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Report self parameter parsing error kind
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Self parameter parsing errors may come from different situations, which
should not be handled in the same way. It is now possible to
differentiate a missing self parameter from a self pointer or a parsing
error.

gcc/rust/ChangeLog:

	* parse/rust-parse-impl.h (Parser::parse_function): Early return on
	unrecoverable errors.
	(Parser::parse_trait_item): Likewise.
	(Parser::parse_self_param): Update return type.
	* parse/rust-parse.h (enum ParseSelfError): Add enumeration to describe
	different self parameter parsing errors.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
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P-E-P committed Nov 15, 2023
1 parent 122ffbe commit 5cbc768
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Showing 2 changed files with 56 additions and 28 deletions.
72 changes: 45 additions & 27 deletions gcc/rust/parse/rust-parse-impl.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2879,8 +2879,13 @@ Parser<ManagedTokenSource>::parse_function (AST::Visibility vis,
return nullptr;
}

std::unique_ptr<AST::Param> initial_param = parse_self_param ();
if (initial_param != nullptr)
auto initial_param = parse_self_param ();

if (!initial_param.has_value ()
&& initial_param.error () != ParseSelfError::NOT_SELF)
return nullptr;

if (initial_param.has_value ())
skip_token (COMMA);

// parse function parameters (only if next token isn't right paren)
Expand All @@ -2890,9 +2895,9 @@ Parser<ManagedTokenSource>::parse_function (AST::Visibility vis,
function_params
= parse_function_params ([] (TokenId id) { return id == RIGHT_PAREN; });

if (initial_param != nullptr)
if (initial_param.has_value ())
function_params.insert (function_params.begin (),
std::move (initial_param));
std::move (initial_param.value ()));

if (!skip_token (RIGHT_PAREN))
{
Expand Down Expand Up @@ -5060,13 +5065,15 @@ Parser<ManagedTokenSource>::parse_trait_item ()

/* now for function vs method disambiguation - method has opening
* "self" param */
std::unique_ptr<AST::Param> initial_param = parse_self_param ();
auto initial_param = parse_self_param ();
if (!initial_param.has_value () && initial_param.error () != NOT_SELF)
return nullptr;
/* FIXME: ensure that self param doesn't accidently consume tokens for
* a function */
bool is_method = false;
if (initial_param != nullptr)
if (initial_param.has_value ())
{
if (initial_param->is_self ())
if (initial_param.value ()->is_self ())
is_method = true;

/* skip comma so function and method regular params can be parsed
Expand All @@ -5086,9 +5093,9 @@ Parser<ManagedTokenSource>::parse_trait_item ()
return nullptr;
}

if (initial_param != nullptr)
if (initial_param.has_value ())
function_params.insert (function_params.begin (),
std::move (initial_param));
std::move (initial_param.value ()));

// parse return type (optional)
std::unique_ptr<AST::Type> return_type = parse_function_return_type ();
Expand Down Expand Up @@ -5605,14 +5612,18 @@ Parser<ManagedTokenSource>::parse_inherent_impl_function_or_method (

// now for function vs method disambiguation - method has opening "self"
// param
std::unique_ptr<AST::Param> initial_param = parse_self_param ();
auto initial_param = parse_self_param ();

if (!initial_param.has_value () && initial_param.error () != NOT_SELF)
return nullptr;

/* FIXME: ensure that self param doesn't accidently consume tokens for a
* function one idea is to lookahead up to 4 tokens to see whether self is
* one of them */
bool is_method = false;
if (initial_param != nullptr)
if (initial_param.has_value ())
{
if (initial_param->is_self ())
if (initial_param.value ()->is_self ())
is_method = true;

/* skip comma so function and method regular params can be parsed in
Expand All @@ -5625,9 +5636,9 @@ Parser<ManagedTokenSource>::parse_inherent_impl_function_or_method (
std::vector<std::unique_ptr<AST::Param>> function_params
= parse_function_params ([] (TokenId id) { return id == RIGHT_PAREN; });

if (initial_param != nullptr)
if (initial_param.has_value ())
function_params.insert (function_params.begin (),
std::move (initial_param));
std::move (initial_param.value ()));

if (!skip_token (RIGHT_PAREN))
{
Expand Down Expand Up @@ -5813,13 +5824,17 @@ Parser<ManagedTokenSource>::parse_trait_impl_function_or_method (

