// -*- c++ -*-
// cc_tcheck.ast            see license.txt for copyright and terms of use
// extension module for cc.ast that defines the entry points
// for the type checker, and the annotations it produces

// the implementations for the functions declared here are in
// cc_tcheck.cc and cc_ast_aux.cc


// extension modules' first "verbatim" section goes after
// the initial verbatims from the base, but before any
// of the classes from the base
verbatim {
  #include "variable.h"                 // Variable
  #include "cc_type.h"                  // Type, FunctonType, CompoundType
  #include "template.h"                 // STemplateArgument
  #include "const_eval.h"               // ConstEval
  #include "macros.h"                   // Restorer
  #include "stdconv.h"                  // StandardConversion
  #include "llvm/ADT/APFloat.h"         // APFloat

  class Env;                            // cc_env.h
  class ArgumentInfo;                   // overload.h
  class DataBlock;                      // smbase/datablok.h
                      
#if RICH
  inline void fromXml(DeclaratorContext &out, sm::string str) {
    out = static_cast<DeclaratorContext>(atoi(str));
  }

  // defined in cc_ast_aux.cc
  sm::string toXml(DataBlock *&block);
#endif
}

impl_verbatim {
  // NOTE: do not include xml_type_id.h in the header, because it needs to
  // include cc.gen.ast.h.
  // RICH: #include "xml_type_id.h"   // type system serialization identity
}

// this code goes into the xml serialization class
xml_verbatim {
  /* this is elsa/cc_tcheck.ast */
  virtual bool shouldSerialize(Variable const *) { return true; }
}

custom ASTVisitor {
public:      // custom data extensions
  // this is true when we are inside the body of a template function
  // or class (uninstantiated)
  bool inTemplate;
}
custom ASTVisitor_ctor { inTemplate=false; }


class TranslationUnit {
  public(xml_TY) Scope *globalScope = NULL;

  // This is the type checker entry point at the top level.  It
  // writes error messages (if any) into 'env' and annotations
  // directly into the AST fields declared below.
  //
  // Most of the AST classes have their own 'tcheck' or similar
  // function, though the exact calling convention (params, etc.)
  // varies.
  //
  // Some classes have an 'itcheck' (internal type check) for the
  // subclasses, meaning the superclass 'tcheck' does some common
  // processing and then delegates to the per-subclass 'itcheck.
  public void tcheck(Env &env);
}


class TopForm {
  public /*no_ignore*/ TopForm *tcheck(Env &env);
  pure_virtual void itcheck(Env &env);
}


class Function {
  // since 'nameAndParams->var' might refer to a previous declaration,
  // and therefore might have differently-named parameters, I'll add
  // another field specifically for a version of the FunctionType
  // which has the parameters for *this* definition
  public(xml_TY) FunctionType *funcType = NULL;

  // since the body of the function (if a class member) may refer
  // to the receiver object, I need to write it down so client
  // analyses can find it
  //
  // 7/29/04: combined this with the old 'ctorReceiver'
  public(xml_TY,xmlShouldSerialize) Variable *receiver = NULL;

  public void printExtras(std::ostream &os, int indent) const;
  custom debugPrint { printExtras(os, indent); }

  // if this Function is intended to be a clone of a template body,
  // but we have not actually cloned the init/body/handlers, then
  // this is a pointer to the Function to eventually clone, acting
  // as a thunk; otherwise it is NULL
  //
  // 2005-08-07: Don't traverse this!  It would make the resulting
  // structure not a tree, and isn't for external consumption anyway.
  // ("const" implies "serf" implies non-tree)
  public Function const *cloneThunkSource = NULL;

  // return a copy of this Function, but with just a clone thunk
  public Function *shallowClone() const;
  custom substituteClone { return shallowClone(); }

  // if 'cloneThunkSource' is not NULL, clone its body elements
  // to fill out 'this' object; otherwise, do nothing
  public void finishClone();

  // if 'instV' is not NULL, then force the declarator 'nameAndParams'
  // to refer to it instead of using the usual lookup/creation
  // mechanism
  public void tcheck(Env &env, Variable *instV = NULL);

  // this is where we end up if 'env.checkFunctionBodies' is true
  public void tcheckBody(Env &env);

  private CompoundType *verifyIsCtor(Env &env, char const *context);
  private void tcheck_memberInits(Env &env);
  private void tcheck_handlers(Env &env);

