Rust-GCC
diff --git a/‎gcc/rust/parse/rust-parse-impl-attribute.hxx‎
Lines changed: 390 additions & 0 deletions b/‎gcc/rust/parse/rust-parse-impl-attribute.hxx‎
Lines changed: 390 additions & 0 deletions
@@ -0,0 +1,390 @@
+// Copyright (C) 2025 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/>.
+
+/* DO NOT INCLUDE ANYWHERE - this is automatically included
+ *   by rust-parse-impl*.h
+ * This is also the reason why there are no include guards. */
+
+#include "rust-parse.h"
+#include "rust-parse-error.h"
+#include "rust-attribute-values.h"
+#include "expected.h"
+
+namespace Rust {
+
+// Parse a inner or outer doc comment into an doc attribute
+template <typename ManagedTokenSource>
+Parse::AttributeBody
+Parser<ManagedTokenSource>::parse_doc_comment ()
+{
+  const_TokenPtr token = lexer.peek_token ();
+  location_t locus = token->get_locus ();
+  AST::SimplePathSegment segment (Values::Attributes::DOC, locus);
+  std::vector<AST::SimplePathSegment> segments;
+  segments.push_back (std::move (segment));
+  AST::SimplePath attr_path (std::move (segments), false, locus);
+  AST::LiteralExpr lit_expr (token->get_str (), AST::Literal::STRING,
+			     PrimitiveCoreType::CORETYPE_STR, {}, locus);
+  std::unique_ptr<AST::AttrInput> attr_input (
+    new AST::AttrInputLiteral (std::move (lit_expr)));
+  lexer.skip_token ();
+
+  return Parse::AttributeBody{std::move (attr_path), std::move (attr_input),
+			      locus};
+}
+
+// Parse a single inner attribute.
+template <typename ManagedTokenSource>
+tl::expected<AST::Attribute, Parse::Error::Attribute>
+Parser<ManagedTokenSource>::parse_inner_attribute ()
+{
+  if (lexer.peek_token ()->get_id () == INNER_DOC_COMMENT)
+    {
+      auto body = parse_doc_comment ();
+      return AST::Attribute (std::move (body.path), std::move (body.input),
+			     body.locus, true);
+    }
+
+  rust_assert (lexer.peek_token ()->get_id () == HASH);
+
+  lexer.skip_token ();
+
+  if (lexer.peek_token ()->get_id () != EXCLAM)
+    {
+      Error error (lexer.peek_token ()->get_locus (),
+		   "expected %<!%> or %<[%> for inner attribute");
+      add_error (std::move (error));
+
+      return Parse::Error::Attribute::make_malformed ();
+    }
+  lexer.skip_token ();
+
+  if (!skip_token (LEFT_SQUARE))
+    return Parse::Error::Attribute::make_malformed ();
+
+  auto body_res = parse_attribute_body ();
+  if (!body_res)
+    return Parse::Error::Attribute::make_malformed ();
+  auto body = std::move (body_res.value ());
+
+  auto actual_attribute
+    = AST::Attribute (std::move (body.path), std::move (body.input), body.locus,
+		      true);
+
+  if (!skip_token (RIGHT_SQUARE))
+    return Parse::Error::Attribute::make_malformed ();
+
+  return actual_attribute;
+}
+
+// Parse a single outer attribute.
+template <typename ManagedTokenSource>
+tl::expected<AST::Attribute, Parse::Error::Attribute>
+Parser<ManagedTokenSource>::parse_outer_attribute ()
+{
+  if (lexer.peek_token ()->get_id () == OUTER_DOC_COMMENT)
+    {
+      auto body = parse_doc_comment ();
+      return AST::Attribute (std::move (body.path), std::move (body.input),
+			     body.locus, false);
+    }
+
+  if (lexer.peek_token ()->get_id () == INNER_DOC_COMMENT)
+    {
+      Error error (
+	lexer.peek_token ()->get_locus (), ErrorCode::E0753,
+	"expected outer doc comment, inner doc (%<//!%> or %</*!%>) only "
+	"allowed at start of item "
+	"and before any outer attribute or doc (%<#[%>, %<///%> or %</**%>)");
+      add_error (std::move (error));
+      lexer.skip_token ();
+      return Parse::Error::Attribute::make_unexpected_inner ();
+    }
+
+  /* OuterAttribute -> '#' '[' Attr ']' */
+
+  if (lexer.peek_token ()->get_id () != HASH)
+    return Parse::Error::Attribute::make_malformed ();
+
+  lexer.skip_token ();
+
+  TokenId id = lexer.peek_token ()->get_id ();
+  if (id != LEFT_SQUARE)
+    {
+      if (id == EXCLAM)
+	{
+	  // this is inner attribute syntax, so throw error
+	  // inner attributes were either already parsed or not allowed here.
