[clang-format] Ignore C++ keywords when formatting Verilog (#167984)

In the sample below, the `private` identifier is the name of the type,
and the `try` identifier is the name of the variable.

new

```SystemVerilog
begin
  private try;
end
```

old

```SystemVerilog
begin
private
  try
    ;
end
```

Author: sstwcw

clang/lib/Format/FormatTokenLexer.cpp

@@ -1408,6 +1408,8 @@ FormatToken *FormatTokenLexer::getNextToken() {
       FormatTok->Tok.setKind(tok::identifier);
     } else if (Style.isTableGen() && !Keywords.isTableGenKeyword(*FormatTok)) {
       FormatTok->Tok.setKind(tok::identifier);
+    } else if (Style.isVerilog() && Keywords.isVerilogIdentifier(*FormatTok)) {
+      FormatTok->Tok.setKind(tok::identifier);
     }
   } else if (const bool Greater = FormatTok->is(tok::greatergreater);
              Greater || FormatTok->is(tok::lessless)) {

clang/unittests/Format/FormatTestVerilog.cpp

@@ -423,6 +423,11 @@ TEST_F(FormatTestVerilog, Declaration) {
   verifyFormat("wire (strong1, pull0) mynet, mynet1 = enable;");
   verifyFormat("wire (strong1, pull0) mynet, //\n"
                "                      mynet1 = enable;");
+
+  // The type or variable can be a C++ keyword.
+  verifyFormat("private mynet;");
+  verifyFormat("switch mynet;");
+  verifyFormat("wire try;");
 }
 
 TEST_F(FormatTestVerilog, Delay) {

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -2918,6 +2918,13 @@ TEST_F(TokenAnnotatorTest, UnderstandsVerilogOperators) {
   EXPECT_EQ(Tokens[0]->TokenText, R"(\busa+index\
 +)");
   EXPECT_TOKEN(Tokens[1], tok::semi, TT_Unknown);
+
+  // A C++ keyword should be treated as an identifier.
+  Tokens = Annotate("volatile delete;");
+  ASSERT_EQ(Tokens.size(), 4u) << Tokens;
+  EXPECT_TOKEN(Tokens[0], tok::identifier, TT_Unknown);
+  EXPECT_TOKEN(Tokens[1], tok::identifier, TT_StartOfName);
+
   // An escaped newline should not be treated as an escaped identifier.
   Tokens = Annotate("\\\n");
   ASSERT_EQ(Tokens.size(), 1u) << Tokens;