internal/gocore: use AttrGoKind to fix named slice type

Use AttrGoKind instead of the name matching to check the slice and string type.

For golang/go#57447.

Change-Id: I8765aa1a6315609b3476b8b84c27130629847235
Reviewed-on: https://go-review.googlesource.com/c/debug/+/593680
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Tim King <taking@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>

internal/gocore/dwarf.go

@@ -15,6 +15,10 @@ import (
 	"golang.org/x/debug/internal/core"
 )
 
+const (
+	AttrGoKind dwarf.Attr = 0x2900
+)
+
 // read DWARF types from core dump.
 func (p *Process) readDWARFTypes() {
 	d, _ := p.proc.DWARF()
@@ -34,6 +38,9 @@ func (p *Process) readDWARFTypes() {
 				continue
 			}
 			t := &Type{Name: gocoreName(dt), Size: dwarfSize(dt, p.proc.PtrSize())}
+			if goKind, ok := e.Val(AttrGoKind).(int64); ok {
+				t.goKind = reflect.Kind(goKind)
+			}
 			p.dwarfMap[dt] = t
 			types = append(types, t)
 		}
@@ -112,13 +119,12 @@ func (p *Process) readDWARFTypes() {
 		if t.Kind != KindStruct {
 			continue
 		}
-		if t.Name == "string" { // TODO: also "struct runtime.stringStructDWARF" ?
+		switch t.goKind {
+		case reflect.String:
 			t.Kind = KindString
 			t.Elem = t.Fields[0].Type.Elem // TODO: check that it is always uint8.
 			t.Fields = nil
-		}
-		if len(t.Name) >= 9 && t.Name[:9] == "struct []" ||
-			len(t.Name) >= 2 && t.Name[:2] == "[]" {
+		case reflect.Slice:
 			t.Kind = KindSlice
 			t.Elem = t.Fields[0].Type.Elem
 			t.Fields = nil

internal/gocore/type.go

@@ -6,6 +6,7 @@ package gocore
 
 import (
 	"fmt"
+	"reflect"
 	"regexp"
 	"strings"
 
@@ -18,7 +19,11 @@ import (
 type Type struct {
 	Name string
 	Size int64
-	Kind Kind
+	Kind Kind // common dwarf types.
+	// go-specific types obtained from AttrGoKind, such as string and slice.
+	// Kind and gokind are not correspond one to one, both need to be preserved now.
+	// For example, slices are described in dwarf by a 3-field struct, so its Kind is Struct and its goKind is Slice.
+	goKind reflect.Kind
 
 	// Fields only valid for a subset of kinds.
 	Count  int64   // for kind == KindArray