#include "rust-session-manager.h"

#include "rust-diagnostics.h"
#include "diagnostic.h"
#include "input.h"

#include "target.h"
#include "tm.h"
#include "tm_p.h"

#include "rust-lex.h"
#include "rust-parse.h"
#include "rust-scan.h"
#include "rust-resolution.h"
#include "rust-compile.h"

#include "rust-target.h"

#include <algorithm>

extern Linemap *
rust_get_linemap ();

extern Backend *
rust_get_backend ();

namespace Rust {
// Simple wrapper for FILE* that simplifies destruction.
struct RAIIFile
{
  FILE *file;

  RAIIFile (const char *filename) : file (fopen (filename, "r")) {}

  ~RAIIFile () { fclose (file); }
};

// Implicitly enable a target_feature (and recursively enable dependencies).
void
Session::implicitly_enable_feature (::std::string feature_name)
{
  // TODO: is this really required since features added would be complete via
  // target spec?

  if (!options.target_data.has_key_value_pair ("target_data", feature_name))
    {
      // if feature has dependencies, enable them
      if (feature_name == "aes")
	{
	  implicitly_enable_feature ("sse2");
	}
      else if (feature_name == "avx")
	{
	  implicitly_enable_feature ("sse4.2");
	}
      else if (feature_name == "avx2")
	{
	  implicitly_enable_feature ("avx");
	}
      else if (feature_name == "fma")
	{
	  implicitly_enable_feature ("avx");
	}
      else if (feature_name == "pclmulqdq")
	{
	  implicitly_enable_feature ("sse2");
	}
      else if (feature_name == "sha")
	{
	  implicitly_enable_feature ("sse2");
	}
      else if (feature_name == "sse2")
	{
	  implicitly_enable_feature ("sse");
	}
      else if (feature_name == "sse3")
	{
	  implicitly_enable_feature ("sse2");
	}
      else if (feature_name == "sse4.1")
	{
	  implicitly_enable_feature ("sse3");
	}
      else if (feature_name == "sse4.2")
	{
	  implicitly_enable_feature ("sse4.1");
	}
      else if (feature_name == "ssse3")
	{
	  implicitly_enable_feature ("sse3");
	}

      options.target_data.insert_key_value_pair ("target_feature",
						 ::std::move (feature_name));
    }
}

// Meant to enable all target features. As this will be done by target hook,
// this method's deprecated.
void
Session::enable_features ()
{
  bool has_target_crt_static = false;
  const char *target = "PLACEHOLDER";

  fprintf (
    stderr,
    "ERROR: Somewhere in call chain Session::enable_features is called.\n");

  if (has_target_crt_static)
    {
      // enable "crt-static" attribute
    }

  /* TODO: do this via target hook. have one for each target that implicitly
   * enables the
   * features for that platform. Would probably have to make custom target hook.
   */

  /*
  if (target == "x86" || target == "x86_64") {
      if (TARGET_ISA_AES) {
	  // enable aes, implicitly enable sse2
	  implicitly_enable_feature("aes");
      }

      if (TARGET_ISA_AVX) {
	  // enable avx, implicitly enable sse4.2
	  implicitly_enable_feature("sse4.2");
      }

      if (TARGET_ISA_AVX2) {
	  // enable avx2, implicitly enable avx
	  implicitly_enable_feature("avx");
      }

      if (TARGET_ISA_BMI) {
	  // enable bmi1
	  implicitly_enable_feature("bmi1");
      }

      if (TARGET_ISA_BMI2) {
	  // enable bmi2
	  implicitly_enable_feature("bmi2");
      }

      if (TARGET_ISA_FMA) {
	  // enable fma, implicitly enable avx
	  implicitly_enable_feature("fma");
      }

      if (TARGET_ISA_FXSR) {
	  // enable fxsr
	  implicitly_enable_feature("fxsr");
      }

      if (TARGET_ISA_LZCNT) {
	  // enable lzcnt
	  implicitly_enable_feature("lzcnt");
      }

      if (TARGET_ISA_VPCLMULQDQ) {
	  // enable pclmulqdq, implicitly enable sse2
	  implicitly_enable_feature("pclmulqdq");
      }

      if (TARGET_ISA_POPCNT) {
	  // enable popcnt
	  implicitly_enable_feature("popcnt");
      }

      if (TARGET_ISA_RDRND) {
	  // enable rdrand
	  implicitly_enable_feature("rdrand");
      }

