Auto merge of rust-lang#120290 - fmease:rollup-f87t55u, r=fmease

Rollup of 7 pull requests

Successful merges:

 - rust-lang#119460 (coverage: Never emit improperly-ordered coverage regions)
 - rust-lang#120062 (llvm: change data layout bug to an error and make it trigger more)
 - rust-lang#120124 (Split assembly tests for ELF and MachO)
 - rust-lang#120165 (Switch `NonZero` alias direction.)
 - rust-lang#120185 (coverage: Don't instrument `#[automatically_derived]` functions)
 - rust-lang#120265 (Remove no-system-llvm)
 - rust-lang#120285 (Remove extra # from url in suggestion)

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

Author: bors

compiler/rustc_codegen_llvm/messages.ftl

@@ -39,6 +39,9 @@ codegen_llvm_lto_dylib = lto cannot be used for `dylib` crate type without `-Zdy
 
 codegen_llvm_lto_proc_macro = lto cannot be used for `proc-macro` crate type without `-Zdylib-lto`
 
+codegen_llvm_mismatch_data_layout =
+    data-layout for target `{$rustc_target}`, `{$rustc_layout}`, differs from LLVM target's `{$llvm_target}` default layout, `{$llvm_layout}`
+
 codegen_llvm_missing_features =
     add the missing features in a `target_feature` attribute
 

compiler/rustc_codegen_llvm/src/context.rs

@@ -34,6 +34,7 @@ use rustc_target::spec::{HasTargetSpec, RelocModel, Target, TlsModel};
 use smallvec::SmallVec;
 
 use libc::c_uint;
+use std::borrow::Borrow;
 use std::cell::{Cell, RefCell};
 use std::ffi::CStr;
 use std::str;
@@ -155,42 +156,21 @@ pub unsafe fn create_module<'ll>(
     }
 
     // Ensure the data-layout values hardcoded remain the defaults.
-    if sess.target.is_builtin {
-        // tm is disposed by its drop impl
+    {
         let tm = crate::back::write::create_informational_target_machine(tcx.sess);
         llvm::LLVMRustSetDataLayoutFromTargetMachine(llmod, &tm);
 
         let llvm_data_layout = llvm::LLVMGetDataLayoutStr(llmod);
         let llvm_data_layout = str::from_utf8(CStr::from_ptr(llvm_data_layout).to_bytes())
             .expect("got a non-UTF8 data-layout from LLVM");
 
-        // Unfortunately LLVM target specs change over time, and right now we
-        // don't have proper support to work with any more than one
-        // `data_layout` than the one that is in the rust-lang/rust repo. If
-        // this compiler is configured against a custom LLVM, we may have a
-        // differing data layout, even though we should update our own to use
-        // that one.
-        //
-        // As an interim hack, if CFG_LLVM_ROOT is not an empty string then we
-        // disable this check entirely as we may be configured with something
-        // that has a different target layout.
-        //
-        // Unsure if this will actually cause breakage when rustc is configured
-        // as such.
-        //
-        // FIXME(#34960)
-        let cfg_llvm_root = option_env!("CFG_LLVM_ROOT").unwrap_or("");
-        let custom_llvm_used = !cfg_llvm_root.trim().is_empty();
-
-        if !custom_llvm_used && target_data_layout != llvm_data_layout {
-            bug!(
-                "data-layout for target `{rustc_target}`, `{rustc_layout}`, \
-                  differs from LLVM target's `{llvm_target}` default layout, `{llvm_layout}`",
-                rustc_target = sess.opts.target_triple,
-                rustc_layout = target_data_layout,
-                llvm_target = sess.target.llvm_target,
-                llvm_layout = llvm_data_layout
-            );
+        if target_data_layout != llvm_data_layout {
+            tcx.dcx().emit_err(crate::errors::MismatchedDataLayout {
+                rustc_target: sess.opts.target_triple.to_string().as_str(),
+                rustc_layout: target_data_layout.as_str(),
+                llvm_target: sess.target.llvm_target.borrow(),
+                llvm_layout: llvm_data_layout,
+            });
         }
     }
 

compiler/rustc_codegen_llvm/src/errors.rs

@@ -244,3 +244,12 @@ pub(crate) struct CopyBitcode {
 pub struct UnknownCompression {
     pub algorithm: &'static str,
 }
+
+#[derive(Diagnostic)]
+#[diag(codegen_llvm_mismatch_data_layout)]
+pub struct MismatchedDataLayout<'a> {
+    pub rustc_target: &'a str,
+    pub rustc_layout: &'a str,
+    pub llvm_target: &'a str,
+    pub llvm_layout: &'a str,
+}

