From f86a35be5536b37c3a1d667a043ad060ae1372c3 Mon Sep 17 00:00:00 2001
From: Shane Carr <shane@unicode.org>
Date: Wed, 9 May 2018 02:26:14 +0000
Subject: [PATCH] ICU-13644 Returning bogus string when toSkeleton() fails.

X-SVN-Rev: 41367
---
 icu4c/source/i18n/number_fluent.cpp           |  2 +-
 icu4c/source/test/intltest/numbertest_api.cpp | 14 ++++++++++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/icu4c/source/i18n/number_fluent.cpp b/icu4c/source/i18n/number_fluent.cpp
index 597df575870..0d3ee2d1238 100644
--- a/icu4c/source/i18n/number_fluent.cpp
+++ b/icu4c/source/i18n/number_fluent.cpp
@@ -320,7 +320,7 @@ Derived NumberFormatterSettings<Derived>::macros(impl::MacroProps&& macros)&& {
 template<typename Derived>
 UnicodeString NumberFormatterSettings<Derived>::toSkeleton(UErrorCode& status) const {
     if (fMacros.copyErrorTo(status)) {
-        return {};
+        return ICU_Utility::makeBogusString();
     }
     return skeleton::generate(fMacros, status);
 }
diff --git a/icu4c/source/test/intltest/numbertest_api.cpp b/icu4c/source/test/intltest/numbertest_api.cpp
index 1295d29ce24..b8ddd44b9f3 100644
--- a/icu4c/source/test/intltest/numbertest_api.cpp
+++ b/icu4c/source/test/intltest/numbertest_api.cpp
@@ -2192,6 +2192,17 @@ void NumberFormatterApiTest::errors() {
             U_NUMBER_ARG_OUTOFBOUNDS_ERROR,
             status);
 
+    // Skeleton string
+    status = U_ZERO_ERROR;
+    UnicodeString output = lnf.toSkeleton(status);
+    assertEquals(
+            "Should fail on toSkeleton terminal method with correct error code",
+            U_NUMBER_ARG_OUTOFBOUNDS_ERROR,
+            status);
+    assertTrue(
+            "Terminal toSkeleton on error object should be bogus",
+            output.isBogus());
+
     // FieldPosition
     status = U_ZERO_ERROR;
     FieldPosition fp;
@@ -2212,8 +2223,7 @@ void NumberFormatterApiTest::errors() {
 
     // Appendable
     status = U_ZERO_ERROR;
-    UnicodeString output;
-    UnicodeStringAppendable appendable(output);
+    UnicodeStringAppendable appendable(output.remove());
     fn.appendTo(appendable, status);
     assertEquals(
             "Should fail on Appendable terminal method with correct error code",