Migrate error state to optionals

gcc/rust/ChangeLog:

	* ast/rust-ast-builder.cc (Builder::self_ref_param): Remove error state
	and use optional.
	* ast/rust-ast-visitor.cc (DefaultASTVisitor::visit): Check label
	before visiting.
	* ast/rust-ast.cc (ContinueExpr::as_string): Retrieve label value.
	(Lifetime::as_string): Retrieve lifetime value.
	(ReferenceType::as_string): Likewise.
	(SelfParam::as_string): Likewise.
	* ast/rust-ast.h: Remove lifetime and LifetimeParam error state.
	* ast/rust-desugar-for-loops.cc (DesugarForLoops::DesugarCtx::make_break_arm):
	Use optional instead of error state.
	* ast/rust-expr.h (class ContinueExpr): Make label optional.
	* ast/rust-item.h (class SelfParam): Make lifetime optional.
	* ast/rust-type.h (class ReferenceType): Likewise.
	* backend/rust-compile-base.cc: Use optional for self param instead
	of error state.
	* backend/rust-compile-base.h: Update function prototype.
	* expand/rust-derive-clone.cc (DeriveClone::clone_fn): Use optional.
	* hir/rust-ast-lower-base.cc (ASTLoweringBase::lower_self): Lower
	lifetime only if it exists.
	* hir/rust-ast-lower-block.h: Lower loop label only if it exists.
	* hir/rust-ast-lower-expr.cc (ASTLoweringExpr::visit): Likewise.
	* hir/rust-ast-lower-implitem.cc (ASTLowerImplItem::visit): Remove
	references to error state.
	(ASTLowerTraitItem::visit): Lower self param only if it exists.
	* hir/rust-ast-lower-item.cc (ASTLoweringItem::visit): Use nullopt
	for default value instead of SelfParam error state.
	* hir/rust-ast-lower.cc (ASTLoweringExprWithBlock::visit): Lower label
	only if it exists.
	* hir/rust-hir-dump.cc (Dump::do_traitfunctiondecl): Print self only if
	it exists.
	(Dump::visit): Liewise.
	* hir/tree/rust-hir-bound.h: Remove error state.
	* hir/tree/rust-hir-expr.cc (ContinueExpr::ContinueExpr): Use optional
	in constructor for loop label.
	(BreakExpr::BreakExpr): Likewise.
	* hir/tree/rust-hir-expr.h (class ContinueExpr): Remove error state
	implementation.
	(class BreakExpr): Likewise.
	* hir/tree/rust-hir-generic-param.h: Likewise.
	* hir/tree/rust-hir-item.cc (SelfParam::SelfParam): Make lifetime
	optional.
	(Function::Function): Make self param optional.
	* hir/tree/rust-hir-item.h (class Function): Likewise.
	* hir/tree/rust-hir-type.cc (ReferenceType::ReferenceType): Make
	lifetime optional.
	* hir/tree/rust-hir-type.h (class ReferenceType): Likewise.
	* hir/tree/rust-hir.cc (ContinueExpr::as_string): Use new getter.
	(BreakExpr::as_string): Likewise.
	(Lifetime::as_string): Likewise.
	(ReferenceType::as_string): Likewise.
	(TraitFunctionDecl::as_string): Likewise.
	(SelfParam::as_string): Remove error state checking.
	* parse/rust-parse-impl.h (Parser::parse_generic_param): Adapt to
	optional.
	(Parser::parse_lifetime_params): Likewise.
	(Parser::parse_lifetime_params_objs): Likewise.
	(Parser::parse_lifetime_param): Likewise.
	(Parser::parse_lifetime_where_clause_item): Likewise.
	(Parser::parse_type_param_bound): Likewise.
	(Parser::parse_lifetime_bounds): Likewise.
	(Parser::parse_path_generic_args): Likewise.
	(Parser::parse_self_param): Likewise.
	(Parser::parse_break_expr): Likewise.
	(Parser::parse_continue_expr): Likewise.
	(Parser::parse_reference_type_inner): Likewise.
	* parse/rust-parse.h (class ParseLifetimeParamError): Add new class for
	lifetime param parsing errors.
	(class ParseLifetimeError): Add new class for lifetime parsing errors.
	(enum ParseSelfError): Add new class for self param parsing errors.
	* typecheck/rust-hir-type-check-implitem.cc (TypeCheckImplItem::visit):
	Use unchecked getter in checked context. And make anonymous region.
	* typecheck/rust-hir-type-check.cc (TraitItemReference::get_type_from_fn):
	Likewise.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

1 files changed, 19 insertions, 8 deletions

diff --git a/gcc/rust/parse/rust-parse.h b/gcc/rust/parse/rust-parse.h
index fc54814..5373106 100644
--- a/gcc/rust/parse/rust-parse.h
+++ b/gcc/rust/parse/rust-parse.h
@@ -25,6 +25,21 @@ along with GCC; see the file COPYING3.  If not see
 #include "expected.h"
 
 namespace Rust {
+
+class ParseLifetimeParamError
+{
+};
+
+class ParseLifetimeError
+{
+};
+enum ParseSelfError
+{
+  SELF_PTR,
+  PARSING,
+  NOT_SELF,
+};
+
 /* HACK: used to resolve the expression-or-statement problem at the end of a
  * block by allowing either to be returned (technically). Tagged union would
  * probably take up the same amount of space. */
@@ -95,12 +110,6 @@ struct ParseRestrictions
   bool allow_close_after_expr_stmt = false;
 };
 
-enum ParseSelfError
-{
-  SELF_PTR,
-  PARSING,
-  NOT_SELF,
-};
 // Parser implementation for gccrs.
 // TODO: if updated to C++20, ManagedTokenSource would be useful as a concept
 template <typename ManagedTokenSource> class Parser
@@ -277,7 +286,8 @@ private:
     ParseFunction parsing_function, EndTokenPred is_end_token,
     std::string error_msg = "failed to parse generic param in generic params")
     -> std::vector<decltype (parsing_function ())>;
-  AST::LifetimeParam parse_lifetime_param ();
+  tl::expected<AST::LifetimeParam, ParseLifetimeParamError>
+  parse_lifetime_param ();
   std::vector<std::unique_ptr<AST::TypeParam>> parse_type_params ();
   template <typename EndTokenPred>
   std::vector<std::unique_ptr<AST::TypeParam>>
@@ -306,7 +316,8 @@ private:
   std::vector<AST::Lifetime> parse_lifetime_bounds ();
   template <typename EndTokenPred>
   std::vector<AST::Lifetime> parse_lifetime_bounds (EndTokenPred is_end_token);
-  AST::Lifetime parse_lifetime (bool allow_elided);
+  tl::expected<AST::Lifetime, ParseLifetimeError>
+  parse_lifetime (bool allow_elided);
   AST::Lifetime lifetime_from_token (const_TokenPtr tok);
   std::unique_ptr<AST::ExternalTypeItem>
   parse_external_type_item (AST::Visibility vis, AST::AttrVec outer_attrs);