internal/lsp: fix docs on hover for var/const blocks

The priorities for which comment to show should be 1) documentation
directly above the var/const, 2) documentation for the var/const block,
3) line comments.

See https://github.com/microsoft/vscode-go/issues/3240.

Change-Id: Ie136f0f25ac8208147070682bb1f3a663d6da25f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/234101
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

@@ -306,9 +306,9 @@ func formatVar(node ast.Spec, obj types.Object, decl *ast.GenDecl) *HoverInforma
 			fieldList = t.Methods
 		}
 	case *ast.ValueSpec:
-		comment := decl.Doc
+		comment := spec.Doc
 		if comment == nil {
-			comment = spec.Doc
+			comment = decl.Doc
 		}
 		if comment == nil {
 			comment = spec.Comment

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

@@ -12,6 +12,14 @@ var (
 	x string //@x,hover("x", x)
 )
 
+// Constant block. When I hover on h, I should see this comment.
+const (
+	// When I hover on g, I should see this comment.
+	g = 1 //@g,hover("g", g)
+
+	h = 2 //@h,hover("h", h)
+)
+
 // z is a variable too.
 var z string //@z,hover("z", z)
 

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

@@ -81,7 +81,7 @@ func Random2(y int) int
 -- aPackage-hover --
 Package a is a package for testing go to definition\.
 -- err-definition --
-godef/a/a.go:25:6-9: defined here as ```go
+godef/a/a.go:33:6-9: defined here as ```go
 var err error
 ```
 
@@ -91,14 +91,14 @@ var err error
 	"span": {
 		"uri": "file://godef/a/a.go",
 		"start": {
-			"line": 25,
+			"line": 33,
 			"column": 6,
-			"offset": 418
+			"offset": 597
 		},
 		"end": {
-			"line": 25,
+			"line": 33,
 			"column": 9,
-			"offset": 421
+			"offset": 600
 		}
 	},
 	"description": "```go\nvar err error\n```\n\n\\@err"
@@ -110,6 +110,18 @@ var err error
 ```go
 var err error
 ```
+-- g-hover --
+When I hover on g, I should see this comment\.
+
+```go
+const g untyped int = 1
+```
+-- h-hover --
+Constant block\.
+
+```go
+const h untyped int = 2
+```
 -- make-hover --
 The make built\-in function allocates and initializes an object of type slice, map, or chan \(only\)\.
 

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

@@ -29,7 +29,7 @@ package a ("golang.org/x/tools/internal/lsp/godef/a")
 package a ("golang.org/x/tools/internal/lsp/godef/a")
 ```
 -- AString-definition --
-godef/a/a.go:18:6-7: defined here as ```go
+godef/a/a.go:26:6-7: defined here as ```go
 A string //@mark(AString, "A")
 
 ```
@@ -40,14 +40,14 @@ A string //@mark(AString, "A")
 	"span": {
 		"uri": "file://godef/a/a.go",
 		"start": {
-			"line": 18,
+			"line": 26,
 			"column": 6,
-			"offset": 273
+			"offset": 452
 		},
 		"end": {
-			"line": 18,
+			"line": 26,
 			"column": 7,
-			"offset": 274
+			"offset": 453
 		}
 	},
 	"description": "```go\nA string //@mark(AString, \"A\")\n\n```\n\n[`a.A` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#A)"
@@ -61,7 +61,7 @@ A string //@mark(AString, "A")
 
 ```
 -- AStuff-definition --
-godef/a/a.go:20:6-12: defined here as ```go
+godef/a/a.go:28:6-12: defined here as ```go
 func a.AStuff()
 ```
 
@@ -71,14 +71,14 @@ func a.AStuff()
 	"span": {
 		"uri": "file://godef/a/a.go",
 		"start": {
-			"line": 20,
+			"line": 28,
 			"column": 6,
-			"offset": 310
+			"offset": 489
 		},
 		"end": {
-			"line": 20,
+			"line": 28,
 			"column": 12,
-			"offset": 316
+			"offset": 495
 		}
 	},
 	"description": "```go\nfunc a.AStuff()\n```\n\n[`a.AStuff` on pkg.go.dev](https://pkg.go.dev/golang.org/x/tools/internal/lsp/godef/a#AStuff)"

internal/lsp/testdata/lsp/summary.txt.golden

@@ -12,7 +12,7 @@ FoldingRangesCount = 2
 FormatCount = 6
 ImportCount = 8
 SuggestedFixCount = 6
-DefinitionsCount = 51
+DefinitionsCount = 53
 TypeDefinitionsCount = 2
 HighlightsCount = 52
 ReferencesCount = 11