From 4b12a8404f3397c93d59711a3499a8e86213a015 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Thu, 31 Oct 2024 23:52:27 -0500
Subject: [PATCH] Expose the `support` module publicly with a test feature

---
 library/compiler-builtins/libm/Cargo.toml                | 3 +++
 .../libm/crates/compiler-builtins-smoke-test/Cargo.toml  | 1 +
 library/compiler-builtins/libm/src/math/mod.rs           | 9 ++++++++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/library/compiler-builtins/libm/Cargo.toml b/library/compiler-builtins/libm/Cargo.toml
index 1786277664a1..98a60bfe3fe9 100644
--- a/library/compiler-builtins/libm/Cargo.toml
+++ b/library/compiler-builtins/libm/Cargo.toml
@@ -26,6 +26,9 @@ unstable = ["unstable-intrinsics"]
 # Enable calls to functions in `core::intrinsics`
 unstable-intrinsics = []
 
+# Make some internal things public for testing.
+unstable-test-support = []
+
 # Used to prevent using any intrinsics or arch-specific code.
 #
 # HACK: this is a negative feature which is generally a bad idea in Cargo, but
diff --git a/library/compiler-builtins/libm/crates/compiler-builtins-smoke-test/Cargo.toml b/library/compiler-builtins/libm/crates/compiler-builtins-smoke-test/Cargo.toml
index 7118bfe06f1d..e75c4f42bfa2 100644
--- a/library/compiler-builtins/libm/crates/compiler-builtins-smoke-test/Cargo.toml
+++ b/library/compiler-builtins/libm/crates/compiler-builtins-smoke-test/Cargo.toml
@@ -13,6 +13,7 @@ bench = false
 # Duplicated from libm's Cargo.toml
 unstable = []
 unstable-intrinsics = []
+unstable-test-support = []
 checked = []
 force-soft-floats = []
 
diff --git a/library/compiler-builtins/libm/src/math/mod.rs b/library/compiler-builtins/libm/src/math/mod.rs
index 2cd77f1327b2..afebdf5864c5 100644
--- a/library/compiler-builtins/libm/src/math/mod.rs
+++ b/library/compiler-builtins/libm/src/math/mod.rs
@@ -74,9 +74,16 @@ macro_rules! div {
     };
 }
 
-// Private modules
+// `support` may be public for testing
 #[macro_use]
+#[cfg(feature = "unstable-test-support")]
+pub mod support;
+
+#[macro_use]
+#[cfg(not(feature = "unstable-test-support"))]
 mod support;
+
+// Private modules
 mod arch;
 mod expo2;
 mod fenv;