Auto merge of #66924 - Centril:rollup-r7pljxh, r=Centril

Rollup of 7 pull requests

Successful merges:

 - #66346 (Replace .unwrap() with ? in std::os::unix::net)
 - #66789 (rustc: move mir::SourceScopeLocalData to a field of SourceScopeData.)
 - #66822 (libunwind_panic: adjust miri panic hack)
 - #66827 (handle diverging functions forwarding their return place)
 - #66828 (Less minification)
 - #66850 (rustc: hide HirId's fmt::Debug output from -Z span_free_formats.)
 - #66907 (rustc: don't just show raw DefIndex's in BrNamed's fmt::Debug impl.)

Failed merges:

 - #66874 (Miri engine: proper support for `Assert` MIR terminators)

r? @ghost

Author: bors

src/libcore/intrinsics.rs

@@ -1348,9 +1348,11 @@ extern "rust-intrinsic" {
     pub fn ptr_offset_from<T>(ptr: *const T, base: *const T) -> isize;
 
     /// Internal hook used by Miri to implement unwinding.
+    /// Compiles to a NOP during non-Miri codegen.
+    ///
     /// Perma-unstable: do not use
     #[cfg(not(bootstrap))]
-    pub fn miri_start_panic(data: *mut (dyn crate::any::Any + crate::marker::Send)) -> !;
+    pub fn miri_start_panic(data: *mut (dyn crate::any::Any + crate::marker::Send)) -> ();
 }
 
 // Some functions are defined here because they accidentally got made

src/libpanic_unwind/lib.rs

@@ -36,10 +36,7 @@ use core::raw;
 use core::panic::BoxMeUp;
 
 cfg_if::cfg_if! {
-    if #[cfg(miri)] {
-        #[path = "miri.rs"]
-        mod imp;
-    } else if #[cfg(target_os = "emscripten")] {
+    if #[cfg(target_os = "emscripten")] {
         #[path = "emcc.rs"]
         mod imp;
     } else if #[cfg(target_arch = "wasm32")] {
@@ -94,5 +91,14 @@ pub unsafe extern "C" fn __rust_maybe_catch_panic(f: fn(*mut u8),
 #[unwind(allowed)]
 pub unsafe extern "C" fn __rust_start_panic(payload: usize) -> u32 {
     let payload = payload as *mut &mut dyn BoxMeUp;
-    imp::panic(Box::from_raw((*payload).take_box()))
+    let payload = (*payload).take_box();
+
+    // Miri panic support: cfg'd out of normal builds just to be sure.
+    // When going through normal codegen, `miri_start_panic` is a NOP, so the
+    // Miri-enabled sysroot still supports normal unwinding. But when executed in
+    // Miri, this line initiates unwinding.
+    #[cfg(miri)]
+    core::intrinsics::miri_start_panic(payload);
+
+    imp::panic(Box::from_raw(payload))
 }

src/libpanic_unwind/miri.rs

@@ -104,10 +104,6 @@ pub struct Body<'tcx> {
     /// and used for debuginfo. Indexed by a `SourceScope`.
     pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
 
-    /// Crate-local information for each source scope, that can't (and
-    /// needn't) be tracked across crates.
-    pub source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
-
     /// The yield type of the function, if it is a generator.
     pub yield_ty: Option<Ty<'tcx>>,
 
@@ -167,7 +163,6 @@ impl<'tcx> Body<'tcx> {
     pub fn new(
         basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
         source_scopes: IndexVec<SourceScope, SourceScopeData>,
-        source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
         local_decls: LocalDecls<'tcx>,
         user_type_annotations: CanonicalUserTypeAnnotations<'tcx>,
         arg_count: usize,
@@ -188,7 +183,6 @@ impl<'tcx> Body<'tcx> {
             phase: MirPhase::Build,
             basic_blocks,
             source_scopes,
-            source_scope_local_data,
             yield_ty: None,
             generator_drop: None,
             generator_layout: None,
@@ -435,6 +429,13 @@ pub enum ClearCrossCrate<T> {
 }
 
 impl<T> ClearCrossCrate<T> {
+    pub fn as_ref(&'a self) -> ClearCrossCrate<&'a T> {
+        match self {
+            ClearCrossCrate::Clear => ClearCrossCrate::Clear,
+            ClearCrossCrate::Set(v) => ClearCrossCrate::Set(v),
+        }
+    }
+
     pub fn assert_crate_local(self) -> T {
         match self {
             ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
@@ -2027,6 +2028,10 @@ rustc_index::newtype_index! {
 pub struct SourceScopeData {
     pub span: Span,
     pub parent_scope: Option<SourceScope>,
+
+    /// Crate-local information for this source scope, that can't (and
+    /// needn't) be tracked across crates.
+    pub local_data: ClearCrossCrate<SourceScopeLocalData>,
 }
 
