CheckLibraryExists

This module provides a command to check whether a C library exists.

在 CMake 專案中使用以下命令載入該模組：

include(CheckLibraryExists)

命令

This module provides the following command:

check_library_exists

Checks once whether a specified library exists and a given C function is available:

check_library_exists(<library> <function> <location> <variable>)

This command attempts to link a test executable that uses the specified C <function> to verify that it is provided by either a system or user-provided <library>.

The arguments are:

<library>

The name of the library, a full path to a library file, or an Imported Target.

<function>

The name of a function that should be available in the system or user-provided library <library>.

<location>

The directory containing the library file. It is added to the link search path during the check. If this is an empty string, only the default library search paths are used.

<variable>

The name of the variable in which to store the check result. This variable will be created as an internal cache variable.

備註

This command is intended for performing basic sanity checks to verify that a library provides the expected functionality, or that the correct library is being located. However, it only verifies that a function symbol can be linked successfully - it does not ensure that the function is declared in library headers, nor can it detect functions that are inlined or defined as preprocessor macros. For more robust detection of function availability, prefer using CheckSymbolExists or CheckSourceCompiles.

影響檢查的變數

可以在呼叫此命令之前設定以下變數，以修改檢查的執行方式：

CMAKE_REQUIRED_FLAGS

一個以空格分隔的字串，包含要傳遞給編譯器的額外旗標。分號分隔列表將無法運作。CMAKE_<LANG>_FLAGS 及其關聯的特定組態 CMAKE_<LANG>_FLAGS_<CONFIG> 變數的內容會在該變數的內容之前自動預置到編譯器命令中。

CMAKE_REQUIRED_DEFINITIONS

一個編譯器定義的分號分隔列表，每個定義的形式為 -DFOO 或 -DFOO=bar。由檢查命令的結果變數引數所指定的名稱的定義也會自動新增。

CMAKE_REQUIRED_LINK_OPTIONS

在 3.14 版被加入.

一個要新增到連結命令的選項的分號分隔列表（詳情請參見 try_compile()）。

CMAKE_REQUIRED_LIBRARIES

一個要新增到連結命令的程式庫的分號分隔列表。這些可以是系統程式庫的名稱，也可以是 Imported Targets`（詳情請參見 :command:`try_compile）。

CMAKE_REQUIRED_LINK_DIRECTORIES

在 3.31 版被加入.

一個要傳遞給連結器的程式庫搜尋路徑的分號分隔列表（詳情請參見 try_compile()）。

CMAKE_REQUIRED_QUIET

在 3.1 版被加入.

如果此變數的值為布林真值，則與檢查相關的所有狀態訊息都將被抑制。

範例

Checking if the curl library exists in the default paths and has the curl_easy_perform() function:

include(CheckLibraryExists)
check_library_exists(curl curl_easy_perform "" HAVE_LIBRARY_CURL)

To check if library exists in specific non-standard location and has a specified function:

include(CheckLibraryExists)
check_library_exists(curl curl_easy_perform "/opt/curl/lib" HAVE_LIBRARY_CURL)

Also 匯入目標 (for example, from the find_package() call) can be used:

find_package(CURL)

# ...

if(TARGET CURL::libcurl)
  include(CheckLibraryExists)
  check_library_exists(CURL::libcurl curl_easy_perform "" HAVE_LIBRARY_CURL)
endif()

另請參見