Auto merge of rust-lang#130854 - matthiaskrgr:rollup-prsu23n, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - rust-lang#129687 (Implement RFC3137 trim-paths sysroot changes - take 2)
 - rust-lang#129759 (Stabilize `const_refs_to_static`)
 - rust-lang#130329 (Reorder stack spills so that constants come later.)
 - rust-lang#130845 (Utf8Chunks: add link to Utf8Chunk)
 - rust-lang#130846 (Revert Break into the debugger on panic (129019))

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

Author: bors

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -1,4 +1,5 @@
 use std::collections::hash_map::Entry;
+use std::marker::PhantomData;
 use std::ops::Range;
 
 use rustc_data_structures::fx::FxHashMap;
@@ -14,7 +15,7 @@ use rustc_target::abi::{Abi, FieldIdx, FieldsShape, Size, VariantIdx};
 
 use super::operand::{OperandRef, OperandValue};
 use super::place::{PlaceRef, PlaceValue};
-use super::{FunctionCx, LocalRef};
+use super::{FunctionCx, LocalRef, PerLocalVarDebugInfoIndexVec};
 use crate::traits::*;
 
 pub struct FunctionDebugContext<'tcx, S, L> {
@@ -48,6 +49,17 @@ pub struct PerLocalVarDebugInfo<'tcx, D> {
     pub projection: &'tcx ty::List<mir::PlaceElem<'tcx>>,
 }
 
+/// Information needed to emit a constant.
+pub struct ConstDebugInfo<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
+    pub name: String,
+    pub source_info: mir::SourceInfo,
+    pub operand: OperandRef<'tcx, Bx::Value>,
+    pub dbg_var: Bx::DIVariable,
+    pub dbg_loc: Bx::DILocation,
+    pub fragment: Option<Range<Size>>,
+    pub _phantom: PhantomData<&'a ()>,
+}
+
 #[derive(Clone, Copy, Debug)]
 pub struct DebugScope<S, L> {
     pub dbg_scope: S,
@@ -427,19 +439,36 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         }
     }
 
-    pub(crate) fn debug_introduce_locals(&self, bx: &mut Bx) {
+    pub(crate) fn debug_introduce_locals(
+        &self,
+        bx: &mut Bx,
+        consts: Vec<ConstDebugInfo<'a, 'tcx, Bx>>,
+    ) {
         if bx.sess().opts.debuginfo == DebugInfo::Full || !bx.sess().fewer_names() {
             for local in self.locals.indices() {
                 self.debug_introduce_local(bx, local);
             }
+
+            for ConstDebugInfo { name, source_info, operand, dbg_var, dbg_loc, fragment, .. } in
+                consts.into_iter()
+            {
+                self.set_debug_loc(bx, source_info);
+                let base = FunctionCx::spill_operand_to_stack(operand, Some(name), bx);
+                bx.clear_dbg_loc();
+
+                bx.dbg_var_addr(dbg_var, dbg_loc, base.val.llval, Size::ZERO, &[], fragment);
+            }
         }
     }
 
     /// Partition all `VarDebugInfo` in `self.mir`, by their base `Local`.
     pub(crate) fn compute_per_local_var_debug_info(
         &self,
         bx: &mut Bx,
-    ) -> Option<IndexVec<mir::Local, Vec<PerLocalVarDebugInfo<'tcx, Bx::DIVariable>>>> {
+    ) -> Option<(
+        PerLocalVarDebugInfoIndexVec<'tcx, Bx::DIVariable>,
+        Vec<ConstDebugInfo<'a, 'tcx, Bx>>,
+    )> {
         let full_debug_info = self.cx.sess().opts.debuginfo == DebugInfo::Full;
 
         let target_is_msvc = self.cx.sess().target.is_like_msvc;
@@ -449,6 +478,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         }
 
         let mut per_local = IndexVec::from_elem(vec![], &self.mir.local_decls);
+        let mut constants = vec![];
         let mut params_seen: FxHashMap<_, Bx::DIVariable> = Default::default();
         for var in &self.mir.var_debug_info {
             let dbg_scope_and_span = if full_debug_info {
@@ -545,23 +575,19 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         let Some(dbg_loc) = self.dbg_loc(var.source_info) else { continue };
 
