Merge changes from topic "header-checker-weak-symbols" into qt-dev

* changes:
  header-checker: Add config file support
  header-checker: Add -allow-adding-removing-weak-symbols

19 files changed, 653 insertions, 30 deletions

diff --git a/vndk/tools/header-checker/Android.bp b/vndk/tools/header-checker/Android.bp
index d83bd477f..aff2d0554 100644
--- a/vndk/tools/header-checker/Android.bp
+++ b/vndk/tools/header-checker/Android.bp
@@ -165,6 +165,7 @@ cc_library_host_static {
         "src/repr/symbol/so_file_parser.cpp",
         "src/repr/symbol/version_script_parser.cpp",
         "src/utils/api_level.cpp",
+        "src/utils/config_file.cpp",
         "src/utils/collect_exported_headers.cpp",
         "src/utils/string_utils.cpp",
     ],
@@ -198,6 +199,7 @@ cc_test_host {
         "src/repr/symbol/exported_symbol_set_test.cpp",
         "src/repr/symbol/version_script_parser_test.cpp",
         "src/utils/api_level_test.cpp",
+        "src/utils/config_file_test.cpp",
         "src/utils/string_utils_test.cpp",
     ],
 
diff --git a/vndk/tools/header-checker/src/diff/abi_diff.cpp b/vndk/tools/header-checker/src/diff/abi_diff.cpp
index 0d2d759dc..b0f1e09a3 100644
--- a/vndk/tools/header-checker/src/diff/abi_diff.cpp
+++ b/vndk/tools/header-checker/src/diff/abi_diff.cpp
@@ -61,7 +61,7 @@ repr::CompatibilityStatusIR HeaderAbiDiff::CompareTUs(
   const AbiElementMap<const repr::TypeIR *> new_types =
       new_tu.GetTypeGraph();
 
