Rollup of 14 pull requests

.gitmodules

@@ -45,7 +45,7 @@
 	shallow = true
 [submodule "src/tools/enzyme"]
 	path = src/tools/enzyme
-	url = https://github.com/rust-lang/Enzyme.git
+	url = https://github.com/rust-lang/enzyme.git
 	shallow = true
 [submodule "src/gcc"]
 	path = src/gcc

compiler/rustc_hir/src/hir.rs

@@ -2744,6 +2744,8 @@ pub enum ExprKind<'hir> {
     ///
     /// The "then" expr is always `ExprKind::Block`. If present, the "else" expr is always
     /// `ExprKind::Block` (for `else`) or `ExprKind::If` (for `else if`).
+    /// Note that using an `Expr` instead of a `Block` for the "then" part is intentional,
+    /// as it simplifies the type coercion machinery.
     If(&'hir Expr<'hir>, &'hir Expr<'hir>, Option<&'hir Expr<'hir>>),
     /// A conditionless loop (can be exited with `break`, `continue`, or `return`).
     ///

compiler/rustc_middle/src/ty/mod.rs

@@ -1184,7 +1184,7 @@ pub struct Destructor {
 #[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
 pub struct AsyncDestructor {
     /// The `DefId` of the `impl AsyncDrop`
-    pub impl_did: LocalDefId,
+    pub impl_did: DefId,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]

compiler/rustc_middle/src/ty/util.rs

@@ -465,7 +465,7 @@ impl<'tcx> TyCtxt<'tcx> {
             dtor_candidate = Some(impl_did);
         }
 
-        Some(ty::AsyncDestructor { impl_did: dtor_candidate? })
+        Some(ty::AsyncDestructor { impl_did: dtor_candidate?.into() })
     }
 
     /// Returns the set of types that are required to be alive in

compiler/rustc_parse/messages.ftl

@@ -815,7 +815,6 @@ parse_switch_ref_box_order = switch the order of `ref` and `box`
     .suggestion = swap them
 
 parse_ternary_operator = Rust has no ternary operator
-    .help = use an `if-else` expression instead
 
 parse_tilde_is_not_unary_operator = `~` cannot be used as a unary operator
     .suggestion = use `!` to perform bitwise not
@@ -963,6 +962,8 @@ parse_use_empty_block_not_semi = expected { "`{}`" }, found `;`
 parse_use_eq_instead = unexpected `==`
     .suggestion = try using `=` instead
 
+parse_use_if_else = use an `if-else` expression instead
+
 parse_use_let_not_auto = write `let` instead of `auto` to introduce a new variable
 parse_use_let_not_var = write `let` instead of `var` to introduce a new variable
 

compiler/rustc_parse/src/errors.rs

@@ -436,10 +436,28 @@ pub(crate) enum IfExpressionMissingThenBlockSub {
 
 #[derive(Diagnostic)]
 #[diag(parse_ternary_operator)]
-#[help]
 pub(crate) struct TernaryOperator {
     #[primary_span]
     pub span: Span,
+    /// If we have a span for the condition expression, suggest the if/else
+    #[subdiagnostic]
+    pub sugg: Option<TernaryOperatorSuggestion>,
+    /// Otherwise, just print the suggestion message
+    #[help(parse_use_if_else)]
+    pub no_sugg: bool,
+}
+
+#[derive(Subdiagnostic, Copy, Clone)]
+#[multipart_suggestion(parse_use_if_else, applicability = "maybe-incorrect", style = "verbose")]
+pub(crate) struct TernaryOperatorSuggestion {
+    #[suggestion_part(code = "if ")]
+    pub before_cond: Span,
+    #[suggestion_part(code = "{{")]
+    pub question: Span,
+    #[suggestion_part(code = "}} else {{")]
+    pub colon: Span,
+    #[suggestion_part(code = " }}")]
+    pub end: Span,
 }
 
 #[derive(Subdiagnostic)]

