Rollup of 8 pull requests

compiler/rustc_attr/src/builtin.rs

@@ -1,8 +1,7 @@
 //! Parsing and validation of builtin attributes
 
 use rustc_ast as ast;
-use rustc_ast::node_id::CRATE_NODE_ID;
-use rustc_ast::{Attribute, Lit, LitKind, MetaItem, MetaItemKind, NestedMetaItem};
+use rustc_ast::{Attribute, Lit, LitKind, MetaItem, MetaItemKind, NestedMetaItem, NodeId};
 use rustc_ast_pretty::pprust;
 use rustc_errors::{struct_span_err, Applicability};
 use rustc_feature::{find_gated_cfg, is_builtin_attr_name, Features, GatedCfg};
@@ -436,7 +435,12 @@ pub fn find_crate_name(sess: &Session, attrs: &[Attribute]) -> Option<Symbol> {
 }
 
 /// Tests if a cfg-pattern matches the cfg set
-pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>) -> bool {
+pub fn cfg_matches(
+    cfg: &ast::MetaItem,
+    sess: &ParseSess,
+    lint_node_id: NodeId,
+    features: Option<&Features>,
+) -> bool {
     eval_condition(cfg, sess, features, &mut |cfg| {
         try_gate_cfg(cfg, sess, features);
         let error = |span, msg| {
@@ -470,7 +474,7 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
                         sess.buffer_lint_with_diagnostic(
                             UNEXPECTED_CFGS,
                             cfg.span,
-                            CRATE_NODE_ID,
+                            lint_node_id,
                             "unexpected `cfg` condition name",
                             BuiltinLintDiagnostics::UnexpectedCfg(ident.span, name, None),
                         );
@@ -482,7 +486,7 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
                             sess.buffer_lint_with_diagnostic(
                                 UNEXPECTED_CFGS,
                                 cfg.span,
-                                CRATE_NODE_ID,
+                                lint_node_id,
                                 "unexpected `cfg` condition value",
                                 BuiltinLintDiagnostics::UnexpectedCfg(
                                     cfg.name_value_literal_span().unwrap(),

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -5,16 +5,21 @@ use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::{AsyncGeneratorKind, GeneratorKind};
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_infer::traits::ObligationCause;
 use rustc_middle::mir::{
     self, AggregateKind, BindingForm, BorrowKind, ClearCrossCrate, ConstraintCategory,
     FakeReadCause, LocalDecl, LocalInfo, LocalKind, Location, Operand, Place, PlaceRef,
     ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind, VarBindingForm,
 };
-use rustc_middle::ty::{self, suggest_constraining_type_param, Ty};
+use rustc_middle::ty::{
+    self, suggest_constraining_type_param, suggest_constraining_type_params, PredicateKind, Ty,
+};
 use rustc_mir_dataflow::move_paths::{InitKind, MoveOutIndex, MovePathIndex};
 use rustc_span::symbol::sym;
 use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP};
 use rustc_trait_selection::infer::InferCtxtExt;
+use rustc_trait_selection::traits::TraitEngineExt as _;
 
 use crate::borrow_set::TwoPhaseActivation;
 use crate::borrowck_errors;
@@ -423,7 +428,63 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             None,
                         );
                     }
+                } else {
+                    // Try to find predicates on *generic params* that would allow copying `ty`
+
+                    let tcx = self.infcx.tcx;
+                    let generics = tcx.generics_of(self.mir_def_id());
+                    if let Some(hir_generics) = tcx
+                        .typeck_root_def_id(self.mir_def_id().to_def_id())
+                        .as_local()
+                        .and_then(|def_id| tcx.hir().get_generics(def_id))
+                    {
+                        let predicates: Result<Vec<_>, _> = tcx.infer_ctxt().enter(|infcx| {
+                            let mut fulfill_cx =
+                                <dyn rustc_infer::traits::TraitEngine<'_>>::new(infcx.tcx);
+
+                            let copy_did = infcx.tcx.lang_items().copy_trait().unwrap();
+                            let cause = ObligationCause::new(
+                                span,
+                                self.mir_hir_id(),
+                                rustc_infer::traits::ObligationCauseCode::MiscObligation,
+                            );
+                            fulfill_cx.register_bound(&infcx, self.param_env, ty, copy_did, cause);
+                            let errors = fulfill_cx.select_where_possible(&infcx);
+
+                            // Only emit suggestion if all required predicates are on generic
+                            errors
+                                .into_iter()
+                                .map(|err| match err.obligation.predicate.kind().skip_binder() {
+                                    PredicateKind::Trait(predicate) => {
+                                        match predicate.self_ty().kind() {
+                                            ty::Param(param_ty) => Ok((
+                                                generics.type_param(param_ty, tcx),
+                                                predicate
+                                                    .trait_ref
+                                                    .print_only_trait_path()
+                                                    .to_string(),
+                                            )),
+                                            _ => Err(()),
+                                        }
+                                    }
+                                    _ => Err(()),
+                                })
+                                .collect()
+                        });
+
+                        if let Ok(predicates) = predicates {
+                            suggest_constraining_type_params(
+                                tcx,
+                                hir_generics,
+                                &mut err,
+                                predicates.iter().map(|(param, constraint)| {
+                                    (param.name.as_str(), &**constraint, None)
+                                }),
+                            );
+                        }
+                    }
                 }
+
                 let span = if let Some(local) = place.as_local() {
                     let decl = &self.body.local_decls[local];
                     Some(decl.source_info.span)