-  // Collect fills in added, removed ,unsafe and safe function diffs.
+  // CollectDynsymExportables() fills in added, removed, unsafe, and safe function diffs.
   if (!CollectDynsymExportables(old_tu.GetFunctions(), new_tu.GetFunctions(),
                                 old_tu.GetElfFunctions(),
                                 new_tu.GetElfFunctions(),
@@ -225,11 +225,11 @@ bool HeaderAbiDiff::Collect(
     const AbiElementMap<const repr::TypeIR *> &old_types_map,
     const AbiElementMap<const repr::TypeIR *> &new_types_map) {
   if (!PopulateRemovedElements(
-          old_elements_map, new_elements_map, new_elf_map, ir_diff_dumper,
-          repr::DiffMessageIR::Removed, old_types_map) ||
+          old_elements_map, new_elements_map, old_elf_map, new_elf_map,
+          ir_diff_dumper, repr::DiffMessageIR::Removed, old_types_map) ||
       !PopulateRemovedElements(
-          new_elements_map, old_elements_map, old_elf_map, ir_diff_dumper,
-          repr::IRDiffDumper::DiffKind::Added, new_types_map)) {
+          new_elements_map, old_elements_map, new_elf_map, old_elf_map,
+          ir_diff_dumper, repr::DiffMessageIR::Added, new_types_map)) {
     llvm::errs() << "Populating functions in report failed\n";
     return false;
   }
@@ -257,6 +257,10 @@ bool HeaderAbiDiff::PopulateElfElements(
     repr::IRDiffDumper *ir_diff_dumper,
     repr::IRDiffDumper::DiffKind diff_kind) {
   for (auto &&elf_element : elf_elements) {
+    if (allow_adding_removing_weak_symbols_ &&
+        elf_element->GetBinding() == repr::ElfSymbolIR::Weak) {
+      continue;
+    }
     if (!ir_diff_dumper->AddElfSymbolMessageIR(elf_element, diff_kind)) {
       return false;
     }
@@ -268,15 +272,16 @@ template <typename T>
 bool HeaderAbiDiff::PopulateRemovedElements(
     const AbiElementMap<const T*> &old_elements_map,
     const AbiElementMap<const T*> &new_elements_map,
-    const AbiElementMap<const repr::ElfSymbolIR *> *elf_map,
+    const AbiElementMap<const repr::ElfSymbolIR *> *old_elf_map,
+    const AbiElementMap<const repr::ElfSymbolIR *> *new_elf_map,
     repr::IRDiffDumper *ir_diff_dumper,
     repr::IRDiffDumper::DiffKind diff_kind,
     const AbiElementMap<const repr::TypeIR *> &removed_types_map) {
   std::vector<const T *> removed_elements =
       utils::FindRemovedElements(old_elements_map, new_elements_map);
-  if (!DumpLoneElements(removed_elements, elf_map, ir_diff_dumper, diff_kind,
-                        removed_types_map)) {
-    llvm::errs() << "Dumping added / removed element to report failed\n";
+  if (!DumpLoneElements(removed_elements, old_elf_map, new_elf_map,
+                        ir_diff_dumper, diff_kind, removed_types_map)) {
+    llvm::errs() << "Dumping added or removed element to report failed\n";
     return false;
   }
   return true;
@@ -306,33 +311,52 @@ bool HeaderAbiDiff::PopulateCommonElements(
 template <typename T>
 bool HeaderAbiDiff::DumpLoneElements(
     std::vector<const T *> &elements,
-    const AbiElementMap<const repr::ElfSymbolIR *> *elf_map,
+    const AbiElementMap<const repr::ElfSymbolIR *> *old_elf_map,
+    const AbiElementMap<const repr::ElfSymbolIR *> *new_elf_map,
     repr::IRDiffDumper *ir_diff_dumper,
     repr::IRDiffDumper::DiffKind diff_kind,
     const AbiElementMap<const repr::TypeIR *> &types_map) {
-  // If the record / enum has source file information, skip it.
   std::smatch source_file_match;
   std::regex source_file_regex(" at ");
+
   for (auto &&element : elements) {
     if (IgnoreSymbol<T>(element, ignored_symbols_,
                         [](const T *e) {return e->GetLinkerSetKey();})) {
       continue;
     }
-    // The element does exist in the .dynsym table, we do not have meta-data
-    // surrounding the element.
+
+    // If an element (FunctionIR or GlobalVarIR) is missing from the new ABI
+    // dump but a corresponding ELF symbol (ElfFunctionIR or ElfObjectIR) can
+    // be found in the new ABI dump file, don't emit error on this element.
+    // This may happen when the standard reference target implements the
+    // function (or the global variable) in C/C++ and the target-under-test
+    // implements the function (or the global variable) in assembly.
     const std::string &element_linker_set_key = element->GetLinkerSetKey();
-    if ((elf_map != nullptr) &&
-        (elf_map->find(element_linker_set_key) != elf_map->end())) {
+    if (new_elf_map &&
+        new_elf_map->find(element_linker_set_key) != new_elf_map->end()) {
       continue;
     }
+
+    // If the `-ignore-weak-symbols` option is enabled, ignore the element if
+    // it was a weak symbol.
+    if (allow_adding_removing_weak_symbols_ && old_elf_map) {
+      auto elem_it = old_elf_map->find(element_linker_set_key);
+      if (elem_it != old_elf_map->end() &&
+          elem_it->second->GetBinding() == repr::ElfSymbolIR::Weak) {
+        continue;
+      }
+    }
+
+    // If the record / enum has source file information, skip it.
     if (std::regex_search(element_linker_set_key, source_file_match,
                           source_file_regex)) {
       continue;
     }
+
     auto element_copy = *element;
     ReplaceTypeIdsWithTypeNames(types_map, &element_copy);
     if (!ir_diff_dumper->AddLinkableMessageIR(&element_copy, diff_kind)) {
-      llvm::errs() << "Couldn't dump added /removed element\n";
+      llvm::errs() << "Couldn't dump added or removed element\n";
       return false;
     }
   }
diff --git a/vndk/tools/header-checker/src/diff/abi_diff.h b/vndk/tools/header-checker/src/diff/abi_diff.h
index cbda960c1..ca64716a5 100644
--- a/vndk/tools/header-checker/src/diff/abi_diff.h
+++ b/vndk/tools/header-checker/src/diff/abi_diff.h
@@ -36,6 +36,7 @@ class HeaderAbiDiff {
                 const std::string &old_dump, const std::string &new_dump,
                 const std::string &compatibility_report,
                 const std::set<std::string> &ignored_symbols,
+                bool allow_adding_removing_weak_symbols,
                 const DiffPolicyOptions &diff_policy_options,
                 bool check_all_apis, repr::TextFormatIR text_format_old,
                 repr::TextFormatIR text_format_new,
@@ -44,6 +45,7 @@ class HeaderAbiDiff {
         new_dump_(new_dump), cr_(compatibility_report),
         ignored_symbols_(ignored_symbols),
         diff_policy_options_(diff_policy_options),
+        allow_adding_removing_weak_symbols_(allow_adding_removing_weak_symbols),
         check_all_apis_(check_all_apis),
         text_format_old_(text_format_old), text_format_new_(text_format_new),
         text_format_diff_(text_format_diff) {}
@@ -90,7 +92,8 @@ class HeaderAbiDiff {
   bool PopulateRemovedElements(
       const AbiElementMap<const T *> &old_elements_map,
       const AbiElementMap<const T *> &new_elements_map,
-      const AbiElementMap<const repr::ElfSymbolIR *> *elf_map,
+      const AbiElementMap<const repr::ElfSymbolIR *> *old_elf_map,
+      const AbiElementMap<const repr::ElfSymbolIR *> *new_elf_map,
       repr::IRDiffDumper *ir_diff_dumper,
       repr::IRDiffDumper::DiffKind diff_kind,
       const AbiElementMap<const repr::TypeIR *> &types_map);
@@ -115,7 +118,8 @@ class HeaderAbiDiff {
   template <typename T>
   bool DumpLoneElements(
       std::vector<const T *> &elements,
-      const AbiElementMap<const repr::ElfSymbolIR *> *elf_map,
+      const AbiElementMap<const repr::ElfSymbolIR *> *old_elf_map,
+      const AbiElementMap<const repr::ElfSymbolIR *> *new_elf_map,
       repr::IRDiffDumper *ir_diff_dumper,
       repr::IRDiffDumper::DiffKind diff_kind,
       const AbiElementMap<const repr::TypeIR *> &old_types_map);
@@ -147,6 +151,7 @@ class HeaderAbiDiff {
   const std::string &cr_;
   const std::set<std::string> &ignored_symbols_;
   const DiffPolicyOptions &diff_policy_options_;
+  bool allow_adding_removing_weak_symbols_;
   bool check_all_apis_;
   std::set<std::string> type_cache_;
   repr::TextFormatIR text_format_old_;
diff --git a/vndk/tools/header-checker/src/diff/header_abi_diff.cpp b/vndk/tools/header-checker/src/diff/header_abi_diff.cpp
index ac13b535f..e0ead7423 100644
--- a/vndk/tools/header-checker/src/diff/header_abi_diff.cpp
+++ b/vndk/tools/header-checker/src/diff/header_abi_diff.cpp
@@ -14,8 +14,13 @@
 
