Rollup of 9 pull requests

compiler/rustc_hir_typeck/src/coercion.rs

@@ -62,6 +62,7 @@ use rustc_span::{self, BytePos, DesugaringKind, Span};
 use rustc_target::spec::abi::Abi;
 use rustc_trait_selection::infer::InferCtxtExt as _;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
+use rustc_trait_selection::traits::TraitEngineExt as _;
 use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode};
 
 use smallvec::{smallvec, SmallVec};
@@ -1038,7 +1039,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let Ok(ok) = coerce.coerce(source, target) else {
                 return false;
             };
-            let mut fcx = traits::FulfillmentContext::new_in_snapshot();
+            let mut fcx = <dyn TraitEngine<'tcx>>::new_in_snapshot(self.tcx);
             fcx.register_predicate_obligations(self, ok.obligations);
             fcx.select_where_possible(&self).is_empty()
         })

compiler/rustc_hir_typeck/src/demand.rs

@@ -42,7 +42,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             || self.suggest_boxing_when_appropriate(err, expr, expected, expr_ty)
             || self.suggest_block_to_brackets_peeling_refs(err, expr, expr_ty, expected)
             || self.suggest_copied_or_cloned(err, expr, expr_ty, expected)
-            || self.suggest_into(err, expr, expr_ty, expected);
+            || self.suggest_into(err, expr, expr_ty, expected)
+            || self.suggest_option_to_bool(err, expr, expr_ty, expected);
 
         self.note_type_is_not_clone(err, expected, expr_ty, expr);
         self.note_need_for_fn_pointer(err, expected, expr_ty);

compiler/rustc_hir_typeck/src/expr.rs

@@ -103,8 +103,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
 
         if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) {
-            let expr = expr.peel_drop_temps();
-            self.suggest_deref_ref_or_into(&mut err, expr, expected_ty, ty, None);
+            // FIXME(compiler-errors): We probably should fold some of the
+            // `suggest_` functions from  `emit_coerce_suggestions` into here,
+            // since some of those aren't necessarily just coerce suggestions.
+            let _ = self.suggest_deref_ref_or_into(
+                &mut err,
+                expr.peel_drop_temps(),
+                expected_ty,
+                ty,
+                None,
+            ) || self.suggest_option_to_bool(&mut err, expr, ty, expected_ty);
             extend_err(&mut err);
             err.emit();
         }

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -13,7 +13,7 @@ use rustc_hir_analysis::astconv::AstConv;
 use rustc_infer::infer::{self, TyCtxtInferExt};
 use rustc_infer::traits::{self, StatementAsExpression};
 use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::{self, Binder, IsSuggestable, ToPredicate, Ty};
+use rustc_middle::ty::{self, Binder, DefIdTree, IsSuggestable, ToPredicate, Ty};
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::symbol::sym;
 use rustc_span::Span;
@@ -1116,6 +1116,53 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         false
     }
 
+    /// When expecting a `bool` and finding an `Option`, suggests using `let Some(..)` or `.is_some()`
+    pub(crate) fn suggest_option_to_bool(
+        &self,
+        diag: &mut Diagnostic,
+        expr: &hir::Expr<'_>,
+        expr_ty: Ty<'tcx>,
+        expected_ty: Ty<'tcx>,
+    ) -> bool {
+        if !expected_ty.is_bool() {
+            return false;
+        }
+
+        let ty::Adt(def, _) = expr_ty.peel_refs().kind() else { return false; };
+        if !self.tcx.is_diagnostic_item(sym::Option, def.did()) {
+            return false;
+        }
+
+        let hir = self.tcx.hir();
+        let cond_parent = hir.parent_iter(expr.hir_id).skip_while(|(_, node)| {
+            matches!(node, hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Binary(op, _, _), .. }) if op.node == hir::BinOpKind::And)
+        }).next();
+        // Don't suggest:
+        //     `let Some(_) = a.is_some() && b`
+        //                     ++++++++++
+        // since the user probably just misunderstood how `let else`
+        // and `&&` work together.
+        if let Some((_, hir::Node::Local(local))) = cond_parent
+            && let hir::PatKind::Path(qpath) | hir::PatKind::TupleStruct(qpath, _, _) = &local.pat.kind
+            && let hir::QPath::Resolved(None, path) = qpath
+            && let Some(did) = path.res.opt_def_id()
+                .and_then(|did| self.tcx.opt_parent(did))
+                .and_then(|did| self.tcx.opt_parent(did))
+            && self.tcx.is_diagnostic_item(sym::Option, did)
+        {
+            return false;
+        }
+
+        diag.span_suggestion(
+            expr.span.shrink_to_hi(),
+            "use `Option::is_some` to test if the `Option` has a value",
+            ".is_some()",
+            Applicability::MachineApplicable,
+        );
+
+        true
+    }
+
     /// Suggest wrapping the block in square brackets instead of curly braces
     /// in case the block was mistaken array syntax, e.g. `{ 1 }` -> `[ 1 ]`.
     pub(crate) fn suggest_block_to_brackets(

