From fe4e86fb58338ec41a0c027fb077791d4efa392c Mon Sep 17 00:00:00 2001
From: Fredrik Roubert <roubert@google.com>
Date: Tue, 7 Jan 2025 19:15:44 +0900
Subject: [PATCH] ICU-22954 Revert to using std::u16string instead of
 UnicodeString.

It seems as if icu4c-windows-cygwin-gcc only crashes if the constructor
is defined inline, so with the exception of the constructor this commit
reverts the code to commit 320220ef694123393a5c5d6eb6a1c7536fc57aba.
---
 icu4c/source/tools/ctestfw/tstdtmod.cpp      |  9 ++++-----
 icu4c/source/tools/ctestfw/unicode/testlog.h | 14 ++------------
 2 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/icu4c/source/tools/ctestfw/tstdtmod.cpp b/icu4c/source/tools/ctestfw/tstdtmod.cpp
index 15e8913d2b8c..66ab79a7db50 100644
--- a/icu4c/source/tools/ctestfw/tstdtmod.cpp
+++ b/icu4c/source/tools/ctestfw/tstdtmod.cpp
@@ -11,7 +11,6 @@
 #include <stdarg.h>
 
 #include "unicode/tstdtmod.h"
-#include "unicode/unistr.h"
 #include "cmemory.h"
 #include <stdio.h>
 #include "cstr.h"
@@ -21,7 +20,7 @@ TestLog::~TestLog() {}
 
 IcuTestErrorCode::IcuTestErrorCode(TestLog &callingTestClass, const char *callingTestName)
     : errorCode(U_ZERO_ERROR),
-      testClass(callingTestClass), testName(callingTestName), scopeMessage(*new UnicodeString) {
+      testClass(callingTestClass), testName(callingTestName), scopeMessage() {
 }
 
 IcuTestErrorCode::~IcuTestErrorCode() {
@@ -29,7 +28,6 @@ IcuTestErrorCode::~IcuTestErrorCode() {
     if(isFailure()) {
         errlog(false, u"destructor: expected success", nullptr);
     }
-    delete &scopeMessage;
 }
 
 UErrorCode IcuTestErrorCode::reset() {
@@ -126,7 +124,8 @@ UBool IcuTestErrorCode::expectErrorAndReset(UErrorCode expectedError, const char
 }
 
 void IcuTestErrorCode::setScope(const char* message) {
-    scopeMessage.remove().append({ message, -1, US_INV });
+    UnicodeString us(message, -1, US_INV);
+    scopeMessage = us;
 }
 
 void IcuTestErrorCode::setScope(std::u16string_view message) {
@@ -142,7 +141,7 @@ void IcuTestErrorCode::errlog(UBool dataErr, std::u16string_view mainMessage, co
     msg.append(u' ').append(mainMessage);
     msg.append(u" but got error: ").append(UnicodeString(errorName(), -1, US_INV));
 
-    if (!scopeMessage.isEmpty()) {
+    if (!scopeMessage.empty()) {
         msg.append(u" scope: ").append(scopeMessage);
     }
 
diff --git a/icu4c/source/tools/ctestfw/unicode/testlog.h b/icu4c/source/tools/ctestfw/unicode/testlog.h
index 44e99954f91c..1b5494bc3fe9 100644
--- a/icu4c/source/tools/ctestfw/unicode/testlog.h
+++ b/icu4c/source/tools/ctestfw/unicode/testlog.h
@@ -13,6 +13,7 @@
 #ifndef U_TESTFW_TESTLOG
 #define U_TESTFW_TESTLOG
 
+#include <string>
 #include <string_view>
 #include "unicode/utypes.h"
 #include "unicode/testtype.h"
@@ -34,10 +35,6 @@ class T_CTEST_EXPORT_API TestLog {
 // unit tests that work without U_SHOW_CPLUSPLUS_API.
 // So instead we *copy* the ErrorCode API.
 
-U_NAMESPACE_BEGIN
-class UnicodeString;
-U_NAMESPACE_END
-
 class T_CTEST_EXPORT_API IcuTestErrorCode {
 public:
     IcuTestErrorCode(const IcuTestErrorCode&) = delete;
@@ -76,14 +73,7 @@ class T_CTEST_EXPORT_API IcuTestErrorCode {
     UErrorCode errorCode;
     TestLog &testClass;
     const char *const testName;
-
-    // It's not possible to use a UnicodeString member directly here because
-    // that won't work without U_SHOW_CPLUSPLUS_API, but it's also not possible
-    // to use a std::u16string member because for unknown reasons that leads to
-    // a crash in the icu4c-windows-cygwin-gcc CI job. As a workaround, the
-    // UnicodeString class is forward declared to make it possible to use a
-    // reference here and then heap allocate the object in the constructor.
-    UnicodeString& scopeMessage;
+    std::u16string scopeMessage;
 
     void errlog(UBool dataErr, std::u16string_view mainMessage, const char* extraMessage) const;
 };