Merge from trunk revision aa8f4242efc99f24de73c59d53996f28db28c13f.

1 files changed, 1246 insertions, 0 deletions

diff --git a/gcc/rust/rust-session-manager.cc b/gcc/rust/rust-session-manager.cc
new file mode 100644
index 0000000..732aabe
--- /dev/null
+++ b/gcc/rust/rust-session-manager.cc
@@ -0,0 +1,1246 @@
+// Copyright (C) 2020-2023 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/>.
+
+#include "rust-session-manager.h"
+#include "rust-diagnostics.h"
+#include "rust-unsafe-checker.h"
+#include "rust-lex.h"
+#include "rust-parse.h"
+#include "rust-macro-expand.h"
+#include "rust-ast-resolve.h"
+#include "rust-ast-lower.h"
+#include "rust-hir-type-check.h"
+#include "rust-privacy-check.h"
+#include "rust-const-checker.h"
+#include "rust-tycheck-dump.h"
+#include "rust-compile.h"
+#include "rust-cfg-parser.h"
+#include "rust-lint-scan-deadcode.h"
+#include "rust-lint-unused-var.h"
+#include "rust-hir-dump.h"
+#include "rust-ast-dump.h"
+#include "rust-export-metadata.h"
+#include "rust-imports.h"
+#include "rust-extern-crate.h"
+#include "rust-attributes.h"
+#include "rust-early-name-resolver.h"
+
+#include "diagnostic.h"
+#include "input.h"
+#include "selftest.h"
+#include "target.h"
+
+extern bool
+saw_errors (void);
+
+extern Linemap *
+rust_get_linemap ();
+
+extern Backend *
+rust_get_backend ();
+
+namespace Rust {
+
+const char *kLexDumpFile = "gccrs.lex.dump";
+const char *kASTDumpFile = "gccrs.ast.dump";
+const char *kASTPrettyDumpFile = "gccrs.ast-pretty.dump";
+const char *kASTPrettyDumpFileExpanded = "gccrs.ast-pretty-expanded.dump";
+const char *kASTExpandedDumpFile = "gccrs.ast-expanded.dump";
+const char *kHIRDumpFile = "gccrs.hir.dump";
+const char *kHIRPrettyDumpFile = "gccrs.hir-pretty.dump";
+const char *kHIRTypeResolutionDumpFile = "gccrs.type-resolution.dump";
+const char *kTargetOptionsDumpFile = "gccrs.target-options.dump";
+
+const std::string kDefaultCrateName = "rust_out";
+const size_t kMaxNameLength = 64;
+
+Session &
+Session::get_instance ()
+{
+  static Session instance;
+  return instance;
+}
+
+static std::string
+infer_crate_name (const std::string &filename)
+{
+  if (filename == "-")
+    return kDefaultCrateName;
+
+  std::string crate = std::string (filename);
+  size_t path_sep = crate.find_last_of (file_separator);
+
+  // find the base filename
+  if (path_sep != std::string::npos)
+    crate.erase (0, path_sep + 1);
+
+  // find the file stem name (remove file extension)
+  size_t ext_position = crate.find_last_of ('.');
+  if (ext_position != std::string::npos)
+    crate.erase (ext_position);
+
+  // Replace all the '-' symbols with '_' per Rust rules
+  for (auto &c : crate)
+    {
+      if (c == '-')
+	c = '_';
+    }
+  return crate;
+}
+
+/* Validate the crate name using the ASCII rules
+   TODO: Support Unicode version of the rules */
+
+static bool
+validate_crate_name (const std::string &crate_name, Error &error)
+{
+  if (crate_name.empty ())
+    {
+      error = Error (Location (), "crate name cannot be empty");
+      return false;
+    }
+  if (crate_name.length () > kMaxNameLength)
+    {
+      error = Error (Location (), "crate name cannot exceed %lu characters",
+		     (unsigned long) kMaxNameLength);
+      return false;
+    }
+  for (auto &c : crate_name)
+    {
+      if (!(ISALNUM (c) || c == '_'))
+	{
+	  error = Error (Location (),
+			 "invalid character %<%c%> in crate name: %<%s%>", c,
+			 crate_name.c_str ());
+	  return false;
+	}
+    }
+  return true;
+}
+
+void
+Session::init ()
+{
+  options.target_data.insert_key_value_pair ("target_pointer_width",
+					     std::to_string (POINTER_SIZE));
+  options.target_data.insert_key_value_pair ("target_endian", BYTES_BIG_ENDIAN
+								? "big"
+								: "little");
+
+  // setup singleton linemap
+  linemap = rust_get_linemap ();
+
+  // setup backend to GCC GIMPLE
+  backend = rust_get_backend ();
+
+  // setup mappings class
+  mappings = Analysis::Mappings::get ();
+}
+
+/* Initialise default options. Actually called before handle_option, unlike init
+ * itself. */
+void
+Session::init_options ()
+{}
+
+// Handle option selection.
+bool
+Session::handle_option (
+  enum opt_code code, const char *arg, HOST_WIDE_INT value ATTRIBUTE_UNUSED,
+  int kind ATTRIBUTE_UNUSED, location_t loc ATTRIBUTE_UNUSED,
+  const struct cl_option_handlers *handlers ATTRIBUTE_UNUSED)
+{
+  // used to store whether results of various stuff are successful
+  bool ret = true;
+
+  // Handles options as listed in lang.opt.
