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new 5c2ff723410 GH-50978: [C++] Enable MSVC's new preprocessor to handle
C++20 grammar (#50979)
5c2ff723410 is described below
commit 5c2ff723410f0841b0ea1158d455bbfa23ff1ca9
Author: Zehua Zou <[email protected]>
AuthorDate: Tue Sep 22 05:13:32 2026 +0800
GH-50978: [C++] Enable MSVC's new preprocessor to handle C++20 grammar
(#50979)
### Rationale for this change
Try to use MSVC's new preprocessor to handle C++20 grammar such as
`__VA_OPT__`.
### What changes are included in this PR?
Change the common flag under MSVC.
### Are these changes tested?
Tested by existed tests.
### Are there any user-facing changes?
No.
* GitHub Issue: #50978
Authored-by: Zehua Zou <[email protected]>
Signed-off-by: Sutou Kouhei <[email protected]>
---
cpp/cmake_modules/SetupCxxFlags.cmake | 17 +++--------------
1 file changed, 3 insertions(+), 14 deletions(-)
diff --git a/cpp/cmake_modules/SetupCxxFlags.cmake
b/cpp/cmake_modules/SetupCxxFlags.cmake
index f6590ddce68..e7a4a3e5dc8 100644
--- a/cpp/cmake_modules/SetupCxxFlags.cmake
+++ b/cpp/cmake_modules/SetupCxxFlags.cmake
@@ -218,22 +218,11 @@ if(WIN32)
set(CXX_COMMON_FLAGS "/W3 /EHsc")
endif()
- # Disable C5105 (macro expansion producing 'defined' has undefined
- # behavior) warning because there are codes that produce this
- # warning in Windows Kits. e.g.:
- #
- # #define _CRT_INTERNAL_NONSTDC_NAMES
\
- # (
\
- # ( defined _CRT_DECLARE_NONSTDC_NAMES &&
_CRT_DECLARE_NONSTDC_NAMES) || \
- # (!defined _CRT_DECLARE_NONSTDC_NAMES && !__STDC__
) \
- # )
+ # Enable the conforming preprocessor to support C++20 features.
#
# See also:
- # * C5105:
https://docs.microsoft.com/en-US/cpp/error-messages/compiler-warnings/c5105
- # * Related reports:
- # *
https://developercommunity.visualstudio.com/content/problem/387684/c5105-with-stdioh-and-experimentalpreprocessor.html
- # *
https://developercommunity.visualstudio.com/content/problem/1249671/stdc17-generates-warning-compiling-windowsh.html
- set(CXX_COMMON_FLAGS "${CXX_COMMON_FLAGS} /wd5105")
+ # *
https://devblogs.microsoft.com/cppblog/announcing-full-support-for-a-c-c-conformant-preprocessor-in-msvc/
+ set(CXX_COMMON_FLAGS "${CXX_COMMON_FLAGS} /Zc:preprocessor")
if(ARROW_USE_STATIC_CRT)
foreach(c_flag
