stabilize const_fn_floating_point_arithmetic

Author: RalfJung

compiler/rustc_const_eval/src/check_consts/check.rs

@@ -575,10 +575,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
 
             Rvalue::UnaryOp(_, operand) => {
                 let ty = operand.ty(self.body, self.tcx);
-                if is_int_bool_or_char(ty) {
-                    // Int, bool, and char operations are fine.
-                } else if ty.is_floating_point() {
-                    self.check_op(ops::FloatingPointOp);
+                if is_int_bool_float_or_char(ty) {
+                    // Int, bool, float, and char operations are fine.
                 } else {
                     span_bug!(self.span, "non-primitive type in `Rvalue::UnaryOp`: {:?}", ty);
                 }
@@ -588,8 +586,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 let lhs_ty = lhs.ty(self.body, self.tcx);
                 let rhs_ty = rhs.ty(self.body, self.tcx);
 
-                if is_int_bool_or_char(lhs_ty) && is_int_bool_or_char(rhs_ty) {
-                    // Int, bool, and char operations are fine.
+                if is_int_bool_float_or_char(lhs_ty) && is_int_bool_float_or_char(rhs_ty) {
+                    // Int, bool, float, and char operations are fine.
                 } else if lhs_ty.is_fn_ptr() || lhs_ty.is_unsafe_ptr() {
                     assert_matches!(
                         op,
@@ -603,8 +601,6 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                     );
 
                     self.check_op(ops::RawPtrComparison);
-                } else if lhs_ty.is_floating_point() || rhs_ty.is_floating_point() {
-                    self.check_op(ops::FloatingPointOp);
                 } else {
                     span_bug!(
                         self.span,
@@ -1009,8 +1005,8 @@ fn place_as_reborrow<'tcx>(
     }
 }
 
-fn is_int_bool_or_char(ty: Ty<'_>) -> bool {
-    ty.is_bool() || ty.is_integral() || ty.is_char()
+fn is_int_bool_float_or_char(ty: Ty<'_>) -> bool {
+    ty.is_bool() || ty.is_integral() || ty.is_char() || ty.is_floating_point()
 }
 
 fn emit_unstable_in_stable_error(ccx: &ConstCx<'_, '_>, span: Span, gate: Symbol) {

compiler/rustc_const_eval/src/check_consts/ops.rs

@@ -55,28 +55,6 @@ pub trait NonConstOp<'tcx>: std::fmt::Debug {
     fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx>;
 }
 
-#[derive(Debug)]
-pub struct FloatingPointOp;
-impl<'tcx> NonConstOp<'tcx> for FloatingPointOp {
-    fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
-        if ccx.const_kind() == hir::ConstContext::ConstFn {
-            Status::Unstable(sym::const_fn_floating_point_arithmetic)
-        } else {
-            Status::Allowed
-        }
-    }
-
-    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
-    fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
-        feature_err(
-            &ccx.tcx.sess,
-            sym::const_fn_floating_point_arithmetic,
-            span,
-            format!("floating point arithmetic is not allowed in {}s", ccx.const_kind()),
-        )
-    }
-}
-
 /// A function call where the callee is a pointer.
 #[derive(Debug)]
 pub struct FnCallIndirect;
@@ -440,22 +418,12 @@ impl<'tcx> NonConstOp<'tcx> for CellBorrow {
         DiagImportance::Secondary
     }
     fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
-        // FIXME: Maybe a more elegant solution to this if else case
-        if let hir::ConstContext::Static(_) = ccx.const_kind() {
-            ccx.dcx().create_err(errors::InteriorMutableDataRefer {
-                span,
-                opt_help: true,
-                kind: ccx.const_kind(),
-                teach: ccx.tcx.sess.teach(E0492),
-            })
-        } else {
-            ccx.dcx().create_err(errors::InteriorMutableDataRefer {
-                span,
-                opt_help: false,
-                kind: ccx.const_kind(),
-                teach: ccx.tcx.sess.teach(E0492),
-            })
-        }
+        ccx.dcx().create_err(errors::InteriorMutableDataRefer {
+            span,
+            opt_help: matches!(ccx.const_kind(), hir::ConstContext::Static(_)),
+            kind: ccx.const_kind(),
+            teach: ccx.tcx.sess.teach(E0492),
+        })
     }
 }
 

compiler/rustc_feature/src/accepted.rs

@@ -115,6 +115,8 @@ declare_features! (
     (accepted, conservative_impl_trait, "1.26.0", Some(34511)),
     /// Allows calling constructor functions in `const fn`.
     (accepted, const_constructor, "1.40.0", Some(61456)),
+    /// Allows basic arithmetic on floating point types in a `const fn`.
+    (accepted, const_fn_floating_point_arithmetic, "CURRENT_RUSTC_VERSION", Some(57241)),
     /// Allows using and casting function pointers in a `const fn`.
     (accepted, const_fn_fn_ptr_basics, "1.61.0", Some(57563)),
     /// Allows trait bounds in `const fn`.

