[英]Qt library link errors in Windows
Project builds fine on Linux however has problem linking in Windows. 项目在Linux上构建良好,但是在Windows中链接存在问题。
LNK2019: unresolved external symbol ...
LNK1120: 21 unresolved externals
.pro
file contains: .pro
文件包含:
isEmpty(IDE_BUILD_TREE): IDE_BUILD_TREE = ../../qt-creator-debug
LIBS += -L$${IDE_BUILD_TREE}/lib/qtcreator/plugins -lMyLibrary
Note. 注意。
MyLibrary
deployed to$${IDE_BUILD_TREE}/lib/qtcreator/plugins
before build. 在构建之前,将MyLibrary
部署到$${IDE_BUILD_TREE}/lib/qtcreator/plugins
。 Building with Qt 5.10.1 and MSVC 2015. 使用Qt 5.10.1和MSVC 2015构建。
What is the problem/trick here? 这是什么问题/技巧? How to solve? 怎么解决?
In the library .pro
file VERSION
variable is defined and resulting library has name MyLibrary1.lib
. 在库.pro
文件中,定义了VERSION
变量,并且生成的库具有名称MyLibrary1.lib
。 Thereafter I get error: 此后我得到错误:
:-1: error: LNK1181: cannot open input file 'MyLibrary.lib'
What is better way to solve the problem here: remove VERSION
or fix .pro
file? 在这里解决问题的更好方法是什么:删除VERSION
或修复.pro
文件? How? 怎么样?
Another link error: 另一个链接错误:
mydialog.obj:-1: error: LNK2001: unresolved external symbol
"struct QMetaObject const MyLibrary::staticMetaObject"
(?staticMetaObject@MyLibrary@@3UQMetaObject@@B)
Error happen because of the following line in code (disappears when commented out): 由于代码中的以下行而发生错误(注释掉时消失):
QMetaEnum myEnum = QMetaEnum::fromType<MyLibrary::MyEnumClass>();
namespace MyLibrary {
Q_NAMESPACE
enum class MYLIBRARYSHARED_EXPORT MyEnumClass {
...
};
Q_ENUM_NS(MyEnumClass)
...
} // namespace MyLibrary
And how to solve the 3rd one? 以及如何解决第三个问题?
My bad: error caused by missed MYLIBRARYSHARED_EXPORT
in some classes' declarations, which defined in global header as: 我的坏处:由某些类的声明中缺少MYLIBRARYSHARED_EXPORT
引起的错误,在全局标头中将其定义为:
#if defined(MYLIBRARY_LIBRARY)
# define MYLIBRARYSHARED_EXPORT Q_DECL_EXPORT
#else
# define MYLIBRARYSHARED_EXPORT Q_DECL_IMPORT
#endif
Without MYLIBRARYSHARED_EXPORT
builds fine in Linux and Mac but fails in Windows. 没有MYLIBRARYSHARED_EXPORT
可以在Linux和Mac上MYLIBRARYSHARED_EXPORT
构建,但是在Windows上无法构建。
Possible solution - add to .pro
file line: 可能的解决方案-添加到.pro
文件行:
win32:CONFIG += skip_target_version_ext
or 要么
win32:TARGET_EXT = .dll
to set the output filename without the major version number on Windows. 在Windows上设置没有主版本号的输出文件名。 However I see, for example, Qt Creator plugins link libraries with major version number without a problem. 但是,例如,我看到Qt Creator插件将库的主要版本号链接在一起没有问题。 How to do this? 这个怎么做?
Need to prepend Q_NAMESPACE
declaration with MYLIBRARYSHARED_EXPORT
as well: 还需要在Q_NAMESPACE
声明前加上MYLIBRARYSHARED_EXPORT
:
namespace MyLibrary {
MYLIBRARYSHARED_EXPORT Q_NAMESPACE
enum class MYLIBRARYSHARED_EXPORT MyEnumClass {
...
};
Q_ENUM_NS(MyEnumClass)
...
} // namespace MyLibrary
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