gopls: group comments for hover

gopls/internal/golang/hover.go

@@ -18,6 +18,7 @@ import (
 	"go/version"
 	"io/fs"
 	"path/filepath"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -305,7 +306,7 @@ func hover(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, pp pro
 		return protocol.Range{}, nil, fmt.Errorf("re-parsing declaration of %s: %v", obj.Name(), err)
 	}
 	decl, spec, field := findDeclInfo([]*ast.File{declPGF.File}, declPos) // may be nil^3
-	comment := chooseDocComment(decl, spec, field)
+	comment := chooseDocComment(pkg.FileSet(), decl, spec, field)
 	docText := comment.Text()
 
 	// By default, types.ObjectString provides a reasonable signature.
@@ -1147,10 +1148,10 @@ func HoverDocForObject(ctx context.Context, snapshot *cache.Snapshot, fset *toke
 	}
 
 	decl, spec, field := findDeclInfo([]*ast.File{pgf.File}, pos)
-	return chooseDocComment(decl, spec, field), nil
+	return chooseDocComment(fset, decl, spec, field), nil
 }
 
-func chooseDocComment(decl ast.Decl, spec ast.Spec, field *ast.Field) *ast.CommentGroup {
+func chooseDocComment(fset *token.FileSet, decl ast.Decl, spec ast.Spec, field *ast.Field) *ast.CommentGroup {
 	if field != nil {
 		if field.Doc != nil {
 			return field.Doc
@@ -1164,28 +1165,87 @@ func chooseDocComment(decl ast.Decl, spec ast.Spec, field *ast.Field) *ast.Comme
 	case *ast.FuncDecl:
 		return decl.Doc
 	case *ast.GenDecl:
-		switch spec := spec.(type) {
-		case *ast.ValueSpec:
-			if spec.Doc != nil {
-				return spec.Doc
-			}
-			if decl.Doc != nil {
-				return decl.Doc
-			}
-			return spec.Comment
-		case *ast.TypeSpec:
-			if spec.Doc != nil {
-				return spec.Doc
-			}
-			if decl.Doc != nil {
-				return decl.Doc
-			}
-			return spec.Comment
+		group := specGroupComment(fset, decl, spec)
+		doc := getDocComment(spec)
+		line := getLineComment(spec)
+
+		cg := &ast.CommentGroup{}
+		if group != nil {
+			cg.List = append(cg.List, group)
+		}
+		if doc != nil {
+			cg.List = append(cg.List, doc.List...)
+		}
+		if line != nil {
+			cg.List = append(cg.List, line.List...)
+		}
+
+		if len(cg.List) != 0 {
+			// Group comment might be part of a Doc comment.
+			cg.List = slices.Compact(cg.List)
+			return cg
 		}
+
+		return decl.Doc
 	}
 	return nil
 }
 
+func specGroupComment(fset *token.FileSet, decl *ast.GenDecl, spec ast.Spec) *ast.Comment {
+	var groupComment *ast.Comment
+	var prevEndPos token.Pos
+	for _, s := range decl.Specs {
+		doc := getDocComment(s)
+
+		startPos := s.Pos()
+		if doc != nil {
+			startPos = doc.Pos()
+		}
+
+		if prevEndPos.IsValid() && fset.PositionFor(startPos, false).Line != fset.PositionFor(prevEndPos, false).Line+1 {
+			groupComment = nil
+		}
+
+		if doc != nil && strings.HasPrefix(doc.List[0].Text, "/*") {
+			groupComment = doc.List[0]
+		}
+
+		if s == spec {
+			return groupComment
+		}
+
+		prevEndPos = s.End()
+		if lc := getLineComment(s); lc != nil {
+			prevEndPos = lc.End()
+		}
+	}
+
+	// The provided spec is not part of the decl.Spec slice.
+	panic("unreachable")
+}
+
+func getLineComment(spec ast.Spec) *ast.CommentGroup {
+	switch spec := spec.(type) {
+	case *ast.ValueSpec:
+		return spec.Comment
+	case *ast.TypeSpec:
+		return spec.Comment
+	default:
+		return nil
+	}
+}
+
+func getDocComment(spec ast.Spec) *ast.CommentGroup {
+	switch spec := spec.(type) {
+	case *ast.ValueSpec:
+		return spec.Doc
+	case *ast.TypeSpec:
+		return spec.Doc
+	default:
+		return nil
+	}
+}
+
 // parseFull fully parses the file corresponding to position pos (for
 // which fset provides file/line information).
 //

gopls/internal/golang/hover_test.go

@@ -0,0 +1,173 @@
+package golang
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func TestGroupComment(t *testing.T) {
+	cases := []struct {
+		src          string
+		groupComment []string
+	}{
+		{
+			src: `package test
+const (
+	A = iota
+	B
+	C
+)
+`,
+			groupComment: []string{"", "", ""},
+		},
+		{
+			src: `package test
+const (
+	// doc comment
+	A = iota
+	B
+	C
+)
+`,
+			groupComment: []string{"", "", ""},
+		},
+		{
+			src: `package test
+const (
+	// doc comment
+	/* doc comment */
+	A = iota
+	B
+	C
+)
+`,
+			groupComment: []string{"", "", ""},
+		},
+		{
+			src: `package test
+const (
+	/* group */
+	A = iota
+	B
+	C
+)
+`,
+			groupComment: []string{"/* group */", "/* group */", "/* group */"},
+		},
+		{
+			src: `package test
+const (
+	/* group */
+	// doc comment
+	A = iota // line comment
+	B        // line comment
+	C        // line comment
+)
+`,
+			groupComment: []string{"/* group */", "/* group */", "/* group */"},
+		},
+		{
+			src: `package test
+const (
+	/* group */
+	A = iota
+	B
+	C
+
+	D
+	E
+	F
+)
+`,
+			groupComment: []string{"/* group */", "/* group */", "/* group */", "", "", ""},
+		},
+		{
+			src: `package test
+const (
+	/* foo */
+	A = iota
+	C
+
+	/* bar */
+	D
+	E
+)
+`,
+			groupComment: []string{"foo", "foo", "bar", "bar"},
+		},
+		{
+			src: `package test
+const (
+	/* foo */
+	A = iota
+	B
+	/* bar */
+	D
+	E
+)
+`,
+			groupComment: []string{"foo", "foo", "bar", "bar"},
+		},
+		{
+			src: `package test
+const (
+	/* foo */
+	A = iota
+	// doc comment
+	C
+
+	/* bar */
+	D
+	// doc comment
+	E // line comment
+)
+`,
+			groupComment: []string{"foo", "foo", "bar", "bar"},
+		},
+		{
+			src: `package test
+const (
+	/* foo */
+	A = iota
+	B
+
+	/* bar */
+	D
+	E
+
+	F
+)
+`,
+			groupComment: []string{"foo", "foo", "bar", "bar", ""},
+		},
+	}
+
+	for i, tt := range cases {
+		fset := token.NewFileSet()
+		f, err := parser.ParseFile(fset, "test.go", tt.src, parser.SkipObjectResolution|parser.ParseComments)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			if testing.Verbose() {
+				t.Logf("src:\n%s", tt.src)
+			}
+			decl := f.Decls[0].(*ast.GenDecl)
+			for i, expect := range tt.groupComment {
+				gc := specGroupComment(fset, decl, decl.Specs[i])
+				var got string
+				if gc != nil {
+					got = gc.Text
+				}
+				if !strings.Contains(got, expect) {
+					t.Errorf("specGroupComment(%v) = %q; want = %q", i, got, expect)
+				}
+			}
+		})
+	}
+}