Auto merge of #82443 - Dylan-DPC:rollup-yni7uio, r=Dylan-DPC

Rollup of 10 pull requests

Successful merges:

 - #81629 (Point out implicit deref coercions in borrow)
 - #82113 (Improve non_fmt_panic lint.)
 - #82258 (Implement -Z hir-stats for nested foreign items)
 - #82296 (Support `pub` on `macro_rules`)
 - #82297 (Consider auto derefs before warning about write only fields)
 - #82305 (Remove many RefCells from DocContext)
 - #82308 (Lower condition of `if` expression before it's "then" block)
 - #82311 (Jsondocck improvements)
 - #82362 (Fix mir-cfg dumps)
 - #82391 (disable atomic_max/min tests in Miri)

Failed merges:

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

Author: bors

compiler/rustc_ast_lowering/src/expr.rs

@@ -347,8 +347,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> hir::ExprKind<'hir> {
         macro_rules! make_if {
             ($opt:expr) => {{
+                let cond = self.lower_expr(cond);
                 let then_expr = self.lower_block_expr(then);
-                hir::ExprKind::If(self.lower_expr(cond), self.arena.alloc(then_expr), $opt)
+                hir::ExprKind::If(cond, self.arena.alloc(then_expr), $opt)
             }};
         }
         if let Some(rslt) = else_opt {

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -665,6 +665,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
         // involved, so we only emit errors where there are no other parsing errors.
         gate_all!(destructuring_assignment, "destructuring assignments are unstable");
     }
+    gate_all!(pub_macro_rules, "`pub` on `macro_rules` items is unstable");
 
     // All uses of `gate_all!` below this point were added in #65742,
     // and subsequently disabled (with the non-early gating readded).

compiler/rustc_feature/src/active.rs

@@ -638,6 +638,9 @@ declare_features! (
     /// Allows macro attributes to observe output of `#[derive]`.
     (active, macro_attributes_in_derive_output, "1.51.0", Some(81119), None),
 
+    /// Allows `pub` on `macro_rules` items.
+    (active, pub_macro_rules, "1.52.0", Some(78855), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------

compiler/rustc_lint/src/non_fmt_panic.rs

@@ -69,23 +69,65 @@ fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tc
 
     let (span, panic) = panic_call(cx, f);
 
-    cx.struct_span_lint(NON_FMT_PANIC, arg.span, |lint| {
+    // Find the span of the argument to `panic!()`, before expansion in the
+    // case of `panic!(some_macro!())`.
+    // We don't use source_callsite(), because this `panic!(..)` might itself
+    // be expanded from another macro, in which case we want to stop at that
+    // expansion.
+    let mut arg_span = arg.span;
+    let mut arg_macro = None;
+    while !span.contains(arg_span) {
+        let expn = arg_span.ctxt().outer_expn_data();
+        if expn.is_root() {
+            break;
+        }
+        arg_macro = expn.macro_def_id;
+        arg_span = expn.call_site;
+    }
+
+    cx.struct_span_lint(NON_FMT_PANIC, arg_span, |lint| {
         let mut l = lint.build("panic message is not a string literal");
         l.note("this is no longer accepted in Rust 2021");
-        if span.contains(arg.span) {
+        if !span.contains(arg_span) {
+            // No clue where this argument is coming from.
+            l.emit();
+            return;
+        }
+        if arg_macro.map_or(false, |id| cx.tcx.is_diagnostic_item(sym::format_macro, id)) {
+            // A case of `panic!(format!(..))`.
+            l.note("the panic!() macro supports formatting, so there's no need for the format!() macro here");
+            if let Some((open, close, _)) = find_delimiters(cx, arg_span) {
+                l.multipart_suggestion(
+                    "remove the `format!(..)` macro call",
+                    vec![
+                        (arg_span.until(open.shrink_to_hi()), "".into()),
+                        (close.until(arg_span.shrink_to_hi()), "".into()),
+                    ],
+                    Applicability::MachineApplicable,
+                );
+            }
+        } else {
             l.span_suggestion_verbose(
-                arg.span.shrink_to_lo(),
+                arg_span.shrink_to_lo(),
                 "add a \"{}\" format string to Display the message",
                 "\"{}\", ".into(),
                 Applicability::MaybeIncorrect,
             );
             if panic == sym::std_panic_macro {
-                l.span_suggestion_verbose(
-                    span.until(arg.span),
-                    "or use std::panic::panic_any instead",
-                    "std::panic::panic_any(".into(),
-                    Applicability::MachineApplicable,
-                );
+                if let Some((open, close, del)) = find_delimiters(cx, span) {
+                    l.multipart_suggestion(
+                        "or use std::panic::panic_any instead",
+                        if del == '(' {
+                            vec![(span.until(open), "std::panic::panic_any".into())]
+                        } else {
+                            vec![
+                                (span.until(open.shrink_to_hi()), "std::panic::panic_any(".into()),
+                                (close, ")".into()),
+                            ]
+                        },
+                        Applicability::MachineApplicable,
+                    );
+                }
             }
         }
         l.emit();
@@ -175,6 +217,19 @@ fn check_panic_str<'tcx>(
     }
 }
 