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -106,6 +106,7 @@ use rustc_ast::LitKind;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::{HashMapExt, Lock};
 use rustc_data_structures::tiny_list::TinyList;
+use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
 use rustc_middle::ty::print::with_no_trimmed_paths;
@@ -176,7 +177,7 @@ pub enum LitToConstError {
     /// This is used for graceful error handling (`delay_span_bug`) in
     /// type checking (`Const::from_anon_const`).
     TypeError,
-    Reported,
+    Reported(ErrorGuaranteed),
 }
 
 #[derive(Copy, Clone, Eq, Hash, Ord, PartialEq, PartialOrd)]

compiler/rustc_middle/src/mir/mod.rs

@@ -2251,7 +2251,9 @@ impl<'tcx> ConstantKind<'tcx> {
                 match tcx.const_eval_resolve(param_env, uneval, None) {
                     Ok(val) => Self::Val(val, ty),
                     Err(ErrorHandled::TooGeneric | ErrorHandled::Linted) => self,
-                    Err(_) => Self::Ty(tcx.const_error(ty)),
+                    Err(ErrorHandled::Reported(guar)) => {
+                        Self::Ty(tcx.const_error_with_guaranteed(ty, guar))
+                    }
                 }
             }
         }

compiler/rustc_middle/src/ty/consts.rs

@@ -2,7 +2,6 @@ use crate::mir::interpret::LitToConstInput;
 use crate::mir::ConstantKind;
 use crate::ty::{self, InternalSubsts, ParamEnv, ParamEnvAnd, Ty, TyCtxt};
 use rustc_data_structures::intern::Interned;
-use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_macros::HashStable;
@@ -225,7 +224,7 @@ impl<'tcx> Const<'tcx> {
         if let Some(val) = self.kind().try_eval_for_typeck(tcx, param_env) {
             match val {
                 Ok(val) => Const::from_value(tcx, val, self.ty()),
-                Err(ErrorGuaranteed { .. }) => tcx.const_error(self.ty()),
+                Err(guar) => tcx.const_error_with_guaranteed(self.ty(), guar),
             }
         } else {
             // Either the constant isn't evaluatable or ValTree creation failed.
@@ -240,7 +239,7 @@ impl<'tcx> Const<'tcx> {
         if let Some(val) = self.kind().try_eval_for_mir(tcx, param_env) {
             match val {
                 Ok(const_val) => ConstantKind::from_value(const_val, self.ty()),
-                Err(ErrorGuaranteed { .. }) => ConstantKind::Ty(tcx.const_error(self.ty())),
+                Err(guar) => ConstantKind::Ty(tcx.const_error_with_guaranteed(self.ty(), guar)),
             }
         } else {
             ConstantKind::Ty(self)

compiler/rustc_middle/src/ty/subst.rs

@@ -506,6 +506,9 @@ impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &'tcx ty::List<T> {
     }
 }
 
