x/tools/gopls: spurious workspace symbol items

[hyangah]

gopls version v0.7.0
go version 1.16.4

I observed workspace/symbol query returns embedded interfaces while testing whether workspace symbol query can be used for improving vscode-go's interface stub generation feature as described in golang/vscode-go#1547.

See the following - where for query Reader, multiple Readers in the "io" packages were reported.
One is the true io.Reader, while the others are other interfaces that embed and extend io.Reader (ReadWriter, ReadCloser, ...)
I am not sure if this is working as intended or not.

[Trace - 3:38:08 PM] Sending request 'workspace/symbol - (43)'.
Params: {
    "query": "Reader"
}


[Trace - 3:38:08 PM] Received response 'workspace/symbol - (43)' in 25ms.
Result: [
...
    {
        "name": "Reader",
        "kind": 11,
        "location": {
            "uri": "file:///usr/local/Cellar/go/1.16.4/libexec/src/io/io.go",
            "range": {
                "start": {
                    "line": 82,
                    "character": 5
                },
                "end": {
                    "line": 82,
                    "character": 11
                }
            }
        },
        "containerName": "io"
    },
...
    {
        "name": "Reader",
        "kind": 11,
        "location": {
            "uri": "file:///usr/local/Cellar/go/1.16.4/libexec/src/io/io.go",
            "range": {
                "start": {
                    "line": 126,
                    "character": 1
                },
                "end": {
                    "line": 126,
                    "character": 7
                }
            }
        },
        "containerName": "io"
    },
    {
        "name": "Reader",
        "kind": 11,
        "location": {
            "uri": "file:///usr/local/Cellar/go/1.16.4/libexec/src/io/io.go",
            "range": {
                "start": {
                    "line": 132,
                    "character": 1
                },
                "end": {
                    "line": 132,
                    "character": 7
                }
            }
        },
        "containerName": "io"
    },
    {
        "name": "Reader",
        "kind": 11,
        "location": {
            "uri": "file:///usr/local/Cellar/go/1.16.4/libexec/src/io/io.go",
            "range": {
                "start": {
                    "line": 144,
                    "character": 1
                },
                "end": {
                    "line": 144,
                    "character": 7
                }
            }
        },
        "containerName": "io"
    },
    {
        "name": "Reader",
        "kind": 11,
        "location": {
            "uri": "file:///usr/local/Cellar/go/1.16.4/libexec/src/io/io.go",
            "range": {
                "start": {
                    "line": 151,
                    "character": 1
                },
                "end": {
                    "line": 151,
                    "character": 7
                }
            }
        },
        "containerName": "io"
    },
    {
        "name": "Reader",
        "kind": 11,
        "location": {
            "uri": "file:///usr/local/Cellar/go/1.16.4/libexec/src/io/io.go",
            "range": {
                "start": {
                    "line": 158,
                    "character": 1
                },
                "end": {
                    "line": 158,
                    "character": 7
                }
            }
        },
        "containerName": "io"
    },
    {
        "name": "Reader",
        "kind": 11,
        "location": {
            "uri": "file:///usr/local/Cellar/go/1.16.4/libexec/src/io/io.go",
            "range": {
                "start": {
                    "line": 171,
                    "character": 1
                },
                "end": {
                    "line": 171,
                    "character": 7
                }
            }
        },
        "containerName": "io"
    },

[gopherbot]

Change https://golang.org/cl/334531 mentions this issue: internal/lsp/source: workspace symbol improvements for selectors