+  switch (code)
+    {
+    case OPT_I:
+      case OPT_L: {
+	// TODO: add search path
+	const std::string p = std::string (arg);
+	add_search_path (p);
+      }
+      break;
+
+    case OPT_frust_crate_:
+      // set the crate name
+      if (arg != nullptr)
+	{
+	  auto error = Error (Location (), std::string ());
+	  if ((ret = validate_crate_name (arg, error)))
+	    {
+	      options.set_crate_name (arg);
+	      options.crate_name_set_manually = true;
+	    }
+	  else
+	    {
+	      rust_assert (!error.message.empty ());
+	      error.emit_error ();
+	    }
+	}
+      else
+	ret = false;
+      break;
+
+    case OPT_frust_dump_:
+      // enable dump and return whether this was successful
+      if (arg != nullptr)
+	{
+	  ret = enable_dump (std::string (arg));
+	}
+      else
+	{
+	  ret = false;
+	}
+      break;
+
+    case OPT_frust_mangling_:
+      Compile::Mangler::set_mangling (flag_rust_mangling);
+      break;
+
+      case OPT_frust_cfg_: {
+	auto string_arg = std::string (arg);
+	ret = handle_cfg_option (string_arg);
+	break;
+      }
+
+    case OPT_frust_edition_:
+      options.set_edition (flag_rust_edition);
+      break;
+    case OPT_frust_compile_until_:
+      options.set_compile_step (flag_rust_compile_until);
+      break;
+    case OPT_frust_metadata_output_:
+      options.set_metadata_output (arg);
+      break;
+
+    default:
+      break;
+    }
+
+  return ret;
+}
+
+bool
+Session::handle_cfg_option (std::string &input)
+{
+  std::string key;
+  std::string value;
+
+  // Refactor this if needed
+  if (!parse_cfg_option (input, key, value))
+    {
+      rust_error_at (
+	Location (),
+	"invalid argument to %<-frust-cfg%>: Accepted formats are "
+	"%<-frust-cfg=key%> or %<-frust-cfg=key=\"value\"%> (quoted)");
+      return false;
+    }
+
+  if (value.empty ())
+    // rustc does not seem to error on dup key
+    options.target_data.insert_key (key);
+  else
+    options.target_data.insert_key_value_pair (key, value);
+
+  return true;
+}
+
+/* Enables a certain dump depending on the name passed in. Returns true if
+ * name is valid, false otherwise. */
+bool
+Session::enable_dump (std::string arg)
+{
+  if (arg.empty ())
+    {
+      rust_error_at (
+	Location (),
+	"dump option was not given a name. choose %<lex%>, %<parse%>, "
+	"%<register_plugins%>, %<injection%>, %<expansion%>, %<resolution%>,"
+	" %<target_options%>, %<hir%>, or %<all%>");
+      return false;
+    }
+
+  if (arg == "all")
+    {
+      options.enable_all_dump_options ();
+    }
+  else if (arg == "lex")
+    {
+      options.enable_dump_option (CompileOptions::LEXER_DUMP);
+    }
+  else if (arg == "parse")
+    {
+      options.enable_dump_option (CompileOptions::PARSER_AST_DUMP);
+    }
+  else if (arg == "ast-pretty")
+    {
+      options.enable_dump_option (CompileOptions::AST_DUMP_PRETTY);
+    }
+  else if (arg == "register_plugins")
+    {
+      options.enable_dump_option (CompileOptions::REGISTER_PLUGINS_DUMP);
+    }
+  else if (arg == "injection")
+    {
+      options.enable_dump_option (CompileOptions::INJECTION_DUMP);
+    }
+  else if (arg == "expansion")
+    {
+      options.enable_dump_option (CompileOptions::EXPANSION_DUMP);
+    }
+  else if (arg == "resolution")
+    {
+      options.enable_dump_option (CompileOptions::RESOLUTION_DUMP);
+    }
+  else if (arg == "target_options")
+    {
+      options.enable_dump_option (CompileOptions::TARGET_OPTION_DUMP);
+    }
+  else if (arg == "hir")
+    {
+      options.enable_dump_option (CompileOptions::HIR_DUMP);
+    }
+  else if (arg == "hir-pretty")
+    {
+      options.enable_dump_option (CompileOptions::HIR_DUMP_PRETTY);
+    }
+  else
+    {
+      rust_error_at (
+	Location (),
+	"dump option %qs was unrecognised. choose %<lex%>, %<parse%>, "
+	"%<register_plugins%>, %<injection%>, %<expansion%>, %<resolution%>,"
+	" %<target_options%>, or %<hir%>",
+	arg.c_str ());
+      return false;
+    }
+  return true;
+}
+
+/* Actual main entry point for front-end. Called from langhook to parse files.
