go/internal/gccgoimporter: test case for issue 30628

Test case for a panic/crash in gccgoimporter caused by incorrect gccgo
export data emission. Note that the *.gox file checked in contains the
correct export data; the main intent of the test is to make sure that
gccgo produces the right export data when run on the Go source.

Updates #30628

Change-Id: I29c0c17b81a43f92ff64fbfcdc58fdb46a5be370
Reviewed-on: https://go-review.googlesource.com/c/go/+/165739
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/go/internal/gccgoimporter/importer_test.go

@@ -91,6 +91,7 @@ var importerTests = [...]importerTest{
 	{pkgpath: "v1reflect", name: "Type", want: "type Type interface{Align() int; AssignableTo(u Type) bool; Bits() int; ChanDir() ChanDir; Elem() Type; Field(i int) StructField; FieldAlign() int; FieldByIndex(index []int) StructField; FieldByName(name string) (StructField, bool); FieldByNameFunc(match func(string) bool) (StructField, bool); Implements(u Type) bool; In(i int) Type; IsVariadic() bool; Key() Type; Kind() Kind; Len() int; Method(int) Method; MethodByName(string) (Method, bool); Name() string; NumField() int; NumIn() int; NumMethod() int; NumOut() int; Out(i int) Type; PkgPath() string; Size() uintptr; String() string; common() *commonType; rawString() string; runtimeType() *runtimeType; uncommon() *uncommonType}"},
 	{pkgpath: "nointerface", name: "I", want: "type I int"},
 	{pkgpath: "issue29198", name: "FooServer", want: "type FooServer struct{FooServer *FooServer; user string; ctx context.Context}"},
+	{pkgpath: "issue30628", name: "Apple", want: "type Apple struct{hey sync.RWMutex; x int; RQ [517]struct{Count uintptr; NumBytes uintptr; Last uintptr}}"},
 }
 
 func TestGoxImporter(t *testing.T) {

src/go/internal/gccgoimporter/testdata/issue30628.go

+package issue30628
+
+import (
+	"os"
+	"sync"
+)
+
+const numR = int32(os.O_TRUNC + 5)
+
+type Apple struct {
+	hey sync.RWMutex
+	x   int
+	RQ  [numR]struct {
+		Count    uintptr
+		NumBytes uintptr
+		Last     uintptr
+	}
+}

src/go/internal/gccgoimporter/testdata/issue30628.gox

+v3;
+package issue30628
+pkgpath issue30628
+import os os "os"
+import sync sync "sync"
+init cpu internal..z2fcpu..import poll internal..z2fpoll..import testlog internal..z2ftestlog..import io io..import os os..import runtime runtime..import sys runtime..z2finternal..z2fsys..import sync sync..import syscall syscall..import time time..import
+init_graph 1 0 1 3 1 5 1 6 1 7 1 8 1 9 3 0 3 5 3 6 3 7 4 0 4 1 4 2 4 3 4 5 4 6 4 7 4 8 4 9 5 0 5 6 7 0 7 5 7 6 8 0 8 5 8 6 8 7 9 0 9 5 9 6 9 7 9 8
+types 13 2 24 84 208 17 30 41 147 86 17 64 25 75
+type 1 "Apple" <type 2>
+type 2 struct { .issue30628.hey <type 3>; .issue30628.x <type -11>; RQ <type 11>; }
+type 3 "sync.RWMutex" <type 7>
+ func (rw <type 4>) Lock ()
+ func (rw <esc:0x12> <type 4>) RLocker () ($ret8 <type 5>)
+ func (rw <type 4>) RUnlock ()
+ func (rw <type 4>) Unlock ()
+ func (rw <type 4>) RLock ()
+type 4 *<type 3>
+type 5 "sync.Locker" <type 6>
+type 6 interface { Lock (); Unlock (); }
+type 7 struct { .sync.w <type 8>; .sync.writerSem <type -7>; .sync.readerSem <type -7>; .sync.readerCount <type -3>; .sync.readerWait <type -3>; }
+type 8 "sync.Mutex" <type 10>
+ func (m <type 9>) Unlock ()
+ func (m <type 9>) Lock ()
+type 9 *<type 8>
+type 10 struct { .sync.state <type -3>; .sync.sema <type -7>; }
+type 11 [517 ] <type 12>
+type 12 struct { Count <type -13>; NumBytes <type -13>; Last <type -13>; }
+checksum 199DCF6D3EE2FCF39F715B4E42B5F87F5B15D3AF