From 94a0819fe3a0d679c3042a77bfe6a2afc505daea Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:11:28 +0200 Subject: Adding upstream version 1.66.0+dfsg1. Signed-off-by: Daniel Baumann --- compiler/rustc_hir_analysis/src/check/mod.rs | 515 +++++++++++++++++++++++++++ 1 file changed, 515 insertions(+) create mode 100644 compiler/rustc_hir_analysis/src/check/mod.rs (limited to 'compiler/rustc_hir_analysis/src/check/mod.rs') diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs new file mode 100644 index 000000000..2e7b10257 --- /dev/null +++ b/compiler/rustc_hir_analysis/src/check/mod.rs @@ -0,0 +1,515 @@ +/*! + +# typeck: check phase + +Within the check phase of type check, we check each item one at a time +(bodies of function expressions are checked as part of the containing +function). Inference is used to supply types wherever they are unknown. + +By far the most complex case is checking the body of a function. This +can be broken down into several distinct phases: + +- gather: creates type variables to represent the type of each local + variable and pattern binding. + +- main: the main pass does the lion's share of the work: it + determines the types of all expressions, resolves + methods, checks for most invalid conditions, and so forth. In + some cases, where a type is unknown, it may create a type or region + variable and use that as the type of an expression. + + In the process of checking, various constraints will be placed on + these type variables through the subtyping relationships requested + through the `demand` module. The `infer` module is in charge + of resolving those constraints. + +- regionck: after main is complete, the regionck pass goes over all + types looking for regions and making sure that they did not escape + into places where they are not in scope. This may also influence the + final assignments of the various region variables if there is some + flexibility. + +- writeback: writes the final types within a function body, replacing + type variables with their final inferred types. These final types + are written into the `tcx.node_types` table, which should *never* contain + any reference to a type variable. + +## Intermediate types + +While type checking a function, the intermediate types for the +expressions, blocks, and so forth contained within the function are +stored in `fcx.node_types` and `fcx.node_substs`. These types +may contain unresolved type variables. After type checking is +complete, the functions in the writeback module are used to take the +types from this table, resolve them, and then write them into their +permanent home in the type context `tcx`. + +This means that during inferencing you should use `fcx.write_ty()` +and `fcx.expr_ty()` / `fcx.node_ty()` to write/obtain the types of +nodes within the function. + +The types of top-level items, which never contain unbound type +variables, are stored directly into the `tcx` typeck_results. + +N.B., a type variable is not the same thing as a type parameter. A +type variable is an instance of a type parameter. That is, +given a generic function `fn foo(t: T)`, while checking the +function `foo`, the type `ty_param(0)` refers to the type `T`, which +is treated in abstract. However, when `foo()` is called, `T` will be +substituted for a fresh type variable `N`. This variable will +eventually be resolved to some concrete type (which might itself be +a type parameter). + +*/ + +mod check; +mod compare_method; +pub mod dropck; +pub mod intrinsic; +pub mod intrinsicck; +mod region; +pub mod wfcheck; + +pub use check::check_abi; + +use check::check_mod_item_types; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_errors::{pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder}; +use rustc_hir as hir; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::intravisit::Visitor; +use rustc_index::bit_set::BitSet; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_middle::ty::{InternalSubsts, SubstsRef}; +use rustc_session::parse::feature_err; +use rustc_span::source_map::DUMMY_SP; +use rustc_span::symbol::{kw, Ident}; +use rustc_span::{self, BytePos, Span, Symbol}; +use rustc_target::abi::VariantIdx; +use rustc_target::spec::abi::Abi; +use rustc_trait_selection::traits::error_reporting::suggestions::ReturnsVisitor; +use std::num::NonZeroU32; + +use crate::require_c_abi_if_c_variadic; +use crate::util::common::indenter; + +use self::compare_method::collect_trait_impl_trait_tys; +use self::region::region_scope_tree; + +pub fn provide(providers: &mut Providers) { + wfcheck::provide(providers); + *providers = Providers { + adt_destructor, + check_mod_item_types, + region_scope_tree, + collect_trait_impl_trait_tys, + compare_assoc_const_impl_item_with_trait_item: compare_method::raw_compare_const_impl, + ..