+/// Similar to [`super::Binder`] except that it tracks early bound generics, i.e. `struct Foo<T>(T)`
+/// needs `T` substituted immediately. This type primarily exists to avoid forgetting to call
+/// `subst`.
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
 #[derive(Encodable, Decodable, HashStable)]
 pub struct EarlyBinder<T>(pub T);

compiler/rustc_mir_build/src/build/expr/as_constant.rs

@@ -9,6 +9,7 @@ use rustc_middle::mir::interpret::{
 use rustc_middle::mir::*;
 use rustc_middle::thir::*;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, TyCtxt};
+use rustc_span::DUMMY_SP;
 use rustc_target::abi::Size;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
@@ -26,7 +27,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let literal =
                     match lit_to_mir_constant(tcx, LitToConstInput { lit: &lit.node, ty, neg }) {
                         Ok(c) => c,
-                        Err(LitToConstError::Reported) => ConstantKind::Ty(tcx.const_error(ty)),
+                        Err(LitToConstError::Reported(guar)) => {
+                            ConstantKind::Ty(tcx.const_error_with_guaranteed(ty, guar))
+                        }
                         Err(LitToConstError::TypeError) => {
                             bug!("encountered type error in `lit_to_mir_constant")
                         }
@@ -105,7 +108,15 @@ pub(crate) fn lit_to_mir_constant<'tcx>(
     let LitToConstInput { lit, ty, neg } = lit_input;
     let trunc = |n| {
         let param_ty = ty::ParamEnv::reveal_all().and(ty);
-        let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
+        let width = tcx
+            .layout_of(param_ty)
+            .map_err(|_| {
+                LitToConstError::Reported(tcx.sess.delay_span_bug(
+                    DUMMY_SP,
+                    format!("couldn't compute width of literal: {:?}", lit_input.lit),
+                ))
+            })?
+            .size;
         trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
         let result = width.truncate(n);
         trace!("trunc result: {}", result);
@@ -136,12 +147,20 @@ pub(crate) fn lit_to_mir_constant<'tcx>(
         (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
             trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
         }
-        (ast::LitKind::Float(n, _), ty::Float(fty)) => {
-            parse_float_into_constval(*n, *fty, neg).ok_or(LitToConstError::Reported)?
-        }
+        (ast::LitKind::Float(n, _), ty::Float(fty)) => parse_float_into_constval(*n, *fty, neg)
+            .ok_or_else(|| {
+                LitToConstError::Reported(tcx.sess.delay_span_bug(
+                    DUMMY_SP,
+                    format!("couldn't parse float literal: {:?}", lit_input.lit),
+                ))
+            })?,
         (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
         (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
-        (ast::LitKind::Err, _) => return Err(LitToConstError::Reported),
+        (ast::LitKind::Err, _) => {
+            return Err(LitToConstError::Reported(
+                tcx.sess.delay_span_bug(DUMMY_SP, "encountered LitKind::Err during mir build"),
+            ));
+        }
         _ => return Err(LitToConstError::TypeError),
     };
 

compiler/rustc_mir_build/src/thir/constant.rs

@@ -1,6 +1,7 @@
 use rustc_ast as ast;
 use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
 use rustc_middle::ty::{self, ParamEnv, ScalarInt, TyCtxt};
+use rustc_span::DUMMY_SP;
 
 pub(crate) fn lit_to_const<'tcx>(
     tcx: TyCtxt<'tcx>,
@@ -10,7 +11,15 @@ pub(crate) fn lit_to_const<'tcx>(
 
     let trunc = |n| {
         let param_ty = ParamEnv::reveal_all().and(ty);
-        let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
+        let width = tcx
+            .layout_of(param_ty)
+            .map_err(|_| {
+                LitToConstError::Reported(tcx.sess.delay_span_bug(
+                    DUMMY_SP,
+                    format!("couldn't compute width of literal: {:?}", lit_input.lit),
+                ))
+            })?
+            .size;
         trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
         let result = width.truncate(n);
         trace!("trunc result: {}", result);
@@ -44,7 +53,11 @@ pub(crate) fn lit_to_const<'tcx>(
         }
         (ast::LitKind::Bool(b), ty::Bool) => ty::ValTree::from_scalar_int((*b).into()),
         (ast::LitKind::Char(c), ty::Char) => ty::ValTree::from_scalar_int((*c).into()),
-        (ast::LitKind::Err, _) => return Err(LitToConstError::Reported),
+        (ast::LitKind::Err, _) => {
+            return Err(LitToConstError::Reported(
+                tcx.sess.delay_span_bug(DUMMY_SP, "encountered LitKind::Err during mir build"),
+            ));
+        }
         _ => return Err(LitToConstError::TypeError),
     };
 

