1 files changed, 20 insertions, 1 deletions
diff --git a/src/go/internal/gcimporter/ureader.go b/src/go/internal/gcimporter/ureader.go
index 5e133f890b..97f0664fe3 100644
--- a/src/go/internal/gcimporter/ureader.go
+++ b/src/go/internal/gcimporter/ureader.go
@@ -31,6 +31,8 @@ type pkgReader struct {
 	// laterFns holds functions that need to be invoked at the end of
 	// import reading.
 	laterFns []func()
+	// laterFors is used in case of 'type A B' to ensure that B is processed before A.
+	laterFors map[types.Type]int
 }
 
 // later adds a function to be invoked at the end of import reading.
@@ -38,6 +40,15 @@ func (pr *pkgReader) later(fn func()) {
 	pr.laterFns = append(pr.laterFns, fn)
 }
 
+// laterFor adds a function to be invoked at the end of import reading, and records the type that function is finishing.
+func (pr *pkgReader) laterFor(t types.Type, fn func()) {
+	if pr.laterFors == nil {
+		pr.laterFors = make(map[types.Type]int)
+	}
+	pr.laterFors[t] = len(pr.laterFns)
+	pr.laterFns = append(pr.laterFns, fn)
+}
+
 // readUnifiedPackage reads a package description from the given
 // unified IR export data decoder.
 func readUnifiedPackage(fset *token.FileSet, ctxt *types.Context, imports map[string]*types.Package, input pkgbits.PkgDecoder) *types.Package {
@@ -487,7 +498,15 @@ func (pr *pkgReader) objIdx(idx pkgbits.Index) (*types.Package, string) {
 			// unit tests expected that), but cmd/compile doesn't care
 			// about it, so maybe we can avoid worrying about that here.
 			rhs := r.typ()
-			r.p.later(func() {
+			pk := r.p
+			pk.laterFor(named, func() {
+				// First be sure that the rhs is initialized, if it needs to be initialized.
+				delete(pk.laterFors, named) // prevent cycles
+				if i, ok := pk.laterFors[rhs]; ok {
+					f := pk.laterFns[i]
+					pk.laterFns[i] = func() {} // function is running now, so replace it with a no-op
+					f()                        // initialize RHS
+				}
 				underlying := rhs.Underlying()
 				named.SetUnderlying(underlying)
 			})