[systemtap.git] / elaborate.cxx

// elaboration functions
// Copyright (C) 2005 Red Hat Inc.
//
// This file is part of systemtap, and is free software.  You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.

#include "config.h"
#include "elaborate.h"
#include "parse.h"

extern "C" {
#include <sys/utsname.h>
}

#include <fstream>
#include <algorithm>

#if 0
#ifdef HAVE_ELFUTILS_LIBDW_H
#include <elfutils/libdw.h>
#else
#error "need <elfutils/libdw.h>"
#endif
#endif

using namespace std;


// ------------------------------------------------------------------------


derived_probe::derived_probe (probe *p):
  base (p)
{
  this->locations = p->locations;
  this->tok = p->tok;
  this->body = p->body;
  this->locals = p->locals;
}


derived_probe::derived_probe (probe *p, probe_point *l):
  base (p)
{
  this->locations.push_back (l);
  this->tok = p->tok;
  this->body = p->body;
  this->locals = p->locals;
}


// ------------------------------------------------------------------------


static int semantic_pass_symbols (systemtap_session&);
static int semantic_pass_types (systemtap_session&);


// Link up symbols to their declarations.  Set the session's
// files/probes/functions/globals vectors from the transitively
// reached set of stapfiles in s.library_files, starting from
// s.user_file.  Perform automatic tapset inclusion and XXX: probe
// alias expansion.
static int
semantic_pass_symbols (systemtap_session& s)
{
  symresolution_info sym (s);

  // NB: s.files can grow during this iteration, so size() can
  // return gradually increasing numbers.
  s.files.push_back (s.user_file);
  for (unsigned i = 0; i < s.files.size(); i++)
    {
      stapfile* dome = s.files[i];

      // Pass 1: add globals and functions to systemtap-session master list,
      //         so the find_* functions find them

      for (unsigned i=0; i<dome->globals.size(); i++)
        s.globals.push_back (dome->globals[i]);

      for (unsigned i=0; i<dome->functions.size(); i++)
        s.functions.push_back (dome->functions[i]);

      // Pass 2: process functions

      for (unsigned i=0; i<dome->functions.size(); i++)
        {
          functiondecl* fd = dome->functions[i];

          try 
            {
              sym.current_function = fd;
              sym.current_probe = 0;
              fd->body->visit (& sym);
            }
          catch (const semantic_error& e)
            {
              s.print_error (e);
            }
        }

      // Pass 3: process probes

      for (unsigned i=0; i<dome->probes.size(); i++)
        {
          probe* p = dome->probes [i];
          vector<derived_probe*> dps;

          try
            {
              // much magic happens here: probe alias expansion,
              // provider identification
              sym.derive_probes (p, dps);
            }
          catch (const semantic_error& e)
            {
              s.print_error (e);
              // dps.erase (dps.begin(), dps.end());
            }

          for (unsigned j=0; j<dps.size(); j++)
            {
              derived_probe* dp = dps[j];
	      s.probes.push_back (dp);

              try 
                {
                  sym.current_function = 0;
                  sym.current_probe = dp;
                  dp->body->visit (& sym);
                }
              catch (const semantic_error& e)
                {
                  s.print_error (e);
                }
            }
        }
    }

  return s.num_errors; // all those print_error calls
}


int
semantic_pass (systemtap_session& s)
{
  int rc = semantic_pass_symbols (s);
  if (rc == 0) rc = semantic_pass_types (s);
  return rc;
}


// ------------------------------------------------------------------------


systemtap_session::systemtap_session ():
  user_file (0), op (0), up (0), num_errors (0)
{
}


void
systemtap_session::print_error (const semantic_error& e)
{
  cerr << "semantic error: " << e.what () << ": ";
  if (e.tok1) cerr << *e.tok1;
  cerr << e.msg2;
  if (e.tok2) cerr << *e.tok2;
  cerr << endl;
  num_errors ++;
}