*providers + }; +} + +fn adt_destructor(tcx: TyCtxt<'_>, def_id: DefId) -> Option { + tcx.calculate_dtor(def_id, dropck::check_drop_impl) +} + +/// Given a `DefId` for an opaque type in return position, find its parent item's return +/// expressions. +fn get_owner_return_paths<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: LocalDefId, +) -> Option<(LocalDefId, ReturnsVisitor<'tcx>)> { + let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); + let parent_id = tcx.hir().get_parent_item(hir_id).def_id; + tcx.hir().find_by_def_id(parent_id).and_then(|node| node.body_id()).map(|body_id| { + let body = tcx.hir().body(body_id); + let mut visitor = ReturnsVisitor::default(); + visitor.visit_body(body); + (parent_id, visitor) + }) +} + +/// Forbid defining intrinsics in Rust code, +/// as they must always be defined by the compiler. +// FIXME: Move this to a more appropriate place. +pub fn fn_maybe_err(tcx: TyCtxt<'_>, sp: Span, abi: Abi) { + if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi { + tcx.sess.span_err(sp, "intrinsic must be in `extern \"rust-intrinsic\" { ... }` block"); + } +} + +fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId) { + // Only restricted on wasm target for now + if !tcx.sess.target.is_like_wasm { + return; + } + + // If `#[link_section]` is missing, then nothing to verify + let attrs = tcx.codegen_fn_attrs(id); + if attrs.link_section.is_none() { + return; + } + + // For the wasm32 target statics with `#[link_section]` are placed into custom + // sections of the final output file, but this isn't link custom sections of + // other executable formats. Namely we can only embed a list of bytes, + // nothing with provenance (pointers to anything else). If any provenance + // show up, reject it here. + // `#[link_section]` may contain arbitrary, or even undefined bytes, but it is + // the consumer's responsibility to ensure all bytes that have been read + // have defined values. + if let Ok(alloc) = tcx.eval_static_initializer(id.to_def_id()) + && alloc.inner().provenance().len() != 0 + { + let msg = "statics with a custom `#[link_section]` must be a \ + simple list of bytes on the wasm target with no \ + extra levels of indirection such as references"; + tcx.sess.span_err(tcx.def_span(id), msg); + } +} + +fn report_forbidden_specialization( + tcx: TyCtxt<'_>, + impl_item: &hir::ImplItemRef, + parent_impl: DefId, +) { + let mut err = struct_span_err!( + tcx.sess, + impl_item.span, + E0520, + "`{}` specializes an item from a parent `impl`, but \ + that item is not marked `default`", + impl_item.ident + ); + err.span_label(impl_item.span, format!("cannot specialize default item `{}`", impl_item.ident)); + + match tcx.span_of_impl(parent_impl) { + Ok(span) => { + err.span_label(span, "parent `impl` is here"); + err.note(&format!( + "to specialize, `{}` in the parent `impl` must be marked `default`", + impl_item.ident + )); + } + Err(cname) => { + err.note(&format!("parent implementation is in crate `{cname}`")); + } + } + + err.emit(); +} + +fn missing_items_err( + tcx: TyCtxt<'_>, + impl_span: Span, + missing_items: &[&ty::AssocItem], + full_impl_span: Span, +) { + let missing_items_msg = missing_items + .iter() + .map(|trait_item| trait_item.name.to_string()) + .collect::>() + .join("`, `"); + + let mut err = struct_span_err!( + tcx.sess, + impl_span, + E0046, + "not all trait items implemented, missing: `{missing_items_msg}`", + ); + err.span_label(impl_span, format!("missing `{missing_items_msg}` in implementation")); + + // `Span` before impl block closing brace. + let hi = full_impl_span.hi() - BytePos(1); + // Point at the place right before the closing brace of the relevant `impl` to suggest + // adding the associated item at the end of its body. + let sugg_sp = full_impl_span.with_lo(hi).with_hi(hi); + // Obtain the level of indentation ending in `sugg_sp`. + let padding = + tcx.sess.source_map().indentation_before(sugg_sp).unwrap_or_else(|| String::new()); + + for trait_item in missing_items { + let snippet = suggestion_signature(trait_item, tcx); + let code = format!