Make some float methods unstable `const fn`

Some float methods are now `const fn` under the `const_float_methods` feature gate.

In order to support `min`, `max`, `abs` and `copysign`, the implementation of some intrinsics had to be moved from Miri to rustc_const_eval.

5 files changed, 25 insertions, 12 deletions

diff --git a/library/std/src/f128.rs b/library/std/src/f128.rs
index b436fe9929c..229f979b5b1 100644
--- a/library/std/src/f128.rs
+++ b/library/std/src/f128.rs
@@ -210,8 +210,9 @@ impl f128 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn abs(self) -> Self {
+    pub const fn abs(self) -> Self {
         // FIXME(f16_f128): replace with `intrinsics::fabsf128` when available
         // We don't do this now because LLVM has lowering bugs for f128 math.
         Self::from_bits(self.to_bits() & !(1 << 127))
@@ -240,8 +241,9 @@ impl f128 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn signum(self) -> f128 {
+    pub const fn signum(self) -> f128 {
         if self.is_nan() { Self::NAN } else { 1.0_f128.copysign(self) }
     }
 
@@ -278,8 +280,9 @@ impl f128 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn copysign(self, sign: f128) -> f128 {
+    pub const fn copysign(self, sign: f128) -> f128 {
         unsafe { intrinsics::copysignf128(self, sign) }
     }
 
diff --git a/library/std/src/f16.rs b/library/std/src/f16.rs
index b2cd5fae9d0..bed21cda1cd 100644
--- a/library/std/src/f16.rs
+++ b/library/std/src/f16.rs
@@ -210,8 +210,9 @@ impl f16 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn abs(self) -> Self {
+    pub const fn abs(self) -> Self {
         // FIXME(f16_f128): replace with `intrinsics::fabsf16` when available
         Self::from_bits(self.to_bits() & !(1 << 15))
     }
@@ -239,8 +240,9 @@ impl f16 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn signum(self) -> f16 {
+    pub const fn signum(self) -> f16 {
         if self.is_nan() { Self::NAN } else { 1.0_f16.copysign(self) }
     }
 
@@ -277,8 +279,9 @@ impl f16 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn copysign(self, sign: f16) -> f16 {
+    pub const fn copysign(self, sign: f16) -> f16 {
         unsafe { intrinsics::copysignf16(self, sign) }
     }
 
diff --git a/library/std/src/f32.rs b/library/std/src/f32.rs
index fa0b3ef6484..30cf4e1f756 100644
--- a/library/std/src/f32.rs
+++ b/library/std/src/f32.rs
@@ -194,8 +194,9 @@ impl f32 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn abs(self) -> f32 {
+    pub const fn abs(self) -> f32 {
         unsafe { intrinsics::fabsf32(self) }
     }
 
@@ -218,8 +219,9 @@ impl f32 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn signum(self) -> f32 {
+    pub const fn signum(self) -> f32 {
         if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
     }
 
@@ -253,7 +255,8 @@ impl f32 {
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline]
     #[stable(feature = "copysign", since = "1.35.0")]
-    pub fn copysign(self, sign: f32) -> f32 {
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+    pub const fn copysign(self, sign: f32) -> f32 {
         unsafe { intrinsics::copysignf32(self, sign) }
     }
 
diff --git a/library/std/src/f64.rs b/library/std/src/f64.rs
index 9fa43a6742e..51d5476b372 100644
--- a/library/std/src/f64.rs
+++ b/library/std/src/f64.rs
@@ -194,8 +194,9 @@ impl f64 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn abs(self) -> f64 {
+    pub const fn abs(self) -> f64 {
         unsafe { intrinsics::fabsf64(self) }
     }
 
@@ -218,8 +219,9 @@ impl f64 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn signum(self) -> f64 {
+    pub const fn signum(self) -> f64 {
         if self.is_nan() { Self::NAN } else { 1.0_f64.copysign(self) }
     }
 
@@ -252,8 +254,9 @@ impl f64 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "copysign", since = "1.35.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn copysign(self, sign: f64) -> f64 {
+    pub const fn copysign(self, sign: f64) -> f64 {
         unsafe { intrinsics::copysignf64(self, sign) }
     }
 
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 65a9aa66c7c..990d83513cf 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -288,6 +288,7 @@
 #![feature(cfg_target_thread_local)]
 #![feature(cfi_encoding)]
 #![feature(concat_idents)]
+#![feature(const_float_methods)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
 #![feature(doc_cfg)]