如何在 CMake 中输出生成器表达式的结果? [英] How do I output the result of a generator expression in CMake?

问题描述

我有以下简单的 CMake 代码:

I have the following simple CMake code:

cmake_minimum_required(VERSION 3.1)

project(PrintGenerators)

set(TEST_OR_GENERATOR "$<$<OR:0,0,1>:YAY!>")

message(STATUS ${TEST_OR_GENERATOR}) # Print out the result of the build

我希望这段代码能打印出YAY!，但它没有.我取而代之的是 $<$:YAY!> 作为输出.如何在配置期间打印计算的生成器表达式的结果?

I expect this code to print out YAY!, but it does not. I instead get $<$<OR:0,0,1>:YAY!> as the output. How do I print the result of the evaluated generator expression during configuration?

推荐答案

如何在配置过程中打印生成器表达式的计算结果?

How do I print the result of the evaluated generator expression during configuration?

你不能.生成器表达式适用于在配置阶段并不完全知道的事物:它们取决于构建类型，在多配置的情况下 generators 仅在构建阶段才被知晓.

You cannot. Generator expressions are intended for things, which are not exactly known at configuration stage: they depends on build type, which, in case of multiconfiguration generators becomes known only at the build stage.

然而，您可以将生成器表达式的值保存到文件中，但文件只会在配置阶段结束时写入:

You may, however, save a value of the generator expression into the file, but the file will be written only at the end of the configuration stage:

file(GENERATE OUTPUT <filename> CONTENT <string-with-generator-expression>)

file(GENERATOR) 的更详细描述见 文档.

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