+	  Error error (
+	    lexer.peek_token ()->get_locus (),
+	    "token %<!%> found, indicating inner attribute definition. Inner "
+	    "attributes are not possible at this location");
+	  add_error (std::move (error));
+	}
+      return Parse::Error::Attribute::make_unexpected_inner ();
+    }
+
+  lexer.skip_token ();
+
+  auto body_res = parse_attribute_body ();
+  if (!body_res)
+    return Parse::Error::Attribute::make_malformed_body ();
+  auto body = std::move (body_res.value ());
+
+  auto actual_attribute
+    = AST::Attribute (std::move (body.path), std::move (body.input), body.locus,
+		      false);
+
+  if (lexer.peek_token ()->get_id () != RIGHT_SQUARE)
+    return Parse::Error::Attribute::make_malformed ();
+
+  lexer.skip_token ();
+
+  return actual_attribute;
+}
+
+// Parses the body of an attribute (inner or outer).
+template <typename ManagedTokenSource>
+tl::expected<Parse::AttributeBody, Parse::Error::AttributeBody>
+Parser<ManagedTokenSource>::parse_attribute_body ()
+{
+  location_t locus = lexer.peek_token ()->get_locus ();
+
+  auto attr_path = parse_simple_path ();
+  // ensure path is valid to parse attribute input
+  if (!attr_path)
+    {
+      Error error (lexer.peek_token ()->get_locus (),
+		   "empty simple path in attribute");
+      add_error (std::move (error));
+
+      // Skip past potential further info in attribute (i.e. attr_input)
+      skip_after_end_attribute ();
+      return Parse::Error::AttributeBody::make_invalid_path ();
+    }
+
+  auto attr_input = parse_attr_input ();
+  // AttrInput is allowed to be null, so no checks here
+  if (attr_input)
+    return Parse::AttributeBody{std::move (attr_path.value ()),
+				std::move (attr_input.value ()), locus};
+  else if (attr_input.error ().kind == Parse::Error::AttrInput::Kind::MISSING)
+    return Parse::AttributeBody{std::move (attr_path.value ()), nullptr, locus};
+  else
+    return Parse::Error::AttributeBody::make_invalid_attrinput ();
+}
+
+// Parse a contiguous block of inner attributes.
+template <typename ManagedTokenSource>
+AST::AttrVec
+Parser<ManagedTokenSource>::parse_inner_attributes ()
+{
+  AST::AttrVec inner_attributes;
+
+  auto has_valid_inner_attribute_prefix = [&] () {
+    auto id = lexer.peek_token ()->get_id ();
+    /* Outer attribute `#[` is not allowed, only accepts `#!` */
+    return (id == HASH && lexer.peek_token (1)->get_id () == EXCLAM)
+	   || id == INNER_DOC_COMMENT;
+  };
+
+  while (has_valid_inner_attribute_prefix ())
+    {
+      auto inner_attr = parse_inner_attribute ();
+
+      /* Ensure only valid inner attributes are added to the inner_attributes
+       * list */
+      if (inner_attr)
+	{
+	  inner_attributes.push_back (std::move (inner_attr.value ()));
+	}
+      else
+	{
+	  /* If no more valid inner attributes, break out of loop (only
+	   * contiguous inner attributes parsed). */
+	  break;
+	}
+    }
+
+  inner_attributes.shrink_to_fit ();
+  return inner_attributes;
+}
+
+// Parses a contiguous block of outer attributes.
