[clang] [clang] Diagnose problematic diagnostic messages (PR #93229)

[Erich Keane via cfe-commits]

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@@ -1355,7 +1357,7 @@ static void verifyDiagnosticWording(const Record &Diag) {
   if (isDigit(FullDiagText.back()) && *(FullDiagText.end() - 2) == '}') {
     // Scan backwards to find the opening curly brace.
     size_t BraceCount = 1;
-    auto Iter = FullDiagText.end() - /*}0*/ 3;
+    auto Iter = FullDiagText.end() - sizeof("}0");
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erichkeane wrote:

Does this not need a -1? Only 2 chars, but was/ends up being 3? Or is this offset because 'end' is 1 past end?

https://github.com/llvm/llvm-project/pull/93229