[llvm-branch-commits] [libcxx] release/23.x: [libcxx] avoid include Uppercase windows headers (#208903) (PR #210292)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/210292

Backport 2580624091e36b85c162439513eef8e752217a1d

Requested by: @mstorsjo

>From 33895ccf1fc365058158f5b9393b5f81f595061a Mon Sep 17 00:00:00 2001
From: cqwrteur <oyzawqgcfc at gmail.com>
Date: Fri, 17 Jul 2026 17:11:45 +0800
Subject: [PATCH] [libcxx] avoid include Uppercase windows headers (#208903)
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We should use unknwn.h and windows.h instead of Unknwn.h and Windows.h
because Linux and other non‑Windows systems treat filenames as
case‑sensitive. Windows does not, so mixed‑case includes work there but
break elsewhere. Both mingw‑w64‑crt and windows‑msvc‑sysroot provide all
Windows headers in fully lowercase, so using the lowercase forms ensures
consistent cross‑platform builds.

Fixes #208901

(cherry picked from commit 2580624091e36b85c162439513eef8e752217a1d)
---
 libcxx/src/support/runtime/exception_pointer_msvc.ipp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libcxx/src/support/runtime/exception_pointer_msvc.ipp b/libcxx/src/support/runtime/exception_pointer_msvc.ipp
index 72360a2d791bd..3102d1ee93db2 100644
--- a/libcxx/src/support/runtime/exception_pointer_msvc.ipp
+++ b/libcxx/src/support/runtime/exception_pointer_msvc.ipp
@@ -14,8 +14,8 @@ _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wmultichar")
 #include <cstdlib>
 #include <cstring>
 
-#include <Unknwn.h>
-#include <Windows.h>
+#include <unknwn.h>
+#include <windows.h>
 struct _ThrowInfo;
 #include <eh.h>
 #include <ehdata.h>