 #include "diff/abi_diff.h"
 
+#include "utils/config_file.h"
+#include "utils/string_utils.h"
+
+#include <llvm/ADT/SmallString.h>
 #include <llvm/Support/CommandLine.h>
 #include <llvm/Support/FileSystem.h>
+#include <llvm/Support/Path.h>
 #include <llvm/Support/raw_ostream.h>
 
 #include <fstream>
@@ -25,6 +30,9 @@ using header_checker::diff::HeaderAbiDiff;
 using header_checker::repr::CompatibilityStatusIR;
 using header_checker::repr::DiffPolicyOptions;
 using header_checker::repr::TextFormatIR;
+using header_checker::utils::ConfigFile;
+using header_checker::utils::ConfigParser;
+using header_checker::utils::ParseBool;
 
 
 static llvm::cl::OptionCategory header_checker_category(
@@ -70,10 +78,6 @@ static llvm::cl::opt<bool> check_all_apis(
                    " the dynsym table of a shared library are checked"),
     llvm::cl::Optional, llvm::cl::cat(header_checker_category));
 
-static llvm::cl::opt<bool> suppress_local_warnings(
-    "suppress_local_warnings", llvm::cl::desc("suppress local warnings"),
-    llvm::cl::Optional, llvm::cl::cat(header_checker_category));
-
 static llvm::cl::opt<bool> allow_extensions(
     "allow-extensions",
     llvm::cl::desc("Do not return a non zero status on extensions"),
@@ -121,6 +125,13 @@ static llvm::cl::opt<TextFormatIR> text_format_diff(
     llvm::cl::init(TextFormatIR::ProtobufTextFormat),
     llvm::cl::cat(header_checker_category));
 
+static llvm::cl::opt<bool> allow_adding_removing_weak_symbols(
+    "allow-adding-removing-weak-symbols",
+    llvm::cl::desc("Do not treat addition or removal of weak symbols as "
+                   "incompatible changes."),
+    llvm::cl::init(false), llvm::cl::Optional,
+    llvm::cl::cat(header_checker_category));
+
 static std::set<std::string> LoadIgnoredSymbols(std::string &symbol_list_path) {
   std::ifstream symbol_ifstream(symbol_list_path);
   std::set<std::string> ignored_symbols;
@@ -135,6 +146,39 @@ static std::set<std::string> LoadIgnoredSymbols(std::string &symbol_list_path) {
   return ignored_symbols;
 }
 
+static std::string GetConfigFilePath(const std::string &dump_file_path) {
+  llvm::SmallString<128> config_file_path(dump_file_path);
+  llvm::sys::path::remove_filename(config_file_path);
+  llvm::sys::path::append(config_file_path, "config.ini");
+  return config_file_path.str();
+}
+
+static void ReadConfigFile(const std::string &config_file_path) {
+  ConfigFile cfg = ConfigParser::ParseFile(config_file_path);
+  if (cfg.HasSection("global")) {
+    for (auto &&[key, value] : cfg.GetSection("global")) {
+      bool value_bool = ParseBool(value);
+      if (key == "allow_adding_removing_weak_symbols") {
+        allow_adding_removing_weak_symbols = value_bool;
+      } else if (key == "advice_only") {
+        advice_only = value_bool;
+      } else if (key == "elf_unreferenced_symbol_errors") {
+        elf_unreferenced_symbol_errors = value_bool;
+      } else if (key == "check_all_apis") {
+        check_all_apis = value_bool;
+      } else if (key == "allow_extensions") {
+        allow_extensions = value_bool;
+      } else if (key == "allow_unreferenced_elf_symbol_changes") {
+        allow_unreferenced_elf_symbol_changes = value_bool;
+      } else if (key == "allow_unreferenced_changes") {
+        allow_unreferenced_changes = value_bool;
+      } else if (key == "consider_opaque_types_different") {
+        consider_opaque_types_different = value_bool;
+      }
+    }
+  }
+}
+
 static const char kWarn[] = "\033[36;1mwarning: \033[0m";
 static const char kError[] = "\033[31;1merror: \033[0m";
 