("{}{}\n{}", padding, snippet, padding); + let msg = format!("implement the missing item: `{snippet}`"); + let appl = Applicability::HasPlaceholders; + if let Some(span) = tcx.hir().span_if_local(trait_item.def_id) { + err.span_label(span, format!("`{}` from trait", trait_item.name)); + err.tool_only_span_suggestion(sugg_sp, &msg, code, appl); + } else { + err.span_suggestion_hidden(sugg_sp, &msg, code, appl); + } + } + err.emit(); +} + +fn missing_items_must_implement_one_of_err( + tcx: TyCtxt<'_>, + impl_span: Span, + missing_items: &[Ident], + annotation_span: Option, +) { + let missing_items_msg = + missing_items.iter().map(Ident::to_string).collect::>().join("`, `"); + + let mut err = struct_span_err!( + tcx.sess, + impl_span, + E0046, + "not all trait items implemented, missing one of: `{missing_items_msg}`", + ); + err.span_label(impl_span, format!("missing one of `{missing_items_msg}` in implementation")); + + if let Some(annotation_span) = annotation_span { + err.span_note(annotation_span, "required because of this annotation"); + } + + err.emit(); +} + +fn default_body_is_unstable( + tcx: TyCtxt<'_>, + impl_span: Span, + item_did: DefId, + feature: Symbol, + reason: Option, + issue: Option, +) { + let missing_item_name = &tcx.associated_item(item_did).name; + let use_of_unstable_library_feature_note = match reason { + Some(r) => format!("use of unstable library feature '{feature}': {r}"), + None => format!("use of unstable library feature '{feature}'"), + }; + + let mut err = struct_span_err!( + tcx.sess, + impl_span, + E0046, + "not all trait items implemented, missing: `{missing_item_name}`", + ); + err.note(format!("default implementation of `{missing_item_name}` is unstable")); + err.note(use_of_unstable_library_feature_note); + rustc_session::parse::add_feature_diagnostics_for_issue( + &mut err, + &tcx.sess.parse_sess, + feature, + rustc_feature::GateIssue::Library(issue), + ); + err.emit(); +} + +/// Re-sugar `ty::GenericPredicates` in a way suitable to be used in structured suggestions. +fn bounds_from_generic_predicates<'tcx>( + tcx: TyCtxt<'tcx>, + predicates: ty::GenericPredicates<'tcx>, +) -> (String, String) { + let mut types: FxHashMap, Vec> = FxHashMap::default(); + let mut projections = vec![]; + for (predicate, _) in predicates.predicates { + debug!("predicate {:?}", predicate); + let bound_predicate = predicate.kind(); + match bound_predicate.skip_binder() { + ty::PredicateKind::Trait(trait_predicate) => { + let entry = types.entry(trait_predicate.self_ty()).or_default(); + let def_id = trait_predicate.def_id(); + if Some(def_id) != tcx.lang_items().sized_trait() { + // Type params are `Sized` by default, do not add that restriction to the list + // if it is a positive requirement. + entry.push(trait_predicate.def_id()); + } + } + ty::PredicateKind::Projection(projection_pred) => { + projections.push(bound_predicate.rebind(projection_pred)); + } + _ => {} + } + } + let generics = if types.is_empty() { + "".to_string() + } else { + format!( + "<{}>", + types + .keys() + .filter_map(|t| match t.kind() { + ty::Param(_) => Some(t.to_string()), + // Avoid suggesting the following: + // fn foo::Bar>(_: T) where T: Trait, ::Bar: Other {} + _ => None, + }) + .collect::>() + .join(", ") + ) + }; + let mut where_clauses = vec![]; + for (ty, bounds) in types { + where_clauses + .extend(bounds.into_iter().map(|bound| format!("{}: {}", ty, tcx.def_path_str(bound)))); + } + for projection in &projections { + let p = projection.skip_binder(); + // FIXME: this is not currently supported syntax, we should be looking at the `types` and + // insert the associated types where they correspond, but for now let's be "lazy" and + // propose this instead of the following valid resugaring: + // `T: Trait, Trait::Assoc = K` → `T: Trait` + where_clauses.push(format!( + "{} = {}", + tcx.def_path_str(p.projection_ty.item_def_id), + p.term, + )); + } + let where_clauses = if where_clauses.is_empty() { + String::new() + } else { + format!