+template <typename ManagedTokenSource>
+AST::AttrVec
+Parser<ManagedTokenSource>::parse_outer_attributes ()
+{
+  AST::AttrVec outer_attributes;
+
+  auto has_valid_attribute_prefix = [&] () {
+    auto id = lexer.peek_token ()->get_id ();
+    /* We allow inner attributes `#!` and catch the error later  */
+    return id == HASH || id == OUTER_DOC_COMMENT || id == INNER_DOC_COMMENT;
+  };
+
+  while (has_valid_attribute_prefix ()) /* For error handling.  */
+    {
+      auto outer_attr = parse_outer_attribute ();
+
+      /* Ensure only valid outer attributes are added to the outer_attributes
+       * list */
+      if (outer_attr)
+	{
+	  outer_attributes.push_back (std::move (outer_attr.value ()));
+	}
+      else
+	{
+	  /* If no more valid outer attributes, break out of loop (only
+	   * contiguous outer attributes parsed). */
+	  break;
+	}
+    }
+
+  outer_attributes.shrink_to_fit ();
+  return outer_attributes;
+
+  /* TODO: this shares basically all code with parse_inner_attributes except
+   * function call - find way of making it more modular? function pointer? */
+}
+
+// Parses an AttrInput AST node (polymorphic, as AttrInput is abstract)
+template <typename ManagedTokenSource>
+tl::expected<std::unique_ptr<AST::AttrInput>, Parse::Error::AttrInput>
+Parser<ManagedTokenSource>::parse_attr_input ()
+{
+  const_TokenPtr t = lexer.peek_token ();
+  switch (t->get_id ())
+    {
+    case LEFT_PAREN:
+    case LEFT_SQUARE:
+    case LEFT_CURLY:
+      {
+	auto dtoken_tree = parse_delim_token_tree ();
+	if (!dtoken_tree)
+	  return Parse::Error::AttrInput::make_bad_token_tree ();
+
+	// must be a delimited token tree, so parse that
+	std::unique_ptr<AST::AttrInput> input_tree (
+	  new AST::DelimTokenTree (dtoken_tree.value ()));
+
+	return tl::expected<std::unique_ptr<AST::AttrInput>,
+			    Parse::Error::AttrInput>{std::move (input_tree)};
+      }
+    case EQUAL:
+      {
+	// = LiteralExpr
+	lexer.skip_token ();
+
+	t = lexer.peek_token ();
+
+	// attempt to parse macro
+	// TODO: macros may/may not be allowed in attributes
+	// this is needed for "#[doc = include_str!(...)]"
+	if (Parse::Utils::is_simple_path_segment (t->get_id ()))
+	  {
+	    std::unique_ptr<AST::MacroInvocation> invoke
+	      = parse_macro_invocation ({});
+
+	    if (!invoke)
+	      return Parse::Error::AttrInput::make_bad_macro_invocation ();
+
+	    return std::unique_ptr<AST::AttrInput> (
+	      new AST::AttrInputMacro (std::move (invoke)));
+	  }
+
+	/* Ensure token is a "literal expression" (literally only a literal
+	 * token of any type) */
+	if (!t->is_literal ())
+	  {
+	    Error error (
+	      t->get_locus (),
+	      "unknown token %qs in attribute body - literal expected",
+	      t->get_token_description ());
+	    add_error (std::move (error));
+
+	    skip_after_end_attribute ();
+	    return Parse::Error::AttrInput::make_malformed ();
+	  }
+
+	AST::Literal::LitType lit_type = AST::Literal::STRING;
+	// Crappy mapping of token type to literal type
+	switch (t->get_id ())
+	  {
+	  case INT_LITERAL:
+	    lit_type = AST::Literal::INT;
+	    break;
+	  case FLOAT_LITERAL:
+	    lit_type = AST::Literal::FLOAT;
+	    break;
+	  case CHAR_LITERAL:
+	    lit_type = AST::Literal::CHAR;
+	    break;
+	  case BYTE_CHAR_LITERAL:
+	    lit_type = AST::Literal::BYTE;
+	    break;
+	  case BYTE_STRING_LITERAL:
+	    lit_type = AST::Literal::BYTE_STRING;
+	    break;
+	  case RAW_STRING_LITERAL:
+	    lit_type = AST::Literal::RAW_STRING;
+	    break;
+	  case STRING_LITERAL:
+	  default:
+	    lit_type = AST::Literal::STRING;
+	    break; // TODO: raw string? don't eliminate it from lexer?
+	  }
+
+	// create actual LiteralExpr
+	AST::LiteralExpr lit_expr (t->get_str (), lit_type, t->get_type_hint (),
+				   {}, t->get_locus ());
+	lexer.skip_token ();
+
+	std::unique_ptr<AST::AttrInput> attr_input_lit (
+	  new AST::AttrInputLiteral (std::move (lit_expr)));
+
+	// do checks or whatever? none required, really
+
+	// FIXME: shouldn't a skip token be required here?
+
+	return tl::expected<std::unique_ptr<AST::AttrInput>,
+			    Parse::Error::AttrInput>{
+	  std::move (attr_input_lit)};
+      }
+      break;
+    case RIGHT_PAREN:
+    case RIGHT_SQUARE:
+    case RIGHT_CURLY:
+    case END_OF_FILE:
+      // means AttrInput is missing, which is allowed
+      return Parse::Error::AttrInput::make_missing_attrinput ();
+    default:
+      add_error (
+	Error (t->get_locus (),
+	       "unknown token %qs in attribute body - attribute input or "
+	       "none expected",
+	       t->get_token_description ()));
+
+      skip_after_end_attribute ();
+      return Parse::Error::AttrInput::make_malformed ();
+    }
+  rust_unreachable ();
+  // TODO: find out how to stop gcc error on "no return value"
+}
+
+} // namespace Rust