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -614,7 +614,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             LitToConstInput { lit: &lit.node, ty: self.typeck_results.expr_ty(expr), neg };
         match self.tcx.at(expr.span).lit_to_mir_constant(lit_input) {
             Ok(constant) => self.const_to_pat(constant, expr.hir_id, lit.span, false).kind,
-            Err(LitToConstError::Reported) => PatKind::Wild,
+            Err(LitToConstError::Reported(_)) => PatKind::Wild,
             Err(LitToConstError::TypeError) => bug!("lower_lit: had type error"),
         }
     }

compiler/rustc_mir_transform/src/required_consts.rs

@@ -17,7 +17,7 @@ impl<'tcx> Visitor<'tcx> for RequiredConstsVisitor<'_, 'tcx> {
         let literal = constant.literal;
         match literal {
             ConstantKind::Ty(c) => match c.kind() {
-                ConstKind::Param(_) => {}
+                ConstKind::Param(_) | ConstKind::Error(_) => {}
                 _ => bug!("only ConstKind::Param should be encountered here, got {:#?}", c),
             },
             ConstantKind::Unevaluated(..) => self.required_consts.push(*constant),

compiler/rustc_resolve/src/late.rs

@@ -527,6 +527,7 @@ struct DiagnosticMetadata<'ast> {
 
     /// Used to detect possible new binding written without `let` and to provide structured suggestion.
     in_assignment: Option<&'ast Expr>,
+    is_assign_rhs: bool,
 
     /// If we are currently in a trait object definition. Used to point at the bounds when
     /// encountering a struct or enum.
@@ -3963,10 +3964,15 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                 self.resolve_expr(elem, Some(expr));
                 self.visit_expr(idx);
             }
-            ExprKind::Assign(..) => {
-                let old = self.diagnostic_metadata.in_assignment.replace(expr);
-                visit::walk_expr(self, expr);
-                self.diagnostic_metadata.in_assignment = old;
+            ExprKind::Assign(ref lhs, ref rhs, _) => {
+                if !self.diagnostic_metadata.is_assign_rhs {
+                    self.diagnostic_metadata.in_assignment = Some(expr);
+                }
+                self.visit_expr(lhs);
+                self.diagnostic_metadata.is_assign_rhs = true;
+                self.diagnostic_metadata.in_assignment = None;
+                self.visit_expr(rhs);
+                self.diagnostic_metadata.is_assign_rhs = false;
             }
             _ => {
                 visit::walk_expr(self, expr);

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1810,29 +1810,22 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         false
     }
 
-    fn let_binding_suggestion(&self, err: &mut Diagnostic, ident_span: Span) -> bool {
-        // try to give a suggestion for this pattern: `name = 1`, which is common in other languages
-        let mut added_suggestion = false;
-        if let Some(Expr { kind: ExprKind::Assign(lhs, _rhs, _), .. }) = self.diagnostic_metadata.in_assignment &&
+    // try to give a suggestion for this pattern: `name = blah`, which is common in other languages
+    // suggest `let name = blah` to introduce a new binding
+    fn let_binding_suggestion(&mut self, err: &mut Diagnostic, ident_span: Span) -> bool {
+        if let Some(Expr { kind: ExprKind::Assign(lhs, .. ), .. }) = self.diagnostic_metadata.in_assignment &&
             let ast::ExprKind::Path(None, _) = lhs.kind {
-                let sm = self.r.session.source_map();
-                let line_span = sm.span_extend_to_line(ident_span);
-                let ident_name = sm.span_to_snippet(ident_span).unwrap();
-                // HACK(chenyukang): make sure ident_name is at the starting of the line to protect against macros
-                if sm
-                    .span_to_snippet(line_span)
-                    .map_or(false, |s| s.trim().starts_with(&ident_name))
-                {
+                if !ident_span.from_expansion() {
                     err.span_suggestion_verbose(
                         ident_span.shrink_to_lo(),
                         "you might have meant to introduce a new binding",
                         "let ".to_string(),
                         Applicability::MaybeIncorrect,
                     );
-                    added_suggestion = true;
+                    return true;
                 }
             }
-        added_suggestion
+        false
     }
 
     fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> {