compiler/rustc_builtin_macros/src/cfg.rs

@@ -19,7 +19,12 @@ pub fn expand_cfg(
 
     match parse_cfg(cx, sp, tts) {
         Ok(cfg) => {
-            let matches_cfg = attr::cfg_matches(&cfg, &cx.sess.parse_sess, cx.ecfg.features);
+            let matches_cfg = attr::cfg_matches(
+                &cfg,
+                &cx.sess.parse_sess,
+                cx.current_expansion.lint_node_id,
+                cx.ecfg.features,
+            );
             MacEager::expr(cx.expr_bool(sp, matches_cfg))
         }
         Err(mut err) => {

compiler/rustc_builtin_macros/src/cfg_eval.rs

@@ -5,6 +5,7 @@ use rustc_ast::mut_visit::MutVisitor;
 use rustc_ast::ptr::P;
 use rustc_ast::tokenstream::CanSynthesizeMissingTokens;
 use rustc_ast::visit::Visitor;
+use rustc_ast::NodeId;
 use rustc_ast::{mut_visit, visit};
 use rustc_ast::{AstLike, Attribute};
 use rustc_expand::base::{Annotatable, ExtCtxt};
@@ -26,15 +27,16 @@ crate fn expand(
 ) -> Vec<Annotatable> {
     check_builtin_macro_attribute(ecx, meta_item, sym::cfg_eval);
     warn_on_duplicate_attribute(&ecx, &annotatable, sym::cfg_eval);
-    vec![cfg_eval(ecx.sess, ecx.ecfg.features, annotatable)]
+    vec![cfg_eval(ecx.sess, ecx.ecfg.features, annotatable, ecx.current_expansion.lint_node_id)]
 }
 
 crate fn cfg_eval(
     sess: &Session,
     features: Option<&Features>,
     annotatable: Annotatable,
+    lint_node_id: NodeId,
 ) -> Annotatable {
-    CfgEval { cfg: &mut StripUnconfigured { sess, features, config_tokens: true } }
+    CfgEval { cfg: &mut StripUnconfigured { sess, features, config_tokens: true, lint_node_id } }
         .configure_annotatable(annotatable)
         // Since the item itself has already been configured by the `InvocationCollector`,
         // we know that fold result vector will contain exactly one element.

compiler/rustc_builtin_macros/src/derive.rs

@@ -64,7 +64,12 @@ impl MultiItemModifier for Expander {
                 match &mut resolutions[..] {
                     [] => {}
                     [(_, first_item, _), others @ ..] => {
-                        *first_item = cfg_eval(sess, features, item.clone());
+                        *first_item = cfg_eval(
+                            sess,
+                            features,
+                            item.clone(),
+                            ecx.current_expansion.lint_node_id,
+                        );
                         for (_, item, _) in others {
                             *item = first_item.clone();
                         }

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1,4 +1,5 @@
 use rustc_arena::TypedArena;
+use rustc_ast::CRATE_NODE_ID;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::temp_dir::MaybeTempDir;
@@ -2434,7 +2435,7 @@ fn add_upstream_native_libraries(
 
 fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool {
     match lib.cfg {
-        Some(ref cfg) => rustc_attr::cfg_matches(cfg, &sess.parse_sess, None),
+        Some(ref cfg) => rustc_attr::cfg_matches(cfg, &sess.parse_sess, CRATE_NODE_ID, None),
         None => true,
     }
 }

