fix f16/f128 lints

usamoi · usamoi · commit fbd6291ec05e · 2025-06-03T20:16:31.000+08:00
diff --git a/clippy_lints/src/casts/cast_lossless.rs b/clippy_lints/src/casts/cast_lossless.rs
@@ -7,7 +7,7 @@ use clippy_utils::ty::is_isize_or_usize;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, QPath, TyKind};
 use rustc_lint::LateContext;
-use rustc_middle::ty::{self, FloatTy, Ty};
+use rustc_middle::ty::{self, Ty};
 use rustc_span::hygiene;
 
 use super::{CAST_LOSSLESS, utils};
@@ -76,28 +76,42 @@ fn should_lint(cx: &LateContext<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>, msrv: M
         return false;
     }
 
-    match (
-        utils::int_ty_to_nbits(cx.tcx, cast_from),
-        utils::int_ty_to_nbits(cx.tcx, cast_to),
-    ) {
-        (Some(from_nbits), Some(to_nbits)) => {
-            let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed();
-            !is_isize_or_usize(cast_from)
-                && !is_isize_or_usize(cast_to)
-                && from_nbits < to_nbits
-                && !cast_signed_to_unsigned
-        },
+    if matches!(cast_from.kind(), ty::Bool) && cast_to.is_integral() {
+        return msrv.meets(cx, msrvs::FROM_BOOL);
+    }
 
-        (Some(from_nbits), None) => {
-            // FIXME: handle `f16` and `f128`
-            let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() {
-                32
-            } else {
-                64
-            };
-            !is_isize_or_usize(cast_from) && from_nbits < to_nbits
-        },
-        (None, Some(_)) if cast_from.is_bool() && msrv.meets(cx, msrvs::FROM_BOOL) => true,
-        _ => matches!(cast_from.kind(), ty::Float(FloatTy::F32)) && matches!(cast_to.kind(), ty::Float(FloatTy::F64)),
+    if cast_from.is_numeric() {
+        return match (cast_from.is_integral(), cast_to.is_integral()) {
+            (true, true) => {
+                let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed();
+                let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
+                let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
+                !is_isize_or_usize(cast_from)
+                    && !is_isize_or_usize(cast_to)
+                    && from_nbits < to_nbits
+                    && !cast_signed_to_unsigned
+            },
+            (true, false) => {
+                let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
+                let to_nbits = utils::float_ty_to_nbits(cast_to);
+                if from_nbits == 64 && to_nbits == 128 {
+                    // FIXME(f16_f128): https://github.com/rust-lang/rust/blob/91fad92585b2dafc52a074e502b2a6c1f093ca35/library/core/src/convert/num.rs#L171
+                    return false;
+                }
+                !is_isize_or_usize(cast_from) && from_nbits < to_nbits
+            },
+            (false, true) => false,
+            (false, false) => {
+                let from_nbits = utils::float_ty_to_nbits(cast_from);
+                let to_nbits = utils::float_ty_to_nbits(cast_to);
+                if from_nbits == 16 && to_nbits == 32 {
+                    // FIXME(f16_f128): https://github.com/rust-lang/rust/issues/123831
+                    return false;
+                }
+                from_nbits < to_nbits
+            },
+        };
     }
+
+    false
 }
diff --git a/clippy_lints/src/casts/cast_possible_truncation.rs b/clippy_lints/src/casts/cast_possible_truncation.rs
@@ -9,7 +9,7 @@ use rustc_errors::{Applicability, Diag};
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::LateContext;
-use rustc_middle::ty::{self, FloatTy, Ty};
+use rustc_middle::ty::{self, Ty};
 use rustc_span::Span;
 
 use super::{CAST_ENUM_TRUNCATION, CAST_POSSIBLE_TRUNCATION, utils};
@@ -91,14 +91,15 @@ pub(super) fn check(
     cast_to: Ty<'_>,
     cast_to_span: Span,
 ) {
-    let msg = match (cast_from.kind(), utils::int_ty_to_nbits(cx.tcx, cast_to)) {
-        (ty::Int(_) | ty::Uint(_), Some(to_nbits)) => {
+    let msg = match (cast_from.kind(), cast_to.is_integral()) {
+        (ty::Int(_) | ty::Uint(_), true) => {
             let from_nbits = apply_reductions(
                 cx,
-                utils::int_ty_to_nbits(cx.tcx, cast_from).unwrap(),
+                utils::int_ty_to_nbits(cast_from, cx.tcx),
                 cast_expr,
                 cast_from.is_signed(),
             );
+            let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
 
