[clang-format] Recognize TableGen paste operator on separate line (#133722)

Formatting this piece of code made the program crash.

```
class TypedVecListRegOperand<RegisterClass Reg, int lanes, string eltsize>
    : RegisterOperand<Reg, "printTypedVectorList<" # lanes # ", '"
                                                   # eltsize # "'>">;
```

The line starting with the `#` was treated as a separate preprocessor
directive line. Then the code dereferenced a null pointer when it tried
to continue parsing the first line that did not end in a semicolon.

Now the 2 problems are fixed.

1 files changed, 9 insertions, 2 deletions

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index b49e80b..60f4f30 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -4842,9 +4842,16 @@ void UnwrappedLineParser::readToken(int LevelDifference) {
     PreviousWasComment = FormatTok->is(tok::comment);
 
     while (!Line->InPPDirective && FormatTok->is(tok::hash) &&
-           (!Style.isVerilog() ||
-            Keywords.isVerilogPPDirective(*Tokens->peekNextToken())) &&
            FirstNonCommentOnLine) {
+      // In Verilog, the backtick is used for macro invocations. In TableGen,
+      // the single hash is used for the paste operator.
+      const auto *Next = Tokens->peekNextToken();
+      if ((Style.isVerilog() && !Keywords.isVerilogPPDirective(*Next)) ||
+          (Style.isTableGen() &&
+           !Next->isOneOf(tok::kw_else, tok::pp_define, tok::pp_ifdef,
+                          tok::pp_ifndef, tok::pp_endif))) {
+        break;
+      }
       distributeComments(Comments, FormatTok);
       Comments.clear();
       // If there is an unfinished unwrapped line, we flush the preprocessor