carbon-lang/toolchain/parser/parse_tree_fuzzer.cpp

// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#include <cstddef>
#include <cstdint>
#include <cstring>

#include "common/check.h"
#include "llvm/ADT/StringRef.h"
#include "toolchain/diagnostics/diagnostic_emitter.h"
#include "toolchain/diagnostics/null_diagnostics.h"
#include "toolchain/lexer/tokenized_buffer.h"
#include "toolchain/parser/parse_tree.h"

namespace Carbon::Testing {

// NOLINTNEXTLINE: Match the documented fuzzer entry point declaration style.
extern "C" int LLVMFuzzerTestOneInput(const unsigned char* data,
                                      std::size_t size) {
  // Ignore large inputs.
  // TODO: See tokenized_buffer_fuzzer.cpp.
  if (size > 100000) {
    return 0;
  }

  auto source = SourceBuffer::CreateFromText(
      llvm::StringRef(reinterpret_cast<const char*>(data), size));

  // Lex the input.
  auto tokens = TokenizedBuffer::Lex(*source, NullDiagnosticConsumer());
  if (tokens.has_errors()) {
    return 0;
  }

  // Now parse it into a tree. Note that parsing will (when asserts are enabled)
  // walk the entire tree to verify it so we don't have to do that here.
  ParseTree tree = ParseTree::Parse(tokens, NullDiagnosticConsumer());
  if (tree.has_errors()) {
    return 0;
  }

  // In the absence of parse errors, we should have exactly as many nodes as
  // tokens.
  CARBON_CHECK(tree.size() == tokens.size())
      << "Unexpected number of tree nodes!";

  return 0;
}

}  // namespace Carbon::Testing