             let (should_lint, suffix) = match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) {
                 (true, true) | (false, false) => (to_nbits < from_nbits, ""),
@@ -120,7 +121,7 @@ pub(super) fn check(
             format!("casting `{cast_from}` to `{cast_to}` may truncate the value{suffix}",)
         },
 
-        (ty::Adt(def, _), Some(to_nbits)) if def.is_enum() => {
+        (ty::Adt(def, _), true) if def.is_enum() => {
             let (from_nbits, variant) = if let ExprKind::Path(p) = &cast_expr.kind
                 && let Res::Def(DefKind::Ctor(..), id) = cx.qpath_res(p, cast_expr.hir_id)
             {
@@ -131,6 +132,7 @@ pub(super) fn check(
             } else {
                 (utils::enum_ty_to_nbits(*def, cx.tcx), None)
             };
+            let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
 
             let cast_from_ptr_size = def.repr().int.is_none_or(|ty| matches!(ty, IntegerType::Pointer(_),));
             let suffix = match (cast_from_ptr_size, is_isize_or_usize(cast_to)) {
@@ -155,12 +157,18 @@ pub(super) fn check(
             format!("casting `{cast_from}` to `{cast_to}` may truncate the value{suffix}")
         },
 
-        (ty::Float(_), Some(_)) => {
+        (ty::Float(_), true) => {
             format!("casting `{cast_from}` to `{cast_to}` may truncate the value")
         },
 
-        (ty::Float(FloatTy::F64), None) if matches!(cast_to.kind(), &ty::Float(FloatTy::F32)) => {
-            "casting `f64` to `f32` may truncate the value".to_string()
+        (ty::Float(_), false) => {
+            let from_nbits = utils::float_ty_to_nbits(cast_from);
+            let to_nbits = utils::float_ty_to_nbits(cast_to);
+            if from_nbits > to_nbits {
+                format!("casting `f{from_nbits}` to `f{to_nbits}` may truncate the value")
+            } else {
+                return;
+            }
         },
 
         _ => return,
diff --git a/clippy_lints/src/casts/cast_possible_wrap.rs b/clippy_lints/src/casts/cast_possible_wrap.rs
@@ -17,12 +17,9 @@ enum EmitState {
 }
 
 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
-    let (Some(from_nbits), Some(to_nbits)) = (
-        utils::int_ty_to_nbits(cx.tcx, cast_from),
-        utils::int_ty_to_nbits(cx.tcx, cast_to),
-    ) else {
+    if !(cast_from.is_integral() && cast_to.is_integral()) {
         return;
-    };
+    }
 
     // emit a lint if a cast is:
     // 1. unsigned to signed
@@ -38,6 +35,9 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, ca
         return;
     }
 
+    let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
+    let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
+
     let should_lint = match (cast_from.is_ptr_sized_integral(), cast_to.is_ptr_sized_integral()) {
         (true, true) => {
             // casts between two ptr sized integers are trivially always the same size
diff --git a/clippy_lints/src/casts/cast_precision_loss.rs b/clippy_lints/src/casts/cast_precision_loss.rs
@@ -2,28 +2,25 @@ use clippy_utils::diagnostics::span_lint;
 use clippy_utils::ty::is_isize_or_usize;
 use rustc_hir::Expr;
 use rustc_lint::LateContext;
-use rustc_middle::ty::{self, FloatTy, Ty};
+use rustc_middle::ty::Ty;
 
 use super::{CAST_PRECISION_LOSS, utils};
 
 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
-    let Some(from_nbits) = utils::int_ty_to_nbits(cx.tcx, cast_from) else {
+    if !cast_from.is_integral() || cast_to.is_integral() {
         return;
-    };
+    }
 