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -41,8 +41,9 @@ use crate::errors::{
     IncorrectSemicolon, IncorrectUseOfAwait, IncorrectUseOfUse, PatternMethodParamWithoutBody,
     QuestionMarkInType, QuestionMarkInTypeSugg, SelfParamNotFirst, StructLiteralBodyWithoutPath,
     StructLiteralBodyWithoutPathSugg, SuggAddMissingLetStmt, SuggEscapeIdentifier, SuggRemoveComma,
-    TernaryOperator, UnexpectedConstInGenericParam, UnexpectedConstParamDeclaration,
-    UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead, WrapType,
+    TernaryOperator, TernaryOperatorSuggestion, UnexpectedConstInGenericParam,
+    UnexpectedConstParamDeclaration, UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets,
+    UseEqInstead, WrapType,
 };
 use crate::parser::attr::InnerAttrPolicy;
 use crate::{exp, fluent_generated as fluent};
@@ -497,7 +498,7 @@ impl<'a> Parser<'a> {
             // If the user is trying to write a ternary expression, recover it and
             // return an Err to prevent a cascade of irrelevant diagnostics.
             if self.prev_token == token::Question
-                && let Err(e) = self.maybe_recover_from_ternary_operator()
+                && let Err(e) = self.maybe_recover_from_ternary_operator(None)
             {
                 return Err(e);
             }
@@ -1602,12 +1603,18 @@ impl<'a> Parser<'a> {
     /// Rust has no ternary operator (`cond ? then : else`). Parse it and try
     /// to recover from it if `then` and `else` are valid expressions. Returns
     /// an err if this appears to be a ternary expression.
-    pub(super) fn maybe_recover_from_ternary_operator(&mut self) -> PResult<'a, ()> {
+    /// If we have the span of the condition, we can provide a better error span
+    /// and code suggestion.
+    pub(super) fn maybe_recover_from_ternary_operator(
+        &mut self,
+        cond: Option<Span>,
+    ) -> PResult<'a, ()> {
         if self.prev_token != token::Question {
             return PResult::Ok(());
         }
 
-        let lo = self.prev_token.span.lo();
+        let question = self.prev_token.span;
+        let lo = cond.unwrap_or(question).lo();
         let snapshot = self.create_snapshot_for_diagnostic();
 
         if match self.parse_expr() {
@@ -1620,11 +1627,20 @@ impl<'a> Parser<'a> {
             }
         } {
             if self.eat_noexpect(&token::Colon) {
+                let colon = self.prev_token.span;
                 match self.parse_expr() {
-                    Ok(_) => {
-                        return Err(self
-                            .dcx()
-                            .create_err(TernaryOperator { span: self.token.span.with_lo(lo) }));
+                    Ok(expr) => {
+                        let sugg = cond.map(|cond| TernaryOperatorSuggestion {
+                            before_cond: cond.shrink_to_lo(),
+                            question,
+                            colon,
+                            end: expr.span.shrink_to_hi(),
+                        });
+                        return Err(self.dcx().create_err(TernaryOperator {
+                            span: self.prev_token.span.with_lo(lo),
+                            sugg,
+                            no_sugg: sugg.is_none(),
+                        }));
                     }
                     Err(err) => {
                         err.cancel();

compiler/rustc_parse/src/parser/stmt.rs

@@ -879,7 +879,12 @@ impl<'a> Parser<'a> {
             {
                 // Just check for errors and recover; do not eat semicolon yet.
 
-                let expect_result = self.expect_one_of(&[], &[exp!(Semi), exp!(CloseBrace)]);
+                let expect_result =
+                    if let Err(e) = self.maybe_recover_from_ternary_operator(Some(expr.span)) {
+                        Err(e)
+                    } else {
+                        self.expect_one_of(&[], &[exp!(Semi), exp!(CloseBrace)])
+                    };
 
                 // Try to both emit a better diagnostic, and avoid further errors by replacing
                 // the `expr` with `ExprKind::Err`.

