go/analysis/passes/fieldalignment: filter comments from suggested fix

go/ast has problem with comments from its design, for now, best way is
to get rid of the comments.

See golang/go#20744 for general problem.

Updates golang/go#43233

Change-Id: I7c29dc9d0573f5f894859cd8b24e010a777ebba2
Reviewed-on: https://go-review.googlesource.com/c/tools/+/278872
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

go/analysis/passes/fieldalignment/fieldalignment.go

@@ -76,6 +76,9 @@ func fieldalignment(pass *analysis.Pass, node *ast.StructType, typ *types.Struct
 	// TODO: Preserve multi-named fields instead of flattening.
 	var flat []*ast.Field
 	for _, f := range node.Fields.List {
+		// TODO: Preserve comment, for now get rid of them.
+		//       See https://github.com/golang/go/issues/20744
+		f.Comment = nil
 		if len(f.Names) <= 1 {
 			flat = append(flat, f)
 			continue

go/analysis/passes/fieldalignment/testdata/src/a/a_amd64.go

@@ -38,3 +38,11 @@ type MultiField struct { // want "struct of size 40 could be 24"
 	a3     [3]bool
 	_      [0]func()
 }
+
+type Issue43233 struct { // want "struct with 88 pointer bytes could be 80"
+	AllowedEvents []*string // allowed events
+	BlockedEvents []*string // blocked events
+	APIVersion    string    `mapstructure:"api_version"`
+	BaseURL       string    `mapstructure:"base_url"`
+	AccessToken   string    `mapstructure:"access_token"`
+}

go/analysis/passes/fieldalignment/testdata/src/a/a_amd64.go.golden

@@ -39,3 +39,11 @@ type MultiField struct {
 	a3 [3]bool
 	b  bool
 }
+
+type Issue43233 struct {
+	APIVersion    string `mapstructure:"api_version"`
+	BaseURL       string `mapstructure:"base_url"`
+	AccessToken   string `mapstructure:"access_token"`
+	AllowedEvents []*string
+	BlockedEvents []*string
+}