proc: replace debug/dwarf with golang.org/x/debug/dwarf

Typedefs that resolve to slices are not recorded in DWARF as typedefs
but instead as structs in a way that there is no way to know they
are really slices using debug/dwarf.
Using golang.org/x/debug/dwarf instead this problem is solved and
as a bonus some types are printed with a nicer names: (struct string
→ string, struct []int → []int, etc)

 Fixes go-delve#356 and go-delve#293

_fixtures/testvariables3.go

@@ -53,6 +53,14 @@ type benchstruct struct {
 	b [64]byte
 }
 
+type Item struct {
+	Name   string
+	Route  string
+	Active int
+}
+
+type Menu []Item
+
 func main() {
 	i1 := 1
 	i2 := 2
@@ -145,6 +153,11 @@ func main() {
 	mapinf["inf"] = mapinf
 	var bencharr [64]benchstruct
 	var benchparr [64]*benchstruct
+	mainMenu := Menu{
+		{Name: "home", Route: "/", Active: 1},
+		{Name: "About", Route: "/about", Active: 1},
+		{Name: "Login", Route: "/login", Active: 1},
+	}
 
 	for i := range benchparr {
 		benchparr[i] = &benchstruct{}
@@ -156,5 +169,5 @@ func main() {
 		fmt.Println(amb1)
 	}
 	runtime.Breakpoint()
-	fmt.Println(i1, i2, i3, p1, amb1, s1, s3, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf)
+	fmt.Println(i1, i2, i3, p1, amb1, s1, s3, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf, mainMenu)
 }

dwarf/reader/reader.go

@@ -1,9 +1,9 @@
 package reader
 
 import (
-	"debug/dwarf"
 	"errors"
 	"fmt"
+	"golang.org/x/debug/dwarf"
 
 	"github.com/derekparker/delve/dwarf/op"
 )

proc/eval.go

@@ -2,14 +2,14 @@ package proc
 
 import (
 	"bytes"
-	"debug/dwarf"
 	"encoding/binary"
 	"fmt"
 	"go/ast"
 	"go/constant"
 	"go/parser"
 	"go/printer"
 	"go/token"
+	"golang.org/x/debug/dwarf"
 	"reflect"
 
 	"github.com/derekparker/delve/dwarf/reader"
@@ -142,9 +142,6 @@ func (scope *EvalScope) evalTypeCast(node *ast.CallExpr) (*Variable, error) {
 
 	switch ttyp := typ.(type) {
 	case *dwarf.PtrType:
-		if ptrTypeKind(ttyp) != reflect.Ptr {
-			return nil, converr
-		}
 		switch argv.Kind {
 		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 			// ok
@@ -1002,7 +999,7 @@ func (v *Variable) isType(typ dwarf.Type, kind reflect.Kind) error {
 		return converr
 	}
 
-	switch t := typ.(type) {
+	switch typ.(type) {
 	case *dwarf.IntType:
 		if v.Value.Kind() != constant.Int {
 			return converr
@@ -1019,10 +1016,7 @@ func (v *Variable) isType(typ dwarf.Type, kind reflect.Kind) error {
 		if v.Value.Kind() != constant.Bool {
 			return converr
 		}
-	case *dwarf.StructType:
-		if t.StructName != "string" {
-			return converr
-		}
+	case *dwarf.StringType:
 		if v.Value.Kind() != constant.String {
 			return converr
 		}
@@ -1092,14 +1086,17 @@ func (v *Variable) reslice(low int64, high int64) (*Variable, error) {
 
 	typ := v.DwarfType
 	if _, isarr := v.DwarfType.(*dwarf.ArrayType); isarr {
-		typ = &dwarf.StructType{
-			CommonType: dwarf.CommonType{
-				ByteSize: 24,
-				Name:     "",
+		typ = &dwarf.SliceType{
+			StructType: dwarf.StructType{
+				CommonType: dwarf.CommonType{
+					ByteSize: 24,
+					Name:     "",
+				},
+				StructName: fmt.Sprintf("[]%s", v.fieldType),
+				Kind:       "struct",
+				Field:      nil,
 			},
-			StructName: fmt.Sprintf("[]%s", v.fieldType),
-			Kind:       "struct",
-			Field:      nil,
+			ElemType: v.fieldType,
 		}
 	}
 

proc/proc.go

@@ -1,14 +1,14 @@
 package proc
 
 import (
-	"debug/dwarf"
 	"debug/gosym"
 	"encoding/binary"
 	"errors"
 	"fmt"
 	"go/ast"
 	"go/constant"
 	"go/token"
+	"golang.org/x/debug/dwarf"
 	"os"
 	"path/filepath"
 	"runtime"

proc/proc_darwin.go

@@ -7,9 +7,9 @@ package proc
 import "C"
 import (
 	"debug/gosym"
-	"debug/macho"
 	"errors"
 	"fmt"
+	"golang.org/x/debug/macho"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -273,11 +273,10 @@ func (dbp *Process) findExecutable(path string) (*macho.File, error) {
 	if err != nil {
 		return nil, err
 	}
-	data, err := exe.DWARF()
+	dbp.dwarf, err = exe.DWARF()
 	if err != nil {
 		return nil, err
 	}
-	dbp.dwarf = data
 	return exe, nil
 }
 