+ */
+void
+Session::handle_input_files (int num_files, const char **files)
+{
+  if (num_files != 1)
+    rust_fatal_error (Location (),
+		      "only one file may be specified on the command line");
+
+  const auto &file = files[0];
+
+  if (options.crate_name.empty ())
+    {
+      auto filename = "-";
+      if (num_files > 0)
+	filename = files[0];
+
+      auto crate_name = infer_crate_name (filename);
+      rust_debug ("inferred crate name: %s", crate_name.c_str ());
+      // set the preliminary crate name here
+      // we will figure out the real crate name in `handle_crate_name`
+      options.set_crate_name (crate_name);
+    }
+
+  CrateNum crate_num = mappings->get_next_crate_num (options.get_crate_name ());
+  mappings->set_current_crate (crate_num);
+
+  rust_debug ("Attempting to parse file: %s", file);
+  compile_crate (file);
+}
+
+void
+Session::handle_crate_name (const AST::Crate &parsed_crate)
+{
+  auto mappings = Analysis::Mappings::get ();
+  auto crate_name_changed = false;
+  auto error = Error (Location (), std::string ());
+
+  for (const auto &attr : parsed_crate.inner_attrs)
+    {
+      if (attr.get_path () != "crate_name")
+	continue;
+      if (!attr.has_attr_input ())
+	{
+	  rust_error_at (attr.get_locus (),
+			 "%<crate_name%> accepts one argument");
+	  continue;
+	}
+
+      auto &literal
+	= static_cast<AST::AttrInputLiteral &> (attr.get_attr_input ());
+      const auto &msg_str = literal.get_literal ().as_string ();
+      if (!validate_crate_name (msg_str, error))
+	{
+	  error.locus = attr.get_locus ();
+	  error.emit_error ();
+	  continue;
+	}
+
+      auto options = Session::get_instance ().options;
+      if (options.crate_name_set_manually && (options.crate_name != msg_str))
+	{
+	  rust_error_at (attr.get_locus (),
+			 "%<-frust-crate-name%> and %<#[crate_name]%> are "
+			 "required to match, but %qs does not match %qs",
+			 options.crate_name.c_str (), msg_str.c_str ());
+	}
+      crate_name_changed = true;
+      options.set_crate_name (msg_str);
+      mappings->set_crate_name (mappings->get_current_crate (), msg_str);
+    }
+
+  options.crate_name_set_manually |= crate_name_changed;
+  if (!options.crate_name_set_manually
+      && !validate_crate_name (options.crate_name, error))
+    {
+      error.emit_error ();
+      rust_inform (linemap->get_location (0),
+		   "crate name inferred from this file");
+    }
+}
+
+// Parses a single file with filename filename.
+void
+Session::compile_crate (const char *filename)
+{
+  if (!flag_rust_experimental
+      && !std::getenv ("GCCRS_INCOMPLETE_AND_EXPERIMENTAL_COMPILER_DO_NOT_USE"))
+    rust_fatal_error (
+      Location (), "%s",
+      "gccrs is not yet able to compile Rust code "
+      "properly. Most of the errors produced will be gccrs' fault and not the "
+      "crate you are trying to compile. Because of this, please reports issues "
+      "to us directly instead of opening issues on said crate's "
+      "repository.\n\nOur github repository: "
+      "https://github.com/rust-gcc/gccrs\nOur bugzilla tracker: "
+      "https://gcc.gnu.org/bugzilla/"
+      "buglist.cgi?bug_status=__open__&component=rust&product=gcc\n\n"
+      "If you understand this, and understand that the binaries produced might "
+      "not behave accordingly, you may attempt to use gccrs in an experimental "
+      "manner by passing the following flag:\n\n"
+      "`-frust-incomplete-and-experimental-compiler-do-not-use`\n\nor by "
+      "defining the following environment variable (any value will "
+      "do)\n\nGCCRS_INCOMPLETE_AND_EXPERIMENTAL_COMPILER_DO_NOT_USE\n\nFor"
+      "cargo-gccrs, this means passing\n\n"
+      "GCCRS_EXTRA_FLAGS=\"-frust-incomplete-and-experimental-compiler-do-not-"
+      "use\"\n\nas an environment variable.");
+
+  RAIIFile file_wrap (filename);
+  if (!file_wrap.ok ())
+    {
+      rust_error_at (Location (), "cannot open filename %s: %m", filename);
+      return;
+    }
+
+  auto last_step = options.get_compile_until ();
+
+  // parse file here
+  /* create lexer and parser - these are file-specific and so aren't instance
+   * variables */
+  Optional<std::ofstream &> dump_lex_opt = Optional<std::ofstream &>::none ();
+  std::ofstream dump_lex_stream;
+  if (options.dump_option_enabled (CompileOptions::LEXER_DUMP))
+    {
+      dump_lex_stream.open (kLexDumpFile);
+      if (dump_lex_stream.fail ())
+	{
+	  rust_error_at (Linemap::unknown_location (),
+			 "cannot open %s:%m; ignored", kLexDumpFile);
+	}
+      auto stream = Optional<std::ofstream &>::some (dump_lex_stream);
+      dump_lex_opt = std::move (stream);
+    }
+
+  Lexer lex (filename, std::move (file_wrap), linemap, dump_lex_opt);
+
+  Parser<Lexer> parser (lex);
+
+  // generate crate from parser
+  std::unique_ptr<AST::Crate> ast_crate = parser.parse_crate ();
+
+  // handle crate name
+  handle_crate_name (*ast_crate.get ());
+
+  // dump options except lexer dump
+  if (options.dump_option_enabled (CompileOptions::PARSER_AST_DUMP))
+    {
+      dump_ast (parser, *ast_crate.get ());
+    }
+  if (options.dump_option_enabled (CompileOptions::AST_DUMP_PRETTY))
+    {
+      dump_ast_pretty (*ast_crate.get ());
+    }
+  if (options.dump_option_enabled (CompileOptions::TARGET_OPTION_DUMP))
+    {
+      options.target_data.dump_target_options ();
+    }
+
+  if (saw_errors ())
+    return;
+
+  // setup the mappings for this AST
+  CrateNum current_crate = mappings->get_current_crate ();
+  AST::Crate &parsed_crate
+    = mappings->insert_ast_crate (std::move (ast_crate), current_crate);
+
+  /* basic pipeline:
+   *  - lex
+   *  - parse
+   *  - register plugins (dummy stage for now) - attribute injection? what is
+   * this? (attribute injection is injecting attributes specified in command
+   * line into crate root)
+   *  - injection (some lint checks or dummy, register builtin macros, crate
+   * injection)
+   *  - expansion (expands all macros, maybe build test harness, AST
+   * validation, maybe macro crate)
+   *  - resolution (name resolution, type resolution, maybe feature checking,
+   * maybe buffered lints)
+   *  TODO not done */
+
+  rust_debug ("\033[0;31mSUCCESSFULLY PARSED CRATE \033[0m");
+
+  // If -fsyntax-only was passed, we can just skip the remaining passes.