  // this returns true if this is an instantiation of a template
  // function that has not yet been tcheck'd
  public bool instButNotTchecked() const;

  // true if this is a function template (uninstantiated)
  public bool isTemplate() const;
}


class MemberInit {
  // if this is initializing a data member, tcheck will set this
  public(xml_TY,xmlShouldSerialize) Variable *member = NULL;

  // if it's a base class ctor call, tcheck will set this instead
  public(xml_TY) CompoundType *base = NULL;

  // the constructor used to initialize the member or subobject
  // (can't call it "ctor".. that's an astgen keyword.. doh),
  // or NULL for non-CompoundTypes
  public(xml_TY,xmlShouldSerialize) Variable *ctorVar = NULL;

  public void printExtras(std::ostream &os, int indent) const;
  custom debugPrint { printExtras(os, indent); }

  custom clone {
    ret->member = member;
    ret->base = base;
    ret->ctorVar = ctorVar;
  }

  public void tcheck(Env &env, CompoundType *enclosing);
}


class Declaration {
  public void tcheck(Env &env, DeclaratorContext context);
}


class ASTTypeId {
  // tcheck params for ASTTypeId
  public struct Tcheck {
    // when non-NULL, we're in an E_new, and this points to an
    // Expression* which should be set to the expression which denotes
    // the number of elements for new[] to allocate
    Expression **newSizeExpr;

    // additional declflags to attach to the resulting Variable;
    // when this includes DF_PARAMETER, it's a function parameter,
    // which knowledge can be applied towards disambiguation
    DeclFlags dflags;

    // syntactic context
    DeclaratorContext context;

  public:
    Tcheck(DeclFlags df, DeclaratorContext dc)
      : newSizeExpr(NULL), dflags(df), context(dc) {}
  };

  // the return value is the ASTTypeId* to store in place of the
  // one used to invoke the function, to resolve ambiguities
  public ASTTypeId *tcheck(Env &env, Tcheck &tc);
  public void mid_tcheck(Env &env, Tcheck &tc);

  public Type *getType() const;      // can use after calling 'tcheck'
}


class PQName {
  // typecheck the template arguments buried in this PQName
  //
  // 8/01/04: Go all the way to looking up the scopes denoted by the
  // qualifiers.  'scope' is the scope denoted by the qualifiers seen
  // so far, or NULL to mean "current scope", and 'lflags' might be
  // LF_DECLARATOR if this PQName is the name of a declarator.
  //
  // 2005-03-14: Do not call this directly if the name might be
  // ambiguous; use 'tcheckPQName' (in cc_tcheck.cc) instead.
  pure_virtual void tcheck_pq(Env &env, Scope *scope = NULL,
                              LookupFlags lflags = LF_NONE);

  -> PQ_qualifier {
       // record the result of looking up just the 'qualifier' portion
       // (without considering template arguments); this is only set
       // for the *first* PQ_qualifier in a PQName; it is needed for
       // applyArgumentMap, since it should not be doing lookup
       public(xml_TY,xmlShouldSerialize) Variable *qualifierVar = NULL;
       custom debugPrint {
         ind(os, indent) << "qualifierVar: " << refersTo(qualifierVar) << "\n";
       }

       // digested template arguments
       public(xml_OL,xmlEmbed_List) ObjList<STemplateArgument> sargs;
     }

  -> PQ_template {
       public(xml_OL,xmlEmbed_List) ObjList<STemplateArgument> sargs;
     }
}


class TypeSpecifier {
  // yield the type named by the specifier; this type may of course
  // get refined when the declarator is considered
  public Type *tcheck(Env &env, DeclFlags dflags, LookupFlags lflags);
  pure_virtual Type *itcheck(Env &env, DeclFlags dflags, LookupFlags lflags);

  // since several of the type specifiers use names, and names are
  // scoped, but we don't want later analyses to have to know about
  // scopes, for those specifiers that use names cc_tcheck writes down
  // which type it refers to

  -> TS_name {
       // typedef Variable this name refers to
       public(xml_TY,xmlShouldSerialize) Variable *var = NULL;

