CMake GCC 在包含的头文件中找不到 curl 结构

Question

我正在尝试使用 CMake 创建一个使用 libcurl 的库，但 GCC 始终无法找到某些结构和定义，即使它们被包含在内。我安装了 curl、libssl-dev 和 libcurl4-openssl-dev。我能够使用 gcc libcurl-out.c -lcurl.

编译由 curl http://example.com --libcurl libcurl-out.c 生成的独立示例程序

这是我的项目结构：

OpenDropC/
├── include/
│   ├── browser.h
│   ├── client.h
│   ├── config.h
│   └── server.h
├── src/
│   ├── browser.c
│   ├── client.c
│   ├── config_private.h
│   ├── config.c
│   ├── server.c
│   ├── utils.c
│   └── utils.h
└── CMakeLists.txt

config.c 包括 config_private.h，其中包括 <curl/curl.h>。将 curl include 直接放在 config.c 中并不能解决问题。

这是我的 CMakeLists.txt:

cmake_minimum_required(VERSION 3.18)

project(OpenDropC VERSION 0.0.1 DESCRIPTION "Implementation of OpenDrop in C for Linux")

include(CTest)
enable_testing()

add_library(OpenDropC SHARED
    src/browser.c
    src/client.c
    src/server.c
    src/config.c
    src/utils.c
)

# set_target_properties(OpenDropC PROPERTIES PUBLIC_HEADER include/browser.h)
target_link_libraries(OpenDropC PRIVATE avahi-common avahi-client curl ssl)

这是我得到的编译器错误：

[main] Building folder: OpenDropC 
[build] Starting build
[proc] Executing command: /usr/local/bin/cmake --build /home/parallels/Code/OpenDropC/build --config Debug --target all -j 4 --
[build] [4/8  12% :: 0.043] Building C object CMakeFiles/OpenDropC.dir/src/server.c.o
[build] [5/8  25% :: 0.063] Building C object CMakeFiles/OpenDropC.dir/src/browser.c.o
[build] [6/8  37% :: 0.072] Building C object CMakeFiles/OpenDropC.dir/src/client.c.o
[build] [6/8  50% :: 0.080] Building C object CMakeFiles/OpenDropC.dir/src/utils.c.o
[build] [6/8  62% :: 0.088] Building C object CMakeFiles/OpenDropC.dir/src/config.c.o
[build] FAILED: CMakeFiles/OpenDropC.dir/src/config.c.o 
[build] /bin/gcc-9 -DOpenDropC_EXPORTS  -g -fPIC -MD -MT CMakeFiles/OpenDropC.dir/src/config.c.o -MF CMakeFiles/OpenDropC.dir/src/config.c.o.d -o CMakeFiles/OpenDropC.dir/src/config.c.o -c /home/parallels/Code/OpenDropC/src/config.c
[build] /home/parallels/Code/OpenDropC/src/config.c: In function ‘opendrop_config_new’:
[build] /home/parallels/Code/OpenDropC/src/config.c:42:70: error: invalid application of ‘sizeof’ to incomplete type ‘struct curl_blob’
[build]    42 |     if (!(config_unwrap->root_ca = (struct curl_blob*) malloc(sizeof(struct curl_blob)))) {
[build]       |                                                                      ^~~~~~
[build] /home/parallels/Code/OpenDropC/src/config.c:48:33: error: dereferencing pointer to incomplete type ‘struct curl_blob’
[build]    48 |     if (!(config_unwrap->root_ca->data = malloc(root_ca_len))) {
[build]       |                                 ^~
[build] /home/parallels/Code/OpenDropC/src/config.c:56:37: error: ‘CURL_BLOB_NOCOPY’ undeclared (first use in this function)
[build]    56 |     config_unwrap->root_ca->flags = CURL_BLOB_NOCOPY;
[build]       |                                     ^~~~~~~~~~~~~~~~
[build] /home/parallels/Code/OpenDropC/src/config.c:56:37: note: each undeclared identifier is reported only once for each function it appears in
[build] /home/parallels/Code/OpenDropC/src/config.c: In function ‘opendrop_config_set_record_data’:
[build] /home/parallels/Code/OpenDropC/src/config.c:280:71: error: invalid application of ‘sizeof’ to incomplete type ‘struct curl_blob’
[build]   280 |         if (!(config->record_data = (struct curl_blob*) malloc(sizeof(struct curl_blob)))) {
[build]       |                                                                       ^~~~~~
[build] /home/parallels/Code/OpenDropC/src/config.c:284:38: error: ‘CURL_BLOB_NOCOPY’ undeclared (first use in this function)
[build]   284 |         config->record_data->flags = CURL_BLOB_NOCOPY;
[build]       |                                      ^~~~~~~~~~~~~~~~
[build] [6/8  75% :: 0.097] Building C object CMakeFiles/OpenDropCTest.dir/test/main.c.o
[build] ninja: build stopped: subcommand failed.
[build] Build finished with exit code 1

运行 curl-config --cflags returns 一个空字符串，但我尝试显式地将目录包含在 curl 文件中，但没有任何改变。我也试过 this answer 没有改变。其他库编译得很好，所以这似乎是一个 libcurl 问题。尝试将 VCPKG 专门用于 curl 确实有效，但使用它会使我的项目过于臃肿。

Answer 1

我通过从源代码安装最新版本的 libcurl 解决了这个问题。 Ubuntu 20.04 的 libcurl 版本似乎有问题。

CMake GCC 在包含的头文件中找不到 curl 结构

CMake GCC can't find curl struct in included header file

c

gcc

cmake

libcurl