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[CI] add C++20 compile probe #79445

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[CI] add C++20 compile probe #79445

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5 changes: 5 additions & 0 deletions paddle/common/enforce.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,11 @@ limitations under the License. */
REGISTER_LOG_SIMPLY_STR(std::string);
COMMON_DECLARE_int32(call_stack_level);
namespace {
// C++20 compile probe: consteval is C++20-only, and this file is built into
// common and common_static.
consteval bool PaddleCxx20CompileProbe() { return true; }

@risemeup1111 risemeup1111 Jul 8, 2026

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P1 优先级：P1

这里无条件使用 consteval 会破坏仓库当前仍显式保留的 C++17 构建路径。cmake/flags.cmake 里 GCC < 11 仍会追加 -std=c++17，Windows 分支也设置 CMAKE_CXX_STANDARD 17；同时 paddle/common/CMakeLists.txt 会把本文件编入 common 和 common_static。在这些路径下，本行会直接语法失败（例如 c++ -std=c++17 -I. -fsyntax-only paddle/common/enforce.cc 会报 consteval does not name a type），导致现有受支持构建无法通过。

处理要求：请针对该评论修复并提交新的 commit。

请在同一个 PR 中先统一构建策略，再保留这个探针。可选方向之一是正式移除这些 C++17 fallback 并让配置阶段直接失败，例如：

if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND
   CMAKE_CXX_COMPILER_VERSION VERSION_LESS 11)
  message(FATAL_ERROR "GCC >= 11 is required for the C++20 baseline.")
endif()
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++20")

如果 GCC < 11 / Windows 的 C++17 路径还需要继续保留，则这个探针不能无条件放在会被这些路径编译的公共源文件中，需要先加条件或改放到只覆盖 C++20 目标的构建检查里。

@PaddlePaddle-bot PaddlePaddle-bot Jul 8, 2026

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🔴 Bug 这里无条件使用 consteval，会让仓库仍显式配置为 C++17 的构建路径直接失败。

paddle/common/enforce.cc 会进入 common 和 common_static，但 cmake/flags.cmake 目前仍对 GCC < 11 走 -std=c++17 fallback，并在 WIN32 下设置 CMAKE_CXX_STANDARD 17。因此这些被 CMake 接受的配置会在编译本文件时失败，而不是按构建系统声明的兼容路径继续工作。

建议修复方式：如果 Paddle 基线已经切到 C++20，请同步修改 cmake/flags.cmake，删除这些 C++17 fallback 或在 configure 阶段对 GCC < 11 / 当前 Windows 工具链给出明确 FATAL_ERROR；如果这些 fallback 仍需保留，则不要在公共源文件中放置无条件 C++20-only 代码。

static_assert(PaddleCxx20CompileProbe());

Comment on lines +26 to +30
class StrSizeCmp {
public:
bool operator()(const std::string& lhs, const std::string& rhs) const {
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