1 files changed, 27 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go
index eb9a8a6c9b..2dbb938191 100644
--- a/src/cmd/compile/internal/reflectdata/reflect.go
+++ b/src/cmd/compile/internal/reflectdata/reflect.go
@@ -1142,6 +1142,33 @@ func writeType(t *types.Type) *obj.LSym {
 	// for security, only the exported fields.
 	case types.TSTRUCT:
 		fields := t.Fields().Slice()
+
+		// omitFieldForAwfulBoringCryptoKludge reports whether
+		// the field t should be omitted from the reflect data.
+		// In the crypto/... packages we omit an unexported field
+		// named "boring", to keep from breaking client code that
+		// expects rsa.PublicKey etc to have only public fields.
+		// As the name suggests, this is an awful kludge, but it is
+		// limited to the dev.boringcrypto branch and avoids
+		// much more invasive effects elsewhere.
+		omitFieldForAwfulBoringCryptoKludge := func(t *types.Field) bool {
+			if t.Sym == nil || t.Sym.Name != "boring" || t.Sym.Pkg == nil {
+				return false
+			}
+			path := t.Sym.Pkg.Path
+			if t.Sym.Pkg == types.LocalPkg {
+				path = base.Ctxt.Pkgpath
+			}
+			return strings.HasPrefix(path, "crypto/")
+		}
+		newFields := fields[:0:0]
+		for _, t1 := range fields {
+			if !omitFieldForAwfulBoringCryptoKludge(t1) {
+				newFields = append(newFields, t1)
+			}
+		}
+		fields = newFields
+
 		for _, t1 := range fields {
 			writeType(t1.Type)
 		}