From 4f72eea0261888239ce7822ba19af222eed22a48 Mon Sep 17 00:00:00 2001
From: Robin Leroy <egg.robin.leroy@gmail.com>
Date: Tue, 24 Sep 2019 17:38:26 +0200
Subject: [PATCH] ICU-20831 Make *fCapitalizationBrkIter const, eliminating a
 data race in SimpleDateFormat::format.

---
 icu4c/source/i18n/smpdtfmt.cpp       | 4 +++-
 icu4c/source/i18n/unicode/smpdtfmt.h | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/icu4c/source/i18n/smpdtfmt.cpp b/icu4c/source/i18n/smpdtfmt.cpp
index b8edff42098..5fcbb5875b2 100644
--- a/icu4c/source/i18n/smpdtfmt.cpp
+++ b/icu4c/source/i18n/smpdtfmt.cpp
@@ -1981,9 +1981,11 @@ SimpleDateFormat::subFormat(UnicodeString &appendTo,
                 break;
         }
         if (titlecase) {
+            BreakIterator* const mutableCapitalizationBrkIter = fCapitalizationBrkIter->clone();
             UnicodeString firstField(appendTo, beginOffset);
-            firstField.toTitle(fCapitalizationBrkIter, fLocale, U_TITLECASE_NO_LOWERCASE | U_TITLECASE_NO_BREAK_ADJUSTMENT);
+            firstField.toTitle(mutableCapitalizationBrkIter, fLocale, U_TITLECASE_NO_LOWERCASE | U_TITLECASE_NO_BREAK_ADJUSTMENT);
             appendTo.replaceBetween(beginOffset, appendTo.length(), firstField);
+            delete mutableCapitalizationBrkIter;
         }
     }
 #endif
diff --git a/icu4c/source/i18n/unicode/smpdtfmt.h b/icu4c/source/i18n/unicode/smpdtfmt.h
index 8a7a17683ce..79fa817d5af 100644
--- a/icu4c/source/i18n/unicode/smpdtfmt.h
+++ b/icu4c/source/i18n/unicode/smpdtfmt.h
@@ -1645,7 +1645,7 @@ private:
 
     UBool fHaveDefaultCentury;
 
-    BreakIterator* fCapitalizationBrkIter;
+    const BreakIterator* fCapitalizationBrkIter;
 };
 
 inline UDate