cmd/link/internal/ld: fix c-archive mach-o compatibility

These workarounds predate proper DWARF support
and are no longer necessary.

Before this patch, running `/usr/bin/symbols go.o`
using the object in the c-archive would fail, causing
App Store rejections.

Fixes #31022 #28997

Change-Id: I6a210b6369c13038777c6e21e874e81afcb50c2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/170377
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/link/dwarf_test.go

@@ -5,6 +5,7 @@
 package main
 
 import (
+	"bytes"
 	cmddwarf "cmd/internal/dwarf"
 	"cmd/internal/objfile"
 	"debug/dwarf"
@@ -86,6 +87,22 @@ func testDWARF(t *testing.T, buildmode string, expectDWARF bool, env ...string)
 				}
 				exe = filepath.Join(tmpDir, "go.o")
 			}
+
+			if runtime.GOOS == "darwin" {
+				if _, err = exec.LookPath("symbols"); err == nil {
+					// Ensure Apple's tooling can parse our object for symbols.
+					out, err = exec.Command("symbols", exe).CombinedOutput()
+					if err != nil {
+						t.Fatal(err)
+					} else {
+						if bytes.HasPrefix(out, []byte("Unable to find file")) {
+							// This failure will cause the App Store to reject our binaries.
+							t.Fatalf("/usr/bin/symbols %v: failed to parse file", filepath.Base(exe))
+						}
+					}
+				}
+			}
+
 			f, err := objfile.Open(exe)
 			if err != nil {
 				t.Fatal(err)
@@ -148,6 +165,9 @@ func testDWARF(t *testing.T, buildmode string, expectDWARF bool, env ...string)
 
 func TestDWARF(t *testing.T) {
 	testDWARF(t, "", true)
+	if runtime.GOOS == "darwin" {
+		testDWARF(t, "c-archive", true)
+	}
 }
 
 func TestDWARFiOS(t *testing.T) {

src/cmd/link/internal/ld/macho.go

@@ -560,12 +560,8 @@ func Asmbmacho(ctxt *Link) {
 		ms = newMachoSeg("", 40)
 
 		ms.fileoffset = Segtext.Fileoff
-		if ctxt.Arch.Family == sys.ARM || ctxt.BuildMode == BuildModeCArchive {
-			ms.filesize = Segdata.Fileoff + Segdata.Filelen - Segtext.Fileoff
-		} else {
-			ms.filesize = Segdwarf.Fileoff + Segdwarf.Filelen - Segtext.Fileoff
-			ms.vsize = Segdwarf.Vaddr + Segdwarf.Length - Segtext.Vaddr
-		}
+		ms.filesize = Segdwarf.Fileoff + Segdwarf.Filelen - Segtext.Fileoff
+		ms.vsize = Segdwarf.Vaddr + Segdwarf.Length - Segtext.Vaddr
 	}
 
 	/* segment for zero page */