+  // Parsing errors are already emitted in `parse_crate()`
+  if (flag_syntax_only || last_step == CompileOptions::CompileStep::Ast)
+    return;
+
+  // register plugins pipeline stage
+  register_plugins (parsed_crate);
+  rust_debug ("\033[0;31mSUCCESSFULLY REGISTERED PLUGINS \033[0m");
+  if (options.dump_option_enabled (CompileOptions::REGISTER_PLUGINS_DUMP))
+    {
+      // TODO: what do I dump here?
+    }
+
+  // injection pipeline stage
+  injection (parsed_crate);
+  rust_debug ("\033[0;31mSUCCESSFULLY FINISHED INJECTION \033[0m");
+  if (options.dump_option_enabled (CompileOptions::INJECTION_DUMP))
+    {
+      // TODO: what do I dump here? injected crate names?
+    }
+
+  if (last_step == CompileOptions::CompileStep::AttributeCheck)
+    return;
+
+  Analysis::AttributeChecker ().go (parsed_crate);
+
+  if (last_step == CompileOptions::CompileStep::Expansion)
+    return;
+
+  // expansion pipeline stage
+  expansion (parsed_crate);
+  rust_debug ("\033[0;31mSUCCESSFULLY FINISHED EXPANSION \033[0m");
+  if (options.dump_option_enabled (CompileOptions::EXPANSION_DUMP))
+    {
+      // dump AST with expanded stuff
+      rust_debug ("BEGIN POST-EXPANSION AST DUMP");
+      dump_ast_expanded (parser, parsed_crate);
+      dump_ast_pretty (parsed_crate, true);
+      rust_debug ("END POST-EXPANSION AST DUMP");
+    }
+
+  if (last_step == CompileOptions::CompileStep::NameResolution)
+    return;
+
+  // resolution pipeline stage
+  Resolver::NameResolution::Resolve (parsed_crate);
+  if (options.dump_option_enabled (CompileOptions::RESOLUTION_DUMP))
+    {
+      // TODO: what do I dump here? resolved names? AST with resolved names?
+    }
+
+  if (saw_errors ())
+    return;
+
+  if (last_step == CompileOptions::CompileStep::Lowering)
+    return;
+
+  // lower AST to HIR
+  std::unique_ptr<HIR::Crate> lowered
+    = HIR::ASTLowering::Resolve (parsed_crate);
+  if (saw_errors ())
+    return;
+
+  // add the mappings to it
+  HIR::Crate &hir = mappings->insert_hir_crate (std::move (lowered));
+  if (options.dump_option_enabled (CompileOptions::HIR_DUMP))
+    {
+      dump_hir (hir);
+    }
+  if (options.dump_option_enabled (CompileOptions::HIR_DUMP_PRETTY))
+    {
+      dump_hir_pretty (hir);
+    }
+
+  if (last_step == CompileOptions::CompileStep::TypeCheck)
+    return;
+
+  // type resolve
+  Resolver::TypeResolution::Resolve (hir);
+  if (options.dump_option_enabled (CompileOptions::TYPE_RESOLUTION_DUMP))
+    {
+      dump_type_resolution (hir);
+    }
+
+  if (saw_errors ())
+    return;
+
+  if (last_step == CompileOptions::CompileStep::Privacy)
+    return;
+
+  // Various HIR error passes. The privacy pass happens before the unsafe checks
+  Privacy::Resolver::resolve (hir);
+  if (saw_errors ())
+    return;
+
+  if (last_step == CompileOptions::CompileStep::Unsafety)
+    return;
+
+  HIR::UnsafeChecker ().go (hir);
+
+  if (last_step == CompileOptions::CompileStep::Const)
+    return;
+
+  HIR::ConstChecker ().go (hir);
+
+  if (saw_errors ())
+    return;
+
+  if (last_step == CompileOptions::CompileStep::Compilation)
+    return;
+
+  // do compile to gcc generic
+  Compile::Context ctx (backend);
+  Compile::CompileCrate::Compile (hir, &ctx);
+
+  // we can't do static analysis if there are errors to worry about
+  if (!saw_errors ())
+    {
+      // lints
+      Analysis::ScanDeadcode::Scan (hir);
+      Analysis::UnusedVariables::Lint (ctx);
+
+      // metadata
+      bool specified_emit_metadata
+	= flag_rust_embed_metadata || options.metadata_output_path_set ();
+      if (!specified_emit_metadata)
+	{
+	  Metadata::PublicInterface::ExportTo (
+	    hir, Metadata::PublicInterface::expected_metadata_filename ());
+	}
+      else
+	{
+	  if (flag_rust_embed_metadata)
+	    Metadata::PublicInterface::Export (hir);
+	  if (options.metadata_output_path_set ())
+	    Metadata::PublicInterface::ExportTo (
+	      hir, options.get_metadata_output ());
+	}
+    }
+
+  // pass to GCC middle-end
+  ctx.write_to_backend ();
+}
+
+void
+Session::register_plugins (AST::Crate &crate ATTRIBUTE_UNUSED)
+{
+  rust_debug ("ran register_plugins (with no body)");
+}
+
+// TODO: move somewhere else
+bool
+contains_name (const AST::AttrVec &attrs, std::string name)
+{
+  for (const auto &attr : attrs)
+    {
+      if (attr.get_path () == name)
+	return true;
+    }
+
+  return false;
+}
+
+void
+Session::injection (AST::Crate &crate)
+{
+  rust_debug ("started injection");
+
+  // lint checks in future maybe?