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -500,15 +500,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // `x % y != 0` or `y == 0` or `x == T::MIN && y == -1`.
         // First, check x % y != 0 (or if that computation overflows).
         let (res, overflow, _ty) = self.overflowing_binary_op(BinOp::Rem, &a, &b)?;
-        if overflow || res.assert_bits(a.layout.size) != 0 {
-            // Then, check if `b` is -1, which is the "MIN / -1" case.
-            let minus1 = Scalar::from_int(-1, dest.layout.size);
-            let b_scalar = b.to_scalar().unwrap();
-            if b_scalar == minus1 {
-                throw_ub_format!("exact_div: result of dividing MIN by -1 cannot be represented")
-            } else {
-                throw_ub_format!("exact_div: {} cannot be divided by {} without remainder", a, b,)
-            }
+        assert!(!overflow); // All overflow is UB, so this should never return on overflow.
+        if res.assert_bits(a.layout.size) != 0 {
+            throw_ub_format!("exact_div: {} cannot be divided by {} without remainder", a, b)
         }
         // `Rem` says this is all right, so we can let `Div` do its job.
         self.binop_ignore_overflow(BinOp::Div, &a, &b, dest)

compiler/rustc_const_eval/src/interpret/operator.rs

@@ -196,16 +196,20 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 _ => None,
             };
             if let Some(op) = op {
+                let l = self.sign_extend(l, left_layout) as i128;
                 let r = self.sign_extend(r, right_layout) as i128;
-                // We need a special check for overflowing remainder:
-                // "int_min % -1" overflows and returns 0, but after casting things to a larger int
-                // type it does *not* overflow nor give an unrepresentable result!
-                if bin_op == Rem {
-                    if r == -1 && l == (1 << (size.bits() - 1)) {
-                        return Ok((Scalar::from_int(0, size), true, left_layout.ty));
+
+                // We need a special check for overflowing Rem and Div since they are *UB*
+                // on overflow, which can happen with "int_min $OP -1".
+                if matches!(bin_op, Rem | Div) {
+                    if l == size.signed_int_min() && r == -1 {
+                        if bin_op == Rem {
+                            throw_ub!(RemainderOverflow)
+                        } else {
+                            throw_ub!(DivisionOverflow)
+                        }
                     }
                 }
-                let l = self.sign_extend(l, left_layout) as i128;
 
                 let (result, oflo) = op(l, r);
                 // This may be out-of-bounds for the result type, so we have to truncate ourselves.

compiler/rustc_expand/src/config.rs

@@ -5,6 +5,7 @@ use rustc_ast::token::{DelimToken, Token, TokenKind};
 use rustc_ast::tokenstream::{AttrAnnotatedTokenStream, AttrAnnotatedTokenTree};
 use rustc_ast::tokenstream::{DelimSpan, Spacing};
 use rustc_ast::tokenstream::{LazyTokenStream, TokenTree};
+use rustc_ast::NodeId;
 use rustc_ast::{self as ast, AstLike, AttrStyle, Attribute, MetaItem};
 use rustc_attr as attr;
 use rustc_data_structures::fx::FxHashMap;
@@ -29,6 +30,7 @@ pub struct StripUnconfigured<'a> {
     /// This is only used for the input to derive macros,
     /// which needs eager expansion of `cfg` and `cfg_attr`
     pub config_tokens: bool,
+    pub lint_node_id: NodeId,
 }
 
 fn get_features(
@@ -196,8 +198,13 @@ fn get_features(
 }
 
 // `cfg_attr`-process the crate's attributes and compute the crate's features.
-pub fn features(sess: &Session, mut krate: ast::Crate) -> (ast::Crate, Features) {
-    let mut strip_unconfigured = StripUnconfigured { sess, features: None, config_tokens: false };
+pub fn features(
+    sess: &Session,
+    mut krate: ast::Crate,
+    lint_node_id: NodeId,
+) -> (ast::Crate, Features) {
+    let mut strip_unconfigured =
+        StripUnconfigured { sess, features: None, config_tokens: false, lint_node_id };
 
     let unconfigured_attrs = krate.attrs.clone();
     let diag = &sess.parse_sess.span_diagnostic;
@@ -353,7 +360,12 @@ impl<'a> StripUnconfigured<'a> {
             );
         }
 
