From 180dde2e3c237cebaadf7333dfc83ebc15c55e27 Mon Sep 17 00:00:00 2001
From: fo4025 <fo40225@hotmail.com>
Date: Sat, 18 Jul 2026 22:27:46 +0800
Subject: [PATCH] Add nan2008 target feature for MIPS

Allow enabling the LLVM `nan2008` subtarget feature (IEEE 754-2008 NaN
encoding) via `-Ctarget-feature` and `#[target_feature]`, gated behind
the existing unstable `mips_target_feature` feature gate. This makes it
possible to link against MIPS libraries built with GCC's `-mnan=2008`.
---
 compiler/rustc_target/src/target_features.rs | 1 +
 tests/ui/check-cfg/target_feature.stderr     | 1 +
 2 files changed, 2 insertions(+)

diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index fc25849b2d602..d7410074b0da8 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -606,6 +606,7 @@ const MIPS_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     // tidy-alphabetical-start
     ("fp64", Unstable(sym::mips_target_feature), &[]),
     ("msa", Unstable(sym::mips_target_feature), &[]),
+    ("nan2008", Unstable(sym::mips_target_feature), &[]),
     ("virt", Unstable(sym::mips_target_feature), &[]),
     // tidy-alphabetical-end
 ];
diff --git a/tests/ui/check-cfg/target_feature.stderr b/tests/ui/check-cfg/target_feature.stderr
index eca0813e6a286..7031f2875be69 100644
--- a/tests/ui/check-cfg/target_feature.stderr
+++ b/tests/ui/check-cfg/target_feature.stderr
@@ -225,6 +225,7 @@ LL |     cfg!(target_feature = "_UNEXPECTED_VALUE");
 `mutable-globals`
 `mve`
 `mve.fp`
+`nan2008`
 `neon`
 `nnp-assist`
 `nontrapping-fptoint`