Don't use f16 and f128 directly in clippy_utils (#14528)

Not all host tools platforms support `f16`/`f128` builtins yet due to
LLVM assertion failures and miscompilations. Until them, Clippy should
avoid using `f16`/`f128` at runtime itself. See
rust-lang/rust#137630.

cc @tgross35

changelog: none

Author: Jarcho

clippy_lints/src/neg_multiply.rs

@@ -49,10 +49,16 @@ impl<'tcx> LateLintPass<'tcx> for NegMultiply {
 }
 
 fn check_mul(cx: &LateContext<'_>, span: Span, lit: &Expr<'_>, exp: &Expr<'_>) {
+    const F16_ONE: u16 = 1.0_f16.to_bits();
+    const F128_ONE: u128 = 1.0_f128.to_bits();
     if let ExprKind::Lit(l) = lit.kind
         && matches!(
             consts::lit_to_mir_constant(&l.node, cx.typeck_results().expr_ty_opt(lit)),
-            Constant::Int(1) | Constant::F16(1.0) | Constant::F32(1.0) | Constant::F64(1.0) | Constant::F128(1.0)
+            Constant::Int(1)
+                | Constant::F16(F16_ONE)
+                | Constant::F32(1.0)
+                | Constant::F64(1.0)
+                | Constant::F128(F128_ONE)
         )
         && cx.typeck_results().expr_ty(exp).is_numeric()
     {

clippy_utils/src/consts.rs

@@ -43,14 +43,16 @@ pub enum Constant<'tcx> {
     Char(char),
     /// An integer's bit representation.
     Int(u128),
-    /// An `f16`.
-    F16(f16),
+    /// An `f16` bitcast to a `u16`.
+    // FIXME(f16_f128): use `f16` once builtins are available on all host tools platforms.
+    F16(u16),
     /// An `f32`.
     F32(f32),
     /// An `f64`.
     F64(f64),
-    /// An `f128`.
-    F128(f128),
+    /// An `f128` bitcast to a `u128`.
+    // FIXME(f16_f128): use `f128` once builtins are available on all host tools platforms.
+    F128(u128),
     /// `true` or `false`.
     Bool(bool),
     /// An array of constants.
@@ -177,7 +179,7 @@ impl Hash for Constant<'_> {
             },
             Self::F16(f) => {
                 // FIXME(f16_f128): once conversions to/from `f128` are available on all platforms,
-                f.to_bits().hash(state);
+                f.hash(state);
             },
             Self::F32(f) => {
                 f64::from(f).to_bits().hash(state);
@@ -186,7 +188,7 @@ impl Hash for Constant<'_> {
                 f.to_bits().hash(state);
             },
             Self::F128(f) => {
-                f.to_bits().hash(state);
+                f.hash(state);
             },
             Self::Bool(b) => {
                 b.hash(state);
@@ -292,12 +294,12 @@ impl Constant<'_> {
 
     fn parse_f16(s: &str) -> Self {
         let f: Half = s.parse().unwrap();
-        Self::F16(f16::from_bits(f.to_bits().try_into().unwrap()))
+        Self::F16(f.to_bits().try_into().unwrap())
     }
 
     fn parse_f128(s: &str) -> Self {
         let f: Quad = s.parse().unwrap();
-        Self::F128(f128::from_bits(f.to_bits()))
+        Self::F128(f.to_bits())
     }
 }
 
@@ -868,10 +870,10 @@ pub fn mir_to_const<'tcx>(tcx: TyCtxt<'tcx>, result: mir::Const<'tcx>) -> Option
             ty::Adt(adt_def, _) if adt_def.is_struct() => Some(Constant::Adt(result)),
             ty::Bool => Some(Constant::Bool(int == ScalarInt::TRUE)),
             ty::Uint(_) | ty::Int(_) => Some(Constant::Int(int.to_bits(int.size()))),
-            ty::Float(FloatTy::F16) => Some(Constant::F16(f16::from_bits(int.into()))),
+            ty::Float(FloatTy::F16) => Some(Constant::F16(int.into())),
             ty::Float(FloatTy::F32) => Some(Constant::F32(f32::from_bits(int.into()))),
             ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(int.into()))),
-            ty::Float(FloatTy::F128) => Some(Constant::F128(f128::from_bits(int.into()))),
+            ty::Float(FloatTy::F128) => Some(Constant::F128(int.into())),
             ty::RawPtr(_, _) => Some(Constant::RawPtr(int.to_bits(int.size()))),
             _ => None,
         },
@@ -892,10 +894,10 @@ pub fn mir_to_const<'tcx>(tcx: TyCtxt<'tcx>, result: mir::Const<'tcx>) -> Option
                 let range = alloc_range(offset + size * idx, size);
                 let val = alloc.read_scalar(&tcx, range, /* read_provenance */ false).ok()?;
                 res.push(match flt {
-                    FloatTy::F16 => Constant::F16(f16::from_bits(val.to_u16().discard_err()?)),
+                    FloatTy::F16 => Constant::F16(val.to_u16().discard_err()?),
                     FloatTy::F32 => Constant::F32(f32::from_bits(val.to_u32().discard_err()?)),
                     FloatTy::F64 => Constant::F64(f64::from_bits(val.to_u64().discard_err()?)),
-                    FloatTy::F128 => Constant::F128(f128::from_bits(val.to_u128().discard_err()?)),
+                    FloatTy::F128 => Constant::F128(val.to_u128().discard_err()?),
                 });
             }
             Some(Constant::Vec(res))

clippy_utils/src/lib.rs

@@ -1,7 +1,5 @@
 #![feature(array_chunks)]
 #![feature(box_patterns)]
-#![feature(f128)]
-#![feature(f16)]
 #![feature(if_let_guard)]
 #![feature(macro_metavar_expr_concat)]
 #![feature(let_chains)]