Switch from StrCat to ShortFormat

To avoid direct dependency on absl.

Author: vitalybuka

examples/libfuzzer/libfuzzer_bin_example.cc

@@ -55,7 +55,7 @@ DEFINE_BINARY_PROTO_FUZZER(const libfuzzer_example::Msg& message) {
       !std::isnan(message.optional_float()) &&
       std::fabs(message.optional_float()) > 1000 &&
       message.any().UnpackTo(&file) && !file.name().empty()) {
-    std::cerr << absl::StrCat(message) << "\n";
+    std::cerr << protobuf_mutator::protobuf::ShortFormat(message) << "\n";
     abort();
   }
 }

examples/libfuzzer/libfuzzer_example.cc

@@ -55,7 +55,7 @@ DEFINE_PROTO_FUZZER(const libfuzzer_example::Msg& message) {
       !std::isnan(message.optional_float()) &&
       std::fabs(message.optional_float()) > 1000 &&
       message.any().UnpackTo(&file) && !file.name().empty()) {
-    std::cerr << absl::StrCat(message) << "\n";
+    std::cerr << protobuf_mutator::protobuf::ShortFormat(message) << "\n";
     abort();
   }
 }

src/field_instance.h

@@ -195,9 +195,9 @@ class ConstFieldInstance {
   const protobuf::FieldDescriptor* descriptor() const { return descriptor_; }
 
   std::string DebugString() const {
-    std::string s = absl::StrCat(*descriptor_);
-    if (is_repeated()) s += absl::StrCat("[", index_, "]");
-    return s + " of\n" + absl::StrCat(*message_);
+    std::string s = descriptor_->DebugString();
+    if (is_repeated()) s += "[" + std::to_string(index_) + "]";
+    return s + " of\n" + protobuf::ShortFormat(*message_);
   }
 
  protected:

src/mutator.cc

@@ -801,7 +801,7 @@ std::string Mutator::MutateUtf8String(const std::string& value,
 
 bool Mutator::IsInitialized(const Message& message) const {
   if (!keep_initialized_ || message.IsInitialized()) return true;
-  std::cerr << "Uninitialized: " << absl::StrCat(message) << "\n";
+  std::cerr << "Uninitialized: " << protobuf::ShortFormat(message) << "\n";
   return false;
 }
 

src/mutator_test.cc

@@ -410,8 +410,8 @@ bool Mutate(const protobuf::Message& from, const protobuf::Message& to,
   }
 
   ADD_FAILURE() << "Failed to get from:\n"
-                << absl::StrCat(from) << "\nto:\n"
-                << absl::StrCat(to);
+                << protobuf::ShortFormat(from) << "\nto:\n"
+                << protobuf::ShortFormat(to);
   return false;
 }