       // if the lookup is *not* dependent (and some other conditions
       // hold...), this will point to 'var' and be preserved when
       // the AST is cloned
       public(xml_TY,xmlShouldSerialize) Variable *nondependentVar = NULL;
       custom clone { ret->nondependentVar = nondependentVar; }
     }

  -> TS_elaborated {
       public(xml_TY) NamedAtomicType *atype = NULL;
     }

  -> TS_classSpec {
       public(xml_TY) CompoundType *ctype = NULL;
       public void tcheckIntoCompound(
           Env &env, DeclFlags dflags, CompoundType *ct, bool suppressErrors = false);
       private void tcheckFunctionBodies(Env &env);

       public void printExtras(std::ostream &os, int indent) const;
       custom debugPrint { printExtras(os, indent); }
     }

  -> TS_enumSpec {
       public(xml_TY) EnumType *etype = NULL;
     }
}


class BaseClassSpec {
  public void printExtras(std::ostream &os, int indent) const;
  custom debugPrint { printExtras(os, indent); }

  // the type named by the 'name'
  public(xml_TY) CompoundType *type = NULL;
}


class Member {
  pure_virtual void tcheck(Env &env);
}


class Enumerator {
  public(xml_TY,xmlShouldSerialize) Variable *var; // (serf) introduction record
  ctor var=NULL;

  // when the enumerator values are computed, I store them here
  // so I can see them in the AST printout; I only print this
  // value if 'var' is non-NULL (i.e. the enumerator has been
  // tcheck'd so the value has been determined)
  public(xml) int enumValue;

  public void printExtras(std::ostream &os, int indent) const;
  custom debugPrint { printExtras(os, indent); }

  // we pass both the base 'enum' and the Type wrapped around it,
  // since both are needed and it's slightly expensive to compute
  // one from the other for each enumerator
  public void tcheck(Env &env, EnumType *parentEnum, Type *parentType);
}


// The "Declarator" AST node appears in many different contexts in the
// AST, and visitor-based analyses often need to do quite different
// things depending on which context a declarator appears in.  So,
// this enumeration lists all the possible contexts.
enum DeclaratorContext {
  DC_UNKNOWN,             // dummy value; nothing should have this after tcheck

  DC_FUNCTION,            // Function::nameAndParams
                          // inside Declaration
  DC_TF_DECL,             //   TF_decl::decl
  DC_TF_EXPLICITINST,     //   TF_explicitInst::d
  DC_MR_DECL,             //   MR_decl::d
  DC_S_DECL,              //   S_decl::decl
  DC_TD_DECL,             //   TD_decl::d
  DC_FEA,                 //   FullExpressionAnnot::declarations
                          // inside ASTTypeId
  DC_D_FUNC,              //   D_func::params
  DC_EXCEPTIONSPEC,       //   ExceptionSpec::types
  DC_ON_CONVERSION,       //   ON_conversion::type
  DC_CN_DECL,             //   CN_decl::typeId
  DC_HANDLER,             //   Handler::typeId
  DC_E_CAST,              //   E_cast::ctype
  DC_E_SIZEOFTYPE,        //   E_sizeofType::atype
  DC_E_NEW,               //   E_new::atype (new)
  DC_E_KEYWORDCAST,       //   E_keywordCast::ctype
  DC_E_TYPEIDTYPE,        //   E_typeidType::ttype
  DC_TP_TYPE,             //   TP_type::defaultType
  DC_TP_NONTYPE,          //   TP_nontype::param
  DC_TA_TYPE,             //   TA_type::type
};


class Declarator {
  // entity declared by this declarator
  public(xml_TY,xmlShouldSerialize) Variable *var = NULL;// (serf) computed information: name, type, etc.
  
  // SGM 2007-09-14: Why do we do this?  It's very dangerous; template
  // instantiation depends on cloning, and cloning the results of
  // tchecking mean that the tcheck of the uninst template can
  // contaminate the results of tchecking the instantiation.  (They
  // deliberately communicate to implement two-phase lookup, but that
  // is not done through 'var'.)  As far as I can tell, the tchecker
  // correctly recomputes 'var' w/o looking at the prior info, but
  // this is a bug waiting to bite.  This was added by dsw in revision
  // 1203, at 2004-10-28 16:09:55 -0700.
  custom clone {ret->var = var;}