+/// Given the span of `some_macro!(args);`, gives the span of `(` and `)`,
+/// and the type of (opening) delimiter used.
+fn find_delimiters<'tcx>(cx: &LateContext<'tcx>, span: Span) -> Option<(Span, Span, char)> {
+    let snippet = cx.sess().parse_sess.source_map().span_to_snippet(span).ok()?;
+    let (open, open_ch) = snippet.char_indices().find(|&(_, c)| "([{".contains(c))?;
+    let close = snippet.rfind(|c| ")]}".contains(c))?;
+    Some((
+        span.from_inner(InnerSpan { start: open, end: open + 1 }),
+        span.from_inner(InnerSpan { start: close, end: close + 1 }),
+        open_ch,
+    ))
+}
+
 fn panic_call<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>) -> (Span, Symbol) {
     let mut expn = f.span.ctxt().outer_expn_data();
 

compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs

@@ -8,11 +8,10 @@ use rustc_index::vec::Idx;
 use rustc_middle::mir::{
     self, AggregateKind, BindingForm, BorrowKind, ClearCrossCrate, ConstraintCategory,
     FakeReadCause, Local, LocalDecl, LocalInfo, LocalKind, Location, Operand, Place, PlaceRef,
-    ProjectionElem, Rvalue, Statement, StatementKind, TerminatorKind, VarBindingForm,
+    ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind, VarBindingForm,
 };
-use rustc_middle::ty::{self, suggest_constraining_type_param, Ty};
-use rustc_span::source_map::DesugaringKind;
-use rustc_span::Span;
+use rustc_middle::ty::{self, suggest_constraining_type_param, Instance, Ty};
+use rustc_span::{source_map::DesugaringKind, symbol::sym, Span};
 
 use crate::dataflow::drop_flag_effects;
 use crate::dataflow::indexes::{MoveOutIndex, MovePathIndex};
@@ -1543,9 +1542,43 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             None,
         );
 
+        self.explain_deref_coercion(loan, &mut err);
+
         err.buffer(&mut self.errors_buffer);
     }
 
+    fn explain_deref_coercion(&mut self, loan: &BorrowData<'tcx>, err: &mut DiagnosticBuilder<'_>) {
+        let tcx = self.infcx.tcx;
+        if let (
+            Some(Terminator { kind: TerminatorKind::Call { from_hir_call: false, .. }, .. }),
+            Some((method_did, method_substs)),
+        ) = (
+            &self.body[loan.reserve_location.block].terminator,
+            crate::util::find_self_call(
+                tcx,
+                self.body,
+                loan.assigned_place.local,
+                loan.reserve_location.block,
+            ),
+        ) {
+            if tcx.is_diagnostic_item(sym::deref_method, method_did) {
+                let deref_target =
+                    tcx.get_diagnostic_item(sym::deref_target).and_then(|deref_target| {
+                        Instance::resolve(tcx, self.param_env, deref_target, method_substs)
+                            .transpose()
+                    });
+                if let Some(Ok(instance)) = deref_target {
+                    let deref_target_ty = instance.ty(tcx, self.param_env);
+                    err.note(&format!(
+                        "borrow occurs due to deref coercion to `{}`",
+                        deref_target_ty
+                    ));
+                    err.span_note(tcx.def_span(instance.def_id()), "deref defined here");
+                }
+            }
+        }
+    }
+
     /// Reports an illegal reassignment; for example, an assignment to
     /// (part of) a non-`mut` local that occurs potentially after that
     /// local has already been initialized. `place` is the path being

compiler/rustc_mir/src/util/graphviz.rs

@@ -2,7 +2,7 @@ use gsgdt::GraphvizSettings;
 use rustc_graphviz as dot;
 use rustc_hir::def_id::DefId;
 use rustc_middle::mir::*;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{self, TyCtxt};
 use std::fmt::Debug;
 use std::io::{self, Write};
 
@@ -16,14 +16,27 @@ where
 {
     let def_ids = dump_mir_def_ids(tcx, single);
 
-    let use_subgraphs = def_ids.len() > 1;
+    let mirs =
+        def_ids
+            .iter()
+            .flat_map(|def_id| {
+                if tcx.is_const_fn_raw(*def_id) {
+                    vec![tcx.optimized_mir(*def_id), tcx.mir_for_ctfe(*def_id)]
+                } else {
+                    vec![tcx.instance_mir(ty::InstanceDef::Item(ty::WithOptConstParam::unknown(
+                        *def_id,
+                    )))]
+                }
+            })
+            .collect::<Vec<_>>();
+
+    let use_subgraphs = mirs.len() > 1;
     if use_subgraphs {
         writeln!(w, "digraph __crate__ {{")?;
     }
 
