[clang-format] Make parseUnaryOperator non-recursive, NFCI

[krasimir]

Summary

This patch makes the implementation of parseUnaryOperator non-recursive. We had
a problem with a file starting with tens of thousands of +'es and -'es which
caused clang-format to stack overflow.

[bkramer]

lg

lib/Format/TokenAnnotator.cpp

1671

for (FormatToken *Token : llvm::reverse(Tokens))

[krasimir]

• Address review comments

[krasimir]

lib/Format/TokenAnnotator.cpp

1671

Wow! That's so cool! Thanks!

lib/Format/TokenAnnotator.cpp

if (Current) {
       if (Precedence > prec::Unknown)
         Previous->EndsBinaryExpression = true;
     }
   }
 
   /// \brief Parse unary operator expressions and surround them with fake
   /// parentheses if appropriate.
   void parseUnaryOperator() {
-    if (!Current || Current->isNot(TT_UnaryOperator)) {
-      parse(PrecedenceArrowAndPeriod);
-      return;
-    }
-
-    FormatToken *Start = Current;
+    llvm::SmallVector<FormatToken *, 2> Tokens;
+    while (Current && Current->is(TT_UnaryOperator)) {
+      Tokens.push_back(Current);
       next();
-    parseUnaryOperator();
-
+    }
+    parse(PrecedenceArrowAndPeriod);
+    for (FormatToken *Token : llvm::reverse(Tokens))
       // The actual precedence doesn't matter.
-    addFakeParenthesis(Start, prec::Unknown);
+      addFakeParenthesis(Token, prec::Unknown);
   }
 
   void parseConditionalExpr() {
     while (Current && Current->isTrailingComment()) {
       next();
     }
     FormatToken *Start = Current;
     parse(prec::LogicalOr);