Auto merge of rust-lang#136684 - matthiaskrgr:rollup-mlpzre5, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#135973 (fix tail call checks wrt `#[track_caller]`)
 - rust-lang#136191 (compiler: replace few consts arrays with statics to remove const dupes)
 - rust-lang#136565 (compiler: Clean up weird `rustc_abi` reexports)
 - rust-lang#136582 (Revert "CI: build FreeBSD artifacts on FreeBSD 13.4")
 - rust-lang#136627 (MIR validation: add comment explaining the limitations of CfgChecker)
 - rust-lang#136634 (Stabilise `Cursor::{get_mut, set_position}` in `const` scenarios.)
 - rust-lang#136643 (ping me for attribute-related changes)
 - rust-lang#136644 (Add `rustc_hir_pretty::item_to_string` function)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_abi/src/callconv.rs

@@ -1,73 +1,10 @@
-mod abi {
-    pub(crate) use crate::Primitive::*;
-    pub(crate) use crate::Variants;
-}
-
-#[cfg(feature = "nightly")]
-use rustc_macros::HashStable_Generic;
-
-use crate::{Align, HasDataLayout, Size};
 #[cfg(feature = "nightly")]
 use crate::{BackendRepr, FieldsShape, TyAbiInterface, TyAndLayout};
+use crate::{Primitive, Size, Variants};
 
-#[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
-pub enum RegKind {
-    Integer,
-    Float,
-    Vector,
-}
-
-#[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
-pub struct Reg {
-    pub kind: RegKind,
-    pub size: Size,
-}
-
-macro_rules! reg_ctor {
-    ($name:ident, $kind:ident, $bits:expr) => {
-        pub fn $name() -> Reg {
-            Reg { kind: RegKind::$kind, size: Size::from_bits($bits) }
-        }
-    };
-}
-
-impl Reg {
-    reg_ctor!(i8, Integer, 8);
-    reg_ctor!(i16, Integer, 16);
-    reg_ctor!(i32, Integer, 32);
-    reg_ctor!(i64, Integer, 64);
-    reg_ctor!(i128, Integer, 128);
-
-    reg_ctor!(f32, Float, 32);
-    reg_ctor!(f64, Float, 64);
-}
+mod reg;
 
-impl Reg {
-    pub fn align<C: HasDataLayout>(&self, cx: &C) -> Align {
-        let dl = cx.data_layout();
-        match self.kind {
-            RegKind::Integer => match self.size.bits() {
-                1 => dl.i1_align.abi,
-                2..=8 => dl.i8_align.abi,
-                9..=16 => dl.i16_align.abi,
-                17..=32 => dl.i32_align.abi,
-                33..=64 => dl.i64_align.abi,
-                65..=128 => dl.i128_align.abi,
-                _ => panic!("unsupported integer: {self:?}"),
-            },
-            RegKind::Float => match self.size.bits() {
-                16 => dl.f16_align.abi,
-                32 => dl.f32_align.abi,
-                64 => dl.f64_align.abi,
-                128 => dl.f128_align.abi,
-                _ => panic!("unsupported float: {self:?}"),
-            },
-            RegKind::Vector => dl.vector_align(self.size).abi,
-        }
-    }
-}
+pub use reg::{Reg, RegKind};
 
 /// Return value from the `homogeneous_aggregate` test function.
 #[derive(Copy, Clone, Debug)]
@@ -134,8 +71,8 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
             // The primitive for this algorithm.
             BackendRepr::Scalar(scalar) => {
                 let kind = match scalar.primitive() {
-                    abi::Int(..) | abi::Pointer(_) => RegKind::Integer,
-                    abi::Float(_) => RegKind::Float,
+                    Primitive::Int(..) | Primitive::Pointer(_) => RegKind::Integer,
+                    Primitive::Float(_) => RegKind::Float,
                 };
                 Ok(HomogeneousAggregate::Homogeneous(Reg { kind, size: self.size }))
             }
@@ -206,8 +143,8 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
                 let (mut result, mut total) = from_fields_at(*self, Size::ZERO)?;
 
                 match &self.variants {
-                    abi::Variants::Single { .. } | abi::Variants::Empty => {}
-                    abi::Variants::Multiple { variants, .. } => {
+                    Variants::Single { .. } | Variants::Empty => {}
+                    Variants::Multiple { variants, .. } => {
                         // Treat enum variants like union members.
                         // HACK(eddyb) pretend the `enum` field (discriminant)
                         // is at the start of every variant (otherwise the gap