      if (TARGET_ISA_RDSEED) {
	  // enable rdseed
	  implicitly_enable_feature("rdseed");
      }

      if (TARGET_ISA_SHA) {
	  // enable sha, implicitly enable sse2
	  implicitly_enable_feature("sha");
      }

      if (TARGET_ISA_SSE) {
	  // enable sse
	  implicitly_enable_feature("sse");
      }

      if (TARGET_ISA_SSE2) {
	  // enable sse2, implicitly enable sse
	  implicitly_enable_feature("sse2");
      }

      if (TARGET_ISA_SSE3) {
	  // enable sse3, implicitly enable sse2
	  implicitly_enable_feature("sse3");
      }

      if (TARGET_ISA_SSE4_1) {
	  // enable sse4.1, implicitly enable sse3
	  implicitly_enable_feature("sse4.1");
      }

      if (TARGET_ISA_SSE4_2) {
	  // enable sse4.2, implicitly enable sse4.1
	  implicitly_enable_feature("sse4.2");
      }

      if (TARGET_ISA_SSSE3) {
	  // enable ssse3, implicitly enable sse3
	  implicitly_enable_feature("ssse3");
      }

      if (TARGET_ISA_XSAVE) {
	  // enable xsave
	  implicitly_enable_feature("xsave");
      }

      if (TARGET_ISA_XSAVEC) {
	  // enable xsavec
	  implicitly_enable_feature("xsavec");
      }

      if (TARGET_ISA_XSAVEOPT) {
	  // enable xsaveopt
	  implicitly_enable_feature("xsaveopt");
      }

      if (TARGET_ISA_XSAVES) {
	  // enable xsaves
	  implicitly_enable_feature("xsaves");
      }
  }
  options.target_data.features.shrink_to_fit();
  ::std::sort(options.target_data.features.begin(),
  options.target_data.features.end());*/
}

void
Session::init ()
{
#ifndef TARGET_RUST_OS_INFO
#define TARGET_RUST_OS_INFO()
#endif
//#define builtin_rust_info(KEY, VALUE) rust_add_target_info (KEY, VALUE)
// might as well use c++ stuff
#define builtin_rust_info(KEY, VALUE)                                          \
  options.target_data.insert_key_value_pair (KEY, VALUE)

  // initialise target hooks
  // targetrustm.rust_cpu_info();
  // targetrustm.rust_os_info();
  // ok, that's not working too well TODO - see if can salvage old
  // implementation
  TARGET_RUST_CPU_INFO ();
  TARGET_RUST_OS_INFO ();

#undef builtin_rust_info

  // target-independent values that should exist in all targets
  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");

  // TODO: find min atomic width and max atomic width
  // from it, add atomic-related stuff for sizes 8, 16, 32, 64, and 128 (if
  // inside bounds) in rustc, min atomic width is a known quantity (or 8 if not
  // known), and max is also a known quantity (or is pointer size if not known)
  // TODO: add atomic pointer if some criteria is satisfied

  // TODO: find whether target has "atomic cas"

  // add debug_assertions if enabled and proc_macro if crate type has it or
  // whatever

  // derived values from hook
  options.target_data.init_derived_values ();
}

// Initialise default options. Actually called before handle_option, unlike init
// itself.
void
Session::init_options ()
{
  options.dump_option = CompileOptions::NO_DUMP;
}

// 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:
      // TODO: add search path
      break;
    case OPT_L:
      // TODO: add library link path or something
      break;
    case OPT_frust_dump_:
      // enable dump and return whether this was successful
      if (arg != NULL)
	{
	  ret = enable_dump (::std::string (arg));
	}
      else
	{
	  ret = false;
	}
      break;
    // no option handling for -o
    default:
      // return 1 to indicate option is valid
      break;
    }

