From a99c95fdacead5f29ac73b1ada78730ba91bcf3e Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Fri, 27 Sep 2024 18:35:30 -0400
Subject: [PATCH 1/2] Enable `f16` tests on non-GNU Windows

There is a MinGW ABI bug that prevents `f16` and `f128` from being
usable on `windows-gnu` targets. This does not affect MSVC; however, we
have `f16` and `f128` tests disabled on all Windows targets.

Update the gating to only affect `windows-gnu`, which means `f16` tests
will be enabled. There is no effect for `f128` since the default
fallback is `false`.
---
 library/std/build.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/library/std/build.rs b/library/std/build.rs
index 359ae4f20eea8..e727007cacde2 100644
--- a/library/std/build.rs
+++ b/library/std/build.rs
@@ -104,7 +104,7 @@ fn main() {
         // Unsupported <https://github.com/llvm/llvm-project/issues/94434>
         ("arm64ec", _) => false,
         // MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
-        ("x86_64", "windows") => false,
+        ("x86_64", "windows") if target_env == "gnu" => false,
         // Apple has a special ABI for `f16` that we do not yet support
         // FIXME(builtins): fixed by <https://github.com/rust-lang/compiler-builtins/pull/675>
         ("x86" | "x86_64", _) if target_vendor == "apple" => false,
@@ -135,10 +135,10 @@ fn main() {
         // ABI unsupported  <https://github.com/llvm/llvm-project/issues/41838>
         ("sparc", _) => false,
         // MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
-        ("x86_64", "windows") => false,
+        ("x86_64", "windows") if target_env == "gnu" => false,
         // 64-bit Linux is about the only platform to have f128 symbols by default
         (_, "linux") if target_pointer_width == 64 => true,
-        // Same as for f16, except MacOS is also missing f128 symbols.
+        // Almost all OSs are missing symbol. compiler-builtins will have to add them.
         _ => false,
     };
 

From 83d56df944a203f0930c81000969a5b1b00739a3 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Fri, 27 Sep 2024 18:59:52 -0400
Subject: [PATCH 2/2] Do not merge: change fallback for testing

---
 library/std/build.rs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/library/std/build.rs b/library/std/build.rs
index e727007cacde2..a8009f28e3a9b 100644
--- a/library/std/build.rs
+++ b/library/std/build.rs
@@ -116,10 +116,9 @@ fn main() {
         ("riscv32" | "riscv64", _) => false,
         // Most OSs are missing `__extendhfsf` and `__truncsfhf`
         (_, "linux" | "macos") => true,
-        // Almost all OSs besides Linux and MacOS are missing symbols until compiler-builtins can
-        // be updated. <https://github.com/rust-lang/rust/pull/125016> will get some of these, the
-        // next CB update should get the rest.
-        _ => false,
+        // todo: only for testing, this line will wind up changed as part of
+        // <https://github.com/rust-lang/rust/pull/129385>.
+        _ => true,
     };
 
     let has_reliable_f128 = match (target_arch.as_str(), target_os.as_str()) {