// ------------------------------------------------------------------------
// semantic processing: symbol resolution


symresolution_info::symresolution_info (systemtap_session& s):
  session (s), current_function (0), current_probe (0)
{
}


void
symresolution_info::visit_block (block* e)
{
  for (unsigned i=0; i<e->statements.size(); i++)
    {
      try 
	{
	  e->statements[i]->visit (this);
	}
      catch (const semantic_error& e)
	{
	  session.print_error (e);
        }
    }
}


void
symresolution_info::visit_foreach_loop (foreach_loop* e)
{
  for (unsigned i=0; i<e->indexes.size(); i++)
    e->indexes[i]->visit (this);

  if (e->base_referent)
    return;

  vardecl* d = find_array (e->base, e->indexes.size ());
  if (d)
    e->base_referent = d;
  else
    throw semantic_error ("unresolved global array " + e->base, e->tok);

  e->block->visit (this);
}


void
symresolution_info::visit_symbol (symbol* e)
{
  if (e->referent)
    return;

  vardecl* d = find_scalar (e->name);
  if (d)
    e->referent = d;
  else
    {
      // new local
      vardecl* v = new vardecl;
      v->name = e->name;
      v->tok = e->tok;
      if (current_function)
        current_function->locals.push_back (v);
      else if (current_probe)
        current_probe->locals.push_back (v);
      else
        // must not happen
        throw semantic_error ("no current probe/function", e->tok);
      e->referent = v;
    }
}


void
symresolution_info::visit_arrayindex (arrayindex* e)
{
  for (unsigned i=0; i<e->indexes.size(); i++)
    e->indexes[i]->visit (this);

  if (e->referent)
    return;

  vardecl* d = find_array (e->base, e->indexes.size ());
  if (d)
    e->referent = d;
  else
    throw semantic_error ("unresolved global array", e->tok);
}


void
symresolution_info::visit_functioncall (functioncall* e)
{
  for (unsigned i=0; i<e->args.size(); i++)
    e->args[i]->visit (this);

  if (e->referent)
    return;

  functiondecl* d = find_function (e->function, e->args.size ());
  if (d)
    e->referent = d;
  else
    throw semantic_error ("unresolved function call", e->tok);
}


vardecl* 
symresolution_info::find_scalar (const string& name)
{
  // search locals
  vector<vardecl*>& locals = (current_function ? 
                              current_function->locals :
                              current_probe->locals);
  for (unsigned i=0; i<locals.size(); i++)
    if (locals[i]->name == name)
      // NB: no need to check arity here: locals always scalar
      return locals[i];

  // search function formal parameters (if any)
  if (current_function)
    for (unsigned i=0; i<current_function->formal_args.size(); i++)
      if (current_function->formal_args[i]->name == name)
        // NB: no need to check arity here: formal args always scalar
        return current_function->formal_args[i];

  // search globals
  for (unsigned i=0; i<session.globals.size(); i++)
    if (session.globals[i]->name == name)
      if (session.globals[i]->arity <= 0)
	  {
	    session.globals[i]->set_arity (0);
	    return session.globals[i];
	  }

  // search library globals
  for (unsigned i=0; i<session.library_files.size(); i++)
    {
      stapfile* f = session.library_files[i];
      for (unsigned j=0; j<f->globals.size(); j++)
        if (f->globals[j]->name == name &&
            f->globals[j]->index_types.size() == 0)
          {
            // put library into the queue if not already there
            if (0) // (session.verbose_resolution)
              cerr << "      scalar " << name << " "
                   << "is defined from " << f->name << endl;

            if (find (session.files.begin(), session.files.end(), f) 
                == session.files.end())
              session.files.push_back (f);
            // else .. print different message?

            return f->globals[j];
          }
    }

  // search builtins that become locals
  // XXX: need to invent a proper formalism for this
  if (name == "$pid" || name == "$tid")
    {
      vardecl_builtin* vb = new vardecl_builtin;
      vb->name = name;
      vb->type = pe_long;

