rustc_hir_typeck: move whole files

1 files changed, 0 insertions, 557 deletions

diff --git a/compiler/rustc_hir_analysis/src/check/_match.rs b/compiler/rustc_hir_analysis/src/check/_match.rs
deleted file mode 100644
index 143508b785f..00000000000
--- a/compiler/rustc_hir_analysis/src/check/_match.rs
+++ /dev/null
@@ -1,557 +0,0 @@
-use crate::check::coercion::{AsCoercionSite, CoerceMany};
-use crate::check::{Diverges, Expectation, FnCtxt, Needs};
-use rustc_errors::{Applicability, MultiSpan};
-use rustc_hir::{self as hir, ExprKind};
-use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::traits::Obligation;
-use rustc_middle::ty::{self, ToPredicate, Ty};
-use rustc_span::Span;
-use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
-use rustc_trait_selection::traits::{
-    IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
-};
-
-impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
-    #[instrument(skip(self), level = "debug", ret)]
-    pub fn check_match(
-        &self,
-        expr: &'tcx hir::Expr<'tcx>,
-        scrut: &'tcx hir::Expr<'tcx>,
-        arms: &'tcx [hir::Arm<'tcx>],
-        orig_expected: Expectation<'tcx>,
-        match_src: hir::MatchSource,
-    ) -> Ty<'tcx> {
-        let tcx = self.tcx;
-
-        let acrb = arms_contain_ref_bindings(arms);
-        let scrutinee_ty = self.demand_scrutinee_type(scrut, acrb, arms.is_empty());
-        debug!(?scrutinee_ty);
-
-        // If there are no arms, that is a diverging match; a special case.
-        if arms.is_empty() {
-            self.diverges.set(self.diverges.get() | Diverges::always(expr.span));
-            return tcx.types.never;
-        }
-
-        self.warn_arms_when_scrutinee_diverges(arms);
-
-        // Otherwise, we have to union together the types that the arms produce and so forth.
-        let scrut_diverges = self.diverges.replace(Diverges::Maybe);
-
-        // #55810: Type check patterns first so we get types for all bindings.
-        let scrut_span = scrut.span.find_ancestor_inside(expr.span).unwrap_or(scrut.span);
-        for arm in arms {
-            self.check_pat_top(&arm.pat, scrutinee_ty, Some(scrut_span), true);
-        }
-
-        // Now typecheck the blocks.
-        //
-        // The result of the match is the common supertype of all the
-        // arms. Start out the value as bottom, since it's the, well,
-        // bottom the type lattice, and we'll be moving up the lattice as
-        // we process each arm. (Note that any match with 0 arms is matching
-        // on any empty type and is therefore unreachable; should the flow
-        // of execution reach it, we will panic, so bottom is an appropriate
-        // type in that case)
-        let mut all_arms_diverge = Diverges::WarnedAlways;
-
-        let expected = orig_expected.adjust_for_branches(self);
-        debug!(?expected);
-
-        let mut coercion = {
-            let coerce_first = match expected {
-                // We don't coerce to `()` so that if the match expression is a
-                // statement it's branches can have any consistent type. That allows
-                // us to give better error messages (pointing to a usually better
-                // arm for inconsistent arms or to the whole match when a `()` type
-                // is required).
-                Expectation::ExpectHasType(ety) if ety != self.tcx.mk_unit() => ety,
-                _ => self.next_ty_var(TypeVariableOrigin {
-                    kind: TypeVariableOriginKind::MiscVariable,
-                    span: expr.span,
-                }),
-            };
-            CoerceMany::with_coercion_sites(coerce_first, arms)
-        };
-
-        let mut other_arms = vec![]; // Used only for diagnostics.
-        let mut prior_arm = None;
-        for arm in arms {
-            if let Some(g) = &arm.guard {
-                self.diverges.set(Diverges::Maybe);
-                match g {
-                    hir::Guard::If(e) => {
-                        self.check_expr_has_type_or_error(e, tcx.types.bool, |_| {});
-                    }
-                    hir::Guard::IfLet(l) => {
-                        self.check_expr_let(l);
-                    }
-                };
-            }
-
-            self.diverges.set(Diverges::Maybe);
-
-            let arm_ty = self.check_expr_with_expectation(&arm.body, expected);
-            all_arms_diverge &= self.diverges.get();
-
-            let opt_suggest_box_span = prior_arm.and_then(|(_, prior_arm_ty, _)| {
-                self.opt_suggest_box_span(prior_arm_ty, arm_ty, orig_expected)
-            });
-
-            let (arm_block_id, arm_span) = if let hir::ExprKind::Block(blk, _) = arm.body.kind {
-                (Some(blk.hir_id), self.find_block_span(blk))
-            } else {
-                (None, arm.body.span)
-            };
-
-            let (span, code) = match prior_arm {
-                // The reason for the first arm to fail is not that the match arms diverge,
-                // but rather that there's a prior obligation that doesn't hold.
