[clang-format] Update removed brace's next token's WhitespaceRange

[owenpan]

Summary

Fixes https://github.com/llvm/llvm-project/issues/57803.

clang/lib/Format/Format.cpp

for (auto I = Lines.begin(); I != End; ++I) {
            Token = Token->Next) {
         if (!Token->Optional)
           continue;
         assert(Token->isOneOf(tok::l_brace, tok::r_brace));
         auto Next = Token->Next;
         assert(Next || Token == Line->Last);
         if (!Next && NextLine)
           Next = NextLine->First;
-        const auto Start =
-            Next && Next->NewlinesBefore == 0 && Next->isNot(tok::eof)
-                ? Token->Tok.getLocation()
-                : Token->WhitespaceRange.getBegin();
+        SourceLocation Start;
+        if (Next && Next->NewlinesBefore == 0 && Next->isNot(tok::eof)) {
+          Start = Token->Tok.getLocation();
+          Next->WhitespaceRange = Token->WhitespaceRange;
+        } else {
+          Start = Token->WhitespaceRange.getBegin();
+        }
         const auto Range =
             CharSourceRange::getCharRange(Start, Token->Tok.getEndLoc());
         cantFail(Result.add(tooling::Replacement(SourceMgr, Range, "")));
       }
     }
   }
 };
 

clang/unittests/Format/FormatTest.cpp

verifyFormat("if not consteval {\n"
                "}",
                Style);
 
   verifyFormat("if !consteval {\n"
                "  g();\n"
                "}",
                Style);
 
+  verifyFormat("while (0)\n"
+               "  if (a)\n"
+               "    return b;\n"
+               "return a;",
+               "while (0) {\n"
+               "  if (a) {\n"
+               "    return b;\n"
+               "}}\n"
+               "return a;",
+               Style);
+
   Style.ColumnLimit = 65;
   verifyFormat("if (condition) {\n"
                "  ff(Indices,\n"
                "     [&](unsigned LHSI, unsigned RHSI) { return true; });\n"
                "} else {\n"
                "  ff(Indices,\n"
                "     [&](unsigned LHSI, unsigned RHSI) { return true; });\n"
                "}",