unstable impl of From<{i64, u64}> for f128

folkertdev · folkertdev · commit 681b48e22838 · 2026-03-17T18:50:39.000+01:00
diff --git a/library/core/src/convert/num.rs b/library/core/src/convert/num.rs
@@ -70,8 +70,8 @@ impl_from_bool!(i8 i16 i32 i64 i128 isize);
 
 /// Implement `From<$small>` for `$large`
 macro_rules! impl_from {
-    ($small:ty => $large:ty, #[$attr:meta]) => {
-        #[$attr]
+    ($small:ty => $large:ty, $(#[$attrs:meta]),+) => {
+        $(#[$attrs])+
         #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
         impl const From<$small> for $large {
             #[doc = concat!("Converts from [`", stringify!($small), "`] to [`", stringify!($large), "`] losslessly.")]
@@ -157,8 +157,7 @@ impl_from!(i16 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0"
 impl_from!(i16 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(i32 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(i32 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
-// FIXME(f128): This impl would allow using `f128` on stable before it is stabilised.
-// impl_from!(i64 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
+impl_from!(i64 => f128, #[unstable(feature = "f128", issue = "116909")], #[unstable_feature_bound(f128)]);
 
 // unsigned integer -> float
 impl_from!(u8 => f16, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
@@ -170,8 +169,7 @@ impl_from!(u16 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0"
 impl_from!(u16 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u32 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u32 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
-// FIXME(f128): This impl would allow using `f128` on stable before it is stabilised.
-// impl_from!(u64 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
+impl_from!(u64 => f128, #[unstable(feature = "f128", issue = "116909")], #[unstable_feature_bound(f128)]);
 
 // float -> float
 // FIXME(f16,f128): adding additional `From<{float}>` impls to `f32` breaks inference. See
diff --git a/tests/ui/feature-gates/feature-gate-f128.e2015.stderr b/tests/ui/feature-gates/feature-gate-f128.e2015.stderr
@@ -19,7 +19,27 @@ LL |     let a: f128 = 100.0;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: the type `f128` is unstable
-  --> $DIR/feature-gate-f128.rs:16:11
+  --> $DIR/feature-gate-f128.rs:13:12
+   |
+LL |     let d: f128 = 1i64.into();
+   |            ^^^^
+   |
+   = note: see issue #116909 <https://github.com/rust-lang/rust/issues/116909> for more information
+   = help: add `#![feature(f128)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: the type `f128` is unstable
+  --> $DIR/feature-gate-f128.rs:16:12
+   |
+LL |     let e: f128 = 1u64.into();
+   |            ^^^^
+   |
+   = note: see issue #116909 <https://github.com/rust-lang/rust/issues/116909> for more information
+   = help: add `#![feature(f128)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: the type `f128` is unstable
+  --> $DIR/feature-gate-f128.rs:21:11
    |
 LL | fn foo(a: f128) {}
    |           ^^^^
@@ -29,7 +49,7 @@ LL | fn foo(a: f128) {}
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: the type `f128` is unstable
-  --> $DIR/feature-gate-f128.rs:19:8
+  --> $DIR/feature-gate-f128.rs:24:8
    |
 LL |     a: f128,
    |        ^^^^
@@ -58,6 +78,17 @@ LL |     let c = 0f128;
    = help: add `#![feature(f128)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 6 previous errors
+error[E0658]: use of unstable library feature `f128`
+  --> $DIR/feature-gate-f128.rs:13:24
+   |
+LL |     let d: f128 = 1i64.into();
+   |                        ^^^^
+   |
+   = help: add `#![feature(f128)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: required for `f128` to implement `From<i64>`
+   = note: required for `i64` to implement `Into<f128>`
+
+error: aborting due to 9 previous errors
 
 For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-f128.e2018.stderr b/tests/ui/feature-gates/feature-gate-f128.e2018.stderr
@@ -19,7 +19,27 @@ LL |     let a: f128 = 100.0;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: the type `f128` is unstable
-  --> $DIR/feature-gate-f128.rs:16:11
+  --> $DIR/feature-gate-f128.rs:13:12
+   |
+LL |     let d: f128 = 1i64.into();
+   |            ^^^^
+   |
+   = note: see issue #116909 <https://github.com/rust-lang/rust/issues/116909> for more information
+   = help: add `#![feature(f128)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: the type `f128` is unstable
+  --> $DIR/feature-gate-f128.rs:16:12
+   |
+LL |     let e: f128 = 1u64.into();
+   |            ^^^^
+   |
+   = note: see issue #116909 <https://github.com/rust-lang/rust/issues/116909> for more information
+   = help: add `#![feature(f128)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: the type `f128` is unstable
+  --> $DIR/feature-gate-f128.rs:21:11
    |
 LL | fn foo(a: f128) {}
    |           ^^^^
@@ -29,7 +49,7 @@ LL | fn foo(a: f128) {}
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: the type `f128` is unstable
-  --> $DIR/feature-gate-f128.rs:19:8
+  --> $DIR/feature-gate-f128.rs:24:8
    |
 LL |     a: f128,
    |        ^^^^
@@ -58,6 +78,17 @@ LL |     let c = 0f128;
    = help: add `#![feature(f128)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 6 previous errors
+error[E0658]: use of unstable library feature `f128`
+  --> $DIR/feature-gate-f128.rs:13:24
+   |
+LL |     let d: f128 = 1i64.into();
+   |                        ^^^^
+   |
+   = help: add `#![feature(f128)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: required for `f128` to implement `From<i64>`
+   = note: required for `i64` to implement `Into<f128>`
+
+error: aborting due to 9 previous errors
 
 For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-f128.rs b/tests/ui/feature-gates/feature-gate-f128.rs
@@ -10,6 +10,11 @@ pub fn main() {
     let a: f128 = 100.0; //~ ERROR the type `f128` is unstable
     let b = 0.0f128; //~ ERROR the type `f128` is unstable
     let c = 0f128; //~ ERROR the type `f128` is unstable
+    let d: f128 = 1i64.into();
+    //~^ ERROR the type `f128` is unstable
+    //~| ERROR use of unstable library feature `f128`
+    let e: f128 = 1u64.into();
+    //~^ ERROR the type `f128` is unstable
     foo(1.23);
 }
 