-    // FIXME: handle `f16` and `f128`
-    let to_nbits = match cast_to.kind() {
-        ty::Float(f @ (FloatTy::F32 | FloatTy::F64)) => f.bit_width(),
-        _ => return,
-    };
+    let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
+    let to_nbits = utils::float_ty_to_nbits(cast_to);
 
     if !(is_isize_or_usize(cast_from) || from_nbits >= to_nbits) {
         return;
     }
 
-    let cast_to_f64 = to_nbits == 64;
-    let mantissa_nbits = if cast_to_f64 { 52 } else { 23 };
-    let arch_dependent = is_isize_or_usize(cast_from) && cast_to_f64;
+    let mantissa_nbits = utils::float_ty_to_mantissa_nbits(cast_to);
+
+    let arch_dependent = is_isize_or_usize(cast_from) && to_nbits == 64;
     let arch_dependent_str = "on targets with 64-bit wide pointers ";
     let from_nbits_str = if arch_dependent {
         "64".to_owned()
@@ -42,7 +39,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, ca
             "casting `{0}` to `{1}` causes a loss of precision {2}(`{0}` is {3} bits wide, \
              but `{1}`'s mantissa is only {4} bits wide)",
             cast_from,
-            if cast_to_f64 { "f64" } else { "f32" },
+            format!("f{to_nbits}"),
             if arch_dependent { arch_dependent_str } else { "" },
             from_nbits_str,
             mantissa_nbits
diff --git a/clippy_lints/src/casts/fn_to_numeric_cast.rs b/clippy_lints/src/casts/fn_to_numeric_cast.rs
@@ -9,16 +9,18 @@ use super::{FN_TO_NUMERIC_CAST, utils};
 
 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
     // We only want to check casts to `ty::Uint` or `ty::Int`
-    let Some(to_nbits) = utils::int_ty_to_nbits(cx.tcx, cast_to) else {
-        return;
-    };
+    match cast_to.kind() {
+        ty::Uint(_) | ty::Int(..) => { /* continue on */ },
+        _ => return,
+    }
 
     match cast_from.kind() {
         ty::FnDef(..) | ty::FnPtr(..) => {
             let mut applicability = Applicability::MaybeIncorrect;
+            let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
+            let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
 
-            if to_nbits >= cx.tcx.data_layout.pointer_size.bits() && !cast_to.is_usize() {
-                let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
+            if (to_nbits >= cx.tcx.data_layout.pointer_size.bits()) && !cast_to.is_usize() {
                 span_lint_and_sugg(
                     cx,
                     FN_TO_NUMERIC_CAST,
diff --git a/clippy_lints/src/casts/fn_to_numeric_cast_with_truncation.rs b/clippy_lints/src/casts/fn_to_numeric_cast_with_truncation.rs
@@ -9,13 +9,16 @@ use super::{FN_TO_NUMERIC_CAST_WITH_TRUNCATION, utils};
 
 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
     // We only want to check casts to `ty::Uint` or `ty::Int`
-    let Some(to_nbits) = utils::int_ty_to_nbits(cx.tcx, cast_to) else {
-        return;
-    };
+    match cast_to.kind() {
+        ty::Uint(_) | ty::Int(..) => { /* continue on */ },
+        _ => return,
+    }
+
     match cast_from.kind() {
         ty::FnDef(..) | ty::FnPtr(..) => {
             let mut applicability = Applicability::MaybeIncorrect;
             let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
+            let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
 
             if to_nbits < cx.tcx.data_layout.pointer_size.bits() {
                 span_lint_and_sugg(
diff --git a/clippy_lints/src/casts/unnecessary_cast.rs b/clippy_lints/src/casts/unnecessary_cast.rs
@@ -1,3 +1,4 @@
+use crate::casts::utils;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::numeric_literal::NumericLiteral;
 use clippy_utils::source::{SpanRangeExt, snippet_opt};
@@ -9,7 +10,7 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{Expr, ExprKind, Lit, Node, Path, QPath, TyKind, UnOp};
 use rustc_lint::{LateContext, LintContext};
 use rustc_middle::ty::adjustment::Adjust;
-use rustc_middle::ty::{self, FloatTy, InferTy, Ty};
+use rustc_middle::ty::{self, Ty};
 use rustc_span::{Symbol, sym};
 use std::ops::ControlFlow;
 