compiler/rustc_feature/src/unstable.rs

@@ -400,8 +400,6 @@ declare_features! (
     (incomplete, const_closures, "1.68.0", Some(106003)),
     /// Allows the definition of `const extern fn` and `const unsafe extern fn`.
     (unstable, const_extern_fn, "1.40.0", Some(64926)),
-    /// Allows basic arithmetic on floating point types in a `const fn`.
-    (unstable, const_fn_floating_point_arithmetic, "1.48.0", Some(57241)),
     /// Allows `for _ in _` loops in const contexts.
     (unstable, const_for, "1.56.0", Some(87575)),
     /// Allows using `&mut` in constant functions.

library/core/src/lib.rs

@@ -194,6 +194,7 @@
 // Language features:
 // tidy-alphabetical-start
 #![cfg_attr(bootstrap, feature(asm_const))]
+#![cfg_attr(bootstrap, feature(const_fn_floating_point_arithmetic))]
 #![cfg_attr(bootstrap, feature(min_exhaustive_patterns))]
 #![feature(abi_unadjusted)]
 #![feature(adt_const_params)]
@@ -203,7 +204,6 @@
 #![feature(cfg_sanitize)]
 #![feature(cfg_target_has_atomic)]
 #![feature(cfg_target_has_atomic_equal_alignment)]
-#![feature(const_fn_floating_point_arithmetic)]
 #![feature(const_for)]
 #![feature(const_mut_refs)]
 #![feature(const_precise_live_drops)]

src/tools/clippy/tests/ui/floating_point_abs.fixed

@@ -1,4 +1,3 @@
-#![feature(const_fn_floating_point_arithmetic)]
 #![warn(clippy::suboptimal_flops)]
 
 /// Allow suboptimal ops in constant context

src/tools/clippy/tests/ui/floating_point_abs.rs

@@ -1,4 +1,3 @@
-#![feature(const_fn_floating_point_arithmetic)]
 #![warn(clippy::suboptimal_flops)]
 
 /// Allow suboptimal ops in constant context

src/tools/clippy/tests/ui/floating_point_abs.stderr

@@ -1,5 +1,5 @@
 error: manual implementation of `abs` method
-  --> tests/ui/floating_point_abs.rs:15:5
+  --> tests/ui/floating_point_abs.rs:14:5
    |
 LL |     if num >= 0.0 { num } else { -num }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `num.abs()`
@@ -8,43 +8,43 @@ LL |     if num >= 0.0 { num } else { -num }
    = help: to override `-D warnings` add `#[allow(clippy::suboptimal_flops)]`
 
 error: manual implementation of `abs` method
-  --> tests/ui/floating_point_abs.rs:19:5
+  --> tests/ui/floating_point_abs.rs:18:5
    |
 LL |     if 0.0 < num { num } else { -num }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `num.abs()`
 
 error: manual implementation of `abs` method
-  --> tests/ui/floating_point_abs.rs:23:5
+  --> tests/ui/floating_point_abs.rs:22:5
    |
 LL |     if a.a > 0.0 { a.a } else { -a.a }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `a.a.abs()`
 
 error: manual implementation of `abs` method
-  --> tests/ui/floating_point_abs.rs:27:5
+  --> tests/ui/floating_point_abs.rs:26:5
    |
 LL |     if 0.0 >= num { -num } else { num }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `num.abs()`
 
 error: manual implementation of `abs` method
-  --> tests/ui/floating_point_abs.rs:31:5
+  --> tests/ui/floating_point_abs.rs:30:5
    |
 LL |     if a.a < 0.0 { -a.a } else { a.a }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `a.a.abs()`
 
 error: manual implementation of negation of `abs` method
-  --> tests/ui/floating_point_abs.rs:35:5
+  --> tests/ui/floating_point_abs.rs:34:5
    |
 LL |     if num < 0.0 { num } else { -num }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `-num.abs()`
 
 error: manual implementation of negation of `abs` method
-  --> tests/ui/floating_point_abs.rs:39:5
+  --> tests/ui/floating_point_abs.rs:38:5
    |
 LL |     if 0.0 >= num { num } else { -num }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `-num.abs()`
 
 error: manual implementation of negation of `abs` method
-  --> tests/ui/floating_point_abs.rs:44:12
+  --> tests/ui/floating_point_abs.rs:43:12
    |
 LL |         a: if a.a >= 0.0 { -a.a } else { a.a },
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `-a.a.abs()`

src/tools/clippy/tests/ui/floating_point_mul_add.fixed

@@ -1,4 +1,3 @@
-#![feature(const_fn_floating_point_arithmetic)]
 #![warn(clippy::suboptimal_flops)]
 
 /// Allow suboptimal_ops in constant context

src/tools/clippy/tests/ui/floating_point_mul_add.rs

@@ -1,4 +1,3 @@
-#![feature(const_fn_floating_point_arithmetic)]
 #![warn(clippy::suboptimal_flops)]
 
 /// Allow suboptimal_ops in constant context