gccrs: Add name resolution pass to the Rust front-end

The name resolution is split into two phases, one toplevel pass which scans
the whole "Crate" which iterates all items and nested items in modules to
generate a context class full of CanonicalPath items. It also generates
a hierarchy of parent->child and child->parent relationships using the AST
NodeId for PathResolution in the second phase.

The second phase drills into each item like functions and creates a stack
of canonical paths for variables etc so that we can store information in
a side table of usage variable 'a' resolves to NodeId '123' which refers
to the NodeId of the "let a;" statement.

	gcc/rust/
	* resolve/rust-ast-resolve-base.cc: New.
	* resolve/rust-ast-resolve-base.h: New.
	* resolve/rust-ast-resolve-expr.cc: New.
	* resolve/rust-ast-resolve-expr.h: New.
	* resolve/rust-ast-resolve-implitem.h: New.
	* resolve/rust-ast-resolve-item.cc: New.
	* resolve/rust-ast-resolve-item.h: New.
	* resolve/rust-ast-resolve-path.cc: New.
	* resolve/rust-ast-resolve-path.h: New.
	* resolve/rust-ast-resolve-pattern.cc: New.
	* resolve/rust-ast-resolve-pattern.h: New.
	* resolve/rust-ast-resolve-stmt.cc: New.
	* resolve/rust-ast-resolve-stmt.h: New.
	* resolve/rust-ast-resolve-struct-expr-field.cc: New.
	* resolve/rust-ast-resolve-struct-expr-field.h: New.
	* resolve/rust-ast-resolve-toplevel.h: New.
	* resolve/rust-ast-resolve-type.cc: New.
	* resolve/rust-ast-resolve-type.h: New.
	* resolve/rust-ast-resolve.cc: New.
	* resolve/rust-ast-resolve.h: New.
	* resolve/rust-ast-verify-assignee.h: New.
	* resolve/rust-name-resolver.cc: New.
	* resolve/rust-name-resolver.h: New.

