Rename enum constants in ObjC code if they would clash with reserved names.

Previously the code just didn't emit a constant at all. Now, we do emit one, but with an extra underscore. For example, if the enum constant is `OVERFLOW`, which collides with a macro in `/usr/include/math.h`, we'll output `OVERFLOW_` instead. So client code can still reference it, albeit a little clumsily.

Eventually we should change the hardcoded list of reserved names to use the same [reserved names list](https://github.com/google/j2objc/blob/master/translator/src/main/resources/com/google/devtools/j2objc/reserved_names.txt) that the j2objc translator uses.

PiperOrigin-RevId: 743258491

Author: eamonnmcmanus

protobuf/compiler/src/google/protobuf/compiler/j2objc/j2objc_enum.cc

@@ -191,7 +191,7 @@ void EnumGenerator::GenerateHeader(io::Printer* printer) {
           "@property(class, readonly, retain) $classname$ *$name$ "
           "NS_SWIFT_NAME($name$);\n",
           "classname", ClassName(descriptor_), "name",
-          canonical_values_[i]->name());
+          SafeName(canonical_values_[i]->name()));
     }
   }
   if (!descriptor_->is_closed()) {
@@ -330,11 +330,12 @@ void EnumGenerator::GenerateSource(io::Printer* printer) {
   for (int i = 0; i < canonical_values_.size(); i++) {
     if (CanGenerateProperty(canonical_values_[i])) {
       printer->Print(
-          "+ ($classname$ *) $name$ {\n"
+          "+ ($classname$ *) $safe_name$ {\n"
           "  return $classname$_get_$name$();\n"
           "}\n",
           "classname", ClassName(descriptor_), "name",
-          canonical_values_[i]->name());
+          canonical_values_[i]->name(), "safe_name",
+          SafeName(canonical_values_[i]->name()));
     }
   }
 

protobuf/compiler/src/google/protobuf/compiler/j2objc/j2objc_helpers.cc

@@ -229,8 +229,8 @@ std::string GetClassPrefix(const FileDescriptor *file,
 
 }  // namespace
 
-std::string SafeName(const std::string &name) {
-  std::string result = name;
+std::string SafeName(absl::string_view name) {
+  std::string result = std::string(name);
   if (kKeywords.count(result) > 0) {
     result.append("_");
   }
@@ -700,8 +700,7 @@ bool CanGenerateProperty(const FieldDescriptor *descriptor) {
 }
 
 bool CanGenerateProperty(const EnumValueDescriptor *descriptor) {
-  return IsGenerateProperties(descriptor->file()) &&
-         kKeywords.find(descriptor->name()) == kKeywords.end();
+  return IsGenerateProperties(descriptor->file());
 }
 
 void ParsePrefixLine(std::string line) {

protobuf/compiler/src/google/protobuf/compiler/j2objc/j2objc_helpers.h

@@ -44,7 +44,7 @@ namespace protobuf {
 namespace compiler {
 namespace j2objc {
 
-std::string SafeName(const std::string &name);
+std::string SafeName(absl::string_view name);
 
 std::string UnderscoresToCamelCase(absl::string_view input,
                                    bool cap_next_letter);