[clang] [clang] Adjust TextDiagnostic style ranges for interesting source region (PR #164941)

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+// RUN: not %clang_cc1 %s -fmessage-length=40 -fcolor-diagnostics -fno-show-source-location -Wunused-value -o - 2>&1 | FileCheck %s
+
+// REQUIRES: ansi-escape-sequences
+
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Sirraide wrote:

I think the test here should also check that we position the caret and any source ranges correctly in the presence of front and/or back ellipses.

https://github.com/llvm/llvm-project/pull/164941