      // XXX: need a better way to synthesize tokens
      token* t = new token;
      t->type = tok_identifier;
      t->content = name;
      t->location.file = "<builtin>";
      vb->tok = t;

      locals.push_back (vb);
      return vb;
    }

  return 0;
  // XXX: add checking for conflicting array or function
}


vardecl* 
symresolution_info::find_array (const string& name, unsigned arity)
{
  // search processed globals
  for (unsigned i=0; i<session.globals.size(); i++)
    if (session.globals[i]->name == name)
      if ((arity > 0 && (session.globals[i]->arity == (int) arity)) ||
	  session.globals[i]->arity < 0)
	{
          if (arity > 0)
            session.globals[i]->set_arity (arity);
	  return session.globals[i];
	}

  // search library globals
  for (unsigned i=0; i<session.library_files.size(); i++)
    {
      stapfile* f = session.library_files[i];
      for (unsigned j=0; j<f->globals.size(); j++)
        if (f->globals[j]->name == name)
          if ((arity > 0 && (f->globals[j]->arity == (int) arity)) ||
              f->globals[j]->arity < 0)
          {
            if (arity > 0)
              f->globals[j]->set_arity (arity);

            // put library into the queue if not already there
            if (0) // (session.verbose_resolution)
              cerr << "      array " << name << " "
                   << "is defined from " << f->name << endl;

            if (find (session.files.begin(), session.files.end(), f) 
                == session.files.end())
              session.files.push_back (f);
            // else .. print different message?

            return f->globals[j];
          }
    }

  return 0;
  // XXX: add checking for conflicting scalar or function
}


functiondecl* 
symresolution_info::find_function (const string& name, unsigned arity)
{
  for (unsigned j = 0; j < session.functions.size(); j++)
    {
      functiondecl* fd = session.functions[j];
      if (fd->name == name &&
          fd->formal_args.size() == arity)
        return fd;
    }

  // search library globals
  for (unsigned i=0; i<session.library_files.size(); i++)
    {
      stapfile* f = session.library_files[i];
      for (unsigned j=0; j<f->functions.size(); j++)
        if (f->functions[j]->name == name &&
            f->functions[j]->formal_args.size() == arity)
          {
            // put library into the queue if not already there
            if (0) // session.verbose_resolution
              cerr << "      function " << name << " "
                   << "is defined from " << f->name << endl;

            if (find (session.files.begin(), session.files.end(), f) 
                == session.files.end())
              session.files.push_back (f);
            // else .. print different message?

            return f->functions[j];
          }
    }

  return 0;
  // XXX: add checking for conflicting variables
}


// ------------------------------------------------------------------------
// type resolution


static int
semantic_pass_types (systemtap_session& s)
{
  int rc = 0;

  // next pass: type inference
  unsigned iterations = 0;
  typeresolution_info ti (s);
  
  ti.assert_resolvability = false;
  // XXX: maybe convert to exception-based error signalling
  while (1)
    {
      iterations ++;
      // cerr << "Type resolution, iteration " << iterations << endl;
      ti.num_newly_resolved = 0;
      ti.num_still_unresolved = 0;

      for (unsigned j=0; j<s.functions.size(); j++)
        {
          functiondecl* fn = s.functions[j];
          ti.current_function = fn;
          ti.t = pe_unknown;
          fn->body->visit (& ti);
	  // NB: we don't have to assert a known type for
	  // functions here, to permit a "void" function.
	  // The translator phase will omit the "retvalue".
	  //
          // if (fn->type == pe_unknown)
          //   ti.unresolved (fn->tok);
        }          

      for (unsigned j=0; j<s.probes.size(); j++)
        {
          derived_probe* pn = s.probes[j];
          ti.current_function = 0;
          ti.t = pe_unknown;
          pn->body->visit (& ti);
        }