 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
@@ -2308,10 +2313,14 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                         }
                     }
 
-                    AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
+                    AggregateKind::Closure(def_id, substs) => ty::tls::with(|tcx| {
                         if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) {
                             let name = if tcx.sess.opts.debugging_opts.span_free_formats {
-                                format!("[closure@{:?}]", hir_id)
+                                let substs = tcx.lift(&substs).unwrap();
+                                format!(
+                                    "[closure@{}]",
+                                    tcx.def_path_str_with_substs(def_id, substs),
+                                )
                             } else {
                                 format!("[closure@{:?}]", tcx.hir().span(hir_id))
                             };

src/librustc/mir/mod.rs

@@ -317,6 +317,7 @@ macro_rules! make_mir_visitor {
                 let SourceScopeData {
                     span,
                     parent_scope,
+                    local_data: _,
                 } = scope_data;
 
                 self.visit_span(span);

src/librustc/mir/visit.rs

@@ -682,7 +682,7 @@ pub trait PrettyPrinter<'tcx>:
                 // FIXME(eddyb) should use `def_span`.
                 if let Some(hir_id) = self.tcx().hir().as_local_hir_id(did) {
                     if self.tcx().sess.opts.debugging_opts.span_free_formats {
-                        p!(write("@{:?}", hir_id));
+                        p!(write("@"), print_def_path(did, substs));
                     } else {
                         p!(write("@{:?}", self.tcx().hir().span(hir_id)));
                     }

src/librustc/ty/print/pretty.rs

@@ -3,6 +3,7 @@
 //! hand, though we've recently added some macros and proc-macros to help with the tedium.
 
 use crate::hir::def::Namespace;
+use crate::hir::def_id::CRATE_DEF_INDEX;
 use crate::mir::ProjectionKind;
 use crate::mir::interpret;
 use crate::ty::{self, Lift, Ty, TyCtxt, InferConst};
@@ -95,8 +96,11 @@ impl fmt::Debug for ty::BoundRegion {
         match *self {
             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
             ty::BrNamed(did, name) => {
-                write!(f, "BrNamed({:?}:{:?}, {})",
-                        did.krate, did.index, name)
+                if did.index == CRATE_DEF_INDEX {
+                    write!(f, "BrNamed({})", name)
+                } else {
+                    write!(f, "BrNamed({:?}, {})", did, name)
+                }
             }
             ty::BrEnv => write!(f, "BrEnv"),
         }

src/librustc/ty/structural_impls.rs

@@ -528,18 +528,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             _ => FnAbi::new(&bx, sig, &extra_args)
         };
 
-        // This should never be reachable at runtime:
-        // We should only emit a call to this intrinsic in #[cfg(miri)] mode,
-        // which means that we will never actually use the generate object files
-        // (we will just be interpreting the MIR)
-        //
-        // Note that we still need to be able to codegen *something* for this intrisnic:
-        // Miri currently uses Xargo to build a special libstd. As a side effect,
-        // we generate normal object files for libstd - while these are never used,
-        // we still need to be able to build them.
+        // For normal codegen, this Miri-specific intrinsic is just a NOP.
         if intrinsic == Some("miri_start_panic") {
-            bx.abort();
-            bx.unreachable();
+            let target = destination.as_ref().unwrap().1;
+            helper.maybe_sideeffect(self.mir, &mut bx, &[target]);
+            helper.funclet_br(self, &mut bx, target);
             return;
         }
 

src/librustc_codegen_ssa/mir/block.rs

@@ -300,11 +300,10 @@ fn do_mir_borrowck<'a, 'tcx>(
         let mut initial_diag =
             mbcx.report_conflicting_borrow(location, (&place, span), bk, &borrow);
 