                         let operand = self.eval_mir_constant_to_operand(bx, &c);
-                        self.set_debug_loc(bx, var.source_info);
-                        let base =
-                            Self::spill_operand_to_stack(operand, Some(var.name.to_string()), bx);
-                        bx.clear_dbg_loc();
-
-                        bx.dbg_var_addr(
+                        constants.push(ConstDebugInfo {
+                            name: var.name.to_string(),
+                            source_info: var.source_info,
+                            operand,
                             dbg_var,
                             dbg_loc,
-                            base.val.llval,
-                            Size::ZERO,
-                            &[],
                             fragment,
-                        );
+                            _phantom: PhantomData,
+                        });
                     }
                 }
             }
         }
-        Some(per_local)
+        Some((per_local, constants))
     }
 }

compiler/rustc_codegen_ssa/src/mir/mod.rs

@@ -41,6 +41,9 @@ enum CachedLlbb<T> {
     Skip,
 }
 
+type PerLocalVarDebugInfoIndexVec<'tcx, V> =
+    IndexVec<mir::Local, Vec<PerLocalVarDebugInfo<'tcx, V>>>;
+
 /// Master context for codegenning from MIR.
 pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
     instance: Instance<'tcx>,
@@ -107,8 +110,7 @@ pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
 
     /// All `VarDebugInfo` from the MIR body, partitioned by `Local`.
     /// This is `None` if no variable debuginfo/names are needed.
-    per_local_var_debug_info:
-        Option<IndexVec<mir::Local, Vec<PerLocalVarDebugInfo<'tcx, Bx::DIVariable>>>>,
+    per_local_var_debug_info: Option<PerLocalVarDebugInfoIndexVec<'tcx, Bx::DIVariable>>,
 
     /// Caller location propagated if this function has `#[track_caller]`.
     caller_location: Option<OperandRef<'tcx, Bx::Value>>,
@@ -216,7 +218,9 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     // monomorphization, and if there is an error during collection then codegen never starts -- so
     // we don't have to do it again.
 
-    fx.per_local_var_debug_info = fx.compute_per_local_var_debug_info(&mut start_bx);
+    let (per_local_var_debug_info, consts_debug_info) =
+        fx.compute_per_local_var_debug_info(&mut start_bx).unzip();
+    fx.per_local_var_debug_info = per_local_var_debug_info;
 
     let traversal_order = traversal::mono_reachable_reverse_postorder(mir, cx.tcx(), instance);
     let memory_locals = analyze::non_ssa_locals(&fx, &traversal_order);
@@ -268,7 +272,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     fx.initialize_locals(local_values);
 
     // Apply debuginfo to the newly allocated locals.
-    fx.debug_introduce_locals(&mut start_bx);
+    fx.debug_introduce_locals(&mut start_bx, consts_debug_info.unwrap_or_default());
 
     // If the backend supports coverage, and coverage is enabled for this function,
     // do any necessary start-of-function codegen (e.g. locals for MC/DC bitmaps).

compiler/rustc_const_eval/src/check_consts/check.rs

@@ -317,7 +317,6 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
         {
             self.error_emitted = Some(guar);
         }
-        self.check_op_spanned(ops::StaticAccess, span)
     }
 
     /// Returns whether this place can possibly escape the evaluation of the current const/static

compiler/rustc_const_eval/src/check_consts/ops.rs

@@ -16,7 +16,6 @@ use rustc_middle::ty::{
     suggest_constraining_type_param,
 };
 use rustc_middle::util::{CallDesugaringKind, CallKind, call_kind};
-use rustc_session::parse::feature_err;
 use rustc_span::symbol::sym;
 use rustc_span::{BytePos, Pos, Span, Symbol};
 use rustc_trait_selection::traits::SelectionContext;
@@ -477,33 +476,6 @@ impl<'tcx> NonConstOp<'tcx> for RawPtrToIntCast {
     }
 }
 
-/// An access to a (non-thread-local) `static`.
-#[derive(Debug)]
-pub(crate) struct StaticAccess;
-impl<'tcx> NonConstOp<'tcx> for StaticAccess {
-    fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
-        if let hir::ConstContext::Static(_) = ccx.const_kind() {
-            Status::Allowed
-        } else {
-            Status::Unstable(sym::const_refs_to_static)
-        }
-    }
-
-    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
-    fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
-        let mut err = feature_err(
-            &ccx.tcx.sess,
-            sym::const_refs_to_static,
-            span,
-            format!("referencing statics in {}s is unstable", ccx.const_kind(),),
-        );
-        err
-            .note("`static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.")
-            .help("to fix this, the value can be extracted to a `const` and then used.");
-        err
-    }
-}
-
 /// An access to a thread-local `static`.
 #[derive(Debug)]
 pub(crate) struct ThreadLocalAccess;

compiler/rustc_error_codes/src/error_codes/E0013.md

@@ -5,7 +5,7 @@ variable cannot refer to a static variable.
 