      for (unsigned j=0; j<s.globals.size(); j++)
        {
          vardecl* gd = s.globals[j];
          if (gd->type == pe_unknown)
            ti.unresolved (gd->tok);
        }
      
      if (ti.num_newly_resolved == 0) // converged
        if (ti.num_still_unresolved == 0)
          break; // successfully
        else if (! ti.assert_resolvability)
          ti.assert_resolvability = true; // last pass, with error msgs
        else
          { // unsuccessful conclusion
            rc ++;
            break;
          }
    }
  
  return rc + s.num_errors;
}


void
typeresolution_info::visit_literal_number (literal_number* e)
{
  assert (e->type == pe_long);
  if ((t == e->type) || (t == pe_unknown))
    return;

  mismatch (e->tok, e->type, t);
}


void
typeresolution_info::visit_literal_string (literal_string* e)
{
  assert (e->type == pe_string);
  if ((t == e->type) || (t == pe_unknown))
    return;

  mismatch (e->tok, e->type, t);
}


void
typeresolution_info::visit_logical_or_expr (logical_or_expr *e)
{
  visit_binary_expression (e);
}


void
typeresolution_info::visit_logical_and_expr (logical_and_expr *e)
{
  visit_binary_expression (e);
}


void
typeresolution_info::visit_comparison (comparison *e)
{
  visit_binary_expression (e);
}


void
typeresolution_info::visit_concatenation (concatenation *e)
{
  visit_binary_expression (e);
}


void
typeresolution_info::visit_exponentiation (exponentiation *e)
{
  visit_binary_expression (e);
}


void
typeresolution_info::visit_assignment (assignment *e)
{
  visit_binary_expression (e);
}


void
typeresolution_info::visit_binary_expression (binary_expression* e)
{
  if (e->op == "<<<") // stats aggregation
    {
      exp_type t1 = t;
      t = pe_stats;
      e->left->visit (this);
      t = pe_long;
      e->right->visit (this);
      if (t1 == pe_stats || t1 == pe_string)
        invalid (e->tok, t1);
      else if (e->type == pe_unknown)
        {
          e->type = pe_long;
          resolved (e->tok, e->type);
        }
    }
  else if (e->op == ".") // string concatenation
    {
      exp_type t1 = t;
      t = pe_string;
      e->left->visit (this);
      t = pe_string;
      e->right->visit (this);
      if (t1 == pe_long || t1 == pe_stats)
        mismatch (e->tok, t1, pe_string);
      else if (e->type == pe_unknown)
        {
          e->type = pe_string;
          resolved (e->tok, e->type);
        }
    }
  else if (e->op == "=="
           || false) // XXX: other comparison operators
    {
      exp_type t1 = t;
      t = pe_unknown;
      e->left->visit (this);
      t = pe_unknown;
      e->right->visit (this);
      if (t1 == pe_string || t1 == pe_stats)
        mismatch (e->tok, t1, pe_long);
      else if (e->type == pe_unknown)
        {
          e->type = pe_long;
          resolved (e->tok, e->type);
        }
    }
  else // general arithmetic operators?
    {
      // propagate e->type downward 
      exp_type sub_type = t;
      if ((sub_type == pe_unknown) && (e->type != pe_unknown))
        sub_type = e->type;
      t = sub_type;
      e->left->visit (this);
      t = sub_type;
      e->right->visit (this);

      if ((sub_type == pe_unknown) && (e->type != pe_unknown))
        ; // already resolved
      else if ((sub_type != pe_unknown) && (e->type == pe_unknown))
        {
          e->type = sub_type;
          resolved (e->tok, e->type);
        }
      else if ((sub_type == pe_unknown) && (e->left->type != pe_unknown))
        {
          e->type = e->left->type;
          resolved (e->tok, e->type);
        }
      else if ((sub_type == pe_unknown) && (e->right->type != pe_unknown))
        {
          e->type = e->right->type;
          resolved (e->tok, e->type);
        }
      else if (e->type != sub_type)
        mismatch (e->tok, sub_type, e->type);
    }
}