-                None => (arm_span, ObligationCauseCode::BlockTailExpression(arm.body.hir_id)),
-                Some((prior_arm_block_id, prior_arm_ty, prior_arm_span)) => (
-                    expr.span,
-                    ObligationCauseCode::MatchExpressionArm(Box::new(MatchExpressionArmCause {
-                        arm_block_id,
-                        arm_span,
-                        arm_ty,
-                        prior_arm_block_id,
-                        prior_arm_ty,
-                        prior_arm_span,
-                        scrut_span: scrut.span,
-                        source: match_src,
-                        prior_arms: other_arms.clone(),
-                        scrut_hir_id: scrut.hir_id,
-                        opt_suggest_box_span,
-                    })),
-                ),
-            };
-            let cause = self.cause(span, code);
-
-            // This is the moral equivalent of `coercion.coerce(self, cause, arm.body, arm_ty)`.
-            // We use it this way to be able to expand on the potential error and detect when a
-            // `match` tail statement could be a tail expression instead. If so, we suggest
-            // removing the stray semicolon.
-            coercion.coerce_inner(
-                self,
-                &cause,
-                Some(&arm.body),
-                arm_ty,
-                Some(&mut |err| {
-                    let Some(ret) = self
-                        .tcx
-                        .hir()
-                        .find_by_def_id(self.body_id.owner.def_id)
-                        .and_then(|owner| owner.fn_decl())
-                        .map(|decl| decl.output.span())
-                    else { return; };
-                    let Expectation::IsLast(stmt) = orig_expected else {
-                        return
-                    };
-                    let can_coerce_to_return_ty = match self.ret_coercion.as_ref() {
-                        Some(ret_coercion) if self.in_tail_expr => {
-                            let ret_ty = ret_coercion.borrow().expected_ty();
-                            let ret_ty = self.inh.infcx.shallow_resolve(ret_ty);
-                            self.can_coerce(arm_ty, ret_ty)
-                                && prior_arm.map_or(true, |(_, t, _)| self.can_coerce(t, ret_ty))
-                                // The match arms need to unify for the case of `impl Trait`.
-                                && !matches!(ret_ty.kind(), ty::Opaque(..))
-                        }
-                        _ => false,
-                    };
-                    if !can_coerce_to_return_ty {
-                        return;
-                    }
-
-                    let semi_span = expr.span.shrink_to_hi().with_hi(stmt.hi());
-                    let mut ret_span: MultiSpan = semi_span.into();
-                    ret_span.push_span_label(
-                        expr.span,
-                        "this could be implicitly returned but it is a statement, not a \
-                            tail expression",
-                    );
-                    ret_span
-                        .push_span_label(ret, "the `match` arms can conform to this return type");
-                    ret_span.push_span_label(
-                        semi_span,
-                        "the `match` is a statement because of this semicolon, consider \
-                            removing it",
-                    );
-                    err.span_note(
-                        ret_span,
-                        "you might have meant to return the `match` expression",
-                    );
-                    err.tool_only_span_suggestion(
-                        semi_span,
-                        "remove this semicolon",
-                        "",
-                        Applicability::MaybeIncorrect,
-                    );
-                }),
-                false,
-            );
-
-            other_arms.push(arm_span);
-            if other_arms.len() > 5 {
-                other_arms.remove(0);
-            }
-
-            prior_arm = Some((arm_block_id, arm_ty, arm_span));
-        }
-
-        // If all of the arms in the `match` diverge,
-        // and we're dealing with an actual `match` block
-        // (as opposed to a `match` desugared from something else'),
-        // we can emit a better note. Rather than pointing
-        // at a diverging expression in an arbitrary arm,
-        // we can point at the entire `match` expression
-        if let (Diverges::Always { .. }, hir::MatchSource::Normal) = (all_arms_diverge, match_src) {
-            all_arms_diverge = Diverges::Always {
-                span: expr.span,
-                custom_note: Some(
-                    "any code following this `match` expression is unreachable, as all arms diverge",
-                ),
-            };
-        }
-
-        // We won't diverge unless the scrutinee or all arms diverge.