 Erroneous code example:
 
-```compile_fail,E0658
+```
 static X: i32 = 42;
 const Y: i32 = X;
 ```

compiler/rustc_feature/src/accepted.rs

@@ -151,6 +151,8 @@ declare_features! (
     (accepted, const_raw_ptr_deref, "1.58.0", Some(51911)),
     /// Allows references to types with interior mutability within constants
     (accepted, const_refs_to_cell, "CURRENT_RUSTC_VERSION", Some(80384)),
+    /// Allows creating pointers and references to `static` items in constants.
+    (accepted, const_refs_to_static, "CURRENT_RUSTC_VERSION", Some(119618)),
     /// Allows implementing `Copy` for closures where possible (RFC 2132).
     (accepted, copy_closures, "1.26.0", Some(44490)),
     /// Allows `crate` in paths.

compiler/rustc_feature/src/unstable.rs

@@ -407,8 +407,6 @@ declare_features! (
     (unstable, const_for, "1.56.0", Some(87575)),
     /// Be more precise when looking for live drops in a const context.
     (unstable, const_precise_live_drops, "1.46.0", Some(73255)),
-    /// Allows creating pointers and references to `static` items in constants.
-    (unstable, const_refs_to_static, "1.78.0", Some(119618)),
     /// Allows `impl const Trait for T` syntax.
     (unstable, const_trait_impl, "1.42.0", Some(67792)),
     /// Allows the `?` operator in const contexts.

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1622,56 +1622,63 @@ impl<'a> CrateMetadataRef<'a> {
             );
 
             for virtual_dir in virtual_rust_source_base_dir.iter().flatten() {
-                if let Some(real_dir) = &sess.opts.real_rust_source_base_dir {
-                    if let rustc_span::FileName::Real(old_name) = name {
-                        if let rustc_span::RealFileName::Remapped { local_path: _, virtual_name } =
-                            old_name
-                        {
-                            if let Ok(rest) = virtual_name.strip_prefix(virtual_dir) {
-                                let virtual_name = virtual_name.clone();
-
-                                // The std library crates are in
-                                // `$sysroot/lib/rustlib/src/rust/library`, whereas other crates
-                                // may be in `$sysroot/lib/rustlib/src/rust/` directly. So we
-                                // detect crates from the std libs and handle them specially.
-                                const STD_LIBS: &[&str] = &[
-                                    "core",
-                                    "alloc",
-                                    "std",
-                                    "test",
-                                    "term",
-                                    "unwind",
-                                    "proc_macro",
-                                    "panic_abort",
-                                    "panic_unwind",
-                                    "profiler_builtins",
-                                    "rtstartup",
-                                    "rustc-std-workspace-core",
-                                    "rustc-std-workspace-alloc",
-                                    "rustc-std-workspace-std",
-                                    "backtrace",
-                                ];
-                                let is_std_lib = STD_LIBS.iter().any(|l| rest.starts_with(l));
-
-                                let new_path = if is_std_lib {
-                                    real_dir.join("library").join(rest)
-                                } else {
-                                    real_dir.join(rest)
-                                };
-
-                                debug!(
-                                    "try_to_translate_virtual_to_real: `{}` -> `{}`",
-                                    virtual_name.display(),
-                                    new_path.display(),
-                                );
-                                let new_name = rustc_span::RealFileName::Remapped {
-                                    local_path: Some(new_path),
-                                    virtual_name,
-                                };
-                                *old_name = new_name;
-                            }
+                if let Some(real_dir) = &sess.opts.real_rust_source_base_dir
+                    && let rustc_span::FileName::Real(old_name) = name
+                    && let rustc_span::RealFileName::Remapped { local_path: _, virtual_name } =
+                        old_name
+                    && let Ok(rest) = virtual_name.strip_prefix(virtual_dir)
+                {
+                    // The std library crates are in
+                    // `$sysroot/lib/rustlib/src/rust/library`, whereas other crates
+                    // may be in `$sysroot/lib/rustlib/src/rust/` directly. So we
