[torque] Add linter rule for module constant naming convention

R=tebbi@chromium.org

Bug: v8:7793
Change-Id: I0314f1b45433c3023f803d67a056ffd6dbf83ce9
Reviewed-on: https://chromium-review.googlesource.com/1221212
Commit-Queue: Simon Zünd <szuend@google.com>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55832}

src/torque/torque-parser.cc

@@ -365,6 +365,13 @@ base::Optional<ParseResult> MakeTorqueBuiltinDeclaration(
 base::Optional<ParseResult> MakeConstDeclaration(
     ParseResultIterator* child_results) {
   auto name = child_results->NextAs<std::string>();
+  if (!IsValidModuleConstName(name)) {
+    std::stringstream sstream;
+    sstream << "Constant \"" << name << "\" doesn't follow "
+            << "\"kUpperCamelCase\" naming convention.";
+    LintError(sstream.str());
+  }
+
   auto type = child_results->NextAs<TypeExpression*>();
   auto expression = child_results->NextAs<Expression*>();
   Declaration* result =

src/torque/utils.cc

@@ -100,6 +100,17 @@ bool ContainsUpperCase(const std::string& s) {
   return std::any_of(s.begin(), s.end(), [](char c) { return isupper(c); });
 }
 
+// Torque has some module constants that are used like language level
+// keywords, e.g.: 'True', 'Undefined', etc.
+// These do not need to follow the default naming convention for constants.
+bool IsKeywordLikeName(const std::string& s) {
+  static const std::vector<std::string> keyword_like_constants{
+      "True", "False", "Hole", "Null", "Undefined"};
+
+  return std::find(keyword_like_constants.begin(), keyword_like_constants.end(),
+                   s) != keyword_like_constants.end();
+}
+
 }  // namespace
 
 bool IsLowerCamelCase(const std::string& s) {
@@ -117,6 +128,13 @@ bool IsSnakeCase(const std::string& s) {
   return !ContainsUpperCase(s);
 }
 
+bool IsValidModuleConstName(const std::string& s) {
+  if (s.empty()) return false;
+  if (IsKeywordLikeName(s)) return true;
+
+  return s[0] == 'k' && IsUpperCamelCase(s.substr(1));
+}
+
 std::string CamelifyString(const std::string& underscore_string) {
   std::string result;
   bool word_beginning = true;

src/torque/utils.h

@@ -38,6 +38,7 @@ void LintError(const std::string& error);
 bool IsLowerCamelCase(const std::string& s);
 bool IsUpperCamelCase(const std::string& s);
 bool IsSnakeCase(const std::string& s);
+bool IsValidModuleConstName(const std::string& s);
 
 std::string CamelifyString(const std::string& underscore_string);
 std::string DashifyString(const std::string& underscore_string);