library/core/Cargo.toml

@@ -35,4 +35,6 @@ check-cfg = [
     # and to stdarch `core_arch` crate which messes-up with Cargo list
     # of declared features, we therefor expect any feature cfg
     'cfg(feature, values(any()))',
+    # Internal features aren't marked known config by default
+    'cfg(target_has_reliable_f16)',
 ]

library/core/src/convert/mod.rs

@@ -464,8 +464,8 @@ pub trait Into<T>: Sized {
 /// orphaning rules.
 /// See [`Into`] for more details.
 ///
-/// Prefer using [`Into`] over using `From` when specifying trait bounds on a generic function.
-/// This way, types that directly implement [`Into`] can be used as arguments as well.
+/// Prefer using [`Into`] over [`From`] when specifying trait bounds on a generic function
+/// to ensure that types that only implement [`Into`] can be used as well.
 ///
 /// The `From` trait is also very useful when performing error handling. When constructing a function
 /// that is capable of failing, the return type will generally be of the form `Result<T, E>`.
@@ -597,6 +597,9 @@ pub trait From<T>: Sized {
 /// standard library. For more information on this, see the
 /// documentation for [`Into`].
 ///
+/// Prefer using [`TryInto`] over [`TryFrom`] when specifying trait bounds on a generic function
+/// to ensure that types that only implement [`TryInto`] can be used as well.
+///
 /// # Implementing `TryInto`
 ///
 /// This suffers the same restrictions and reasoning as implementing
@@ -636,6 +639,9 @@ pub trait TryInto<T>: Sized {
 /// When the [`!`] type is stabilized [`Infallible`] and [`!`] will be
 /// equivalent.
 ///
+/// Prefer using [`TryInto`] over [`TryFrom`] when specifying trait bounds on a generic function
+/// to ensure that types that only implement [`TryInto`] can be used as well.
+///
 /// `TryFrom<T>` can be implemented as follows:
 ///
 /// ```

library/core/src/fmt/float.rs

@@ -20,6 +20,8 @@ macro_rules! impl_general_format {
     }
 }
 
+#[cfg(target_has_reliable_f16)]
+impl_general_format! { f16 }
 impl_general_format! { f32 f64 }
 
 // Don't inline this so callers don't use the stack space this function
@@ -231,6 +233,13 @@ macro_rules! floating {
 
 floating! { f32 f64 }
 
+#[cfg(target_has_reliable_f16)]
+floating! { f16 }
+
+// FIXME(f16_f128): A fallback is used when the backend+target does not support f16 well, in order
+// to avoid ICEs.
+
+#[cfg(not(target_has_reliable_f16))]
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Debug for f16 {
     #[inline]
@@ -239,6 +248,33 @@ impl Debug for f16 {
     }
 }
 
+#[cfg(not(target_has_reliable_f16))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Display for f16 {
+    #[inline]
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
+        Debug::fmt(self, fmt)
+    }
+}
+
+#[cfg(not(target_has_reliable_f16))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl LowerExp for f16 {
+    #[inline]
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
+        Debug::fmt(self, fmt)
+    }
+}
+
+#[cfg(not(target_has_reliable_f16))]
+#[stable(feature = "rust1", since = "1.0.0")]
+impl UpperExp for f16 {
+    #[inline]
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
+        Debug::fmt(self, fmt)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Debug for f128 {
     #[inline]

library/core/src/lib.rs

@@ -101,6 +101,7 @@
 #![feature(bstr)]
 #![feature(bstr_internals)]
 #![feature(cfg_match)]
+#![feature(cfg_target_has_reliable_f16_f128)]
 #![feature(const_carrying_mul_add)]
 #![feature(const_eval_select)]
 #![feature(core_intrinsics)]

library/core/src/num/dec2flt/float.rs

@@ -45,7 +45,7 @@ macro_rules! int {
     }
 }
 
-int!(u32, u64);
+int!(u16, u32, u64);
 
 /// A helper trait to avoid duplicating basically all the conversion code for IEEE floats.
 ///
@@ -189,9 +189,14 @@ pub trait RawFloat:
 
     /// Returns the mantissa, exponent and sign as integers.
     ///
-    /// That is, this returns `(m, p, s)` such that `s * m * 2^p` represents the original float.
-    /// For 0, the exponent will be `-(EXP_BIAS + SIG_BITS`, which is the
-    /// minimum subnormal power.
+    /// This returns `(m, p, s)` such that `s * m * 2^p` represents the original float. For 0, the
+    /// exponent will be `-(EXP_BIAS + SIG_BITS)`, which is the minimum subnormal power. For
+    /// infinity or NaN, the exponent will be `EXP_SAT - EXP_BIAS - SIG_BITS`.
+    ///
+    /// If subnormal, the mantissa will be shifted one bit to the left. Otherwise, it is returned
+    /// with the explicit bit set but otherwise unshifted
+    ///
+    /// `s` is only ever +/-1.
     fn integer_decode(self) -> (u64, i16, i8) {
         let bits = self.to_bits();
         let sign: i8 = if bits >> (Self::BITS - 1) == Self::Int::ZERO { 1 } else { -1 };
@@ -213,6 +218,50 @@ const fn pow2_to_pow10(a: i64) -> i64 {
     res as i64
 }
 