void
typeresolution_info::visit_pre_crement (pre_crement *e)
{
  visit_unary_expression (e);
}


void
typeresolution_info::visit_post_crement (post_crement *e)
{
  visit_unary_expression (e);
}


void
typeresolution_info::visit_unary_expression (unary_expression* e)
{
  // all unary operators only work on numerics
  exp_type t1 = t;
  t = pe_long;
  e->operand->visit (this);

  if (t1 == pe_unknown && e->type != pe_unknown)
    ; // already resolved
  else if (t1 == pe_string || t1 == pe_stats)
    mismatch (e->tok, t1, pe_long);
  else if (e->type == pe_unknown)
    {
      e->type = pe_long;
      resolved (e->tok, e->type);
    }
}


void
typeresolution_info::visit_ternary_expression (ternary_expression* e)
{
  exp_type sub_type = t;

  t = pe_long;
  e->cond->visit (this);

  // Match ordinary binary_expression type inference for the true/false
  // arms of the ternary expression.

  if (sub_type == pe_unknown && e->type != pe_unknown)
    sub_type = e->type;
  t = sub_type;
  e->truevalue->visit (this);
  t = sub_type;
  e->falsevalue->visit (this);

  if ((sub_type == pe_unknown) && (e->type != pe_unknown))
    ; // already resolved
  else if ((sub_type != pe_unknown) && (e->type == pe_unknown))
    {
      e->type = sub_type;
      resolved (e->tok, e->type);
    }
  else if ((sub_type == pe_unknown) && (e->truevalue->type != pe_unknown))
    {
      e->type = e->truevalue->type;
      resolved (e->tok, e->type);
    }
  else if ((sub_type == pe_unknown) && (e->falsevalue->type != pe_unknown))
    {
      e->type = e->falsevalue->type;
      resolved (e->tok, e->type);
    }
  else if (e->type != sub_type)
    mismatch (e->tok, sub_type, e->type);
}


template <class Referrer, class Referent>
void resolve_2types (Referrer* referrer, Referent* referent,
                    typeresolution_info* r, exp_type t)
{
  exp_type& re_type = referrer->type;
  const token* re_tok = referrer->tok;
  exp_type& te_type = referent->type;
  const token* te_tok = referent->tok;

  if (t != pe_unknown && re_type == t && re_type == te_type)
    ; // do nothing: all three e->types in agreement
  else if (t == pe_unknown && re_type != pe_unknown && re_type == te_type)
    ; // do nothing: two known e->types in agreement
  else if (re_type != pe_unknown && te_type != pe_unknown && re_type != te_type)
    r->mismatch (re_tok, re_type, te_type);
  else if (re_type != pe_unknown && t != pe_unknown && re_type != t)
    r->mismatch (re_tok, re_type, t);
  else if (te_type != pe_unknown && t != pe_unknown && te_type != t)
    r->mismatch (te_tok, te_type, t);
  else if (re_type == pe_unknown && t != pe_unknown)
    {
      // propagate from upstream
      re_type = t;
      r->resolved (re_tok, re_type);
      // catch re_type/te_type mismatch later
    }
  else if (re_type == pe_unknown && te_type != pe_unknown)
    {
      // propagate from referent
      re_type = te_type;
      r->resolved (re_tok, re_type);
      // catch re_type/t mismatch later
    }
  else if (re_type != pe_unknown && te_type == pe_unknown)
    {
      // propagate to referent
      te_type = re_type;
      r->resolved (te_tok, te_type);
      // catch re_type/t mismatch later
    }
  else
    r->unresolved (re_tok);
}


void
typeresolution_info::visit_symbol (symbol* e)
{
  assert (e->referent != 0);

  if (e->referent->arity > 0)
    unresolved (e->tok); // symbol resolution should not permit this
  // XXX: but consider "delete <array>;" and similar constructs
  else
    resolve_2types (e, e->referent, this, t);
}


void
typeresolution_info::visit_arrayindex (arrayindex* e)
{
  assert (e->referent != 0);

  resolve_2types (e, e->referent, this, t);

