add_custom_command不生成目标 [英] add_custom_command is not generating a target

问题描述

也许这是不可能的，我误读了 cmake 3.2文档，但是我虽然创建一个自定义命令将在Makefile中创建一个自定义目标，以便我可以通过调用输出文件的名称来构建目标。 CMake文档说：

Perhaps this is impossible and I'm misreading the cmake 3.2 documentation, but I though creating a custom command would create a custom "target" in the Makefile so that I could build the target by invoking the name of the output file. The CMake docs says:

在makefile术语中，这将创建一个新的目标，形式如下：

In makefile terms this creates a new target in the following form:

 OUTPUT: MAIN_DEPENDENCY DEPENDS
    COMMAND

所以我想我可以运行 make OUTPUT 。也许该文档使CMake目标与Makefile目标混淆？

so I thought I could then run make OUTPUT. Perhaps the documentation is confusing CMake targets with Makefile targets?

例如，

 add_custom_command(OUTPUT foo_out
    COMMAND post_process foo_in > foo_out
    DEPENDS foo_in
 )

我想做

 make foo_out

，它会使 foo_out 。但是，如果我这样做，我得到

and it will make foo_out. However, if I do this, I get

make: **** No rule to make target `foo_out`. Stop.

并且肯定的，单词foo_out不存在于cmake二进制文件中的任何文件输出目录。如果我将其更改为

and sure enough, the word "foo_out" doesn't exist anywhere in any file in the cmake binary output directory. If I change it to this

add_custom_target(bar DEPENDS foo_out)
add_custom_command(OUTPUT foo_out COMMAND post_process foo_in > foo_out)

然后我可以做

make bar

我可以做

make foo_in

仍然无法做到

make foo_out

make bar 的问题是它不直观，因为实际的文件输出是 foo_out 不 bar 。

The problem with make bar is that it is unintuitive, as the actual file output is foo_out not bar.

我如何做？

在我的例子中，我需要对标准可执行目标运行一个特殊的处理步骤，将可选资源插入到ELF文件中。我想要有两个可执行文件作为Makefile目标的能力，所以我可以构建裸体ELF可执行文件以及注入资源的ELF可执行文件。

In my case, I need to run a special processing step to the standard executable target which inserts optional resources into the ELF file. I would like the ability to have both executables as Makefile targets, so I can build the naked ELF executable as well as the resource-injected ELF executable.

如果我写一个自定义Makefile，这是无关紧要的！

If I was writing a custom Makefile, this is trivial to do!

foo_in: foo.c
    $(CC) $< -o $@

foo_out: foo_in
    post_process $< > $@   

我可以做 make foo_in 和 make foo_out 。

推荐答案

add_custom_command 不创建新目标。您必须通过 add_executable ， add_library 或 add_custom_target

add_custom_command does not create a new target. You have to define targets explicitly by add_executable, add_library or add_custom_target in order to make them visible to make.

如果您需要修复部署，可以

If you have to fix things up for deployment, you could

1。使用 install 命令（在CMakeLists.txt中的某个位置），如下所示：

1. use the install command (somewhere in your CMakeLists.txt) like this:

install(SCRIPT <dir>/post_install.cmake)

$ b b

存储只有在单独的 .cmake 文件中运行 make install 时才执行的命令。或者，如果安装目标已预留给其他项目，或者您有更复杂的工作：

to store commands which are executed only when you run make install in a separate .cmake file. Or if the install target is already reserved for other things or you have more complex stuff going on:

2。手动定义部署目标。一旦你得到了，你可以创建一个自定义后生成命令，只有当你明确地运行make在你的部署目标。

2. manually define a deploy target. Once you got that, you can create a custom post-build command which is only executed when you explicitly run make on your deploy target. This allows you to execute commands through a separate target.

在您的CMakeLists.txt中，这可能如下所示：

In your CMakeLists.txt this could look like:

cmake_minimum_required(VERSION 3.0)

add_executable("App" <sources>)

# option 1: do deployment stuff only when installing
install(SCRIPT <dir>/post_install.cmake)

# option 2: define a deploy target and add post-build commands
add_custom_target("deploy")
add_custom_command(TARGET "deploy" POST_BUILD <some command>)

单独的开发从昂贵的现成部署构建（如果我理解正确，这是这里的目标）。我会推荐选项1，因为它只是更干净。

Both approaches allow you to separate dev builds from expensive ready-to-deploy builds (if I understand correctly, that's the goal here). I would recommend option 1 since it's just cleaner.

希望这有助于！

这篇关于add_custom_command不生成目标的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！