@@ -150,15 +194,20 @@ bool ShouldEmitWarningMessage(CompatibilityStatusIR status) {
 
 int main(int argc, const char **argv) {
   llvm::cl::ParseCommandLineOptions(argc, argv, "header-checker");
+
+  ReadConfigFile(GetConfigFilePath(old_dump));
+
   std::set<std::string> ignored_symbols;
   if (llvm::sys::fs::exists(ignore_symbol_list)) {
     ignored_symbols = LoadIgnoredSymbols(ignore_symbol_list);
   }
-  DiffPolicyOptions diff_policy_options(
-      consider_opaque_types_different);
+
+  DiffPolicyOptions diff_policy_options(consider_opaque_types_different);
+
   HeaderAbiDiff judge(lib_name, arch, old_dump, new_dump, compatibility_report,
-                      ignored_symbols, diff_policy_options, check_all_apis,
-                      text_format_old, text_format_new, text_format_diff);
+                      ignored_symbols, allow_adding_removing_weak_symbols,
+                      diff_policy_options, check_all_apis, text_format_old,
+                      text_format_new, text_format_diff);
 
   CompatibilityStatusIR status = judge.GenerateCompatibilityReport();
 
diff --git a/vndk/tools/header-checker/src/repr/symbol/version_script_parser.cpp b/vndk/tools/header-checker/src/repr/symbol/version_script_parser.cpp
index 98ecea3f3..eecbfe554 100644
--- a/vndk/tools/header-checker/src/repr/symbol/version_script_parser.cpp
+++ b/vndk/tools/header-checker/src/repr/symbol/version_script_parser.cpp
@@ -120,11 +120,17 @@ VersionScriptParser::ParsedTags VersionScriptParser::ParseSymbolTags(
       continue;
     }
 
-    // Check future tags.
+    // Check the future tag.
     if (tag == "future") {
       result.has_future_tag_ = true;
       continue;
     }
+
+    // Check the weak binding tag.
+    if (tag == "weak") {
+      result.has_weak_tag_ = true;
+      continue;
+    }
   }
 
   return result;
@@ -183,11 +189,14 @@ bool VersionScriptParser::ParseSymbolLine(const std::string &line,
     return true;
   }
 
+  ElfSymbolIR::ElfSymbolBinding binding =
+      tags.has_weak_tag_ ? ElfSymbolIR::ElfSymbolBinding::Weak
+                         : ElfSymbolIR::ElfSymbolBinding::Global;
+
   if (tags.has_var_tag_) {
-    exported_symbols_->AddVar(symbol, ElfSymbolIR::ElfSymbolBinding::Global);
+    exported_symbols_->AddVar(symbol, binding);
   } else {
-    exported_symbols_->AddFunction(symbol,
-                                   ElfSymbolIR::ElfSymbolBinding::Global);
+    exported_symbols_->AddFunction(symbol, binding);
   }
   return true;
 }
diff --git a/vndk/tools/header-checker/src/repr/symbol/version_script_parser.h b/vndk/tools/header-checker/src/repr/symbol/version_script_parser.h
index 7a047a299..d3bb63708 100644
--- a/vndk/tools/header-checker/src/repr/symbol/version_script_parser.h
+++ b/vndk/tools/header-checker/src/repr/symbol/version_script_parser.h
@@ -44,6 +44,7 @@ class VersionScriptParser {
     unsigned has_excluded_tags_ : 1;
     unsigned has_future_tag_ : 1;
     unsigned has_var_tag_ : 1;
+    unsigned has_weak_tag_ : 1;
     utils::ApiLevel introduced_;
 