(" where {}", where_clauses.join(", ")) + }; + (generics, where_clauses) +} + +/// Return placeholder code for the given function. +fn fn_sig_suggestion<'tcx>( + tcx: TyCtxt<'tcx>, + sig: ty::FnSig<'tcx>, + ident: Ident, + predicates: ty::GenericPredicates<'tcx>, + assoc: &ty::AssocItem, +) -> String { + let args = sig + .inputs() + .iter() + .enumerate() + .map(|(i, ty)| { + Some(match ty.kind() { + ty::Param(_) if assoc.fn_has_self_parameter && i == 0 => "self".to_string(), + ty::Ref(reg, ref_ty, mutability) if i == 0 => { + let reg = format!("{reg} "); + let reg = match ®[..] { + "'_ " | " " => "", + reg => reg, + }; + if assoc.fn_has_self_parameter { + match ref_ty.kind() { + ty::Param(param) if param.name == kw::SelfUpper => { + format!("&{}{}self", reg, mutability.prefix_str()) + } + + _ => format!("self: {ty}"), + } + } else { + format!("_: {ty}") + } + } + _ => { + if assoc.fn_has_self_parameter && i == 0 { + format!("self: {ty}") + } else { + format!("_: {ty}") + } + } + }) + }) + .chain(std::iter::once(if sig.c_variadic { Some("...".to_string()) } else { None })) + .flatten() + .collect::>() + .join(", "); + let output = sig.output(); + let output = if !output.is_unit() { format!(" -> {output}") } else { String::new() }; + + let unsafety = sig.unsafety.prefix_str(); + let (generics, where_clauses) = bounds_from_generic_predicates(tcx, predicates); + + // FIXME: this is not entirely correct, as the lifetimes from borrowed params will + // not be present in the `fn` definition, not will we account for renamed + // lifetimes between the `impl` and the `trait`, but this should be good enough to + // fill in a significant portion of the missing code, and other subsequent + // suggestions can help the user fix the code. + format!("{unsafety}fn {ident}{generics}({args}){output}{where_clauses} {{ todo!() }}") +} + +pub fn ty_kind_suggestion(ty: Ty<'_>) -> Option<&'static str> { + Some(match ty.kind() { + ty::Bool => "true", + ty::Char => "'a'", + ty::Int(_) | ty::Uint(_) => "42", + ty::Float(_) => "3.14159", + ty::Error(_) | ty::Never => return None, + _ => "value", + }) +} + +/// Return placeholder code for the given associated item. +/// Similar to `ty::AssocItem::suggestion`, but appropriate for use as the code snippet of a +/// structured suggestion. +fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String { + match assoc.kind { + ty::AssocKind::Fn => { + // We skip the binder here because the binder would deanonymize all + // late-bound regions, and we don't want method signatures to show up + // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound + // regions just fine, showing `fn(&MyType)`. + fn_sig_suggestion( + tcx, + tcx.fn_sig(assoc.def_id).skip_binder(), + assoc.ident(tcx), + tcx.predicates_of(assoc.def_id), + assoc, + ) + } + ty::AssocKind::Type => format!("type {} = Type;", assoc.name), + ty::AssocKind::Const => { + let ty = tcx.type_of(assoc.def_id); + let val = ty_kind_suggestion(ty).unwrap_or("value"); + format!("const {}: {} = {};", assoc.name, ty, val) + } + } +} + +/// Emit an error when encountering two or more variants in a transparent enum. +fn bad_variant_count<'tcx>(tcx: TyCtxt<'tcx>, adt: ty::AdtDef<'tcx>, sp: Span, did: DefId) { + let variant_spans: Vec<_> = adt + .variants() + .iter() + .map(|variant| tcx.hir().span_if_local(variant.def_id).unwrap()) + .collect(); + let msg = format!("needs exactly one variant, but has {}", adt.variants().len(),); + let mut err = struct_span_err!(tcx.sess, sp, E0731, "transparent enum {msg}"); + err.span_label(sp, &msg); + if let [start @ .., end] = &*variant_spans { + for variant_span in start { + err.span_label(*variant_span, ""); + } + err.span_label(*end, &format!("too many variants in `{}`", tcx.def_path_str(did))); + } + err.emit(); +} + +/// Emit an error when encountering two or more non-zero-sized fields in a transparent +/// enum. +fn bad_non_zero_sized_fields<'tcx>( + tcx: TyCtxt<'tcx>, + adt: ty::AdtDef<'tcx>, + field_count: usize, + field_spans: impl Iterator, + sp: Span, +) { + let msg = format!("needs at most one non-zero-sized field, but has {field_count}"); + let mut err = struct_span_err!( + tcx.sess, + sp, + E0690, + "{}transparent {} {}", + if adt.is_enum() { "the variant of a " } else { "" }, + adt.descr(), + msg, + ); + err.span_label(sp, &msg); + for sp in field_spans { + err.span_label(sp, "this field is non-zero-sized"); + } + err.emit(); +} + +// FIXME: Consider moving this method to a more fitting place. +pub fn potentially_plural_count(count: usize, word: &str) -> String { + format!("{} {}{}", count, word, pluralize!(count)) +} -- cgit v1.2.3