-        if !attr::cfg_matches(&cfg_predicate, &self.sess.parse_sess, self.features) {
+        if !attr::cfg_matches(
+            &cfg_predicate,
+            &self.sess.parse_sess,
+            self.lint_node_id,
+            self.features,
+        ) {
             return vec![];
         }
 
@@ -445,7 +457,7 @@ impl<'a> StripUnconfigured<'a> {
             }
         };
         parse_cfg(&meta_item, &self.sess).map_or(true, |meta_item| {
-            attr::cfg_matches(&meta_item, &self.sess.parse_sess, self.features)
+            attr::cfg_matches(&meta_item, &self.sess.parse_sess, self.lint_node_id, self.features)
         })
     }
 

compiler/rustc_expand/src/expand.rs

@@ -551,11 +551,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 // attribute is expanded. Therefore, we don't need to configure the tokens
                 // Derive macros *can* see the results of cfg-expansion - they are handled
                 // specially in `fully_expand_fragment`
-                cfg: StripUnconfigured {
-                    sess: &self.cx.sess,
-                    features: self.cx.ecfg.features,
-                    config_tokens: false,
-                },
                 cx: self.cx,
                 invocations: Vec::new(),
                 monotonic: self.monotonic,
@@ -1538,12 +1533,20 @@ impl InvocationCollectorNode for AstLikeWrapper<P<ast::Expr>, OptExprTag> {
 
 struct InvocationCollector<'a, 'b> {
     cx: &'a mut ExtCtxt<'b>,
-    cfg: StripUnconfigured<'a>,
     invocations: Vec<(Invocation, Option<Lrc<SyntaxExtension>>)>,
     monotonic: bool,
 }
 
 impl<'a, 'b> InvocationCollector<'a, 'b> {
+    fn cfg(&self) -> StripUnconfigured<'_> {
+        StripUnconfigured {
+            sess: &self.cx.sess,
+            features: self.cx.ecfg.features,
+            config_tokens: false,
+            lint_node_id: self.cx.current_expansion.lint_node_id,
+        }
+    }
+
     fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
         let expn_id = LocalExpnId::fresh_empty();
         let vis = kind.placeholder_visibility();
@@ -1683,7 +1686,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
         attr: ast::Attribute,
         pos: usize,
     ) -> bool {
-        let res = self.cfg.cfg_true(&attr);
+        let res = self.cfg().cfg_true(&attr);
         if res {
             // FIXME: `cfg(TRUE)` attributes do not currently remove themselves during expansion,
             // and some tools like rustdoc and clippy rely on that. Find a way to remove them
@@ -1696,7 +1699,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
 
     fn expand_cfg_attr(&self, node: &mut impl AstLike, attr: ast::Attribute, pos: usize) {
         node.visit_attrs(|attrs| {
-            attrs.splice(pos..pos, self.cfg.expand_cfg_attr(attr, false));
+            attrs.splice(pos..pos, self.cfg().expand_cfg_attr(attr, false));
         });
     }
 
@@ -1718,7 +1721,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                         continue;
                     }
                     _ => {
-                        Node::pre_flat_map_node_collect_attr(&self.cfg, &attr);
+                        Node::pre_flat_map_node_collect_attr(&self.cfg(), &attr);
                         self.collect_attr((attr, pos, derives), node.to_annotatable(), Node::KIND)
                             .make_ast::<Node>()
                     }
@@ -1882,7 +1885,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
     fn visit_expr(&mut self, node: &mut P<ast::Expr>) {
         // FIXME: Feature gating is performed inconsistently between `Expr` and `OptExpr`.
         if let Some(attr) = node.attrs.first() {
-            self.cfg.maybe_emit_expr_attr_err(attr);
+            self.cfg().maybe_emit_expr_attr_err(attr);
         }
         self.visit_node(node)
     }

compiler/rustc_interface/src/passes.rs

@@ -2,6 +2,7 @@ use crate::interface::{Compiler, Result};
 use crate::proc_macro_decls;
 use crate::util;
 
+use ast::CRATE_NODE_ID;
 use rustc_ast::mut_visit::MutVisitor;
 use rustc_ast::{self as ast, visit};
 use rustc_borrowck as mir_borrowck;
@@ -188,7 +189,7 @@ pub fn register_plugins<'a>(
         )
     });
 
-    let (krate, features) = rustc_expand::config::features(sess, krate);
+    let (krate, features) = rustc_expand::config::features(sess, krate, CRATE_NODE_ID);
     // these need to be set "early" so that expansion sees `quote` if enabled.
     sess.init_features(features);