x/tools/gopls: callHierarchy/incomingCalls for a top-level function alias returns package declaration #49124

andrejtokarcik · 2021-10-23T02:59:51Z

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

$ gopls version
golang.org/x/tools/gopls v0.7.3
    golang.org/x/tools/gopls@v0.7.3 h1:Lru57ht8vtDMouRskFC085VAjBAZRAISd/lwvwOOV0Q=
$ go version  # should be irrelevant?
go version go1.16.2 linux/amd64

Does this issue reproduce with the latest release?

Yes, with the latest release of gopls, including the current tools master golang/tools@316ba0b.

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

go env Output (should be irrelevant?)

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/andrej/.cache/go-build"
GOENV="/home/andrej/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/andrej/.go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/andrej/.go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/andrej/.go1.16.2"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/andrej/.go1.16.2/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.16.2"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3160952985=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Create example.go:

package p

func f() {}

var alias = f

func g() {
	alias()
}

Run gopls, initialize an LSP exchange and fetch the incoming calls for the function f, e.g.:

// First prepare the call hierarchy:
{
    "method": "textDocument/prepareCallHierarchy",
    "params": {
        "textDocument": {
            "uri": "file:///home/andrej/gopls-panic/example.go"
        },
        "position": {
            "character": 5,
            "line": 2
        }
    },
    "jsonrpc": "2.0",
    "id": 1
}
// Handle the received call hierarchy items and send:
{
    "method": "callHierarchy/incomingCalls",
    "params": {
        "item": {
            "name": "f",
            "range": {
                "end": {
                    "character": 6,
                    "line": 2
                },
                "start": {
                    "character": 5,
                    "line": 2
                }
            },
            "selectionRange": {
                "end": {
                    "character": 6,
                    "line": 2
                },
                "start": {
                    "character": 5,
                    "line": 2
                }
            },
            "kind": 12,
            "uri": "file:///home/andrej/gopls-panic/example.go",
            "detail": "command-line-arguments:file=/home/andrej/gopls-panic/example.go â¢ example.go"
        }
    },
    "jsonrpc": "2.0",
    "id": 2
}

What did you expect to see?

Either return a reference to alias as one of the incoming calls of f (i.e. as though alias was a caller of f),
or resolve the indirection and include the incoming calls of alias (i.e. g in example.go) among the incoming calls of f.

What did you see instead?

The returned incoming calls consist of just a reference to the name in the package declaration (p in example.go).

The response for the above example request is:

{
    "result": [
        {
            "from": {
                "name": "p",
                "range": {
                    "end": {
                        "character": 9,
                        "line": 0
                    },
                    "start": {
                        "character": 8,
                        "line": 0
                    }
                },
                "selectionRange": {
                    "end": {
                        "character": 9,
                        "line": 0
                    },
                    "start": {
                        "character": 8,
                        "line": 0
                    }
                },
                "kind": 4,
                "uri": "file:///home/andrej/gopls-panic/example.go",
                "detail": "command-line-arguments:file=/home/andrej/gopls-panic/example.go â¢ example.go"
            },
            "fromRanges": [
                {
                    "end": {
                        "character": 13,
                        "line": 4
                    },
                    "start": {
                        "character": 12,
                        "line": 4
                    }
                }
            ]
        }
    ],
    "jsonrpc": "2.0",
    "id": 2
}

The text was updated successfully, but these errors were encountered:

findleyr · 2021-10-28T15:25:50Z

I don't think this is feasible to do. In your example, alias is not really an alias. Rather, it is a variable that holds function values. Figuring out which values a variable assumes is a Hard Problem. Consider the following more complicated example:

package p

import "time"

func f() {}

var alias = f

func init() {
   now := time.Now()
   if time.Since(now) > time.Millisecond {
     alias = func() {}
   }
}

func g() {
	alias()
}

Closing as infeasible. Please re-open if you disagree.

andrejtokarcik · 2021-10-30T19:54:17Z

@findleyr Thanks for your reply, I don't seem to be able to reopen the issue though.

I understand your argument to rule out only my latter suggestion:

resolve the indirection and include the incoming calls of alias (i.e. g in example.go) among the incoming calls of f.

However, I'd still consider it feasible to go with my first suggestion and return a reference to alias (with SymbolKind = Variable) -- leaving it to the client/user to determine which incoming calls of alias can be false positives in the sense of not being transitive callers of f.

Finally, resolving this issue need not be restricted to my suggested solutions. As I see it, it's rather confusing to return a SymbolKind = Package as a CallHierarchyIncomingCall result in its own right so some fix would still be desired, e.g. entirely omitting any alias related result.

gopherbot added Tools This label describes issues relating to any tools in the x/tools repository. gopls Issues related to the Go language server, gopls. labels Oct 23, 2021

gopherbot added this to the Unreleased milestone Oct 23, 2021

andrejtokarcik changed the title ~~x/tools/gopls: callHierarchy/incomingCalls for a top-level var func returns package declaration~~ x/tools/gopls: callHierarchy/incomingCalls for a top-level function alias returns package declaration Oct 23, 2021

findleyr added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Oct 26, 2021

findleyr closed this as completed Oct 28, 2021

golang locked and limited conversation to collaborators Oct 30, 2022

gopherbot added the FrozenDueToAge label Oct 30, 2022

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x/tools/gopls: callHierarchy/incomingCalls for a top-level function alias returns package declaration #49124

x/tools/gopls: callHierarchy/incomingCalls for a top-level function alias returns package declaration #49124

andrejtokarcik commented Oct 23, 2021 •

edited

findleyr commented Oct 28, 2021

andrejtokarcik commented Oct 30, 2021 •

edited

x/tools/gopls: callHierarchy/incomingCalls for a top-level function alias returns package declaration #49124

x/tools/gopls: callHierarchy/incomingCalls for a top-level function alias returns package declaration #49124

Comments

andrejtokarcik commented Oct 23, 2021 • edited

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

Does this issue reproduce with the latest release?

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

What did you do?

What did you expect to see?

What did you see instead?

findleyr commented Oct 28, 2021

andrejtokarcik commented Oct 30, 2021 • edited

andrejtokarcik commented Oct 23, 2021 •

edited

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

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

andrejtokarcik commented Oct 30, 2021 •

edited