[clang] [llvm] [Clang] Reduce the number of ways we have to print a codepoint. (PR #206990)

[Corentin Jabot via cfe-commits]

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@@ -83,7 +83,7 @@ void named(void) {
   char b  = '\N{DOLLAR SIGN}'; // ext-warning {{extension}} cxx23-warning {{C++23}}
   char b_ = '\N{ DOL-LAR _SIGN }'; // expected-error {{' DOL-LAR _SIGN ' is not a valid Unicode character name}} \
                                // expected-note {{character names in Unicode escape sequences are sensitive to case and whitespaces}} \
-                               // expected-note {{character '_' U+005F cannot appear in a Unicode character name}}
+                               // expected-note {{character '_' cannot appear in a Unicode character name}}
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cor3ntin wrote:

The idea is to not print a Unicode codepoint for the ascii range - if you have a non-ascii thing that looks like a `_`, you'd get a codepoint number

https://github.com/llvm/llvm-project/pull/206990