[libc++] Add clang-20 to failing tests on Windows

[gulfemsavrun]

After we switched to LLVM version 20, some libc++ tests started failing on Windows. This patch adds the clang-20 condition to XFAIL to fix the issue. The way that these tests are excluded from Windows are fragile and need to be updated every time we bump the LLVM version.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: None (gulfemsavrun)

Changes

After we switched to LLVM version 20, some libc++ tests started failing on Windows. This patch adds the clang-20 condition to XFAIL to fix the issue. The way that these tests are excluded from Windows are fragile and need to be updated every time we bump the LLVM version.

---

Full diff: https://github.com/llvm/llvm-project/pull/100119.diff

3 Files Affected:

• (modified) libcxx/test/libcxx/fuzzing/random.pass.cpp (+1-1)
• (modified) libcxx/test/std/depr/depr.c.headers/math_h.pass.cpp (+1-1)
• (modified) libcxx/test/std/numerics/c.math/cmath.pass.cpp (+1-1)

diff --git a/libcxx/test/libcxx/fuzzing/random.pass.cpp b/libcxx/test/libcxx/fuzzing/random.pass.cpp
index 663977696f2df..af80fb8ba18d9 100644
--- a/libcxx/test/libcxx/fuzzing/random.pass.cpp
+++ b/libcxx/test/libcxx/fuzzing/random.pass.cpp
@@ -8,7 +8,7 @@
 
 // This test fails because Clang no longer enables -fdelayed-template-parsing
 // by default on Windows with C++20 (#69431).
-// XFAIL: msvc && (clang-18 || clang-19)
+// XFAIL: msvc && (clang-18 || clang-19 || clang-20)
 
 // UNSUPPORTED: c++03, c++11
 
diff --git a/libcxx/test/std/depr/depr.c.headers/math_h.pass.cpp b/libcxx/test/std/depr/depr.c.headers/math_h.pass.cpp
index bbfb0c5548fab..0f47a513ea0e8 100644
--- a/libcxx/test/std/depr/depr.c.headers/math_h.pass.cpp
+++ b/libcxx/test/std/depr/depr.c.headers/math_h.pass.cpp
@@ -8,7 +8,7 @@
 
 // This test fails because Clang no longer enables -fdelayed-template-parsing
 // by default on Windows with C++20 (#69431).
-// XFAIL: msvc && (clang-18 || clang-19)
+// XFAIL: msvc && (clang-18 || clang-19 || clang-20)
 
 // <math.h>
 
diff --git a/libcxx/test/std/numerics/c.math/cmath.pass.cpp b/libcxx/test/std/numerics/c.math/cmath.pass.cpp
index 9379084499792..f53d8f259f47e 100644
--- a/libcxx/test/std/numerics/c.math/cmath.pass.cpp
+++ b/libcxx/test/std/numerics/c.math/cmath.pass.cpp
@@ -8,7 +8,7 @@
 
 // This test fails because Clang no longer enables -fdelayed-template-parsing
 // by default on Windows with C++20 (#69431).
-// XFAIL: msvc && (clang-18 || clang-19)
+// XFAIL: msvc && (clang-18 || clang-19 || clang-20)
 
 // <cmath>
 

[ldionne]

LGTM. It is true that this is a brittle way to XFAIL tests, but it does force us to reconsider whether the XFAIL still makes sense at every release, instead of forever disabling that test coverage.