  return ret;
}

/* 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)
{
  // FIXME: change dumping algorithm when new non-inhibiting dump system is
  // created
  if (arg == "all")
    {
      error_at (
	UNKNOWN_LOCATION,
	"dumping all is not supported as of now. choose 'lex', 'parse', or 'target_options");
      return false;
    }
  else if (arg == "lex")
    {
      options.dump_option = CompileOptions::LEXER_DUMP;
    }
  else if (arg == "parse")
    {
      options.dump_option = CompileOptions::PARSER_AST_DUMP;
    }
  else if (arg == "register_plugins")
    {
      options.dump_option = CompileOptions::REGISTER_PLUGINS_DUMP;
    }
  else if (arg == "injection")
    {
      options.dump_option = CompileOptions::INJECTION_DUMP;
    }
  else if (arg == "expansion")
    {
      options.dump_option = CompileOptions::EXPANSION_DUMP;
    }
  else if (arg == "resolution")
    {
      options.dump_option = CompileOptions::RESOLUTION_DUMP;
    }
  else if (arg == "target_options")
    {
      // special case - dump all target options, and then quit compilation
      // nope, option handling called before init, so have to make this an
      // actual compile option
      // options.target_data.dump_target_options();
      // return false;
      options.dump_option = CompileOptions::TARGET_OPTION_DUMP;
    }
  else if (arg == "")
    {
      error_at (UNKNOWN_LOCATION,
		"dump option was not given a name. choose 'lex', 'parse', or 'target_options'");
      return false;
    }
  else
    {
      error_at (UNKNOWN_LOCATION,
		"dump option '%s' was unrecognised. choose 'lex', 'parse', or 'target_options",
		arg.c_str ());
      return false;
    }
  return true;
}

/* Actual main entry point for front-end. Called from langhook to parse files.
 */
void
Session::parse_files (int num_files, const char **files)
{
  for (int i = 0; i < num_files; i++)
    {
      parse_file (files[i]);
    }
  // TODO: should semantic analysis be dealed with here? or per file? for now,
  // per-file.
}

// Parses a single file with filename filename.
void
Session::parse_file (const char *filename)
{
  RAIIFile file_wrap (filename);

  if (file_wrap.file == NULL)
    {
      fatal_error (UNKNOWN_LOCATION, "cannot open filename %s: %m", filename);
    }

  Backend *backend = rust_get_backend ();

  // parse file here
  // create lexer and parser - these are file-specific and so aren't instance
  // variables
  Rust::Lexer lex (filename, file_wrap.file, rust_get_linemap ());
  Rust::Parser parser (lex);

  // generate crate from parser
  auto parsed_crate = parser.parse_crate ();

  // give a chance to give some debug
  switch (options.dump_option)
    {
    case CompileOptions::LEXER_DUMP:
      parser.debug_dump_lex_output ();
      break;
    case CompileOptions::PARSER_AST_DUMP:
      parser.debug_dump_ast_output (parsed_crate);
      break;
    default:
      break;
    }

  /* 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 */

  fprintf (stderr, "\033[0;31mSUCCESSFULLY PARSED CRATE \n\033[0m");

  // register plugins pipeline stage
  register_plugins (parsed_crate);
  fprintf (stderr, "\033[0;31mSUCCESSFULLY REGISTERED PLUGINS \n\033[0m");

  if (options.dump_option == CompileOptions::REGISTER_PLUGINS_DUMP)
    {
      // TODO: what do I dump here?
      return;
    }

  // injection pipeline stage
  injection (parsed_crate);
  fprintf (stderr, "\033[0;31mSUCCESSFULLY FINISHED INJECTION \n\033[0m");

  if (options.dump_option == CompileOptions::INJECTION_DUMP)
    {
      // TODO: what do I dump here? injected crate names?
      return;
    }

  // expansion pipeline stage
  expansion (parsed_crate);
  fprintf (stderr, "\033[0;31mSUCCESSFULLY FINISHED EXPANSION \n\033[0m");

  if (options.dump_option == CompileOptions::EXPANSION_DUMP)
    {
      // TODO: what do I dump here? expanded macros? AST with expanded macros?
      return;
    }

  // resolution pipeline stage
  resolution (parsed_crate);
  fprintf (stderr, "\033[0;31mSUCCESSFULLY FINISHED RESOLUTION \n\033[0m");

  if (options.dump_option == CompileOptions::RESOLUTION_DUMP)
    {
      // TODO: what do I dump here? resolved names? AST with resolved names?
      return;
    }

  if (saw_errors ())
    return;

  // do compile
  Compile::Compilation::Compile (parsed_crate, backend);
}

// Checks whether 'cfg' attribute prevents compilation.
bool
check_cfg (const AST::Attribute &attr ATTRIBUTE_UNUSED)
{
  // if "has sub items", and if 'cfg' attr, recursively call this on sub items?