 
diff --git a/vndk/tools/header-checker/src/utils/config_file.cpp b/vndk/tools/header-checker/src/utils/config_file.cpp
new file mode 100644
index 000000000..e4861c62a
--- /dev/null
+++ b/vndk/tools/header-checker/src/utils/config_file.cpp
@@ -0,0 +1,87 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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 "utils/config_file.h"
+
+#include "utils/string_utils.h"
+
+#include <fstream>
+#include <map>
+#include <string>
+
+
+namespace header_checker {
+namespace utils {
+
+
+ConfigFile ConfigParser::ParseFile(std::istream &istream) {
+  ConfigParser parser(istream);
+  return parser.ParseFile();
+}
+
+
+ConfigFile ConfigParser::ParseFile(const std::string &path) {
+  std::ifstream stream(path, std::ios_base::in);
+  return ParseFile(stream);
+}
+
+
+ConfigFile ConfigParser::ParseFile() {
+  size_t line_no = 0;
+  std::string line;
+  while (std::getline(stream_, line)) {
+    ParseLine(++line_no, line);
+  }
+  return std::move(cfg_);
+}
+
+
+void ConfigParser::ParseLine(size_t line_no, std::string_view line) {
+  if (line.empty() || line[0] == ';' || line[0] == '#') {
+    // Skip empty or comment line.
+    return;
+  }
+
+  // Parse section name line.
+  if (line[0] == '[') {
+    std::string::size_type pos = line.rfind(']');
+    if (pos == std::string::npos) {
+      ReportError(line_no, "bad section name line");
+      return;
+    }
+    std::string_view section_name = line.substr(1, pos - 1);
+    section_ = &cfg_.map_[std::string(section_name)];
+    return;
+  }
+
+  // Parse key-value line.
+  std::string::size_type pos = line.find('=');
+  if (pos == std::string::npos) {
+    ReportError(line_no, "bad key-value line");
+    return;
+  }
+
+  // Add key-value entry to current section.
+  std::string_view key = Trim(line.substr(0, pos));
+  std::string_view value = Trim(line.substr(pos + 1));
+
+  if (!section_) {
+    section_ = &cfg_.map_[""];
+  }
+  section_->map_[std::string(key)] = std::string(value);
+}
+
+
+}  // namespace utils
+}  // namespace header_checker
diff --git a/vndk/tools/header-checker/src/utils/config_file.h b/vndk/tools/header-checker/src/utils/config_file.h
new file mode 100644
index 000000000..cf8c6d905
--- /dev/null
+++ b/vndk/tools/header-checker/src/utils/config_file.h
@@ -0,0 +1,193 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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.
+
+#ifndef CONFIG_FILE_H_
+#define CONFIG_FILE_H_
+
+#include <cassert>
+#include <iosfwd>
+#include <map>
+#include <string>
+
+
+namespace header_checker {
+namespace utils {
+
+
+class ConfigParser;
+
+
+class ConfigSection {
+ public:
+  using MapType = std::map<std::string, std::string>;
+  using const_iterator = MapType::const_iterator;
+
+
+ public:
+  ConfigSection() = default;
+  ConfigSection(ConfigSection &&) = default;
+  ConfigSection &operator=(ConfigSection &&) = default;
+
+  bool HasProperty(const std::string &name) const {
+    return map_.find(name) != map_.end();
+  }
+
+  std::string GetProperty(const std::string &name) const {
+    auto &&it = map_.find(name);
+    if (it == map_.end()) {
+      return "";
+    }
+    return it->second;
+  }
+
+  std::string operator[](const std::string &name) const {
+    return GetProperty(name);
+  }
+
+  const_iterator begin() const {
+    return map_.begin();
+  }
+
+  const_iterator end() const {
+    return map_.end();
+  }
+
+
+ private:
+  ConfigSection(const ConfigSection &) = delete;
+  ConfigSection &operator=(const ConfigSection &) = delete;
+
+
+ private:
+  std::map<std::string, std::string> map_;
+
+  friend class ConfigParser;
+};
+
+
+class ConfigFile {
+ public:
+  using MapType = std::map<std::string, ConfigSection>;
+  using const_iterator = MapType::const_iterator;
+
+
+ public:
+  ConfigFile() = default;
+  ConfigFile(ConfigFile &&) = default;
+  ConfigFile &operator=(ConfigFile &&) = default;
+
+  bool HasSection(const std::string &section_name) const {
+    return map_.find(section_name) != map_.end();
+  }
+
+  const ConfigSection &GetSection(const std::string &section_name) const {
+    auto &&it = map_.find(section_name);
+    assert(it != map_.end());
+    return it->second;
+  }
+
+  const ConfigSection &operator[](const std::string &section_name) const {
+    return GetSection(section_name);
+  }
+
+  bool HasProperty(const std::string &section_name,
+                   const std::string &property_name) const {
+    auto &&it = map_.find(section_name);
+    if (it == map_.end()) {
+      return false;
+    }
+    return it->second.HasProperty(property_name);