+
+  // register builtin macros
+  /* In rustc, builtin macros are divided into 3 categories depending on use -
+   * "bang" macros, "attr" macros, and "derive" macros. I think the meanings
+   * of these categories should be fairly obvious to anyone who has used rust.
+   * Builtin macro list by category: Bang
+   *      - asm
+   *      - assert
+   *      - cfg
+   *      - column
+   *      - compile_error
+   *      - concat_idents
+   *      - concat
+   *      - env
+   *      - file
+   *      - format_args_nl
+   *      - format_args
+   *      - global_asm
+   *      - include_bytes
+   *      - include_str
+   *      - include
+   *      - line
+   *      - log_syntax
+   *      - module_path
+   *      - option_env
+   *      - stringify
+   *      - trace_macros
+   *  Attr
+   *      - bench
+   *      - global_allocator
+   *      - test
+   *      - test_case
+   *  Derive
+   *      - Clone
+   *      - Copy
+   *      - Debug
+   *      - Default
+   *      - Eq
+   *      - Hash
+   *      - Ord
+   *      - PartialEq
+   *      - PartialOrd
+   *      - RustcDecodable
+   *      - RustcEncodable
+   * rustc also has a "quote" macro that is defined differently and is
+   * supposedly not stable so eh. */
+  /* TODO: actually implement injection of these macros. In particular, derive
+   * macros, cfg, and test should be prioritised since they seem to be used
+   * the most. */
+
+  // crate injection
+  std::vector<std::string> names;
+  if (contains_name (crate.inner_attrs, "no_core"))
+    {
+      // no prelude
+      injected_crate_name = "";
+    }
+  else if (contains_name (crate.inner_attrs, "no_std"))
+    {
+      names.push_back ("core");
+
+      if (!contains_name (crate.inner_attrs, "compiler_builtins"))
+	{
+	  names.push_back ("compiler_builtins");
+	}
+
+      injected_crate_name = "core";
+    }
+  else
+    {
+      names.push_back ("std");
+
+      injected_crate_name = "std";
+    }
+
+  // reverse iterate through names to insert crate items in "forward" order at
+  // beginning of crate
+  for (auto it = names.rbegin (); it != names.rend (); ++it)
+    {
+      // create "macro use" attribute for use on extern crate item to enable
+      // loading macros from it
+      AST::Attribute attr (AST::SimplePath::from_str ("macro_use", Location ()),
+			   nullptr);
+
+      // create "extern crate" item with the name
+      std::unique_ptr<AST::ExternCrate> extern_crate (
+	new AST::ExternCrate (*it, AST::Visibility::create_error (),
+			      {std::move (attr)},
+			      Linemap::unknown_location ()));
+
+      // insert at beginning
+      // crate.items.insert (crate.items.begin (), std::move (extern_crate));
+    }
+
+  // create use tree path
+  // prelude is injected_crate_name
+  // FIXME: Once we do want to include the standard library, add the prelude
+  // use item
+  // std::vector<AST::SimplePathSegment> segments
+  //   = {AST::SimplePathSegment (injected_crate_name, Location ()),
+  //      AST::SimplePathSegment ("prelude", Location ()),
+  //      AST::SimplePathSegment ("v1", Location ())};
+  // // create use tree and decl
+  // std::unique_ptr<AST::UseTreeGlob> use_tree (
+  //   new AST::UseTreeGlob (AST::UseTreeGlob::PATH_PREFIXED,
+  //     		  AST::SimplePath (std::move (segments)), Location ()));
+  // AST::Attribute prelude_attr (AST::SimplePath::from_str ("prelude_import",
+  //     						  Location ()),
+  //     		       nullptr);
+  // std::unique_ptr<AST::UseDeclaration> use_decl (
+  //   new AST::UseDeclaration (std::move (use_tree),
+  //     		     AST::Visibility::create_error (),
+  //     		     {std::move (prelude_attr)}, Location ()));
+
+  // crate.items.insert (crate.items.begin (), std::move (use_decl));
+
+  /* TODO: potentially add checking attribute crate type? I can't figure out
+   * what this does currently comment says "Unconditionally collect crate
+   * types from attributes to make them used", which presumably refers to
+   * checking the linkage info by "crate_type". It also seems to ensure that
+   * an invalid crate type is not specified, so maybe just do that. Valid
+   * crate types: bin lib dylib staticlib cdylib rlib proc-macro */
+
+  // this crate type will have options affecting the metadata ouput
+
+  rust_debug ("finished injection");
+}
+
+void
+Session::expansion (AST::Crate &crate)
+{
+  /* We need to name resolve macros and imports here */
+  Resolver::EarlyNameResolver ().go (crate);
+
+  rust_debug ("started expansion");
+
+  /* rustc has a modification to windows PATH temporarily here, which may end
+   * up being required */
+
+  // create macro expansion config?