  // TODO: actually implement. assume true for now

  return true;
}
// TODO: deprecated - don't use

// Checks whether any 'cfg' attribute on the item prevents compilation of that
// item.
bool
check_item_cfg (::std::vector<AST::Attribute> attrs)
{
  for (const auto &attr : attrs)
    {
      if (attr.get_path () == "cfg" && !check_cfg (attr))
	{
	  return false;
	}
    }

  return true;
}
// TODO: deprecated - don't use

// TODO: actually implement method
void
load_extern_crate (::std::string crate_name ATTRIBUTE_UNUSED)
{}
// TODO: deprecated - don't use

// Parses up to the "load (external) crates" part of the frontend.
// TODO: lots of this code is probably actually useful outside of dumping, so
// maybe split off function
void
Session::debug_dump_load_crates (Parser &parser)
{
  // parse crate as AST
  AST::Crate crate = parser.parse_crate ();

  /* TODO: search through inner attrs and see whether any of those attr paths
   * contain "no_core", "no_std", "compiler_builtins". If so/not, save certain
   * crate names. In these names, insert items at beginning of crate items. This
   * is crate injection. Also, inject prelude use decl at beginning (first name
   * is assumed to be prelude - prelude is a use decl automatically generated to
   * enable using Option and Copy without qualifying it or importing it via
   * 'use' manually) */

  ::std::vector< ::std::string> crate_names;
  for (const auto &item : crate.items)
    {
      // if item is extern crate, add name? to list of stuff ONLY IF config is
      // checked if item is module, iterate this loop inside it as well
      // (recursive?) ONLY IF config is checked

      // TODO: actually do the checks somewhere - probably in the items

      item->add_crate_name (crate_names);
    }

  /* loop through list of crate names/paths/whatever, attempting to load each
   * one. save loaded crates to a Session variable? Or save to current
   * AST::Crate? */
  for (const auto &name : crate_names)
    {
      load_extern_crate (name /*, basename = ""?*/);
    }
  //  for each loaded crate, load dependencies of it as well
}
// TODO: deprecated - don't use

void
Session::register_plugins (AST::Crate &crate ATTRIBUTE_UNUSED)
{
  fprintf (stderr, "ran register_plugins (with no body)\n");
}

// TODO: move somewhere else
bool
contains_name (const std::vector<AST::Attribute> &attrs, std::string name)
{
  for (const auto &attr : attrs)
    {
      if (attr.get_path () == name)
	{
	  return true;
	}
    }

  return false;
}

void
Session::injection (AST::Crate &crate)
{
  fprintf (stderr, "started injection\n");

  // 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"), NULL);

      // 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
  ::std::vector<AST::SimplePathSegment> segments
    = {AST::SimplePathSegment (injected_crate_name),
       AST::SimplePathSegment ("prelude"), AST::SimplePathSegment ("v1")};
  // 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"),
			       NULL);
  ::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 */

  fprintf (stderr, "finished injection\n");
}

void
Session::expansion (AST::Crate &crate ATTRIBUTE_UNUSED)
{
  fprintf (stderr, "started expansion\n");

  // 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

  // create extctxt? from parse session, cfg, and resolver?
  // expand by calling cxtctxt object's monotonic_expander's expand_crate
  // method.

  // 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

  fprintf (stderr, "finished expansion\n");
}

void
Session::resolution (AST::Crate &crate)
{
  fprintf (stderr, "started name resolution\n");
  Analysis::TopLevelScan toplevel (crate);
  // Name resolution must be in front of type resolution
  Analysis::TypeResolution::ResolveNamesAndTypes (crate, toplevel);
  fprintf (stderr, "finished name resolution\n");
}

void
TargetOptions::dump_target_options () const
{
  fprintf (stderr,
	   "\033[0;31m--PREPARING TO DUMP ALL TARGET OPTIONS--\n\033[0m");
  for (const auto &pairs : features)
    {
      for (const auto &value : pairs.second)
	{
	  fprintf (stderr, "%s: \"%s\"\n", pairs.first.c_str (),
		   value.c_str ());
	}
      if (pairs.second.empty ())
	{
	  fprintf (stderr, "%s\n", pairs.first.c_str ());
	}
    }
  if (features.empty ())
    {
      fprintf (stderr, "No target options available!\n");
    }

  fprintf (stderr, "\033[0;31m--END OF TARGET OPTION DUMP--\n\033[0m");
}

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
  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);
}

// 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