5 files changed, 56 insertions, 7 deletions

diff --git a/src/pkg/debug/dwarf/testdata/typedef.c b/src/pkg/debug/dwarf/testdata/typedef.c
index 664d021ced..f05f01564f 100644
--- a/src/pkg/debug/dwarf/testdata/typedef.c
+++ b/src/pkg/debug/dwarf/testdata/typedef.c
@@ -28,8 +28,13 @@ typedef struct my_struct {
 	volatile int vi;
 	char x : 1;
 	int y : 4;
+	int z[0];
 	long long array[40];
+	int zz[0];
 } t_my_struct;
+typedef struct my_struct1 {
+	int zz [1];
+} t_my_struct1;
 typedef union my_union {
 	volatile int vi;
 	char x : 1;
@@ -65,7 +70,8 @@ t_func_void_of_char *a9;
 t_func_void_of_void *a10;
 t_func_void_of_ptr_char_dots *a11;
 t_my_struct *a12;
-t_my_union *a12a;
+t_my_struct1 *a12a;
+t_my_union *a12b;
 t_my_enum *a13;
 t_my_list *a14;
 t_my_tree *a15;
diff --git a/src/pkg/debug/dwarf/testdata/typedef.elf b/src/pkg/debug/dwarf/testdata/typedef.elf
index 44df8da9bc..b2062d2c4b 100755
--- a/src/pkg/debug/dwarf/testdata/typedef.elf
+++ b/src/pkg/debug/dwarf/testdata/typedef.elf
diff --git a/src/pkg/debug/dwarf/testdata/typedef.macho b/src/pkg/debug/dwarf/testdata/typedef.macho
index 41019c1e14..f75afcccbf 100644
--- a/src/pkg/debug/dwarf/testdata/typedef.macho
+++ b/src/pkg/debug/dwarf/testdata/typedef.macho
diff --git a/src/pkg/debug/dwarf/type.go b/src/pkg/debug/dwarf/type.go
index 9be66658fe..4502355022 100644
--- a/src/pkg/debug/dwarf/type.go
+++ b/src/pkg/debug/dwarf/type.go
@@ -426,6 +426,8 @@ func (d *Data) Type(off Offset) (Type, error) {
 		t.StructName, _ = e.Val(AttrName).(string)
 		t.Incomplete = e.Val(AttrDeclaration) != nil
 		t.Field = make([]*StructField, 0, 8)
+		var lastFieldType Type
+		var lastFieldBitOffset int64
 		for kid := next(); kid != nil; kid = next() {
 			if kid.Tag == TagMember {
 				f := new(StructField)
@@ -444,11 +446,32 @@ func (d *Data) Type(off Offset) (Type, error) {
 						goto Error
 					}
 				}
+
+				haveBitOffset := false
 				f.Name, _ = kid.Val(AttrName).(string)
 				f.ByteSize, _ = kid.Val(AttrByteSize).(int64)
-				f.BitOffset, _ = kid.Val(AttrBitOffset).(int64)
+				f.BitOffset, haveBitOffset = kid.Val(AttrBitOffset).(int64)
 				f.BitSize, _ = kid.Val(AttrBitSize).(int64)
 				t.Field = append(t.Field, f)
+
+				bito := f.BitOffset
+				if !haveBitOffset {
+					bito = f.ByteOffset * 8
+				}
+				if bito == lastFieldBitOffset && t.Kind != "union" {
+					// Last field was zero width.  Fix array length.
+					// (DWARF writes out 0-length arrays as if they were 1-length arrays.)
+					zeroArray(lastFieldType)
+				}
+				lastFieldType = f.Type
+				lastFieldBitOffset = bito
+			}
+		}
+		if t.Kind != "union" {
+			b, ok := e.Val(AttrByteSize).(int64)
+			if ok && b*8 == lastFieldBitOffset {
+				// Final field must be zero width.  Fix array length.
+				zeroArray(lastFieldType)
 			}
 		}
 
@@ -579,3 +602,14 @@ Error:
 	delete(d.typeCache, off)
 	return nil, err
 }
+
+func zeroArray(t Type) {
+	for {
+		at, ok := t.(*ArrayType)
+		if !ok {
+			break
+		}
+		at.Count = 0
+		t = at.Type
+	}
+}
diff --git a/src/pkg/debug/dwarf/type_test.go b/src/pkg/debug/dwarf/type_test.go
index b9470a4fcb..b5b255f6f4 100644
--- a/src/pkg/debug/dwarf/type_test.go
+++ b/src/pkg/debug/dwarf/type_test.go
@@ -25,13 +25,22 @@ var typedefTests = map[string]string{
 	"t_func_void_of_char":                   "func(char) void",
 	"t_func_void_of_void":                   "func() void",
 	"t_func_void_of_ptr_char_dots":          "func(*char, ...) void",
-	"t_my_struct":                           "struct my_struct {vi volatile int@0; x char@4 : 1@7; y int@4 : 4@27; array [40]long long int@8}",
+	"t_my_struct":                           "struct my_struct {vi volatile int@0; x char@4 : 1@7; y int@4 : 4@27; z [0]int@8; array [40]long long int@8; zz [0]int@328}",
+	"t_my_struct1":                          "struct my_struct1 {zz [1]int@0}",
 	"t_my_union":                            "union my_union {vi volatile int@0; x char@0 : 1@7; y int@0 : 4@28; array [40]long long int@0}",
 	"t_my_enum":                             "enum my_enum {e1=1; e2=2; e3=-5; e4=1000000000000000}",
 	"t_my_list":                             "struct list {val short int@0; next *t_my_list@8}",
 	"t_my_tree":                             "struct tree {left *struct tree@0; right *struct tree@8; val long long unsigned int@16}",
 }
 
+// As Apple converts gcc to a clang-based front end
+// they keep breaking the DWARF output.  This map lists the
+// conversion from real answer to Apple answer.
+var machoBug = map[string]string{
+	"func(*char, ...) void":                                 "func(*char) void",
+	"enum my_enum {e1=1; e2=2; e3=-5; e4=1000000000000000}": "enum my_enum {e1=1; e2=2; e3=-5; e4=-1530494976}",
+}
+
 func elfData(t *testing.T, name string) *Data {
 	f, err := elf.Open(name)
 	if err != nil {
@@ -58,13 +67,13 @@ func machoData(t *testing.T, name string) *Data {
 	return d
 }
 
-func TestTypedefsELF(t *testing.T) { testTypedefs(t, elfData(t, "testdata/typedef.elf")) }
+func TestTypedefsELF(t *testing.T) { testTypedefs(t, elfData(t, "testdata/typedef.elf"), "elf") }
 
 func TestTypedefsMachO(t *testing.T) {
-	testTypedefs(t, machoData(t, "testdata/typedef.macho"))
+	testTypedefs(t, machoData(t, "testdata/typedef.macho"), "macho")
 }
 
-func testTypedefs(t *testing.T, d *Data) {
+func testTypedefs(t *testing.T, d *Data, kind string) {
 	r := d.Reader()
 	seen := make(map[string]bool)
 	for {
@@ -93,7 +102,7 @@ func testTypedefs(t *testing.T, d *Data) {
 					t.Errorf("multiple definitions for %s", t1.Name)
 				}
 				seen[t1.Name] = true
-				if typstr != want {
+				if typstr != want && (kind != "macho" || typstr != machoBug[want]) {
 					t.Errorf("%s:\n\thave %s\n\twant %s", t1.Name, typstr, want)
 				}
 			}