+#[cfg(target_has_reliable_f16)]
+impl RawFloat for f16 {
+    type Int = u16;
+
+    const INFINITY: Self = Self::INFINITY;
+    const NEG_INFINITY: Self = Self::NEG_INFINITY;
+    const NAN: Self = Self::NAN;
+    const NEG_NAN: Self = -Self::NAN;
+
+    const BITS: u32 = 16;
+    const SIG_TOTAL_BITS: u32 = Self::MANTISSA_DIGITS;
+    const EXP_MASK: Self::Int = Self::EXP_MASK;
+    const SIG_MASK: Self::Int = Self::MAN_MASK;
+
+    const MIN_EXPONENT_ROUND_TO_EVEN: i32 = -22;
+    const MAX_EXPONENT_ROUND_TO_EVEN: i32 = 5;
+    const SMALLEST_POWER_OF_TEN: i32 = -27;
+
+    #[inline]
+    fn from_u64(v: u64) -> Self {
+        debug_assert!(v <= Self::MAX_MANTISSA_FAST_PATH);
+        v as _
+    }
+
+    #[inline]
+    fn from_u64_bits(v: u64) -> Self {
+        Self::from_bits((v & 0xFFFF) as u16)
+    }
+
+    fn pow10_fast_path(exponent: usize) -> Self {
+        #[allow(clippy::use_self)]
+        const TABLE: [f16; 8] = [1e0, 1e1, 1e2, 1e3, 1e4, 0.0, 0.0, 0.];
+        TABLE[exponent & 7]
+    }
+
+    fn to_bits(self) -> Self::Int {
+        self.to_bits()
+    }
+
+    fn classify(self) -> FpCategory {
+        self.classify()
+    }
+}
+
 impl RawFloat for f32 {
     type Int = u32;
 

library/core/src/num/dec2flt/mod.rs

@@ -171,9 +171,25 @@ macro_rules! from_str_float_impl {
         }
     };
 }
+
+#[cfg(target_has_reliable_f16)]
+from_str_float_impl!(f16);
 from_str_float_impl!(f32);
 from_str_float_impl!(f64);
 
+// FIXME(f16_f128): A fallback is used when the backend+target does not support f16 well, in order
+// to avoid ICEs.
+
+#[cfg(not(target_has_reliable_f16))]
+impl FromStr for f16 {
+    type Err = ParseFloatError;
+
+    #[inline]
+    fn from_str(_src: &str) -> Result<Self, ParseFloatError> {
+        unimplemented!("requires target_has_reliable_f16")
+    }
+}
+
 /// An error which can be returned when parsing a float.
 ///
 /// This error is used as the error type for the [`FromStr`] implementation

library/core/src/num/flt2dec/decoder.rs

@@ -45,6 +45,13 @@ pub trait DecodableFloat: RawFloat + Copy {
     fn min_pos_norm_value() -> Self;
 }
 
+#[cfg(target_has_reliable_f16)]
+impl DecodableFloat for f16 {
+    fn min_pos_norm_value() -> Self {
+        f16::MIN_POSITIVE
+    }
+}
+
 impl DecodableFloat for f32 {
     fn min_pos_norm_value() -> Self {
         f32::MIN_POSITIVE

library/coretests/Cargo.toml

@@ -26,3 +26,12 @@ test = true
 [dev-dependencies]
 rand = { version = "0.9.0", default-features = false }
 rand_xorshift = { version = "0.4.0", default-features = false }
+
+[lints.rust.unexpected_cfgs]
+level = "warn"
+check-cfg = [
+    'cfg(bootstrap)',
+    # Internal features aren't marked known config by default, we use these to
+    # gate tests.
+    'cfg(target_has_reliable_f16)',
+]