+  // if not, would at least have to configure recursion_limit
+  ExpansionCfg cfg;
+
+  // create extctxt? from parse session, cfg, and resolver?
+  /* expand by calling cxtctxt object's monotonic_expander's expand_crate
+   * method. */
+  MacroExpander expander (crate, cfg, *this);
+  expander.expand_crate ();
+
+  // error reporting - check unused macros, get missing fragment specifiers
+
+  // build test harness
+
+  // ast validation (also with proc macro decls)
+
+  // maybe create macro crate if not rustdoc
+
+  rust_debug ("finished expansion");
+}
+
+void
+Session::dump_ast (Parser<Lexer> &parser, AST::Crate &crate) const
+{
+  std::ofstream out;
+  out.open (kASTDumpFile);
+  if (out.fail ())
+    {
+      rust_error_at (Linemap::unknown_location (), "cannot open %s:%m; ignored",
+		     kASTDumpFile);
+      return;
+    }
+
+  parser.debug_dump_ast_output (crate, out);
+  out.close ();
+}
+
+void
+Session::dump_ast_pretty (AST::Crate &crate, bool expanded) const
+{
+  std::ofstream out;
+  if (expanded)
+    out.open (kASTPrettyDumpFileExpanded);
+  else
+    out.open (kASTPrettyDumpFile);
+
+  if (out.fail ())
+    {
+      rust_error_at (Linemap::unknown_location (), "cannot open %s:%m; ignored",
+		     kASTDumpFile);
+      return;
+    }
+
+  AST::Dump (out).go (crate);
+
+  out.close ();
+}
+
+void
+Session::dump_ast_expanded (Parser<Lexer> &parser, AST::Crate &crate) const
+{
+  std::ofstream out;
+  out.open (kASTExpandedDumpFile);
+  if (out.fail ())
+    {
+      rust_error_at (Linemap::unknown_location (), "cannot open %s:%m; ignored",
+		     kASTExpandedDumpFile);
+      return;
+    }
+
+  parser.debug_dump_ast_output (crate, out);
+  out.close ();
+}
+
+void
+Session::dump_hir (HIR::Crate &crate) const
+{
+  std::ofstream out;
+  out.open (kHIRDumpFile);
+  if (out.fail ())
+    {
+      rust_error_at (Linemap::unknown_location (), "cannot open %s:%m; ignored",
+		     kHIRDumpFile);
+      return;
+    }
+
+  out << crate.as_string ();
+  out.close ();
+}
+
+void
+Session::dump_hir_pretty (HIR::Crate &crate) const
+{
+  std::ofstream out;
+  out.open (kHIRPrettyDumpFile);
+  if (out.fail ())
+    {
+      rust_error_at (Linemap::unknown_location (), "cannot open %s:%m; ignored",
+		     kHIRPrettyDumpFile);
+      return;
+    }
+
+  HIR::Dump (out).go (crate);
+  out.close ();
+}
+
+void
+Session::dump_type_resolution (HIR::Crate &hir) const
+{
+  std::ofstream out;
+  out.open (kHIRTypeResolutionDumpFile);
+  if (out.fail ())
+    {
+      rust_error_at (Linemap::unknown_location (), "cannot open %s:%m; ignored",
+		     kHIRTypeResolutionDumpFile);
+      return;
+    }
+
+  Resolver::TypeResolverDump::go (hir, out);
+  out.close ();
+}
+
+// imports
+
+NodeId
+Session::load_extern_crate (const std::string &crate_name, Location locus)
+{
+  // has it already been loaded?
+  CrateNum found_crate_num = UNKNOWN_CREATENUM;
+  bool found = mappings->lookup_crate_name (crate_name, found_crate_num);
+  if (found)
+    {
+      NodeId resolved_node_id = UNKNOWN_NODEID;
+      bool resolved
+	= mappings->crate_num_to_nodeid (found_crate_num, resolved_node_id);
+      rust_assert (resolved);
+
+      return resolved_node_id;
+    }
+
+  std::string relative_import_path = "";
+  Import::Stream *s
+    = Import::open_package (crate_name, locus, relative_import_path);
+  if (s == NULL)
+    {
+      rust_error_at (locus, "failed to locate crate %<%s%>",
+		     crate_name.c_str ());
+      return UNKNOWN_NODEID;
+    }
+
+  Imports::ExternCrate extern_crate (*s);
+  bool ok = extern_crate.load (locus);
+  if (!ok)
+    {
+      rust_error_at (locus, "failed to load crate metadata");
+      return UNKNOWN_NODEID;
+    }
+
+  // ensure the current vs this crate name don't collide
+  const std::string current_crate_name = mappings->get_current_crate_name ();
+  if (current_crate_name.compare (extern_crate.get_crate_name ()) == 0)
+    {
+      rust_error_at (locus, "current crate name %<%s%> collides with this",
+		     current_crate_name.c_str ());
+      return UNKNOWN_NODEID;
+    }
+
+  // setup mappings
+  CrateNum saved_crate_num = mappings->get_current_crate ();
+  CrateNum crate_num
+    = mappings->get_next_crate_num (extern_crate.get_crate_name ());
+  mappings->set_current_crate (crate_num);
+
+  // then lets parse this as a 2nd crate
+  Lexer lex (extern_crate.get_metadata ());
+  Parser<Lexer> parser (lex);
+  std::unique_ptr<AST::Crate> metadata_crate = parser.parse_crate ();
+  AST::Crate &parsed_crate
+    = mappings->insert_ast_crate (std::move (metadata_crate), crate_num);
+
+  // name resolve it