compiler/rustc_abi/src/callconv/reg.rs

@@ -0,0 +1,63 @@
+#[cfg(feature = "nightly")]
+use rustc_macros::HashStable_Generic;
+
+use crate::{Align, HasDataLayout, Size};
+
+#[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub enum RegKind {
+    Integer,
+    Float,
+    Vector,
+}
+
+#[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct Reg {
+    pub kind: RegKind,
+    pub size: Size,
+}
+
+macro_rules! reg_ctor {
+    ($name:ident, $kind:ident, $bits:expr) => {
+        pub fn $name() -> Reg {
+            Reg { kind: RegKind::$kind, size: Size::from_bits($bits) }
+        }
+    };
+}
+
+impl Reg {
+    reg_ctor!(i8, Integer, 8);
+    reg_ctor!(i16, Integer, 16);
+    reg_ctor!(i32, Integer, 32);
+    reg_ctor!(i64, Integer, 64);
+    reg_ctor!(i128, Integer, 128);
+
+    reg_ctor!(f32, Float, 32);
+    reg_ctor!(f64, Float, 64);
+}
+
+impl Reg {
+    pub fn align<C: HasDataLayout>(&self, cx: &C) -> Align {
+        let dl = cx.data_layout();
+        match self.kind {
+            RegKind::Integer => match self.size.bits() {
+                1 => dl.i1_align.abi,
+                2..=8 => dl.i8_align.abi,
+                9..=16 => dl.i16_align.abi,
+                17..=32 => dl.i32_align.abi,
+                33..=64 => dl.i64_align.abi,
+                65..=128 => dl.i128_align.abi,
+                _ => panic!("unsupported integer: {self:?}"),
+            },
+            RegKind::Float => match self.size.bits() {
+                16 => dl.f16_align.abi,
+                32 => dl.f32_align.abi,
+                64 => dl.f64_align.abi,
+                128 => dl.f128_align.abi,
+                _ => panic!("unsupported float: {self:?}"),
+            },
+            RegKind::Vector => dl.vector_align(self.size).abi,
+        }
+    }
+}

compiler/rustc_abi/src/extern_abi/mod.rs renamed to compiler/rustc_abi/src/extern_abi.rs

@@ -1,13 +1,15 @@
 use std::fmt;
 use std::ops::Deref;
 
-use Float::*;
-use Primitive::*;
 use rustc_data_structures::intern::Interned;
 use rustc_macros::HashStable_Generic;
 
+use crate::{
+    AbiAndPrefAlign, Align, BackendRepr, FieldsShape, Float, HasDataLayout, LayoutData, Niche,
+    PointeeInfo, Primitive, Scalar, Size, TargetDataLayout, Variants,
+};
+
 // Explicitly import `Float` to avoid ambiguity with `Primitive::Float`.
-use crate::{Float, *};
 
 rustc_index::newtype_index! {
     /// The *source-order* index of a field in a variant.
@@ -197,7 +199,9 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
         C: HasDataLayout,
     {
         match self.backend_repr {
-            BackendRepr::Scalar(scalar) => matches!(scalar.primitive(), Float(F32 | F64)),
+            BackendRepr::Scalar(scalar) => {
+                matches!(scalar.primitive(), Primitive::Float(Float::F32 | Float::F64))
+            }
             BackendRepr::Memory { .. } => {
                 if self.fields.count() == 1 && self.fields.offset(0).bytes() == 0 {
                     self.field(cx, 0).is_single_fp_element(cx)

compiler/rustc_abi/src/layout/ty.rs

@@ -9,7 +9,7 @@ macro_rules! declare_features {
         $(#[doc = $doc:tt])* (accepted, $feature:ident, $ver:expr, $issue:expr),
     )+) => {
         /// Formerly unstable features that have now been accepted (stabilized).
-        pub const ACCEPTED_LANG_FEATURES: &[Feature] = &[
+        pub static ACCEPTED_LANG_FEATURES: &[Feature] = &[
             $(Feature {
                 name: sym::$feature,
                 since: $ver,

compiler/rustc_feature/src/accepted.rs

@@ -318,7 +318,7 @@ pub struct BuiltinAttribute {
 
 /// Attributes that have a special meaning to rustc or rustdoc.
 #[rustfmt::skip]
-pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
+pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // ==========================================================================
     // Stable attributes:
     // ==========================================================================