-        let lint_root = if let ClearCrossCrate::Set(ref vsi) = mbcx.body.source_scope_local_data {
-            let scope = mbcx.body.source_info(location).scope;
-            vsi[scope].lint_root
-        } else {
-            id
+        let scope = mbcx.body.source_info(location).scope;
+        let lint_root = match &mbcx.body.source_scopes[scope].local_data {
+            ClearCrossCrate::Set(data) => data.lint_root,
+            _ => id,
         };
 
         // Span and message don't matter; we overwrite them below anyway
@@ -338,38 +337,40 @@ fn do_mir_borrowck<'a, 'tcx>(
     debug!("mbcx.used_mut: {:?}", mbcx.used_mut);
     let used_mut = mbcx.used_mut;
     for local in mbcx.body.mut_vars_and_args_iter().filter(|local| !used_mut.contains(local)) {
-        if let ClearCrossCrate::Set(ref vsi) = mbcx.body.source_scope_local_data {
-            let local_decl = &mbcx.body.local_decls[local];
-
-            // Skip over locals that begin with an underscore or have no name
-            match mbcx.local_names[local] {
-                Some(name) => if name.as_str().starts_with("_") {
-                    continue;
-                },
-                None => continue,
-            }
+        let local_decl = &mbcx.body.local_decls[local];
+        let lint_root = match &mbcx.body.source_scopes[local_decl.source_info.scope].local_data {
+            ClearCrossCrate::Set(data) => data.lint_root,
+            _ => continue,
+        };
 
-            let span = local_decl.source_info.span;
-            if span.desugaring_kind().is_some() {
-                // If the `mut` arises as part of a desugaring, we should ignore it.
+        // Skip over locals that begin with an underscore or have no name
+        match mbcx.local_names[local] {
+            Some(name) => if name.as_str().starts_with("_") {
                 continue;
-            }
+            },
+            None => continue,
+        }
 
-            let mut_span = tcx.sess.source_map().span_until_non_whitespace(span);
-            tcx.struct_span_lint_hir(
-                UNUSED_MUT,
-                vsi[local_decl.source_info.scope].lint_root,
-                span,
-                "variable does not need to be mutable",
-            )
-            .span_suggestion_short(
-                mut_span,
-                "remove this `mut`",
-                String::new(),
-                Applicability::MachineApplicable,
-            )
-            .emit();
+        let span = local_decl.source_info.span;
+        if span.desugaring_kind().is_some() {
+            // If the `mut` arises as part of a desugaring, we should ignore it.
+            continue;
         }
+
+        let mut_span = tcx.sess.source_map().span_until_non_whitespace(span);
+        tcx.struct_span_lint_hir(
+            UNUSED_MUT,
+            lint_root,
+            span,
+            "variable does not need to be mutable",
+        )
+        .span_suggestion_short(
+            mut_span,
+            "remove this `mut`",
+            String::new(),
+            Applicability::MachineApplicable,
+        )
+        .emit();
     }
 
     // Buffer any move errors that we collected and de-duplicated.

src/librustc_mir/borrow_check/mod.rs

@@ -309,7 +309,6 @@ struct Builder<'a, 'tcx> {
     /// The vector of all scopes that we have created thus far;
     /// we track this for debuginfo later.
     source_scopes: IndexVec<SourceScope, SourceScopeData>,
-    source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
     source_scope: SourceScope,
 
     /// The guard-context: each time we build the guard expression for
@@ -704,7 +703,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             block_context: BlockContext::new(),
             source_scopes: IndexVec::new(),
             source_scope: OUTERMOST_SOURCE_SCOPE,
-            source_scope_local_data: IndexVec::new(),
             guard_context: vec![],
             push_unsafe_count: 0,
             unpushed_unsafe: safety,
@@ -741,7 +739,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         Body::new(
             self.cfg.basic_blocks,
             self.source_scopes,
-            ClearCrossCrate::Set(self.source_scope_local_data),
             self.local_decls,
             self.canonical_user_type_annotations,
             self.arg_count,
@@ -942,7 +939,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             self.hir.root_lint_level
         );
         let parent_root = tcx.maybe_lint_level_root_bounded(
-            self.source_scope_local_data[original_source_scope].lint_root,
+            self.source_scopes[original_source_scope]
+                .local_data
+                .as_ref()
+                .assert_crate_local()
+                .lint_root,
             self.hir.root_lint_level,
         );
         if current_root != parent_root {