+  }
+
+  std::string GetProperty(const std::string &section_name,
+                          const std::string &property_name) const {
+    auto &&it = map_.find(section_name);
+    if (it == map_.end()) {
+      return "";
+    }
+    return it->second.GetProperty(property_name);
+  }
+
+  const_iterator begin() const {
+    return map_.begin();
+  }
+
+  const_iterator end() const {
+    return map_.end();
+  }
+
+
+ private:
+  ConfigFile(const ConfigFile &) = delete;
+  ConfigFile &operator=(const ConfigFile &) = delete;
+
+
+ private:
+  std::map<std::string, ConfigSection> map_;
+
+  friend class ConfigParser;
+};
+
+
+class ConfigParser {
+ public:
+  using ErrorListener = std::function<void (size_t, const char *)>;
+
+
+ public:
+  ConfigParser(std::istream &stream)
+      : stream_(stream), section_(nullptr) { }
+
+  ConfigFile ParseFile();
+
+  static ConfigFile ParseFile(std::istream &istream);
+
+  static ConfigFile ParseFile(const std::string &path);
+
+  void SetErrorListener(ErrorListener listener) {
+    error_listener_ = std::move(listener);
+  }
+
+
+ private:
+  void ParseLine(size_t line_no, std::string_view line);
+
+  void ReportError(size_t line_no, const char *cause) {
+    if (error_listener_) {
+      error_listener_(line_no, cause);
+    }
+  }
+
+
+ private:
+  ConfigParser(const ConfigParser &) = delete;
+  ConfigParser &operator=(const ConfigParser &) = delete;
+
+
+ private:
+  std::istream &stream_;
+
+  ErrorListener error_listener_;
+
+  ConfigSection *section_;
+
+  ConfigFile cfg_;
+};
+
+
+}  // namespace utils
+}  // namespace header_checker
+
+
+#endif  // CONFIG_FILE_H_
diff --git a/vndk/tools/header-checker/src/utils/config_file_test.cpp b/vndk/tools/header-checker/src/utils/config_file_test.cpp
new file mode 100644
index 000000000..28ead1040
--- /dev/null
+++ b/vndk/tools/header-checker/src/utils/config_file_test.cpp
@@ -0,0 +1,111 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// 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 "utils/config_file.h"
+
+#include <sstream>
+
+#include <gtest/gtest.h>
+
+
+namespace header_checker {
+namespace utils {
+
+
+TEST(ConfigParserTest, Parse) {
+  std::stringstream stream(R"(
+# Comment line starts with hash symbol
+; Comment line starts with semicolon
+
+[section1]
+key1 = value1
+key2 = value2
+
+[section2]
+key1 = true
+key2 = false
+)");
+
+  auto &&cfg = ConfigParser::ParseFile(stream);
+  EXPECT_TRUE(cfg.HasSection("section1"));
+  EXPECT_TRUE(cfg.HasSection("section2"));
+  EXPECT_FALSE(cfg.HasSection("section3"));
+
+  auto &&section1 = cfg.GetSection("section1");
+  EXPECT_TRUE(section1.HasProperty("key1"));
+  EXPECT_EQ("value1", section1.GetProperty("key1"));
+  EXPECT_TRUE(section1.HasProperty("key2"));
+  EXPECT_EQ("value2", section1.GetProperty("key2"));
+
+  EXPECT_FALSE(section1.HasProperty("key3"));
+  EXPECT_EQ("", section1.GetProperty("key3"));
+
+  auto &&section2 = cfg.GetSection("section2");
+  EXPECT_TRUE(section2.HasProperty("key1"));
+  EXPECT_EQ("true", section2.GetProperty("key1"));
+  EXPECT_TRUE(section2.HasProperty("key2"));
+  EXPECT_EQ("false", section2.GetProperty("key2"));
+
+  EXPECT_EQ("value1", cfg.GetProperty("section1", "key1"));
+  EXPECT_EQ("value2", cfg.GetProperty("section1", "key2"));
+
+  EXPECT_EQ("value1", cfg["section1"]["key1"]);
+  EXPECT_EQ("value2", cfg["section1"]["key2"]);
+}
+
+
+TEST(ConfigParserTest, BadSectionNameLine) {
+  std::stringstream stream(R"(
+[section1
+key1 = value1
+)");
+
+  size_t num_errors = 0;
+
+  ConfigParser parser(stream);
+  parser.SetErrorListener(
+      [&num_errors](size_t line_no, const char *cause) {
+        ++num_errors;
+        EXPECT_EQ(2, line_no);
+        EXPECT_STREQ("bad section name line", cause);
+      });
+  parser.ParseFile();
+
+  EXPECT_EQ(1, num_errors);
+}
+
+
+TEST(ConfigParserTest, BadKeyValueLine) {
+  std::stringstream stream(R"(
+[section1]
+key1
+)");
+
+  size_t num_errors = 0;
+
+  ConfigParser parser(stream);
+  parser.SetErrorListener(
+      [&num_errors](size_t line_no, const char *cause) {
+        ++num_errors;
+        EXPECT_EQ(3, line_no);
+        EXPECT_STREQ("bad key-value line", cause);
+      });
+  parser.ParseFile();
+
+  EXPECT_EQ(1, num_errors);
+}
+
+
+}  // namespace utils
+}  // namespace header_checker
diff --git a/vndk/tools/header-checker/src/utils/string_utils.cpp b/vndk/tools/header-checker/src/utils/string_utils.cpp
index ced07f754..2dd97aded 100644
--- a/vndk/tools/header-checker/src/utils/string_utils.cpp
+++ b/vndk/tools/header-checker/src/utils/string_utils.cpp
@@ -14,6 +14,8 @@
 