-        self.diverges.set(scrut_diverges | all_arms_diverge);
-
-        coercion.complete(self)
-    }
-
-    /// When the previously checked expression (the scrutinee) diverges,
-    /// warn the user about the match arms being unreachable.
-    fn warn_arms_when_scrutinee_diverges(&self, arms: &'tcx [hir::Arm<'tcx>]) {
-        for arm in arms {
-            self.warn_if_unreachable(arm.body.hir_id, arm.body.span, "arm");
-        }
-    }
-
-    /// Handle the fallback arm of a desugared if(-let) like a missing else.
-    ///
-    /// Returns `true` if there was an error forcing the coercion to the `()` type.
-    pub(super) fn if_fallback_coercion<T>(
-        &self,
-        span: Span,
-        then_expr: &'tcx hir::Expr<'tcx>,
-        coercion: &mut CoerceMany<'tcx, '_, T>,
-    ) -> bool
-    where
-        T: AsCoercionSite,
-    {
-        // If this `if` expr is the parent's function return expr,
-        // the cause of the type coercion is the return type, point at it. (#25228)
-        let ret_reason = self.maybe_get_coercion_reason(then_expr.hir_id, span);
-        let cause = self.cause(span, ObligationCauseCode::IfExpressionWithNoElse);
-        let mut error = false;
-        coercion.coerce_forced_unit(
-            self,
-            &cause,
-            &mut |err| {
-                if let Some((span, msg)) = &ret_reason {
-                    err.span_label(*span, msg);
-                } else if let ExprKind::Block(block, _) = &then_expr.kind
-                    && let Some(expr) = &block.expr
-                {
-                    err.span_label(expr.span, "found here");
-                }
-                err.note("`if` expressions without `else` evaluate to `()`");
-                err.help("consider adding an `else` block that evaluates to the expected type");
-                error = true;
-            },
-            false,
-        );
-        error
-    }
-
-    fn maybe_get_coercion_reason(&self, hir_id: hir::HirId, sp: Span) -> Option<(Span, String)> {
-        let node = {
-            let rslt = self.tcx.hir().get_parent_node(self.tcx.hir().get_parent_node(hir_id));
-            self.tcx.hir().get(rslt)
-        };
-        if let hir::Node::Block(block) = node {
-            // check that the body's parent is an fn
-            let parent = self
-                .tcx
-                .hir()
-                .get(self.tcx.hir().get_parent_node(self.tcx.hir().get_parent_node(block.hir_id)));
-            if let (Some(expr), hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(..), .. })) =
-                (&block.expr, parent)
-            {
-                // check that the `if` expr without `else` is the fn body's expr
-                if expr.span == sp {
-                    return self.get_fn_decl(hir_id).and_then(|(fn_decl, _)| {
-                        let span = fn_decl.output.span();
-                        let snippet = self.tcx.sess.source_map().span_to_snippet(span).ok()?;
-                        Some((span, format!("expected `{snippet}` because of this return type")))
-                    });
-                }
-            }
-        }
-        if let hir::Node::Local(hir::Local { ty: Some(_), pat, .. }) = node {
-            return Some((pat.span, "expected because of this assignment".to_string()));
-        }
-        None
-    }
-
-    pub(crate) fn if_cause(
-        &self,
-        span: Span,
-        cond_span: Span,
-        then_expr: &'tcx hir::Expr<'tcx>,
-        else_expr: &'tcx hir::Expr<'tcx>,
-        then_ty: Ty<'tcx>,
-        else_ty: Ty<'tcx>,
-        opt_suggest_box_span: Option<Span>,
-    ) -> ObligationCause<'tcx> {
-        let mut outer_span = if self.tcx.sess.source_map().is_multiline(span) {
-            // The `if`/`else` isn't in one line in the output, include some context to make it
-            // clear it is an if/else expression:
-            // ```
-            // LL |      let x = if true {
-            //    | _____________-
-            // LL ||         10i32
-            //    ||         ----- expected because of this
-            // LL ||     } else {
-            // LL ||         10u32
-            //    ||         ^^^^^ expected `i32`, found `u32`
-            // LL ||     };
-            //    ||_____- `if` and `else` have incompatible types
-            // ```
-            Some(span)
-        } else {
-            // The entire expression is in one line, only point at the arms
-            // ```
-            // LL |     let x = if true { 10i32 } else { 10u32 };
-            //    |                       -----          ^^^^^ expected `i32`, found `u32`
-            //    |                       |
-            //    |                       expected because of this