-    for def_id in def_ids {
-        let body = &tcx.optimized_mir(def_id);
-        write_mir_fn_graphviz(tcx, body, use_subgraphs, w)?;
+    for mir in mirs {
+        write_mir_fn_graphviz(tcx, mir, use_subgraphs, w)?;
     }
 
     if use_subgraphs {

compiler/rustc_parse/src/parser/item.rs

@@ -1475,15 +1475,7 @@ impl<'a> Parser<'a> {
         let vstr = pprust::vis_to_string(vis);
         let vstr = vstr.trim_end();
         if macro_rules {
-            let msg = format!("can't qualify macro_rules invocation with `{}`", vstr);
-            self.struct_span_err(vis.span, &msg)
-                .span_suggestion(
-                    vis.span,
-                    "try exporting the macro",
-                    "#[macro_export]".to_owned(),
-                    Applicability::MaybeIncorrect, // speculative
-                )
-                .emit();
+            self.sess.gated_spans.gate(sym::pub_macro_rules, vis.span);
         } else {
             self.struct_span_err(vis.span, "can't qualify macro invocation with `pub`")
                 .span_suggestion(

compiler/rustc_passes/src/dead.rs

@@ -37,15 +37,6 @@ fn should_explore(tcx: TyCtxt<'_>, hir_id: hir::HirId) -> bool {
     )
 }
 
-fn base_expr<'a>(mut expr: &'a hir::Expr<'a>) -> &'a hir::Expr<'a> {
-    loop {
-        match expr.kind {
-            hir::ExprKind::Field(base, ..) => expr = base,
-            _ => return expr,
-        }
-    }
-}
-
 struct MarkSymbolVisitor<'tcx> {
     worklist: Vec<hir::HirId>,
     tcx: TyCtxt<'tcx>,
@@ -143,6 +134,22 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
         }
     }
 
+    fn handle_assign(&mut self, expr: &'tcx hir::Expr<'tcx>) {
+        if self
+            .typeck_results()
+            .expr_adjustments(expr)
+            .iter()
+            .any(|adj| matches!(adj.kind, ty::adjustment::Adjust::Deref(_)))
+        {
+            self.visit_expr(expr);
+        } else if let hir::ExprKind::Field(base, ..) = expr.kind {
+            // Ignore write to field
+            self.handle_assign(base);
+        } else {
+            self.visit_expr(expr);
+        }
+    }
+
     fn handle_field_pattern_match(
         &mut self,
         lhs: &hir::Pat<'_>,
@@ -272,8 +279,7 @@ impl<'tcx> Visitor<'tcx> for MarkSymbolVisitor<'tcx> {
                 self.lookup_and_handle_method(expr.hir_id);
             }
             hir::ExprKind::Assign(ref left, ref right, ..) => {
-                // Ignore write to field
-                self.visit_expr(base_expr(left));
+                self.handle_assign(left);
                 self.visit_expr(right);
                 return;
             }

compiler/rustc_passes/src/hir_stats.rs

@@ -114,6 +114,11 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> {
         self.visit_impl_item(nested_impl_item)
     }
 
+    fn visit_nested_foreign_item(&mut self, id: hir::ForeignItemId) {
+        let nested_foreign_item = self.krate.unwrap().foreign_item(id);
+        self.visit_foreign_item(nested_foreign_item);
+    }
+
     fn visit_nested_body(&mut self, body_id: hir::BodyId) {
         let nested_body = self.krate.unwrap().body(body_id);
         self.visit_body(nested_body)

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -1230,13 +1230,13 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
         };
 
         let res = Res::Def(DefKind::Macro(ext.macro_kind()), def_id.to_def_id());
+        let is_macro_export = self.r.session.contains_name(&item.attrs, sym::macro_export);
         self.r.macro_map.insert(def_id.to_def_id(), ext);
         self.r.local_macro_def_scopes.insert(def_id, parent_scope.module);
 
-        if macro_rules {
+        if macro_rules && matches!(item.vis.kind, ast::VisibilityKind::Inherited) {
             let ident = ident.normalize_to_macros_2_0();
             self.r.macro_names.insert(ident);
-            let is_macro_export = self.r.session.contains_name(&item.attrs, sym::macro_export);
             let vis = if is_macro_export {
                 ty::Visibility::Public
             } else {
@@ -1261,6 +1261,11 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                 }),
             ))
         } else {
+            if is_macro_export {
+                let what = if macro_rules { "`macro_rules` with `pub`" } else { "`macro` items" };
+                let msg = format!("`#[macro_export]` cannot be used on {what}");
+                self.r.session.span_err(item.span, &msg);
+            }
             let module = parent_scope.module;
             let vis = match item.kind {
                 // Visibilities must not be resolved non-speculatively twice