Add codemod: remove_redundant_field_custom_default_values

Reviewed By: yoney

Differential Revision: D68311949

fbshipit-source-id: 3a04c50d0c9ab75a7de31c2192278053f0d6f1d9

thrift/compiler/codemod/remove_redundant_field_custom_default_values.cc

@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <algorithm>
+#include <iostream>
+#include <string>
+#include <string_view>
+#include <thrift/compiler/ast/ast_visitor.h>
+#include <thrift/compiler/ast/t_program_bundle.h>
+#include <thrift/compiler/ast/t_struct.h>
+#include <thrift/compiler/codemod/file_manager.h>
+#include <thrift/compiler/compiler.h>
+#include <thrift/compiler/diagnostic.h>
+#include <thrift/compiler/generate/cpp/util.h>
+#include <thrift/compiler/sema/standard_validator.h>
+#include <thrift/compiler/source_location.h>
+
+namespace apache::thrift::compiler {
+namespace {
+
+class RemoveRedundantFieldCustomDefaultValues final {
+ public:
+  RemoveRedundantFieldCustomDefaultValues(
+      source_manager& src_manager, t_program& program)
+      : source_manager_(src_manager),
+        throwaway_diagnostic_engine_(
+            source_manager_, [](const diagnostic&) { /* ignore */ }),
+        program_(program),
+        file_manager_(source_manager_, program) {}
+
+  void run() {
+    bool any_changed = false;
+
+    const_ast_visitor visitor;
+    visitor.add_field_visitor([&](const t_field& field) {
+      any_changed |= maybe_change_field(field);
+    });
+    visitor(program_);
+
+    if (any_changed) {
+      file_manager_.apply_replacements();
+    }
+  }
+
+ private:
+  source_manager& source_manager_;
+  diagnostics_engine throwaway_diagnostic_engine_;
+  t_program& program_;
+  std::unique_ptr<t_program_bundle> program_bundle_;
+  codemod::file_manager file_manager_;
+
+  bool maybe_change_field(const t_field& field) {
+    if (!should_change_field(field)) {
+      return false;
+    }
+
+    return attempt_change_field(field);
+  }
+
+  bool should_change_field(const t_field& field) {
+    // NOTE: logic below mirrors `validate_field_default_value()` in
+    // `standard_validator.cc`
+
+    // No custom default value => nothing to do.
+    if (field.default_value() == nullptr) {
+      return false;
+    }
+
+    // Skip if the field type cannot be resolved.
+    try {
+      field.type().deref();
+    } catch (const std::runtime_error&) {
+      return false;
+    }
+
+    if (!detail::check_initializer(
+            throwaway_diagnostic_engine_,
+            field,
+            &field.type().deref(),
+            field.default_value())) {
+      // If initializer is not valid to begin with, stop checks and return
+      // error.
+      return false;
+    }
+
+    return detail::is_initializer_default_value(
+        field.type().deref(), *field.default_value());
+  }
+
+  bool attempt_change_field(const t_field& field) {
+    // Syntax reminder:
+    // field :=
+    //   attributes
+    //   field_id ":" [field_qualifier] type identifier
+    //     [default_value] annotations [';'] [inline_doc]
+    const source_range& field_name_range = field.name_range().value();
+    const source_range& default_value_src_range =
+        field.default_value()->src_range().value();
+    file_manager_.add(
+        {.begin_pos = field_name_range.end.offset(),
+         .end_pos = default_value_src_range.end.offset(),
+         .new_content = ""});
+
+    return true;
+  }
+};
+
+int run_main(int argc, char** argv) {
+  source_manager src_manager;
+  const std::unique_ptr<t_program_bundle> program_bundle =
+      parse_and_get_program(
+          src_manager, std::vector<std::string>(argv, argv + argc));
+
+  if (program_bundle == nullptr) {
+    return 1;
+  }
+
+  RemoveRedundantFieldCustomDefaultValues(
+      src_manager, *program_bundle->root_program())
+      .run();
+  return 0;
+}
+
+} // namespace
+} // namespace apache::thrift::compiler
+
+int main(int argc, char** argv) {
+  return apache::thrift::compiler::run_main(argc, argv);
+}