cmake在windows上找到sqlite3库。-cmakefindsqlite3libraryonwindows

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There are some issues here and also some weird Windows stuff!

这里有一些问题，还有一些奇怪的Windows操作系统!

First issue; when searching for a library on Windows with MSVC as the generator, CMake will always look for a ".lib" file - never a ".dll", even if you specify e.g. sqlite3.dll as the NAMES argument to find_library. This is unfortunately not properly documented, in fact the docs for CMAKE_FIND_LIBRARY_SUFFIXES wrongly state:

第一个问题;当用MSVC搜索Windows上的一个库时，CMake会一直寻找a。lib“文件-从不a”。即使你指定了sqlite3。dll作为名称参数到find_library。不幸的是，这并没有被正确地记录下来，事实上，cmake_find_library_suffix的文档错误地表示:

This specifies what suffixes to add to library names when the find_library command looks for libraries. On Windows systems this is typically .lib and .dll, meaning that when trying to find the foo library it will look for foo.dll etc.

当find_library命令查找库时，它指定添加到库名称的后缀。在Windows系统上，这是典型的。lib和。dll，意思是当试图查找foo库时，它会查找foo。dll等。

You can easily check this; simply add

你可以很容易地检查这个;简单的添加

message("CMAKE_FIND_LIBRARY_SUFFIXES:  ${CMAKE_FIND_LIBRARY_SUFFIXES}")

to your CMakeLists.txt. You should see output like:

CMakeLists.txt。您应该会看到如下输出:

CMAKE_FIND_LIBRARY_SUFFIXES:  .lib

This thread from the CMake mailing list further confirms this behaviour. If you really need to find the dlls, you'll need to use the find_file command, e.g:

来自CMake邮件列表的这个线程进一步证实了这种行为。如果您真的需要找到dll，您需要使用find_file命令，例如:

find_file(SQLITE3_DLL_DEBUG NAMES sqlite3d.dll PATHS ...)

The next issue is a minor one. You should prefer PATHS to HINTS as the argument in find_xxx commands if it's a hard-coded guess. From the docs for find_library:

下一个问题是次要的。如果这是一个硬编码的猜测，那么您应该更喜欢在find_xxx命令中作为参数提示的路径。来自find_library的文档:

3. Search the paths specified by the HINTS option. These should be paths computed by system introspection, such as a hint provided by the location of another item already found. Hard-coded guesses should be specified with the PATHS option.

3所示。搜索提示选项指定的路径。这些路径应该是由系统内省所计算的路径，例如由已经找到的另一个项目的位置提供的提示。硬编码的猜测应该用路径选项指定。

A slightly more serious issue is in the line:

一个稍微严肃点的问题是:

FIND_LIBRARY(SQLITE3_LIBRARY_DEBUG NAMES sqlite3 sqlite3d ...)

You should specify sqlite3d first then sqlite3 or sqlite3 will incorrectly be chosen as the Debug library if both are available.

您应该首先指定sqlite3d，如果两者都可用，那么sqlite3或sqlite3将被错误地选择为调试库。

And now the weirdness...

现在,不可思议……

On a Windows x64 system, the find_xxx partially ignores the C:\Windows\System32 directory in favour of the C:\Windows\SysWOW64 one.

在Windows x64系统,find_xxx部分忽略了C:\Windows\System32目录支持C:\Windows\SysWOW64。

If you don't have the sqlite3.lib in C:\Windows\SysWOW64, then the find_library command will always fail, regardless of the PATHS argument.

如果你没有sqlite3。自由在C:\Windows\ SysWOW64,find_library命令总是失败,无论路径参数。

However, if you do have C:\Windows\SysWOW64\sqlite3.lib, then any combination of C:/Windows/SysWOW64 and/or C:/Windows/System32 as the PATHS argument finds the library, but sets the full path to C:/Windows/System32/sqlite3.lib even if C:/Windows/System32/sqlite3.lib doesn't exist! This is obviously useless if the library isn't there; a linker error will result.

然而,如果你确实有C:\Windows\SysWOW64\sqlite3.lib，然后是C:/Windows/SysWOW64和/或C:/Windows/System32的任意组合，因为路径参数找到了库，但是将完整路径设置为C:/Windows/System32/sqlite3。自由即使C:/ Windows / System32系统/ sqlite3。自由不存在!如果库不存在，这显然是没有用的;一个链接器错误将导致。

There is some further reading again from the CMake mailing list here.

这里还有一些来自CMake邮件列表的进一步阅读。

Having said that, if you're linking, you'll be using the .lib files, not the .dlls, and System32 & SysWOW64 aren't really the place for .lib files.

已经说过，如果链接的话，将使用.lib文件，而不是.dll, System32 & SysWOW64并不是.lib文件的真正位置。