tdf#171370: a char must stringify to itself

Regression after commit 2143c0a694
(Simplify getter/setter implementations, 2025-06-03): sal_Unicode is
std::integral, and took the generic numeric path.

Co-authored-by: Andreas Heinisch <andreas.heinisch@yahoo.de>
Signed-off-by: Mike Kaganski <mike.kaganski@collabora.com>
Change-Id: I0c12590c06536f4d2efefcbe09657fff454ed2a4
Reviewed-on: https://gerrit.collaboraoffice.com/c/online/+/8798
Tested-by: Jenkins CPCI <releng@collaboraoffice.com>
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
(cherry picked from commit e725c25d6cb8c9cd1af08f70f6fea541df121b1d)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/209264
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>
Tested-by: Jenkins

basic/qa/basic_coverage/test_tdf171370.bas

@@ -0,0 +1,32 @@
+'
+' This file is part of the LibreOffice project.
+'
+' This Source Code Form is subject to the terms of the Mozilla Public
+' License, v. 2.0. If a copy of the MPL was not distributed with this
+' file, You can obtain one at http://mozilla.org/MPL/2.0/.
+'
+
+Option Explicit
+
+Function doUnitTest() As String
+    TestUtil.TestInit
+    verify_tdf171370
+    doUnitTest = TestUtil.GetResult()
+End Function
+
+Sub verify_tdf171370()
+    On Error GoTo errorHandler
+
+    Dim aEvent As New com.sun.star.awt.KeyEvent ' KeyChar is a UNO char
+    aEvent.KeyChar = 87
+
+    TestUtil.AssertEqual(TypeName(aEvent.KeyChar), "Char", "TypeName(aEvent.KeyChar)")
+    TestUtil.AssertEqual(CStr(aEvent.KeyChar), "W", "CStr(aEvent.KeyChar)")
+    TestUtil.AssertEqual("" & aEvent.KeyChar, "W", "concatenated aEvent.KeyChar")
+    TestUtil.AssertEqual(Len(aEvent.KeyChar), 1, "Len(aEvent.KeyChar)")
+    TestUtil.AssertEqual(Asc(aEvent.KeyChar), 87, "Asc(aEvent.KeyChar)")
+
+    Exit Sub
+errorHandler:
+    TestUtil.ReportErrorHandler("verify_tdf171370", Err, Error$, Erl)
+End Sub

basic/source/sbx/sbxint.cxx

@@ -136,6 +136,8 @@ template <> void assignTo<double>(SbxDecimal& dest, double n) { dest.setWithOver
 template <> void assignTo<float>(SbxDecimal& dest, float n) { dest.setWithOverflow(n); }
 
 template <std::integral I> void assignTo(OUString& dest, I n, bool) { dest = OUString::number(n); }
+// tdf#171370: a character stringifies to itself, not to its numeric code
+void assignTo(OUString& dest, sal_Unicode n, bool) { dest = OUString(n); }
 void assignTo(OUString& dest, double n, bool bCoreString)
 {
     // tdf#107953 - show 17 significant digits