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -2140,46 +2140,50 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr_ty: Ty<'tcx>,
     ) -> bool {
         let tcx = self.tcx;
-        let (adt, unwrap) = match expected.kind() {
+        let (adt, substs, unwrap) = match expected.kind() {
             // In case Option<NonZero*> is wanted, but * is provided, suggest calling new
-            ty::Adt(adt, args) if tcx.is_diagnostic_item(sym::Option, adt.did()) => {
-                // Unwrap option
-                let ty::Adt(adt, _) = args.type_at(0).kind() else {
+            ty::Adt(adt, substs) if tcx.is_diagnostic_item(sym::Option, adt.did()) => {
+                let nonzero_type = substs.type_at(0); // Unwrap option type.
+                let ty::Adt(adt, substs) = nonzero_type.kind() else {
                     return false;
                 };
-
-                (adt, "")
+                (adt, substs, "")
             }
-            // In case NonZero* is wanted, but * is provided also add `.unwrap()` to satisfy types
-            ty::Adt(adt, _) => (adt, ".unwrap()"),
+            // In case `NonZero<*>` is wanted but `*` is provided, also add `.unwrap()` to satisfy types.
+            ty::Adt(adt, substs) => (adt, substs, ".unwrap()"),
             _ => return false,
         };
 
-        let map = [
-            (sym::NonZeroU8, tcx.types.u8),
-            (sym::NonZeroU16, tcx.types.u16),
-            (sym::NonZeroU32, tcx.types.u32),
-            (sym::NonZeroU64, tcx.types.u64),
-            (sym::NonZeroU128, tcx.types.u128),
-            (sym::NonZeroI8, tcx.types.i8),
-            (sym::NonZeroI16, tcx.types.i16),
-            (sym::NonZeroI32, tcx.types.i32),
-            (sym::NonZeroI64, tcx.types.i64),
-            (sym::NonZeroI128, tcx.types.i128),
+        if !self.tcx.is_diagnostic_item(sym::NonZero, adt.did()) {
+            return false;
+        }
+
+        // FIXME: This can be simplified once `NonZero<T>` is stable.
+        let coercable_types = [
+            ("NonZeroU8", tcx.types.u8),
+            ("NonZeroU16", tcx.types.u16),
+            ("NonZeroU32", tcx.types.u32),
+            ("NonZeroU64", tcx.types.u64),
+            ("NonZeroU128", tcx.types.u128),
+            ("NonZeroI8", tcx.types.i8),
+            ("NonZeroI16", tcx.types.i16),
+            ("NonZeroI32", tcx.types.i32),
+            ("NonZeroI64", tcx.types.i64),
+            ("NonZeroI128", tcx.types.i128),
         ];
 
-        let Some((s, _)) = map.iter().find(|&&(s, t)| {
-            self.tcx.is_diagnostic_item(s, adt.did()) && self.can_coerce(expr_ty, t)
+        let int_type = substs.type_at(0);
+
+        let Some(nonzero_alias) = coercable_types.iter().find_map(|(nonzero_alias, t)| {
+            if *t == int_type && self.can_coerce(expr_ty, *t) { Some(nonzero_alias) } else { None }
         }) else {
             return false;
         };
 
-        let path = self.tcx.def_path_str(adt.non_enum_variant().def_id);
-
         err.multipart_suggestion(
-            format!("consider calling `{s}::new`"),
+            format!("consider calling `{nonzero_alias}::new`"),
             vec![
-                (expr.span.shrink_to_lo(), format!("{path}::new(")),
+                (expr.span.shrink_to_lo(), format!("{nonzero_alias}::new(")),
                 (expr.span.shrink_to_hi(), format!("){unwrap}")),
             ],
             Applicability::MaybeIncorrect,

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -329,7 +329,7 @@ fn make_code_region(
     start_line = source_map.doctest_offset_line(&file.name, start_line);
     end_line = source_map.doctest_offset_line(&file.name, end_line);
 