proc/proc_linux.go

@@ -1,10 +1,10 @@
 package proc
 
 import (
-	"debug/elf"
 	"debug/gosym"
 	"errors"
 	"fmt"
+	"golang.org/x/debug/elf"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -168,11 +168,10 @@ func (dbp *Process) findExecutable(path string) (*elf.File, error) {
 	if err != nil {
 		return nil, err
 	}
-	data, err := elfFile.DWARF()
+	dbp.dwarf, err = elfFile.DWARF()
 	if err != nil {
 		return nil, err
 	}
-	dbp.dwarf = data
 	return elfFile, nil
 }
 

proc/proc_test.go

@@ -1426,3 +1426,15 @@ func TestCondBreakpointError(t *testing.T) {
 		}
 	})
 }
+
+func TestIssue356(t *testing.T) {
+	// slice with a typedef does not get printed correctly
+	withTestProcess("testvariables3", t, func(p *Process, fixture protest.Fixture) {
+		assertNoError(p.Continue(), t, "Continue() returned an error")
+		mmvar, err := evalVariable(p, "mainMenu")
+		assertNoError(err, t, "EvalVariable()")
+		if mmvar.Kind != reflect.Slice {
+			t.Fatalf("Wrong kind for mainMenu: %v\n", mmvar.Kind)
+		}
+	})
+}

proc/proc_windows.go

@@ -15,6 +15,8 @@ import (
 	"syscall"
 	"unsafe"
 
+	"golang.org/x/debug/dwarf"
+
 	sys "golang.org/x/sys/windows"
 
 	"github.com/derekparker/delve/dwarf/frame"
@@ -304,14 +306,40 @@ func (dbp *Process) findExecutable(path string) (*pe.File, error) {
 	if err != nil {
 		return nil, err
 	}
-	data, err := peFile.DWARF()
+	dbp.dwarf, err = dwarfFromPE(peFile)
 	if err != nil {
 		return nil, err
 	}
-	dbp.dwarf = data
 	return peFile, nil
 }
 
+// Adapted from src/debug/pe/file.go: pe.(*File).DWARF()
+func dwarfFromPE(f *pe.File) (*dwarf.Data, error) {
+	// There are many other DWARF sections, but these
+	// are the ones the debug/dwarf package uses.
+	// Don't bother loading others.
+	var names = [...]string{"abbrev", "info", "line", "str"}
+	var dat [len(names)][]byte
+	for i, name := range names {
+		name = ".debug_" + name
+		s := f.Section(name)
+		if s == nil {
+			continue
+		}
+		b, err := s.Data()
+		if err != nil && uint32(len(b)) < s.Size {
+			return nil, err
+		}
+		if 0 < s.VirtualSize && s.VirtualSize < s.Size {
+			b = b[:s.VirtualSize]
+		}
+		dat[i] = b
+	}
+
+	abbrev, info, line, str := dat[0], dat[1], dat[2], dat[3]
+	return dwarf.New(abbrev, nil, nil, info, line, nil, nil, str)
+}
+
 func (dbp *Process) waitForDebugEvent() (threadID, exitCode int, err error) {
 	var debugEvent C.DEBUG_EVENT
 	for {

proc/threads.go

@@ -1,11 +1,12 @@
 package proc
 
 import (
-	"debug/dwarf"
 	"debug/gosym"
 	"encoding/binary"
 	"fmt"
+	"golang.org/x/debug/dwarf"
 	"path/filepath"
+	"reflect"
 	"runtime"
 
 	"github.com/derekparker/delve/dwarf/frame"
@@ -284,7 +285,7 @@ func (thread *Thread) newGVariable(gaddr uintptr, deref bool) (*Variable, error)
 	name := ""
 
 	if deref {
-		typ = &dwarf.PtrType{dwarf.CommonType{int64(thread.dbp.arch.PtrSize()), ""}, typ}
+		typ = &dwarf.PtrType{dwarf.CommonType{int64(thread.dbp.arch.PtrSize()), "", reflect.Ptr, 0}, typ}
 	} else {
 		name = "runtime.curg"
 	}

proc/types.go

@@ -1,8 +1,9 @@
 package proc
 
 import (
-	"debug/dwarf"
 	"go/ast"
+	"golang.org/x/debug/dwarf"
+	"reflect"
 	"strings"
 )
 
@@ -17,7 +18,7 @@ func (dbp *Process) findType(name string) (dwarf.Type, error) {
 }
 
 func (dbp *Process) pointerTo(typ dwarf.Type) dwarf.Type {
-	return &dwarf.PtrType{dwarf.CommonType{int64(dbp.arch.PtrSize()), ""}, typ}
+	return &dwarf.PtrType{dwarf.CommonType{int64(dbp.arch.PtrSize()), "", reflect.Ptr, 0}, typ}
 }
 
 func (dbp *Process) findTypeExpr(expr ast.Expr) (dwarf.Type, error) {