-            // ```
-            None
-        };
-
-        let (error_sp, else_id) = if let ExprKind::Block(block, _) = &else_expr.kind {
-            let block = block.innermost_block();
-
-            // Avoid overlapping spans that aren't as readable:
-            // ```
-            // 2 |        let x = if true {
-            //   |   _____________-
-            // 3 |  |         3
-            //   |  |         - expected because of this
-            // 4 |  |     } else {
-            //   |  |____________^
-            // 5 | ||
-            // 6 | ||     };
-            //   | ||     ^
-            //   | ||_____|
-            //   | |______if and else have incompatible types
-            //   |        expected integer, found `()`
-            // ```
-            // by not pointing at the entire expression:
-            // ```
-            // 2 |       let x = if true {
-            //   |               ------- `if` and `else` have incompatible types
-            // 3 |           3
-            //   |           - expected because of this
-            // 4 |       } else {
-            //   |  ____________^
-            // 5 | |
-            // 6 | |     };
-            //   | |_____^ expected integer, found `()`
-            // ```
-            if block.expr.is_none() && block.stmts.is_empty()
-                && let Some(outer_span) = &mut outer_span
-                && let Some(cond_span) = cond_span.find_ancestor_inside(*outer_span)
-            {
-                *outer_span = outer_span.with_hi(cond_span.hi())
-            }
-
-            (self.find_block_span(block), block.hir_id)
-        } else {
-            (else_expr.span, else_expr.hir_id)
-        };
-
-        let then_id = if let ExprKind::Block(block, _) = &then_expr.kind {
-            let block = block.innermost_block();
-            // Exclude overlapping spans
-            if block.expr.is_none() && block.stmts.is_empty() {
-                outer_span = None;
-            }
-            block.hir_id
-        } else {
-            then_expr.hir_id
-        };
-
-        // Finally construct the cause:
-        self.cause(
-            error_sp,
-            ObligationCauseCode::IfExpression(Box::new(IfExpressionCause {
-                else_id,
-                then_id,
-                then_ty,
-                else_ty,
-                outer_span,
-                opt_suggest_box_span,
-            })),
-        )
-    }
-
-    pub(super) fn demand_scrutinee_type(
-        &self,
-        scrut: &'tcx hir::Expr<'tcx>,
-        contains_ref_bindings: Option<hir::Mutability>,
-        no_arms: bool,
-    ) -> Ty<'tcx> {
-        // Not entirely obvious: if matches may create ref bindings, we want to
-        // use the *precise* type of the scrutinee, *not* some supertype, as
-        // the "scrutinee type" (issue #23116).
-        //
-        // arielb1 [writes here in this comment thread][c] that there
-        // is certainly *some* potential danger, e.g., for an example
-        // like:
-        //
-        // [c]: https://github.com/rust-lang/rust/pull/43399#discussion_r130223956
-        //
-        // ```
-        // let Foo(x) = f()[0];
-        // ```
-        //
-        // Then if the pattern matches by reference, we want to match
-        // `f()[0]` as a lexpr, so we can't allow it to be
-        // coerced. But if the pattern matches by value, `f()[0]` is
-        // still syntactically a lexpr, but we *do* want to allow
-        // coercions.
-        //
-        // However, *likely* we are ok with allowing coercions to
-        // happen if there are no explicit ref mut patterns - all
-        // implicit ref mut patterns must occur behind a reference, so
-        // they will have the "correct" variance and lifetime.
-        //
-        // This does mean that the following pattern would be legal:
-        //
-        // ```
-        // struct Foo(Bar);
-        // struct Bar(u32);
-        // impl Deref for Foo {
-        //     type Target = Bar;
-        //     fn deref(&self) -> &Bar { &self.0 }
-        // }
-        // impl DerefMut for Foo {
-        //     fn deref_mut(&mut self) -> &mut Bar { &mut self.0 }
-        // }
-        // fn foo(x: &mut Foo) {
-        //     {
-        //         let Bar(z): &mut Bar = x;
-        //         *z = 42;
-        //     }
-        //     assert_eq!(foo.0.0, 42);
-        // }
-        // ```
-        //
-        // FIXME(tschottdorf): don't call contains_explicit_ref_binding, which
-        // is problematic as the HIR is being scraped, but ref bindings may be
-        // implicit after #42640. We need to make sure that pat_adjustments
-        // (once introduced) is populated by the time we get here.