-    Some(CodeRegion {
+    check_code_region(CodeRegion {
         file_name,
         start_line: start_line as u32,
         start_col: start_col as u32,
@@ -338,6 +338,39 @@ fn make_code_region(
     })
 }
 
+/// If `llvm-cov` sees a code region that is improperly ordered (end < start),
+/// it will immediately exit with a fatal error. To prevent that from happening,
+/// discard regions that are improperly ordered, or might be interpreted in a
+/// way that makes them improperly ordered.
+fn check_code_region(code_region: CodeRegion) -> Option<CodeRegion> {
+    let CodeRegion { file_name: _, start_line, start_col, end_line, end_col } = code_region;
+
+    // Line/column coordinates are supposed to be 1-based. If we ever emit
+    // coordinates of 0, `llvm-cov` might misinterpret them.
+    let all_nonzero = [start_line, start_col, end_line, end_col].into_iter().all(|x| x != 0);
+    // Coverage mappings use the high bit of `end_col` to indicate that a
+    // region is actually a "gap" region, so make sure it's unset.
+    let end_col_has_high_bit_unset = (end_col & (1 << 31)) == 0;
+    // If a region is improperly ordered (end < start), `llvm-cov` will exit
+    // with a fatal error, which is inconvenient for users and hard to debug.
+    let is_ordered = (start_line, start_col) <= (end_line, end_col);
+
+    if all_nonzero && end_col_has_high_bit_unset && is_ordered {
+        Some(code_region)
+    } else {
+        debug!(
+            ?code_region,
+            ?all_nonzero,
+            ?end_col_has_high_bit_unset,
+            ?is_ordered,
+            "Skipping code region that would be misinterpreted or rejected by LLVM"
+        );
+        // If this happens in a debug build, ICE to make it easier to notice.
+        debug_assert!(false, "Improper code region: {code_region:?}");
+        None
+    }
+}
+
 fn is_eligible_for_coverage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
     // Only instrument functions, methods, and closures (not constants since they are evaluated
     // at compile time by Miri).
@@ -351,7 +384,18 @@ fn is_eligible_for_coverage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
         return false;
     }
 
+    // Don't instrument functions with `#[automatically_derived]` on their
+    // enclosing impl block, on the assumption that most users won't care about
+    // coverage for derived impls.
+    if let Some(impl_of) = tcx.impl_of_method(def_id.to_def_id())
+        && tcx.is_automatically_derived(impl_of)
+    {
+        trace!("InstrumentCoverage skipped for {def_id:?} (automatically derived)");
+        return false;
+    }
+
     if tcx.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::NO_COVERAGE) {
+        trace!("InstrumentCoverage skipped for {def_id:?} (`#[coverage(off)]`)");
         return false;
     }
 

compiler/rustc_span/src/symbol.rs

@@ -246,17 +246,7 @@ symbols! {
         MutexGuard,
         N,
         NonNull,
-        NonZeroI128,
-        NonZeroI16,
-        NonZeroI32,
-        NonZeroI64,
-        NonZeroI8,
-        NonZeroU128,
-        NonZeroU16,
-        NonZeroU32,
-        NonZeroU64,
-        NonZeroU8,
-        NonZeroUsize,
+        NonZero,
         None,
         Normal,
         Ok,

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -3155,7 +3155,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 } else {
                     // FIXME: we may suggest array::repeat instead
                     err.help("consider using `core::array::from_fn` to initialize the array");
-                    err.help("see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information");
+                    err.help("see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information");
                 }
 
                 if self.tcx.sess.is_nightly_build()

library/core/src/num/mod.rs

@@ -61,7 +61,15 @@ pub use dec2flt::ParseFloatError;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use error::ParseIntError;
 
-pub(crate) use nonzero::NonZero;
+#[unstable(
+    feature = "nonzero_internals",
+    reason = "implementation detail which may disappear or be replaced at any time",
+    issue = "none"
+)]
+pub use nonzero::ZeroablePrimitive;
+
+#[unstable(feature = "generic_nonzero", issue = "82363")]
+pub use nonzero::NonZero;
 
 #[stable(feature = "nonzero", since = "1.28.0")]
 pub use nonzero::{NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize};

library/core/src/num/nonzero.rs

@@ -3,7 +3,7 @@
 use crate::cmp::Ordering;
 use crate::fmt;
 use crate::hash::{Hash, Hasher};
-use crate::marker::StructuralPartialEq;
+use crate::marker::{StructuralEq, StructuralPartialEq};
 use crate::ops::{BitOr, BitOrAssign, Div, Neg, Rem};
 use crate::str::FromStr;
 
