go/doc: `AllMethods` mode erroneously includes methods shadowed by field declarations

[bcmills]

What version of Go are you using (go version)?

$ go version
go version devel go1.22-ee788dba Sat Sep 9 01:48:44 2023 +0000 linux/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/usr/local/google/home/bcmills/.cache/go-build'
GOENV='/usr/local/google/home/bcmills/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/tmp/tmp.VIszpiTnn8/.gopath/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/tmp/tmp.VIszpiTnn8/.gopath'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/google/home/bcmills/sdk/gotip'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='local'
GOTOOLDIR='/usr/local/google/home/bcmills/sdk/gotip/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.22-ee788dba Sat Sep 9 01:48:44 2023 +0000'
GCCGO='/usr/bin/gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/tmp/tmp.VIszpiTnn8/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build150804637=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Extract the following test to a local directory and run it:

-- example.go --
package example

type E struct{}

// F should be hidden within S because of the S.F field.
func (e E) F() string {
    return "blargh"
}

type S struct {
    E
    F int
}
-- example_test.go --
package example_test

import (
    "go/ast"
    "go/doc"
    "go/parser"
    "go/token"
    "testing"
)

func TestDoc(t *testing.T) {
    fset := token.NewFileSet()
    f, err := parser.ParseFile(fset, "example.go", nil, parser.ParseComments|parser.AllErrors)
    if err != nil {
        t.Fatal(err)
    }
    p, err := doc.NewFromFiles(fset, []*ast.File{f}, "example", doc.AllMethods)
    if err != nil {
        t.Fatal(err)
    }
    for _, typ := range p.Types {
        if typ.Name == "S" {
            for _, m := range typ.Methods {
                t.Fatalf("unexpected method on S: %v%s", p.Text(m.Doc))
            }
        }
    }
}

What did you expect to see?

The doc.Package for example.go should not include any methods on type S, since the method F is shadowed by the field S.F. (For confirmation that the field actually does shadow the method, see https://go.dev/play/p/OdO3BIxNHgd.)

What did you see instead?

$ go test .
--- FAIL: TestDoc (0.00s)
    example_test.go:24: unexpected method on S: F should be hidden within S because of the S.F field.
FAIL
FAIL    example 0.005s

(CC @griesemer @agnivade)

[bcmills]

(Found while addressing code review comments on https://go.dev/cl/510315, for #61394.)

[griesemer]

go/doc doesn't use type information produced by the type checker and has various heuristics/approx. mechanisms to get things mostly right. Looks like this is another situation where these mechanisms need to be improved.

[gopherbot]

Change https://go.dev/cl/528402 mentions this issue: go/doc: add a golden test that reproduces #62640

[gopherbot]

Change https://go.dev/cl/510315 mentions this issue: go/doc: track struct fields during reading

[bcmills]

Moving to Backlog because this is currently stalled awaiting code review.