compiler/rustc_feature/src/builtin_attrs.rs

@@ -14,7 +14,7 @@ macro_rules! declare_features {
         $(#[doc = $doc:tt])* (removed, $feature:ident, $ver:expr, $issue:expr, $reason:expr),
     )+) => {
         /// Formerly unstable features that have now been removed.
-        pub const REMOVED_LANG_FEATURES: &[RemovedFeature] = &[
+        pub static REMOVED_LANG_FEATURES: &[RemovedFeature] = &[
             $(RemovedFeature {
                 feature: Feature {
                     name: sym::$feature,

compiler/rustc_feature/src/removed.rs

@@ -104,7 +104,7 @@ macro_rules! declare_features {
     )+) => {
         /// Unstable language features that are being implemented or being
         /// considered for acceptance (stabilization) or removal.
-        pub const UNSTABLE_LANG_FEATURES: &[Feature] = &[
+        pub static UNSTABLE_LANG_FEATURES: &[Feature] = &[
             $(Feature {
                 name: sym::$feature,
                 since: $ver,

compiler/rustc_feature/src/unstable.rs

@@ -325,6 +325,10 @@ pub fn expr_to_string(ann: &dyn PpAnn, pat: &hir::Expr<'_>) -> String {
     to_string(ann, |s| s.print_expr(pat))
 }
 
+pub fn item_to_string(ann: &dyn PpAnn, pat: &hir::Item<'_>) -> String {
+    to_string(ann, |s| s.print_item(pat))
+}
+
 impl<'a> State<'a> {
     fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
         self.maybe_print_comment(span.hi());

compiler/rustc_hir_pretty/src/lib.rs

@@ -132,11 +132,24 @@ impl<'tcx> TailCallCkVisitor<'_, 'tcx> {
         }
 
         {
+            // `#[track_caller]` affects the ABI of a function (by adding a location argument),
+            // so a `track_caller` can only tail call other `track_caller` functions.
+            //
+            // The issue is however that we can't know if a function is `track_caller` or not at
+            // this point (THIR can be polymorphic, we may have an unresolved trait function).
+            // We could only allow functions that we *can* resolve and *are* `track_caller`,
+            // but that would turn changing `track_caller`-ness into a breaking change,
+            // which is probably undesirable.
+            //
+            // Also note that we don't check callee's `track_caller`-ness at all, mostly for the
+            // reasons above, but also because we can always tailcall the shim we'd generate for
+            // coercing the function to an `fn()` pointer. (although in that case the tailcall is
+            // basically useless -- the shim calls the actual function, so tailcalling the shim is
+            // equivalent to calling the function)
             let caller_needs_location = self.needs_location(self.caller_ty);
-            let callee_needs_location = self.needs_location(ty);
 
-            if caller_needs_location != callee_needs_location {
-                self.report_track_caller_mismatch(expr.span, caller_needs_location);
+            if caller_needs_location {
+                self.report_track_caller_caller(expr.span);
             }
         }
 
@@ -150,7 +163,9 @@ impl<'tcx> TailCallCkVisitor<'_, 'tcx> {
     }
 
     /// Returns true if function of type `ty` needs location argument
-    /// (i.e. if a function is marked as `#[track_caller]`)
+    /// (i.e. if a function is marked as `#[track_caller]`).
+    ///
+    /// Panics if the function's instance can't be immediately resolved.
     fn needs_location(&self, ty: Ty<'tcx>) -> bool {
         if let &ty::FnDef(did, substs) = ty.kind() {
             let instance =
@@ -293,25 +308,15 @@ impl<'tcx> TailCallCkVisitor<'_, 'tcx> {
         self.found_errors = Err(err);
     }
 
-    fn report_track_caller_mismatch(&mut self, sp: Span, caller_needs_location: bool) {
-        let err = match caller_needs_location {
-            true => self
-                .tcx
-                .dcx()
-                .struct_span_err(
-                    sp,
-                    "a function marked with `#[track_caller]` cannot tail-call one that is not",
-                )
-                .emit(),
-            false => self
-                .tcx
-                .dcx()
-                .struct_span_err(
-                    sp,
-                    "a function mot marked with `#[track_caller]` cannot tail-call one that is",
-                )
-                .emit(),
-        };
+    fn report_track_caller_caller(&mut self, sp: Span) {
+        let err = self
+            .tcx
+            .dcx()
+            .struct_span_err(
+                sp,
+                "a function marked with `#[track_caller]` cannot perform a tail-call",
+            )
+            .emit();
 
         self.found_errors = Err(err);
     }