 #include "utils/string_utils.h"
 
+#include <algorithm>
+#include <cctype>
 #include <cstdlib>
 #include <string>
 #include <utility>
@@ -86,6 +88,13 @@ std::optional<int> ParseInt(const std::string &s) {
 }
 
 
+bool ParseBool(const std::string &s) {
+  std::string value(s);
+  std::transform(value.begin(), value.end(), value.begin(), std::tolower);
+  return (value == "true" || value == "on" || value == "1");
+}
+
+
 bool IsGlobPattern(std::string_view s) {
   return s.find_first_of("*?[") != std::string::npos;
 }
diff --git a/vndk/tools/header-checker/src/utils/string_utils.h b/vndk/tools/header-checker/src/utils/string_utils.h
index 8d546f400..bcb840504 100644
--- a/vndk/tools/header-checker/src/utils/string_utils.h
+++ b/vndk/tools/header-checker/src/utils/string_utils.h
@@ -35,6 +35,8 @@ std::vector<std::string_view> Split(std::string_view s,
 
 std::optional<int> ParseInt(const std::string &s);
 
+bool ParseBool(const std::string &s);
+
 bool IsGlobPattern(std::string_view s);
 
 
diff --git a/vndk/tools/header-checker/src/utils/string_utils_test.cpp b/vndk/tools/header-checker/src/utils/string_utils_test.cpp
index 6c5a874a8..4ad007440 100644
--- a/vndk/tools/header-checker/src/utils/string_utils_test.cpp
+++ b/vndk/tools/header-checker/src/utils/string_utils_test.cpp
@@ -94,6 +94,20 @@ TEST(StringUtilsTest, ParseInt) {
 }
 
 
+TEST(StringUtilsTest, ParseBool) {
+  EXPECT_FALSE(ParseBool(""));
+  EXPECT_FALSE(ParseBool("false"));
+  EXPECT_FALSE(ParseBool("off"));
+  EXPECT_FALSE(ParseBool("0"));
+
+  EXPECT_TRUE(ParseBool("TRUE"));
+  EXPECT_TRUE(ParseBool("True"));
+  EXPECT_TRUE(ParseBool("true"));
+  EXPECT_TRUE(ParseBool("ON"));
+  EXPECT_TRUE(ParseBool("1"));
+}
+
+
 TEST(StringUtilsTest, IsGlobPattern) {
   EXPECT_TRUE(IsGlobPattern("*.so"));
   EXPECT_TRUE(IsGlobPattern("[ab].txt"));
diff --git a/vndk/tools/header-checker/tests/integration/weak_symbols/example.c b/vndk/tools/header-checker/tests/integration/weak_symbols/example.c
new file mode 100644
index 000000000..65c35bf47
--- /dev/null
+++ b/vndk/tools/header-checker/tests/integration/weak_symbols/example.c
@@ -0,0 +1,8 @@
+#if !defined(NEW)
+
+extern void example(void) __attribute__((weak));
+
+void example(void) {
+}
+
+#endif  // !defined(NEW)
diff --git a/vndk/tools/header-checker/tests/integration/weak_symbols/libexample_new.map.txt b/vndk/tools/header-checker/tests/integration/weak_symbols/libexample_new.map.txt
new file mode 100644
index 000000000..060916683
--- /dev/null
+++ b/vndk/tools/header-checker/tests/integration/weak_symbols/libexample_new.map.txt
@@ -0,0 +1,3 @@
+LIBTEST_1.0 {
+  global:
+};
diff --git a/vndk/tools/header-checker/tests/integration/weak_symbols/libexample_old.map.txt b/vndk/tools/header-checker/tests/integration/weak_symbols/libexample_old.map.txt
new file mode 100644
index 000000000..f457f27a6
--- /dev/null
+++ b/vndk/tools/header-checker/tests/integration/weak_symbols/libexample_old.map.txt
@@ -0,0 +1,4 @@
+LIBTEST_1.0 {
+  global:
+    example;  # weak
+};
diff --git a/vndk/tools/header-checker/tests/module.py b/vndk/tools/header-checker/tests/module.py
index 3c281777d..9397ac19c 100755
--- a/vndk/tools/header-checker/tests/module.py
+++ b/vndk/tools/header-checker/tests/module.py
@@ -555,6 +555,37 @@ TEST_MODULES = [
             '--exclude-symbol-tag', 'mytag',
         ]
     ),
+
+    # Test data for test_allow_adding_removing_weak_symbols
+    LsdumpModule(
+        name='libweak_symbols_old',
+        arch='arm64',
+        srcs=[
+            'integration/weak_symbols/example.c',
+        ],
+        version_script='integration/weak_symbols/libexample_old.map.txt',
+        export_include_dirs=[],
+        dumper_flags=['-output-format', 'Json'],
+        linker_flags=[
+            '-input-format', 'Json',
+            '-output-format', 'Json',
+        ]
+    ),
+    LsdumpModule(
+        name='libweak_symbols_new',
+        arch='arm64',
+        srcs=[
+            'integration/weak_symbols/example.c',
+        ],
+        version_script='integration/weak_symbols/libexample_new.map.txt',
+        export_include_dirs=[],
+        dumper_flags=['-output-format', 'Json'],
+        linker_flags=[
+            '-input-format', 'Json',
+            '-output-format', 'Json',
+        ],
+        cflags=['-DNEW=1']
+    ),
 ]
 