+  Resolver::NameResolution::Resolve (parsed_crate);
+
+  // perform hir lowering
+  std::unique_ptr<HIR::Crate> lowered
+    = HIR::ASTLowering::Resolve (parsed_crate);
+  HIR::Crate &hir = mappings->insert_hir_crate (std::move (lowered));
+
+  // perform type resolution
+  Resolver::TypeResolution::Resolve (hir);
+
+  // always restore the crate_num
+  mappings->set_current_crate (saved_crate_num);
+
+  return parsed_crate.get_node_id ();
+}
+//
+
+void
+TargetOptions::dump_target_options () const
+{
+  std::ofstream out;
+  out.open (kTargetOptionsDumpFile);
+  if (out.fail ())
+    {
+      rust_error_at (Linemap::unknown_location (), "cannot open %s:%m; ignored",
+		     kTargetOptionsDumpFile);
+      return;
+    }
+
+  if (features.empty ())
+    {
+      out << "No target options available!\n";
+    }
+
+  for (const auto &pairs : features)
+    {
+      for (const auto &value : pairs.second)
+	out << pairs.first + ": \"" + value + "\"\n";
+
+      if (pairs.second.empty ())
+	out << pairs.first + "\n";
+    }
+
+  out.close ();
+}
+
+void
+TargetOptions::init_derived_values ()
+{
+  // enable derived values based on target families
+  if (has_key_value_pair ("target_family", "unix"))
+    insert_key ("unix");
+  if (has_key_value_pair ("target_family", "windows"))
+    insert_key ("windows");
+
+  // implicitly enable features - this should not be required in general
+  if (has_key_value_pair ("target_feature", "aes"))
+    enable_implicit_feature_reqs ("aes");
+  if (has_key_value_pair ("target_feature", "avx"))
+    enable_implicit_feature_reqs ("sse4.2");
+  if (has_key_value_pair ("target_feature", "avx2"))
+    enable_implicit_feature_reqs ("avx");
+  if (has_key_value_pair ("target_feature", "pclmulqdq"))
+    enable_implicit_feature_reqs ("sse2");
+  if (has_key_value_pair ("target_feature", "sha"))
+    enable_implicit_feature_reqs ("sse2");
+  if (has_key_value_pair ("target_feature", "sse2"))
+    enable_implicit_feature_reqs ("sse");
+  if (has_key_value_pair ("target_feature", "sse3"))
+    enable_implicit_feature_reqs ("sse2");
+  if (has_key_value_pair ("target_feature", "sse4.1"))
+    enable_implicit_feature_reqs ("sse3");
+  if (has_key_value_pair ("target_feature", "sse4.2"))
+    enable_implicit_feature_reqs ("sse4.1");
+  if (has_key_value_pair ("target_feature", "ssse3"))
+    enable_implicit_feature_reqs ("sse3");
+}
+
+void
+TargetOptions::enable_implicit_feature_reqs (std::string feature)
+{
+  if (feature == "aes")
+    enable_implicit_feature_reqs ("sse2");
+  else if (feature == "avx")
+    enable_implicit_feature_reqs ("sse4.2");
+  else if (feature == "avx2")
+    enable_implicit_feature_reqs ("avx");
+  else if (feature == "fma")
+    enable_implicit_feature_reqs ("avx");
+  else if (feature == "pclmulqdq")
+    enable_implicit_feature_reqs ("sse2");
+  else if (feature == "sha")
+    enable_implicit_feature_reqs ("sse2");
+  else if (feature == "sse2")
+    enable_implicit_feature_reqs ("sse");
+  else if (feature == "sse3")
+    enable_implicit_feature_reqs ("sse2");
+  else if (feature == "sse4.1")
+    enable_implicit_feature_reqs ("sse3");
+  else if (feature == "sse4.2")
+    enable_implicit_feature_reqs ("sse4.1");
+  else if (feature == "ssse3")
+    enable_implicit_feature_reqs ("sse3");
+
+  if (!has_key_value_pair ("target_feature", feature))
+    {
+      insert_key_value_pair ("target_feature", feature);
+
+      rust_debug ("had to implicitly enable feature '%s'!", feature.c_str ());
+    }
+}
+
+// NOTEs:
+/* mrustc compile pipeline:
+ *  - target load (pass target spec to parser?)
+ *  - parse (convert source to AST)
+ *  - load crates (load any explicitly mentioned extern crates [not all of
+ * them])
+ *  - expand (AST transformations from attributes and macros, loads remaining
+ * extern crates [std/core and any triggered by macro expansion])
+ *  - implicit crates (test harness, allocator crate, panic crate)
+ *  - resolve use (annotate every 'use' item with source [supposedly handles
+ * nasty recursion])
+ *  - resolve index (generate index of visible items for every module [avoids
+ * recursion in next pass])
+ *  - resolve absolute (resolve all paths into either variable names
+ * [types/values] or absolute paths)
+ *  - HIR lower (convert modified AST to simpler HIR [both expressions and
+ * module tree])
+ *  - resolve type aliases (replace any usages of type aliases with actual
+ * type [except associated types])
+ *  - resolve bind (iterate HIR tree and set binding annotations on all
+ * concrete types [avoids path lookups later])
+ *  - resolve HIR markings (generate "markings" [e.g. for Copy/Send/Sync/...]