+                    // detect crates from the std libs and handle them specially.
+                    const STD_LIBS: &[&str] = &[
+                        "core",
+                        "alloc",
+                        "std",
+                        "test",
+                        "term",
+                        "unwind",
+                        "proc_macro",
+                        "panic_abort",
+                        "panic_unwind",
+                        "profiler_builtins",
+                        "rtstartup",
+                        "rustc-std-workspace-core",
+                        "rustc-std-workspace-alloc",
+                        "rustc-std-workspace-std",
+                        "backtrace",
+                    ];
+                    let is_std_lib = STD_LIBS.iter().any(|l| rest.starts_with(l));
+
+                    let new_path = if is_std_lib {
+                        real_dir.join("library").join(rest)
+                    } else {
+                        real_dir.join(rest)
+                    };
+
+                    debug!(
+                        "try_to_translate_virtual_to_real: `{}` -> `{}`",
+                        virtual_name.display(),
+                        new_path.display(),
+                    );
+
+                    // Check if the translated real path is affected by any user-requested
+                    // remaps via --remap-path-prefix. Apply them if so.
+                    // Note that this is a special case for imported rust-src paths specified by
+                    // https://rust-lang.github.io/rfcs/3127-trim-paths.html#handling-sysroot-paths.
+                    // Other imported paths are not currently remapped (see #66251).
+                    let (user_remapped, applied) =
+                        sess.source_map().path_mapping().map_prefix(&new_path);
+                    let new_name = if applied {
+                        rustc_span::RealFileName::Remapped {
+                            local_path: Some(new_path.clone()),
+                            virtual_name: user_remapped.to_path_buf(),
                         }
-                    }
+                    } else {
+                        rustc_span::RealFileName::LocalPath(new_path)
+                    };
+                    *old_name = new_name;
                 }
             }
         };

library/core/src/str/lossy.rs

@@ -8,6 +8,8 @@ impl [u8] {
     /// Creates an iterator over the contiguous valid UTF-8 ranges of this
     /// slice, and the non-UTF-8 fragments in between.
     ///
+    /// See the [`Utf8Chunk`] type for documenation of the items yielded by this iterator.
+    ///
     /// # Examples
     ///
     /// This function formats arbitrary but mostly-UTF-8 bytes into Rust source
@@ -148,6 +150,8 @@ impl fmt::Debug for Debug<'_> {
 /// If you want a simple conversion from UTF-8 byte slices to string slices,
 /// [`from_utf8`] is easier to use.
 ///
+/// See the [`Utf8Chunk`] type for documenation of the items yielded by this iterator.
+///
 /// [byteslice]: slice
 /// [`from_utf8`]: super::from_utf8
 ///

library/std/src/panicking.rs

@@ -23,8 +23,8 @@ use crate::mem::{self, ManuallyDrop};
 use crate::panic::{BacktraceStyle, PanicHookInfo};
 use crate::sync::atomic::{AtomicBool, Ordering};
 use crate::sync::{PoisonError, RwLock};
+use crate::sys::backtrace;
 use crate::sys::stdio::panic_output;
-use crate::sys::{backtrace, dbg};
 use crate::{fmt, intrinsics, process, thread};
 
 // Binary interface to the panic runtime that the standard library depends on.
@@ -859,29 +859,13 @@ pub fn rust_panic_without_hook(payload: Box<dyn Any + Send>) -> ! {
 #[cfg_attr(not(test), rustc_std_internal_symbol)]
 #[cfg(not(feature = "panic_immediate_abort"))]
 fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
-    // Break into the debugger if it is attached.
-    // The return value is not currently used.
-    //
-    // This function isn't used anywhere else, and
-    // using inside `#[panic_handler]` doesn't seem
-    // to count, so a warning is issued.
-    let _ = dbg::breakpoint_if_debugging();
-
     let code = unsafe { __rust_start_panic(msg) };
     rtabort!("failed to initiate panic, error {code}")
 }
 
 #[cfg_attr(not(test), rustc_std_internal_symbol)]
 #[cfg(feature = "panic_immediate_abort")]
 fn rust_panic(_: &mut dyn PanicPayload) -> ! {
-    // Break into the debugger if it is attached.
-    // The return value is not currently used.
-    //
-    // This function isn't used anywhere else, and
-    // using inside `#[panic_handler]` doesn't seem
-    // to count, so a warning is issued.
-    let _ = dbg::breakpoint_if_debugging();
-
     unsafe {
         crate::intrinsics::abort();
     }