-        //
-        // See #44848.
-        if let Some(m) = contains_ref_bindings {
-            self.check_expr_with_needs(scrut, Needs::maybe_mut_place(m))
-        } else if no_arms {
-            self.check_expr(scrut)
-        } else {
-            // ...but otherwise we want to use any supertype of the
-            // scrutinee. This is sort of a workaround, see note (*) in
-            // `check_pat` for some details.
-            let scrut_ty = self.next_ty_var(TypeVariableOrigin {
-                kind: TypeVariableOriginKind::TypeInference,
-                span: scrut.span,
-            });
-            self.check_expr_has_type_or_error(scrut, scrut_ty, |_| {});
-            scrut_ty
-        }
-    }
-
-    /// When we have a `match` as a tail expression in a `fn` with a returned `impl Trait`
-    /// we check if the different arms would work with boxed trait objects instead and
-    /// provide a structured suggestion in that case.
-    pub(crate) fn opt_suggest_box_span(
-        &self,
-        first_ty: Ty<'tcx>,
-        second_ty: Ty<'tcx>,
-        orig_expected: Expectation<'tcx>,
-    ) -> Option<Span> {
-        // FIXME(compiler-errors): This really shouldn't need to be done during the
-        // "good" path of typeck, but here we are.
-        match orig_expected {
-            Expectation::ExpectHasType(expected) => {
-                let TypeVariableOrigin {
-                    span,
-                    kind: TypeVariableOriginKind::OpaqueTypeInference(rpit_def_id),
-                    ..
-                } = self.type_var_origin(expected)? else { return None; };
-
-                let sig = *self
-                    .typeck_results
-                    .borrow()
-                    .liberated_fn_sigs()
-                    .get(hir::HirId::make_owner(self.body_id.owner.def_id))?;
-
-                let substs = sig.output().walk().find_map(|arg| {
-                    if let ty::GenericArgKind::Type(ty) = arg.unpack()
-                        && let ty::Opaque(def_id, substs) = *ty.kind()
-                        && def_id == rpit_def_id
-                    {
-                        Some(substs)
-                    } else {
-                        None
-                    }
-                })?;
-                let opaque_ty = self.tcx.mk_opaque(rpit_def_id, substs);
-
-                if !self.can_coerce(first_ty, expected) || !self.can_coerce(second_ty, expected) {
-                    return None;
-                }
-
-                for ty in [first_ty, second_ty] {
-                    for pred in self.tcx.bound_explicit_item_bounds(rpit_def_id).transpose_iter() {
-                        let pred = pred.map_bound(|(pred, _)| *pred).subst(self.tcx, substs);
-                        let pred = match pred.kind().skip_binder() {
-                            ty::PredicateKind::Trait(mut trait_pred) => {
-                                assert_eq!(trait_pred.trait_ref.self_ty(), opaque_ty);
-                                trait_pred.trait_ref.substs =
-                                    self.tcx.mk_substs_trait(ty, &trait_pred.trait_ref.substs[1..]);
-                                pred.kind().rebind(trait_pred).to_predicate(self.tcx)
-                            }
-                            ty::PredicateKind::Projection(mut proj_pred) => {
-                                assert_eq!(proj_pred.projection_ty.self_ty(), opaque_ty);
-                                proj_pred.projection_ty.substs = self
-                                    .tcx
-                                    .mk_substs_trait(ty, &proj_pred.projection_ty.substs[1..]);
-                                pred.kind().rebind(proj_pred).to_predicate(self.tcx)
-                            }
-                            _ => continue,
-                        };
-                        if !self.predicate_must_hold_modulo_regions(&Obligation::new(
-                            ObligationCause::misc(span, self.body_id),
-                            self.param_env,
-                            pred,
-                        )) {
-                            return None;
-                        }
-                    }
-                }
-
-                Some(span)
-            }
-            _ => None,
-        }
-    }
-}
-
-fn arms_contain_ref_bindings<'tcx>(arms: &'tcx [hir::Arm<'tcx>]) -> Option<hir::Mutability> {
-    arms.iter().filter_map(|a| a.pat.contains_explicit_ref_binding()).max_by_key(|m| match *m {
-        hir::Mutability::Mut => 1,
-        hir::Mutability::Not => 0,
-    })
-}