// now for function vs method disambiguation - method has opening "self"
// param
std::unique_ptr<AST::Param> initial_param = parse_self_param ();
auto initial_param = parse_self_param ();

if (!initial_param.has_value () && initial_param.error () != NOT_SELF)
return nullptr;

// FIXME: ensure that self param doesn't accidently consume tokens for a
// function
bool is_method = false;
if (initial_param != nullptr)
if (initial_param.has_value ())
{
if (initial_param->is_self ())
if (initial_param.value ()->is_self ())
is_method = true;

// skip comma so function and method regular params can be parsed in
Expand Down Expand Up @@ -5857,9 +5872,9 @@ Parser<ManagedTokenSource>::parse_trait_impl_function_or_method (
}
}

if (initial_param != nullptr)
if (initial_param.has_value ())
function_params.insert (function_params.begin (),
std::move (initial_param));
std::move (initial_param.value ()));

// DEBUG
rust_debug ("successfully parsed function params in function or method "
Expand Down Expand Up @@ -7108,7 +7123,7 @@ Parser<ManagedTokenSource>::parse_qualified_path_in_type ()

// Parses a self param. Also handles self param not existing.
template <typename ManagedTokenSource>
std::unique_ptr<AST::Param>
tl::expected<std::unique_ptr<AST::Param>, ParseSelfError>
Parser<ManagedTokenSource>::parse_self_param ()
{
bool has_reference = false;
Expand All @@ -7129,8 +7144,11 @@ Parser<ManagedTokenSource>::parse_self_param ()
if (lexer.peek_token (i)->get_id () != s[i])
break;
if (i == s.size ())
rust_error_at (lexer.peek_token ()->get_locus (),
"cannot pass %<self%> by raw pointer");
{
rust_error_at (lexer.peek_token ()->get_locus (),
"cannot pass %<self%> by raw pointer");
return tl::make_unexpected (ParseSelfError::SELF_PTR);
}
}

// Trying to find those patterns:
Expand All @@ -7150,7 +7168,7 @@ Parser<ManagedTokenSource>::parse_self_param ()
is_self = true;

if (!is_self)
return nullptr;
return tl::make_unexpected (ParseSelfError::NOT_SELF);

// test if self is a reference parameter
if (lexer.peek_token ()->get_id () == AMP)
Expand All @@ -7171,7 +7189,7 @@ Parser<ManagedTokenSource>::parse_self_param ()
add_error (std::move (error));

// skip after somewhere?
return nullptr;
return tl::make_unexpected (ParseSelfError::PARSING);
}
}
}
Expand All @@ -7189,7 +7207,7 @@ Parser<ManagedTokenSource>::parse_self_param ()
if (self_tok->get_id () != SELF)
{
// skip after somewhere?
return nullptr;
return tl::make_unexpected (ParseSelfError::NOT_SELF);
}
lexer.skip_token ();

Expand All @@ -7208,7 +7226,7 @@ Parser<ManagedTokenSource>::parse_self_param ()
add_error (std::move (error));

// skip after somewhere?
return nullptr;
return tl::make_unexpected (ParseSelfError::PARSING);
}
}

Expand All @@ -7221,7 +7239,7 @@ Parser<ManagedTokenSource>::parse_self_param ()
add_error (std::move (error));

// skip after somewhere?
return nullptr;
return tl::make_unexpected (ParseSelfError::PARSING);
}

if (has_reference)
Expand Down
12 changes: 11 additions & 1 deletion gcc/rust/parse/rust-parse.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ along with GCC; see the file COPYING3. If not see
#include "rust-ast-full.h"
#include "rust-diagnostics.h"

#include "expected.h"

namespace Rust {
/* 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
Expand Down Expand Up @@ -92,6 +94,12 @@ 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
Expand Down Expand Up @@ -334,7 +342,9 @@ template <typename ManagedTokenSource> class Parser
parse_trait_type (AST::AttrVec outer_attrs);
std::unique_ptr<AST::TraitItemConst>
parse_trait_const (AST::AttrVec outer_attrs);
std::unique_ptr<AST::Param> parse_self_param ();

tl::expected<std::unique_ptr<AST::Param>, ParseSelfError> parse_self_param ();

std::unique_ptr<AST::Impl> parse_impl (AST::Visibility vis,
AST::AttrVec outer_attrs);
std::unique_ptr<AST::InherentImplItem>
Expand Down

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