 TEST_MODULES = {m.name: m for m in TEST_MODULES}
diff --git a/vndk/tools/header-checker/tests/reference_dumps/arm64/libweak_symbols_new.so.lsdump b/vndk/tools/header-checker/tests/reference_dumps/arm64/libweak_symbols_new.so.lsdump
new file mode 100644
index 000000000..30e1b67b6
--- /dev/null
+++ b/vndk/tools/header-checker/tests/reference_dumps/arm64/libweak_symbols_new.so.lsdump
@@ -0,0 +1,15 @@
+{
+ "array_types" : [],
+ "builtin_types" : [],
+ "elf_functions" : [],
+ "elf_objects" : [],
+ "enum_types" : [],
+ "function_types" : [],
+ "functions" : [],
+ "global_vars" : [],
+ "lvalue_reference_types" : [],
+ "pointer_types" : [],
+ "qualified_types" : [],
+ "record_types" : [],
+ "rvalue_reference_types" : []
+}
diff --git a/vndk/tools/header-checker/tests/reference_dumps/arm64/libweak_symbols_old.so.lsdump b/vndk/tools/header-checker/tests/reference_dumps/arm64/libweak_symbols_old.so.lsdump
new file mode 100644
index 000000000..a63ae1666
--- /dev/null
+++ b/vndk/tools/header-checker/tests/reference_dumps/arm64/libweak_symbols_old.so.lsdump
@@ -0,0 +1,37 @@
+{
+ "array_types" : [],
+ "builtin_types" :
+ [
+  {
+   "linker_set_key" : "void",
+   "name" : "void",
+   "referenced_type" : "type-1",
+   "self_type" : "type-1"
+  }
+ ],
+ "elf_functions" :
+ [
+  {
+   "binding" : "weak",
+   "name" : "example"
+  }
+ ],
+ "elf_objects" : [],
+ "enum_types" : [],
+ "function_types" : [],
+ "functions" :
+ [
+  {
+   "function_name" : "example",
+   "linker_set_key" : "example",
+   "return_type" : "type-1",
+   "source_file" : "/development/vndk/tools/header-checker/tests/integration/weak_symbols/example.c"
+  }
+ ],
+ "global_vars" : [],
+ "lvalue_reference_types" : [],
+ "pointer_types" : [],
+ "qualified_types" : [],
+ "record_types" : [],
+ "rvalue_reference_types" : []
+}
diff --git a/vndk/tools/header-checker/tests/test.py b/vndk/tools/header-checker/tests/test.py
index 1ed8852dc..57df7d378 100755
--- a/vndk/tools/header-checker/tests/test.py
+++ b/vndk/tools/header-checker/tests/test.py
@@ -309,6 +309,25 @@ class HeaderCheckerTest(unittest.TestCase):
             ["-input-format-old", "Json", "-input-format-new", "Json",
              "-consider-opaque-types-different"])
 
+    def test_allow_adding_removing_weak_symbols(self):
+        module_old = Module.get_test_modules_by_name("libweak_symbols_old")[0]
+        module_new = Module.get_test_modules_by_name("libweak_symbols_new")[0]
+        lsdump_old = self.get_or_create_ref_dump(module_old, False)
+        lsdump_new = self.get_or_create_ref_dump(module_new, False)
+
+        options = ["-input-format-old", "Json", "-input-format-new", "Json"]
+
+        # If `-allow-adding-removing-weak-symbols` is not specified, removing a
+        # weak symbol must be treated as an incompatible change.
+        self.run_and_compare_abi_diff(
+            lsdump_old, lsdump_new, "libweak_symbols", "arm64", 8, options)
+
+        # If `-allow-adding-removing-weak-symbols` is specified, removing a
+        # weak symbol must be fine and mustn't be a fatal error.
+        self.run_and_compare_abi_diff(
+            lsdump_old, lsdump_new, "libweak_symbols", "arm64", 0,
+            options + ["-allow-adding-removing-weak-symbols"])
+
     def test_linker_shared_object_file_and_version_script(self):
         base_dir = os.path.join(
             SCRIPT_DIR, 'integration', 'version_script_example')