design that I don't know, but the error message does not tell the point of problem.

Let's have a package with the following contents,

// file: a.go
package a

func Hello() {
}

func IsInternalErr(err error) (ok bool) {
    _, ok = err.(interface{internal()})
    return
}

// file: a_test.go
package a

import "testing"

func TestHello(t *testing.T) {
    Hello()
}

Then test it,

$ go test a
# testmain
/var/folders/c3/vzt2kvj51f14fs5nsr992z_w0000gn/T/go-build849241500/a/_test/_testmain.go:12: syntax error: unexpected @
FAIL a [build failed]

Note that the problem is not about testing. If this package is used by a program, it reports the problem at the line of import.

In the function IsInternalErr(), change this line,

  _, ok = err.(interface{internal()})

to the following with capitalized interface method name Internal,

  _, ok = err.(interface{Internal()})

the problem is gone.
@griesemer griesemer self-assigned this Jan 30, 2016
@griesemer
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Haven't investigated yet but if real it's related to the new parser. Will look into this later this weekend.

@griesemer
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Definitively an error with the rewritten parser. Given a 3rd file, main.go:

package main
import "./a"
func main() {}

The error is due to a bug in the parser:

$ go tool compile a.go a_test.go
$ go tool compile -h main.go 
main.go:2: syntax error: unexpected @
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x1fded0]

goroutine 1 [running]:
cmd/compile/internal/gc.hcrash()
    /Users/gri/go/src/cmd/compile/internal/gc/subr.go:96 +0x50
cmd/compile/internal/gc.yyerrorl(0x2, 0x442ee0, 0x2, 0xc8200aee98, 0x1, 0x1)
    /Users/gri/go/src/cmd/compile/internal/gc/subr.go:103 +0x76
cmd/compile/internal/gc.Yyerror(0x484780, 0x1b, 0xc8200af008, 0x1, 0x1)
    /Users/gri/go/src/cmd/compile/internal/gc/subr.go:137 +0x464
cmd/compile/internal/gc.(*parser).syntax_error(0x974b80, 0x0, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:158 +0x1af
cmd/compile/internal/gc.(*parser).interfacedcl(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:2513 +0x25f
cmd/compile/internal/gc.(*parser).interfacetype(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:2008 +0x71
cmd/compile/internal/gc.(*parser).try_ntype(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1914 +0x3b7
cmd/compile/internal/gc.(*parser).ntype(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1831 +0x2e
cmd/compile/internal/gc.(*parser).operand(0x974b80, 0x0, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1496 +0x1a7
cmd/compile/internal/gc.(*parser).pexpr(0x974b80, 0x0, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1537 +0x48
cmd/compile/internal/gc.(*parser).uexpr(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1399 +0x19f
cmd/compile/internal/gc.(*parser).bexpr(0x974b80, 0x1, 0x974b88)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1278 +0x25
cmd/compile/internal/gc.(*parser).expr(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1297 +0x33
cmd/compile/internal/gc.(*parser).pexpr(0x974b80, 0xc800000000, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1554 +0x66d
cmd/compile/internal/gc.(*parser).uexpr(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1399 +0x19f
cmd/compile/internal/gc.(*parser).bexpr(0x974b80, 0x1, 0x117a8)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1278 +0x25
cmd/compile/internal/gc.(*parser).expr(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:1297 +0x33
cmd/compile/internal/gc.(*parser).expr_list(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:2769 +0x2e
cmd/compile/internal/gc.(*parser).simple_stmt(0x974b80, 0x1, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:712 +0x4c2
cmd/compile/internal/gc.(*parser).stmt(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:2631 +0x6f
cmd/compile/internal/gc.(*parser).stmt_list(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:2714 +0x59
cmd/compile/internal/gc.(*parser).fnbody(0x974b80, 0x0)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:2215 +0x5d
cmd/compile/internal/gc.(*parser).hidden_import(0x974b80)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:3000 +0x178
cmd/compile/internal/gc.(*parser).hidden_import_list(0x974b80)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:3444 +0x28
cmd/compile/internal/gc.(*parser).import_there(0x974b80)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:503 +0x26
cmd/compile/internal/gc.(*parser).import_stmt(0x974b80)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:369 +0x6b
cmd/compile/internal/gc.(*parser).import_(0x974b80)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:357 +0xb5
cmd/compile/internal/gc.(*parser).file(0x974b80)
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:316 +0x53
cmd/compile/internal/gc.parse_file()
    /Users/gri/go/src/cmd/compile/internal/gc/parser.go:56 +0x5a
cmd/compile/internal/gc.Main()
    /Users/gri/go/src/cmd/compile/internal/gc/lex.go:345 +0x1d44
cmd/compile/internal/amd64.Main()
    /Users/gri/go/src/cmd/compile/internal/amd64/galign.go:127 +0x58d
main.main()
    /Users/gri/go/src/cmd/compile/main.go:32 +0x395

parser.interfacedcl needs to accept also '@', not just LNAME.

Will fix.

@griesemer griesemer added this to the Go1.6 milestone Jan 30, 2016
@bradfitz bradfitz changed the title Using lower case interface method name causes error message at import: "syntax error: unexpected @" cmd/compile: using lower case interface method name causes error message at import: "syntax error: unexpected @" Jan 31, 2016
@griesemer griesemer changed the title cmd/compile: using lower case interface method name causes error message at import: "syntax error: unexpected @" cmd/compile: unexported interface method in declared in body of exported inlined function causes error message at import: "syntax error: unexpected @" Feb 1, 2016
@griesemer griesemer changed the title cmd/compile: unexported interface method in declared in body of exported inlined function causes error message at import: "syntax error: unexpected @" cmd/compile: unexported interface method declared in body of exported inlined function causes error message at import: "syntax error: unexpected @" Feb 1, 2016
@griesemer griesemer changed the title cmd/compile: unexported interface method declared in body of exported inlined function causes error message at import: "syntax error: unexpected @" cmd/compile: unexported interface method declared in body of exported inlined function causes import error Feb 1, 2016
@griesemer
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https://go-review.googlesource.com/19087

@gopherbot
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CL https://golang.org/cl/19087 mentions this issue.

@golang golang locked and limited conversation to collaborators Feb 3, 2017
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