internal/lsp: fix links for interface methods

This change handles fixes the link behavior for interface methods.
For example, before this change, hovering on "Name"  would point to an
incorrect link: https://pkg.go.dev/go/types?tab=doc#object.Name.
The correct link is
https://pkg.go.dev/go/types?tab=doc#TypeName.Name.

var typ *types.Named
typ.Obj().Name()

Change-Id: If28bff6069239d487e5d86cacafc20800493ebe8
Reviewed-on: https://go-review.googlesource.com/c/tools/+/211585
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

internal/lsp/source/hover.go

@@ -110,7 +110,13 @@ func (i *IdentifierInfo) linkAndSymbolName() (string, string) {
 			case *types.Struct:
 				rTypeName = r.Name()
 			case *types.Named:
-				rTypeName = rtyp.Obj().Name()
+				if named, ok := i.enclosing.(*types.Named); ok {
+					rTypeName = named.Obj().Name()
+				} else if !rtyp.Obj().Exported() {
+					return "", ""
+				} else {
+					rTypeName = rtyp.Obj().Name()
+				}
 			}
 		}
 	}

internal/lsp/testdata/godef/a/a.go

@@ -4,6 +4,7 @@ package a
 
 import (
 	"fmt"
+	"go/types"
 	"sync"
 )
 
@@ -22,4 +23,7 @@ func AStuff() { //@AStuff
 
 	var mu sync.Mutex
 	mu.Lock() //@Lock,hover("Lock", Lock)
+
+	var typ *types.Named
+	typ.Obj().Name() //@Name,hover("Name", Name)
 }

internal/lsp/testdata/godef/a/a.go.golden

@@ -6,6 +6,14 @@ Lock locks m\.
 ```go
 func (*sync.Mutex).Lock()
 ```
+-- Name-hover --
+Name returns the object\'s \(package\-local, unqualified\) name\.
+
+[`(types.TypeName).Name` on pkg.go.dev](https://pkg.go.dev/go/types#TypeName.Name)
+
+```go
+func (*types.object).Name() string
+```
 -- Random-definition --
 godef/a/random.go:3:6-12: defined here as [`a.Random` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#Random)
 
@@ -67,7 +75,7 @@ func Random2(y int) int
 func Random2(y int) int
 ```
 -- err-definition --
-godef/a/a.go:17:6-9: defined here as ```go
+godef/a/a.go:18:6-9: defined here as ```go
 var err error
 ```
 -- err-definition-json --
@@ -75,14 +83,14 @@ var err error
 	"span": {
 		"uri": "file://godef/a/a.go",
 		"start": {
-			"line": 17,
+			"line": 18,
 			"column": 6,
-			"offset": 216
+			"offset": 228
 		},
 		"end": {
-			"line": 17,
+			"line": 18,
 			"column": 9,
-			"offset": 219
+			"offset": 231
 		}
 	},
 	"description": "```go\nvar err error\n```"

internal/lsp/testdata/godef/b/b.go.golden

@@ -1,5 +1,5 @@
 -- A-definition --
-godef/a/a.go:10:6-7: defined here as [`a.A` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#A)
+godef/a/a.go:11:6-7: defined here as [`a.A` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#A)
 
 ```go
 A string //@A
@@ -10,14 +10,14 @@ A string //@A
 	"span": {
 		"uri": "file://godef/a/a.go",
 		"start": {
-			"line": 10,
+			"line": 11,
 			"column": 6,
-			"offset": 88
+			"offset": 100
 		},
 		"end": {
-			"line": 10,
+			"line": 11,
 			"column": 7,
-			"offset": 89
+			"offset": 101
 		}
 	},
 	"description": "[`a.A` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#A)\n\n```go\nA string //@A\n\n```"
@@ -61,7 +61,7 @@ package a ("golang.org/x/tools/internal/lsp/godef/a")
 package a ("golang.org/x/tools/internal/lsp/godef/a")
 ```
 -- AStuff-definition --
-godef/a/a.go:12:6-12: defined here as [`a.AStuff` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#AStuff)
+godef/a/a.go:13:6-12: defined here as [`a.AStuff` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#AStuff)
 
 ```go
 func a.AStuff()
@@ -71,14 +71,14 @@ func a.AStuff()
 	"span": {
 		"uri": "file://godef/a/a.go",
 		"start": {
-			"line": 12,
+			"line": 13,
 			"column": 6,
-			"offset": 108
+			"offset": 120
 		},
 		"end": {
-			"line": 12,
+			"line": 13,
 			"column": 12,
-			"offset": 114
+			"offset": 126
 		}
 	},
 	"description": "[`a.AStuff` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#AStuff)\n\n```go\nfunc a.AStuff()\n```"

internal/lsp/testdata/summary.txt.golden

@@ -11,7 +11,7 @@ FoldingRangesCount = 2
 FormatCount = 6
 ImportCount = 7
 SuggestedFixCount = 1
-DefinitionsCount = 41
+DefinitionsCount = 42
 TypeDefinitionsCount = 2
 HighlightsCount = 44
 ReferencesCount = 7