@@ -108,8 +109,8 @@ pub(super) fn check<'tcx>(
             && let Some(src) = cast_expr.span.get_source_text(cx)
             && cast_to.is_floating_point()
             && let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit.node)
-            && let from_nbits = 128 - n.get().leading_zeros()
-            && let to_nbits = fp_ty_mantissa_nbits(cast_to)
+            && let from_nbits = 128 - u64::from(n.get().leading_zeros())
+            && let to_nbits = utils::float_ty_to_mantissa_nbits(cast_to)
             && from_nbits != 0
             && to_nbits != 0
             && from_nbits <= to_nbits
@@ -257,16 +258,6 @@ fn get_numeric_literal<'e>(expr: &'e Expr<'e>) -> Option<&'e Lit> {
     }
 }
 
-/// Returns the mantissa bits wide of a fp type.
-/// Will return 0 if the type is not a fp
-fn fp_ty_mantissa_nbits(typ: Ty<'_>) -> u32 {
-    match typ.kind() {
-        ty::Float(FloatTy::F32) => 23,
-        ty::Float(FloatTy::F64) | ty::Infer(InferTy::FloatVar(_)) => 52,
-        _ => 0,
-    }
-}
-
 /// Finds whether an `Expr` returns a type alias.
 ///
 /// TODO: Maybe we should move this to `clippy_utils` so others won't need to go down this dark,
diff --git a/clippy_lints/src/casts/utils.rs b/clippy_lints/src/casts/utils.rs
@@ -1,14 +1,55 @@
 use clippy_utils::ty::{EnumValue, read_explicit_enum_value};
-use rustc_middle::ty::{self, AdtDef, IntTy, Ty, TyCtxt, UintTy, VariantDiscr};
+use rustc_middle::ty::{self, AdtDef, FloatTy, IntTy, Ty, TyCtxt, UintTy, VariantDiscr};
 
-/// Returns the size in bits of an integral type, or `None` if `ty` is not an
-/// integral type.
-pub(super) fn int_ty_to_nbits(tcx: TyCtxt<'_>, ty: Ty<'_>) -> Option<u64> {
-    match ty.kind() {
-        ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => Some(tcx.data_layout.pointer_size.bits()),
-        ty::Int(i) => i.bit_width(),
-        ty::Uint(i) => i.bit_width(),
-        _ => None,
+/// Returns the size in bits of an integral type.
+/// Panics if the type is not an int or uint variant
+pub(super) fn int_ty_to_nbits(typ: Ty<'_>, tcx: TyCtxt<'_>) -> u64 {
+    match typ.kind() {
+        ty::Int(i) => match i {
+            IntTy::Isize => tcx.data_layout.pointer_size.bits(),
+            IntTy::I8 => 8,
+            IntTy::I16 => 16,
+            IntTy::I32 => 32,
+            IntTy::I64 => 64,
+            IntTy::I128 => 128,
+        },
+        ty::Uint(i) => match i {
+            UintTy::Usize => tcx.data_layout.pointer_size.bits(),
+            UintTy::U8 => 8,
+            UintTy::U16 => 16,
+            UintTy::U32 => 32,
+            UintTy::U64 => 64,
+            UintTy::U128 => 128,
+        },
+        _ => unreachable!(),
+    }
+}
+
+/// Returns the size in bits of an floating type.
+/// Panics if the type is not an float variant
+pub(super) fn float_ty_to_nbits(typ: Ty<'_>) -> u64 {
+    match typ.kind() {
+        ty::Float(i) => match i {
+            FloatTy::F16 => 16,
+            FloatTy::F32 => 32,
+            FloatTy::F64 => 64,
+            FloatTy::F128 => 128,
+        },
+        _ => unreachable!(),
+    }
+}
+
+/// Returns the mantissa size in bits of an floating type.
+/// Panics if the type is not an float variant
+pub(super) fn float_ty_to_mantissa_nbits(typ: Ty<'_>) -> u64 {
+    match typ.kind() {
+        ty::Float(i) => match i {
+            FloatTy::F16 => 10,
+            FloatTy::F32 => 23,
+            FloatTy::F64 => 52,
+            FloatTy::F128 => 112,
+        },
+        _ => unreachable!(),
     }
 }
 