1 files changed, 221 insertions, 0 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve-base.h b/gcc/rust/resolve/rust-ast-resolve-base.h
new file mode 100644
index 0000000..32f30bc
--- /dev/null
+++ b/gcc/rust/resolve/rust-ast-resolve-base.h
@@ -0,0 +1,221 @@
+// Copyright (C) 2020-2022 Free Software Foundation, Inc.
+
+// This file is part of GCC.
+
+// GCC is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free
+// Software Foundation; either version 3, or (at your option) any later
+// version.
+
+// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+// for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with GCC; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef RUST_AST_RESOLVE_BASE_H
+#define RUST_AST_RESOLVE_BASE_H
+
+#include "rust-ast-visitor.h"
+#include "rust-name-resolver.h"
+#include "rust-diagnostics.h"
+#include "rust-location.h"
+
+namespace Rust {
+namespace Resolver {
+
+class ResolverBase : public AST::ASTVisitor
+{
+public:
+  virtual ~ResolverBase () {}
+
+  void visit (AST::Token &);
+  void visit (AST::DelimTokenTree &);
+  void visit (AST::AttrInputMetaItemContainer &);
+  void visit (AST::IdentifierExpr &);
+  void visit (AST::Lifetime &);
+  void visit (AST::LifetimeParam &);
+  void visit (AST::ConstGenericParam &);
+  void visit (AST::PathInExpression &);
+  void visit (AST::TypePathSegment &);
+  void visit (AST::TypePathSegmentGeneric &);
+  void visit (AST::TypePathSegmentFunction &);
+  void visit (AST::TypePath &);
+  void visit (AST::QualifiedPathInExpression &);
+  void visit (AST::QualifiedPathInType &);
+  void visit (AST::LiteralExpr &);
+  void visit (AST::AttrInputLiteral &);
+  void visit (AST::MetaItemLitExpr &);
+  void visit (AST::MetaItemPathLit &);
+  void visit (AST::BorrowExpr &);
+  void visit (AST::DereferenceExpr &);
+  void visit (AST::ErrorPropagationExpr &);
+  void visit (AST::NegationExpr &);
+  void visit (AST::ArithmeticOrLogicalExpr &);
+  void visit (AST::ComparisonExpr &);
+  void visit (AST::LazyBooleanExpr &);
+  void visit (AST::TypeCastExpr &);
+  void visit (AST::AssignmentExpr &);
+  void visit (AST::CompoundAssignmentExpr &);
+  void visit (AST::GroupedExpr &);
+  void visit (AST::ArrayElemsValues &);
+  void visit (AST::ArrayElemsCopied &);
+  void visit (AST::ArrayExpr &);
+  void visit (AST::ArrayIndexExpr &);
+  void visit (AST::TupleExpr &);
+  void visit (AST::TupleIndexExpr &);
+  void visit (AST::StructExprStruct &);
+  void visit (AST::StructExprFieldIdentifier &);
+  void visit (AST::StructExprFieldIdentifierValue &);
+  void visit (AST::StructExprFieldIndexValue &);
+  void visit (AST::StructExprStructFields &);
+  void visit (AST::StructExprStructBase &);
+  void visit (AST::CallExpr &);
+  void visit (AST::MethodCallExpr &);
+  void visit (AST::FieldAccessExpr &);
+  void visit (AST::ClosureExprInner &);
+  void visit (AST::BlockExpr &);
+  void visit (AST::ClosureExprInnerTyped &);
+  void visit (AST::ContinueExpr &);
+  void visit (AST::BreakExpr &);
+  void visit (AST::RangeFromToExpr &);
+  void visit (AST::RangeFromExpr &);
+  void visit (AST::RangeToExpr &);
+  void visit (AST::RangeFullExpr &);
+  void visit (AST::RangeFromToInclExpr &);
+  void visit (AST::RangeToInclExpr &);
+  void visit (AST::ReturnExpr &);
+  void visit (AST::UnsafeBlockExpr &);
+  void visit (AST::LoopExpr &);
+  void visit (AST::WhileLoopExpr &);
+  void visit (AST::WhileLetLoopExpr &);
+  void visit (AST::ForLoopExpr &);
+  void visit (AST::IfExpr &);
+  void visit (AST::IfExprConseqElse &);
+  void visit (AST::IfExprConseqIf &);
+  void visit (AST::IfExprConseqIfLet &);
+  void visit (AST::IfLetExpr &);
+  void visit (AST::IfLetExprConseqElse &);
+  void visit (AST::IfLetExprConseqIf &);
+  void visit (AST::IfLetExprConseqIfLet &);
+
+  void visit (AST::MatchExpr &);
+  void visit (AST::AwaitExpr &);
+  void visit (AST::AsyncBlockExpr &);
+
+  void visit (AST::TypeParam &);
+
+  void visit (AST::LifetimeWhereClauseItem &);
+  void visit (AST::TypeBoundWhereClauseItem &);
+  void visit (AST::Method &);
+  void visit (AST::Module &);
+  void visit (AST::ExternCrate &);
+
+  void visit (AST::UseTreeGlob &);
+  void visit (AST::UseTreeList &);
+  void visit (AST::UseTreeRebind &);
+  void visit (AST::UseDeclaration &);
+  void visit (AST::Function &);
+  void visit (AST::TypeAlias &);
+  void visit (AST::StructStruct &);
+  void visit (AST::TupleStruct &);
+  void visit (AST::EnumItem &);
+  void visit (AST::EnumItemTuple &);
+  void visit (AST::EnumItemStruct &);
+  void visit (AST::EnumItemDiscriminant &);
+  void visit (AST::Enum &);
+  void visit (AST::Union &);
+  void visit (AST::ConstantItem &);
+  void visit (AST::StaticItem &);
+  void visit (AST::TraitItemFunc &);
+  void visit (AST::TraitItemMethod &);
+  void visit (AST::TraitItemConst &);
+  void visit (AST::TraitItemType &);
+  void visit (AST::Trait &);
+  void visit (AST::InherentImpl &);
+  void visit (AST::TraitImpl &);
+
+  void visit (AST::ExternalStaticItem &);
+  void visit (AST::ExternalFunctionItem &);
+  void visit (AST::ExternBlock &);
+
+  void visit (AST::MacroMatchFragment &);
+  void visit (AST::MacroMatchRepetition &);
+  void visit (AST::MacroMatcher &);
+  void visit (AST::MacroRulesDefinition &);
+  void visit (AST::MacroInvocation &);
+  void visit (AST::MetaItemPath &);
+  void visit (AST::MetaItemSeq &);
+  void visit (AST::MetaWord &);
+  void visit (AST::MetaNameValueStr &);
+  void visit (AST::MetaListPaths &);
+  void visit (AST::MetaListNameValueStr &);
+
+  void visit (AST::LiteralPattern &);
+  void visit (AST::IdentifierPattern &);
+  void visit (AST::WildcardPattern &);
+
+  void visit (AST::RangePatternBoundLiteral &);
+  void visit (AST::RangePatternBoundPath &);
+  void visit (AST::RangePatternBoundQualPath &);
+  void visit (AST::RangePattern &);
+  void visit (AST::ReferencePattern &);
+
+  void visit (AST::StructPatternFieldTuplePat &);
+  void visit (AST::StructPatternFieldIdentPat &);
+  void visit (AST::StructPatternFieldIdent &);
+  void visit (AST::StructPattern &);
+
+  void visit (AST::TupleStructItemsNoRange &);
+  void visit (AST::TupleStructItemsRange &);
+  void visit (AST::TupleStructPattern &);
+
+  void visit (AST::TuplePatternItemsMultiple &);
+  void visit (AST::TuplePatternItemsRanged &);
+  void visit (AST::TuplePattern &);
+  void visit (AST::GroupedPattern &);
+  void visit (AST::SlicePattern &);
+
+  void visit (AST::EmptyStmt &);
+  void visit (AST::LetStmt &);
+  void visit (AST::ExprStmtWithoutBlock &);
+  void visit (AST::ExprStmtWithBlock &);
+
+  void visit (AST::TraitBound &);
+  void visit (AST::ImplTraitType &);
+  void visit (AST::TraitObjectType &);
+  void visit (AST::ParenthesisedType &);
+  void visit (AST::ImplTraitTypeOneBound &);
+  void visit (AST::TraitObjectTypeOneBound &);
+  void visit (AST::TupleType &);
+  void visit (AST::NeverType &);
+  void visit (AST::RawPointerType &);
+  void visit (AST::ReferenceType &);
+  void visit (AST::ArrayType &);
+  void visit (AST::SliceType &);
+  void visit (AST::InferredType &);
+  void visit (AST::BareFunctionType &);
+
+protected:
+  ResolverBase ()
+    : resolver (Resolver::get ()), mappings (Analysis::Mappings::get ()),
+      resolved_node (UNKNOWN_NODEID)
+  {}
+
+  /**
+   * Resolve a visibility's path through the name resolver
+   */
+  bool resolve_visibility (const AST::Visibility &vis);
+
+  Resolver *resolver;
+  Analysis::Mappings *mappings;
+  NodeId resolved_node;
+};
+
+} // namespace Resolver
+} // namespace Rust
+
+#endif // RUST_AST_RESOLVE_BASE_H