@@ -30,9 +30,7 @@ mod private {
     issue = "none"
 )]
 #[const_trait]
-pub trait ZeroablePrimitive: Sized + Copy + private::Sealed {
-    type NonZero;
-}
+pub trait ZeroablePrimitive: Sized + Copy + private::Sealed {}
 
 macro_rules! impl_zeroable_primitive {
     ($NonZero:ident ( $primitive:ty )) => {
@@ -48,9 +46,7 @@ macro_rules! impl_zeroable_primitive {
             reason = "implementation detail which may disappear or be replaced at any time",
             issue = "none"
         )]
-        impl const ZeroablePrimitive for $primitive {
-            type NonZero = $NonZero;
-        }
+        impl const ZeroablePrimitive for $primitive {}
     };
 }
 
@@ -67,12 +63,23 @@ impl_zeroable_primitive!(NonZeroI64(i64));
 impl_zeroable_primitive!(NonZeroI128(i128));
 impl_zeroable_primitive!(NonZeroIsize(isize));
 
-#[unstable(
-    feature = "nonzero_internals",
-    reason = "implementation detail which may disappear or be replaced at any time",
-    issue = "none"
-)]
-pub(crate) type NonZero<T> = <T as ZeroablePrimitive>::NonZero;
+/// A value that is known not to equal zero.
+///
+/// This enables some memory layout optimization.
+/// For example, `Option<NonZero<u32>>` is the same size as `u32`:
+///
+/// ```
+/// #![feature(generic_nonzero)]
+/// use core::mem::size_of;
+///
+/// assert_eq!(size_of::<Option<core::num::NonZero<u32>>>(), size_of::<u32>());
+/// ```
+#[unstable(feature = "generic_nonzero", issue = "82363")]
+#[repr(transparent)]
+#[rustc_layout_scalar_valid_range_start(1)]
+#[rustc_nonnull_optimization_guaranteed]
+#[rustc_diagnostic_item = "NonZero"]
+pub struct NonZero<T: ZeroablePrimitive>(T);
 
 macro_rules! impl_nonzero_fmt {
     ( #[$stability: meta] ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
@@ -131,12 +138,7 @@ macro_rules! nonzero_integer {
         ///
         /// [null pointer optimization]: crate::option#representation
         #[$stability]
-        #[derive(Copy, Eq)]
-        #[repr(transparent)]
-        #[rustc_layout_scalar_valid_range_start(1)]
-        #[rustc_nonnull_optimization_guaranteed]
-        #[rustc_diagnostic_item = stringify!($Ty)]
-        pub struct $Ty($Int);
+        pub type $Ty = NonZero<$Int>;
 
         impl $Ty {
             /// Creates a non-zero without checking whether the value is non-zero.
@@ -506,6 +508,9 @@ macro_rules! nonzero_integer {
             }
         }
 
+        #[$stability]
+        impl Copy for $Ty {}
+
         #[$stability]
         impl PartialEq for $Ty {
             #[inline]
@@ -522,6 +527,12 @@ macro_rules! nonzero_integer {
         #[unstable(feature = "structural_match", issue = "31434")]
         impl StructuralPartialEq for $Ty {}
 
+        #[$stability]
+        impl Eq for $Ty {}
+
+        #[unstable(feature = "structural_match", issue = "31434")]
+        impl StructuralEq for $Ty {}
+
         #[$stability]
         impl PartialOrd for $Ty {
             #[inline]

library/std/src/num.rs

@@ -16,6 +16,16 @@ pub use core::num::Wrapping;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::num::{FpCategory, ParseFloatError, ParseIntError, TryFromIntError};
 
+#[unstable(
+    feature = "nonzero_internals",
+    reason = "implementation detail which may disappear or be replaced at any time",
+    issue = "none"
+)]
+pub use core::num::ZeroablePrimitive;
+
+#[unstable(feature = "generic_nonzero", issue = "82363")]
+pub use core::num::NonZero;
+
 #[stable(feature = "signed_nonzero", since = "1.34.0")]
 pub use core::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};
 #[stable(feature = "nonzero", since = "1.28.0")]