+ * for all types
+ *  - sort impls (small pass - sort impls into groups)
+ *  - resolve UFCS outer (determine source trait for all top-level <T>::Type
+ * [qualified] paths)
+ *  - resolve UFCS paths (do the same, but include for exprs this time. also
+ * normalises results of previous pass [expanding known associated types])
+ *  - constant evaluate (evaluate all constants)
+ *  - typecheck outer (checks impls are sane)
+ *  - typecheck expressions (resolve and check types for all exprs)
+ *  - expand HIR annotate (annotate how exprs are used - used for closure
+ * extractions and reborrows)
+ *  - expand HIR closures (extract closures into structs implementing Fn*
+ * traits)
+ *  - expand HIR vtables (generate vtables for types with dyn dispatch)
+ *  - expand HIR calls (converts method and callable calls into explicit
+ * function calls)
+ *  - expand HIR reborrows (apply reborrow rules [taking '&mut *v' instead of
+ * 'v'])
+ *  - expand HIR erasedtype (replace all erased types 'impl Trait' with the
+ * true type)
+ *  - typecheck expressions (validate - double check that previous passes
+ * haven't broke type system rules)
+ *  - lower MIR (convert HIR exprs into a control-flow graph [MIR])
+ *  - MIR validate (check that the generated MIR is consistent)
+ *  - MIR cleanup (perform various transformations on MIR - replace reads of
+ * const items with the item itself; convert casts to unsized types into
+ * 'MakeDst' operations)
+ *  - MIR optimise (perform various simple optimisations on the MIR - constant
+ * propagation, dead code elimination, borrow elimination, some inlining)
+ *  - MIR validate PO (re-validate the MIR)
+ *  - MIR validate full (optionally: perform expensive state-tracking
+ * validation on MIR)
+ *  - trans enumerate (enumerate all items needed for code generation,
+ * primarily types used for generics)
+ *  - trans auto impls (create magic trait impls as enumerated in previous
+ * pass)
+ *  - trans monomorph (generate monomorphised copies of all functions [with
+ * generics replaced with real types])
+ *  - MIR optimise inline (run optimisation again, this time with full type
+ * info [primarily for inlining])
+ *  - HIR serialise (write out HIR dump [module tree and generic/inline MIR])
+ *  - trans codegen (generate final output file: emit C source file and call C
+ * compiler) */
+
+/* rustc compile pipeline (basic, in way less detail):
+ *  - parse input (parse .rs to AST)
+ *  - name resolution, macro expansion, and configuration (process AST
+ * recursively, resolving paths, expanding macros, processing #[cfg] nodes
+ * [i.e. maybe stripping stuff from AST])
+ *  - lower to HIR
+ *  - type check and other analyses (e.g. privacy checking)
+ *  - lower to MIR and post-processing (and do stuff like borrow checking)
+ *  - translation to LLVM IR and LLVM optimisations (produce the .o files)
+ *  - linking (link together .o files) */
+
+/* Pierced-together rustc compile pipeline (from source):
+ *  - parse input (parse file to crate)
+ *  - register plugins (attributes injection, set various options, register
+ * lints, load plugins)
+ *  - expansion/configure and expand (initial 'cfg' processing, 'loading
+ * compiler plugins', syntax expansion, secondary 'cfg' expansion, synthesis
+ * of a test harness if required, injection of any std lib dependency and
+ * prelude, and name resolution) - actually documented inline
+ *      - seeming pierced-together order: pre-AST expansion lint checks,
+ * registering builtin macros, crate injection, then expand all macros, then
+ * maybe build test harness, AST validation, maybe create a macro crate (if
+ * not rustdoc), name resolution, complete gated feature checking, add all
+ * buffered lints
+ *  - create global context (lower to HIR)
+ *  - analysis on global context (HIR optimisations? create MIR?)
+ *  - code generation
+ *  - link */
+} // namespace Rust
+
+#if CHECKING_P
+namespace selftest {
+void
+rust_crate_name_validation_test (void)
+{
+  auto error = Rust::Error (Location (), std::string ());
+  ASSERT_TRUE (Rust::validate_crate_name ("example", error));
+  ASSERT_TRUE (Rust::validate_crate_name ("abcdefg_1234", error));
+  ASSERT_TRUE (Rust::validate_crate_name ("1", error));
+  // FIXME: The next test does not pass as of current implementation
+  // ASSERT_TRUE (Rust::CompileOptions::validate_crate_name ("惊吓"));
+  // NOTE: - is not allowed in the crate name ...
+
+  ASSERT_FALSE (Rust::validate_crate_name ("abcdefg-1234", error));
+  ASSERT_FALSE (Rust::validate_crate_name ("a+b", error));
+  ASSERT_FALSE (Rust::validate_crate_name ("/a+b/", error));
+
+  /* Tests for crate name inference */
+  ASSERT_EQ (Rust::infer_crate_name ("c.rs"), "c");
+  // NOTE: ... but - is allowed when in the filename
+  ASSERT_EQ (Rust::infer_crate_name ("a-b.rs"), "a_b");
+  ASSERT_EQ (Rust::infer_crate_name ("book.rs.txt"), "book.rs");
+#if defined(HAVE_DOS_BASED_FILE_SYSTEM)
+  ASSERT_EQ (Rust::infer_crate_name ("a\\c\\a-b.rs"), "a_b");
+#else
+  ASSERT_EQ (Rust::infer_crate_name ("a/c/a-b.rs"), "a_b");
+#endif
+}
+} // namespace selftest
+#endif // CHECKING_P