Techlog插件开发：Qt qHash重载匹配失败编译报错求助

问题描述 #

• 正在进行Techlog工具的插件开发，该工具提供的SDK UI基于Qt实现。
• 引入SDK的tsdkvariable.h头文件后编译代码，出现两类错误：
  • error C2665: 'qHash': none of the 23 overloads could convert all the argument types
  • error C2056: illegal expression
• SDK附带的Qt没有qmake，不清楚如何推进问题解决。

编译错误详情 #

error C2665: 'qHash': none of the 23 overloads could convert all the argument types
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(108): note: could be 'uint qHash(std::nullptr_t,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(105): note: or       'uint qHash(QLatin1String,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(104): note: or       'uint qHash(const QBitArray &,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(103): note: or       'uint qHash(QStringView,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(101): note: or       'uint qHash(const QStringRef &,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(100): note: or       'uint qHash(const QString &,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(98): note: or       'uint qHash(const QByteArray &,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(97): note: or       'uint qHash(const QChar,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(95): note: or       'uint qHash(long double,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(93): note: or       'uint qHash(double,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(92): note: or       'uint qHash(float,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(91): note: or       'uint qHash(qint64,uint) noexcept'
3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(87): note: or       'uint qHash(quint64,uint) noexcept'
1>c:\program files\schlumberger\ocean for techlog 2022.1\3rdparty\qt 5.15.2\include\qtcore\qhash.h(291): note: see reference to function template instantiation 'void QHash<T,QHashDummyValue>::detach_helper(void)' being compiled
1>        with
1>        [
1>            T=Slb::Ocean::Techlog::Droid
1>        ]
1>c:\program files (x86)\microsoft visual studio\2019\enterprise\vc\tools\msvc\14.16.27023\include\stdexcept(23): note: see reference to class template instantiation 'std::basic_string<char,std::char_traits<char>,std::allocator<char>>' being compiled
1>c:\program files\schlumberger\ocean for techlog 2022.1\3rdparty\qt 5.15.2\include\qtcore\qhashfunctions.h(118): error C2056: illegal expression

解决建议 #

处理qHash编译错误 #

从错误栈可知，编译器在为Slb::Ocean::Techlog::Droid类型实例化QHash模板时，找不到匹配的qHash重载函数，导致报错。可按以下步骤排查：

• 确认类型定义完整性：检查tsdkvariable.h是否完整包含Slb::Ocean::Techlog::Droid的类声明，避免前向声明导致的类型不完整问题。
• 手动实现qHash重载：如果SDK未提供该类型的哈希实现，在对应命名空间下添加qHash函数：

  #include <QtCore/QHash>
  namespace Slb::Ocean::Techlog {
      uint qHash(const Droid& obj, uint seed = 0) noexcept {
          // 根据Droid的核心成员生成哈希值，示例如下：
          return qHash(obj.uniqueIdentifier(), seed); // 假设存在返回可哈希类型的方法
      }
  }
  

• 排查非法表达式：error C2056多由语法错误或头文件包含顺序问题引发。检查qhashfunctions.h第118行附近代码，或调整Qt头文件与SDK头文件的包含顺序，确保Qt核心头文件先于SDK头文件引入。

处理无qmake的问题 #

Techlog的Ocean SDK默认使用MSBuild（Visual Studio）构建，无需qmake：

• 参考SDK官方文档：查看Ocean SDK的开发手册，通常会提供Visual Studio项目模板或预配置的项目文件，直接基于MSBuild编译即可。
• 使用CMake构建：若需自定义构建流程，可通过CMake配置项目，指定SDK和Qt路径，CMake会自动处理依赖：

  cmake_minimum_required(VERSION 3.16)
  project(TechlogPluginDemo)
  set(CMAKE_CXX_STANDARD 17)
  
  # 配置SDK和Qt路径
  set(OCEAN_SDK_ROOT "C:/Program Files/Schlumberger/Ocean for Techlog 2022.1")
  set(Qt5_DIR "${OCEAN_SDK_ROOT}/3rdparty/qt 5.15.2/lib/cmake/Qt5")
  
  find_package(Qt5 REQUIRED COMPONENTS Core Widgets)
  include_directories("${OCEAN_SDK_ROOT}/include")
  link_directories("${OCEAN_SDK_ROOT}/lib")
  
  add_library(TechlogPluginDemo SHARED plugin_main.cpp)
  target_link_libraries(TechlogPluginDemo Qt5::Core Qt5::Widgets OceanCore) # 根据实际SDK库名调整
  

• 联系官方支持：若以上方法无效，直接联系Schlumberger的Ocean SDK技术支持，获取针对性的构建指导。

内容的提问来源于stack exchange，提问作者NJMR