ICU-20646 make Edits::copyErrorTo() const
diff --git a/icu4c/source/common/edits.cpp b/icu4c/source/common/edits.cpp
index 00a8d60..95f0c19 100644
--- a/icu4c/source/common/edits.cpp
+++ b/icu4c/source/common/edits.cpp
@@ -243,7 +243,7 @@
     return TRUE;
 }
 
-UBool Edits::copyErrorTo(UErrorCode &outErrorCode) {
+UBool Edits::copyErrorTo(UErrorCode &outErrorCode) const {
     if (U_FAILURE(outErrorCode)) { return TRUE; }
     if (U_SUCCESS(errorCode_)) { return FALSE; }
     outErrorCode = errorCode_;
diff --git a/icu4c/source/common/unicode/edits.h b/icu4c/source/common/unicode/edits.h
index 01155ab..c3ceacc 100644
--- a/icu4c/source/common/unicode/edits.h
+++ b/icu4c/source/common/unicode/edits.h
@@ -162,7 +162,7 @@
      * @return TRUE if U_FAILURE(outErrorCode)
      * @stable ICU 59
      */
-    UBool copyErrorTo(UErrorCode &outErrorCode);
+    UBool copyErrorTo(UErrorCode &outErrorCode) const;
 
     /**
      * How much longer is the new text compared with the old text?