  // now resolve the array indexes

  // if (e->referent->index_types.size() == 0)
  //   // redesignate referent as array
  //   e->referent->set_arity (e->indexes.size ());

  if (e->indexes.size() != e->referent->index_types.size())
    unresolved (e->tok); // symbol resolution should prevent this
  else for (unsigned i=0; i<e->indexes.size(); i++)
    {
      expression* ee = e->indexes[i];
      exp_type& ft = e->referent->index_types [i];
      t = ft;
      ee->visit (this);
      exp_type at = ee->type;

      if ((at == pe_string || at == pe_long) && ft == pe_unknown)
        {
          // propagate to formal type
          ft = at;
          resolved (e->referent->tok, ft);
          // uses array decl as there is no token for "formal type"
        }
      if (at == pe_stats)
        invalid (ee->tok, at);
      if (ft == pe_stats)
        invalid (ee->tok, ft);
      if (at != pe_unknown && ft != pe_unknown && ft != at)
        mismatch (e->tok, at, ft);
      if (at == pe_unknown)
        unresolved (ee->tok);
    }
}


void
typeresolution_info::visit_functioncall (functioncall* e)
{
  assert (e->referent != 0);

  resolve_2types (e, e->referent, this, t);

  if (e->type == pe_stats)
    invalid (e->tok, e->type);

  // XXX: but what about functions that return no value,
  // and are used only as an expression-statement for side effects?

  // now resolve the function parameters
  if (e->args.size() != e->referent->formal_args.size())
    unresolved (e->tok); // symbol resolution should prevent this
  else for (unsigned i=0; i<e->args.size(); i++)
    {
      expression* ee = e->args[i];
      exp_type& ft = e->referent->formal_args[i]->type;
      const token* fe_tok = e->referent->formal_args[i]->tok;
      t = ft;
      ee->visit (this);
      exp_type at = ee->type;
      
      if (((at == pe_string) || (at == pe_long)) && ft == pe_unknown)
        {
          // propagate to formal arg
          ft = at;
          resolved (e->referent->formal_args[i]->tok, ft);
        }
      if (at == pe_stats)
        invalid (e->tok, at);
      if (ft == pe_stats)
        invalid (fe_tok, ft);
      if (at != pe_unknown && ft != pe_unknown && ft != at)
        mismatch (e->tok, at, ft);
      if (at == pe_unknown)
        unresolved (e->tok);
    }
}


void
typeresolution_info::visit_block (block* e)
{
  for (unsigned i=0; i<e->statements.size(); i++)
    {
      try 
	{
	  t = pe_unknown;
	  e->statements[i]->visit (this);
	}
      catch (const semantic_error& e)
	{
	  session.print_error (e);
        }
    }
}


void
typeresolution_info::visit_if_statement (if_statement* e)
{
  t = pe_long;
  e->condition->visit (this);

  t = pe_unknown;
  e->thenblock->visit (this);

  if (e->elseblock)
    {
      t = pe_unknown;
      e->elseblock->visit (this);
    }
}


void
typeresolution_info::visit_for_loop (for_loop* e)
{
  t = pe_unknown;
  e->init->visit (this);
  t = pe_long;
  e->cond->visit (this);
  t = pe_unknown;
  e->incr->visit (this);  
  t = pe_unknown;
  e->block->visit (this);  
}


void
typeresolution_info::visit_foreach_loop (foreach_loop* e)
{
  // See also visit_arrayindex.
  // This is different in that, being a statement, we can't assign
  // a type to the outer array, only propagate to/from the indexes

