CMP0091 cmake config_error ai_generated true

CMake 错误：未设置策略 CMP0091：MSVC 运行时库标志由 CMAKE_MSVC_RUNTIME_LIBRARY 变量选择。

CMake Error: Policy CMP0091 is not set: MSVC runtime library flags are selected by the CMAKE_MSVC_RUNTIME_LIBRARY variable.

ID: cmake/missing-override-policy-visibility-inline

其他格式: JSON · Markdown 中文 · English
90%修复率
85%置信度
1证据数
2023-08-15首次发现

版本兼容性

版本状态引入弃用备注
CMake 3.15 active — — —
CMake 3.16 active — — —
CMake 3.20 active — — —
Visual Studio 2019 active — — —
Visual Studio 2022 active — — —

根因分析

CMake 3.15+ 引入了 CMP0091 策略，通过 CMAKE_MSVC_RUNTIME_LIBRARY 变量控制 MSVC 运行时库的选择，但未显式设置该策略，导致静默回退到旧行为，可能与项目预期不匹配。

English

CMake 3.15+ introduces CMP0091 to control MSVC runtime library selection via CMAKE_MSVC_RUNTIME_LIBRARY, but the policy is not explicitly set, causing silent fallback to older behavior that may mismatch with project expectations.

generic

官方文档

https://cmake.org/cmake/help/latest/policy/CMP0091.html

解决方案

  1. 在顶层 CMakeLists.txt 中的任何 project() 调用之前添加 `cmake_policy(SET CMP0091 NEW)`，然后将 CMAKE_MSVC_RUNTIME_LIBRARY 设置为所需值（例如 MultiThreadedDLL）。
  2. 在工具链文件中使用 `set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreadedDLL")` 和 `cmake_policy(SET CMP0091 NEW)` 进行跨平台构建。
  3. 如果使用 CMake 3.14 或更早版本，升级到 3.15+ 并采用新策略；否则，避免使用 CMAKE_MSVC_RUNTIME_LIBRARY，依赖手动标志管理。

无效尝试

常见但无效的做法:

  1. Setting CMAKE_MSVC_RUNTIME_LIBRARY directly without cmake_policy(SET CMP0091 NEW) 70% 失败

    Manually setting CMAKE_MSVC_RUNTIME_LIBRARY without setting the policy may still produce the warning or error, as the policy governs whether the variable is honored.

  2. Hardcoding MSVC runtime flags in CMAKE_CXX_FLAGS 85% 失败

    Adding /MD or /MT flags manually via CMAKE_CXX_FLAGS can conflict with CMake's runtime library selection, causing linker errors or undefined behavior.

  3. Suppressing the warning with cmake_policy(SET CMP0091 OLD) 60% 失败

    Ignoring the warning may allow the build to proceed, but the resulting binaries may link against mismatched runtime libraries, leading to crashes.