  // if (e->referent->index_types.size() == 0)
  //   // redesignate referent as array
  //   e->referent->set_arity (e->indexes.size ());

  if (e->indexes.size() != e->base_referent->index_types.size())
    unresolved (e->tok); // symbol resolution should prevent this
  else for (unsigned i=0; i<e->indexes.size(); i++)
    {
      expression* ee = e->indexes[i];
      exp_type& ft = e->base_referent->index_types [i];
      t = ft;
      ee->visit (this);
      exp_type at = ee->type;

      if ((at == pe_string || at == pe_long) && ft == pe_unknown)
        {
          // propagate to formal type
          ft = at;
          resolved (e->base_referent->tok, ft);
          // uses array decl as there is no token for "formal type"
        }
      if (at == pe_stats)
        invalid (ee->tok, at);
      if (ft == pe_stats)
        invalid (ee->tok, ft);
      if (at != pe_unknown && ft != pe_unknown && ft != at)
        mismatch (e->tok, at, ft);
      if (at == pe_unknown)
        unresolved (ee->tok);
    }

  t = pe_unknown;
  e->block->visit (this);  
}


void
typeresolution_info::visit_null_statement (null_statement* e)
{
}


void
typeresolution_info::visit_expr_statement (expr_statement* e)
{
  t = pe_unknown;
  e->value->visit (this);
}


void
typeresolution_info::visit_delete_statement (delete_statement* e)
{
  // XXX: not yet supported
  unresolved (e->tok);
}


void
typeresolution_info::visit_array_in (array_in* e)
{
  // all unary operators only work on numerics
  exp_type t1 = t;
  t = pe_unknown; // array value can be anything
  e->operand->visit (this);

  if (t1 == pe_unknown && e->type != pe_unknown)
    ; // already resolved
  else if (t1 == pe_string || t1 == pe_stats)
    mismatch (e->tok, t1, pe_long);
  else if (e->type == pe_unknown)
    {
      e->type = pe_long;
      resolved (e->tok, e->type);
    }
}


void
typeresolution_info::visit_return_statement (return_statement* e)
{
  // This is like symbol, where the referent is
  // the return value of the function.

  // XXX: need control flow semantic checking; until then:
  if (current_function == 0)
    {
      unresolved (e->tok);
      return;
    }

  exp_type& e_type = current_function->type;
  t = current_function->type;
  e->value->visit (this);

  if (e_type != pe_unknown && e->value->type != pe_unknown
      && e_type != e->value->type)
    mismatch (current_function->tok, e_type, e->value->type);
  if (e_type == pe_unknown && 
      (e->value->type == pe_long || e->value->type == pe_string))
    {
      // propagate non-statistics from value
      e_type = e->value->type;
      resolved (current_function->tok, e->value->type);
    }
  if (e->value->type == pe_stats)
    invalid (e->value->tok, e->value->type);
}


void
typeresolution_info::unresolved (const token* tok)
{
  num_still_unresolved ++;

  if (assert_resolvability)
    {
      cerr << "error: unresolved type for ";
      if (tok)
        cerr << *tok;
      else
        cerr << "a token";
      cerr << endl;
    }
}


void
typeresolution_info::invalid (const token* tok, exp_type pe)
{
  num_still_unresolved ++;

  if (assert_resolvability)
    {
      cerr << "error: invalid type " << pe << " for ";
      if (tok)
        cerr << *tok;
      else
        cerr << "a token";
      cerr << endl;
    }
}


void
typeresolution_info::mismatch (const token* tok, exp_type t1, exp_type t2)
{
  num_still_unresolved ++;

  if (assert_resolvability)
    {
      cerr << "error: type mismatch for ";
      if (tok)
        cerr << *tok;
      else
        cerr << "a token";
      cerr << ": " << t1 << " vs. " << t2 << endl;
    }
}


void
typeresolution_info::resolved (const token* tok, exp_type t)
{
  num_newly_resolved ++;
  // cerr << "resolved " << *e->tok << " type " << t << endl;
}