  // This field need not be identical to 'var->type'; the 'type' here
  // comes directly from the declartor syntax, but 'var' might refer
  // to a previous declaration (e.g. two protoypes of the same
  // function), and hence 'var->type' might differ in details like
  // parameter names.  Otherwise, nominally, 'var->type' and 'type'
  // denote equivalent types.
  public(xml_TY) Type *type = NULL;

  // syntactic context; sometimes useful to visitors
  public(xml) DeclaratorContext context = DC_UNKNOWN;
  custom clone {ret->context = context;}

  public void printExtras(std::ostream &os, int indent) const;
  custom debugPrint { printExtras(os, indent); }

  // this class contains the data passed into and out of the
  // declarator checking functions
  public struct Tcheck {
    // Normally, a declarator creates a Variable and inserts it
    // into the environment.  If this field is non-NULL, then the
    // declarator simply uses the supplied Variable instead.
    // Either way, the Variable* is then stored in Declarator::var.
    Variable *existingVar;

    // on the way in, this is the type computed so far; initially
    // it's just the type specifier but additional declarators will
    // layer additional type constructors on top of it and replace
    // the pointer here with a pointer to the constructed type; at
    // the end it is the fully-constructed type
    Type *type;

    // these are the declflags attached to the outer declaration
    DeclFlags dflags;

    // in a new[] declarator, when we hit the final [size], stash
    // the size's AST node pointer here; then E_new can collect it
    Expression *size_E_new;

    // if this is non-NULL, then it points at the D_func responsible
    // for creating 'type', a FunctionType; this is used to determine
    // the cv flags of the implicit 'this' parameter of member functions
    D_func *funcSyntax;

    // syntactic context
    DeclaratorContext context;

    // Assembler label.
    StringRef asmname;

  public:
    Tcheck(Type *t, DeclFlags d, DeclaratorContext dc)
      : existingVar (NULL)
      , type        (t)
      , dflags      (d)
      , size_E_new  (NULL)
      , funcSyntax  (NULL)
      , context     (dc)
      , asmname     (NULL)
    {}
    Tcheck(Tcheck const &obj)
      : existingVar (obj.existingVar)
      , type        (obj.type)
      , dflags      (obj.dflags)
      , size_E_new  (obj.size_E_new)
      , funcSyntax  (obj.funcSyntax)
      , context     (obj.context)
      , asmname     (obj.asmname)
    {}
    Tcheck& operator= (Tcheck const &obj) {
      existingVar = obj.existingVar;
      type        = obj.type;
      dflags      = obj.dflags;
      size_E_new  = obj.size_E_new;
      funcSyntax  = obj.funcSyntax;
      context     = obj.context;
      asmname     = obj.asmname;
      return *this;
    }

    bool hasFlag(DeclFlags f) const { return !!(dflags &f); }
  };

  // determine the type denoted by the combination of 'dt.type' and
  // the type constructors in this declarator, then make a Variable
  // that has that type; if this declarator refers to something that
  // is *already* declared (like a function with a prior prototype),
  // the 'var' field will be shared among the various declarations; if
  // not, put it into the environment
  //
  // the return value specifies which of possibly ambiguous
  // alternatives was selected
  public /*no_ignore*/ Declarator *tcheck(Env &env, Tcheck &dt);
  public void mid_tcheck(Env &env, Tcheck &dt);
  public void tcheck_init(Env &env);
}


class IDeclarator {
  // 8/11/04: There used to be a 'type' field here, but I decided that
  // analyses probably have no need to know about the types denoted by
  // IDeclarators, only that denoted by the full Declarator, which is
  // stored in Declarator::type.

  // external interface; add the type constructor represented by this
  // IDeclarator to 'dt.type'
  pure_virtual void tcheck(Env &env, Declarator::Tcheck &dt);

  // returns true if there is a D_grouping that does not have
  // any D_pointer, D_reference or D_ptrToMember inside it
  public bool hasInnerGrouping() const;

  -> D_func {
       // I want to know which D_funcs are members of classes (whether
       // static or not), but it's not sufficient to just check my
       // environment context since I get confused by pointers to
       // functions.. so I set this to true in MR_decl::tcheck and
       // MR_func::tcheck
       public(xml) bool isMember = false;
     }

  -> D_array {
       // client analyses find it difficult to know whether this
       // D_array means "array" or "new[] size", so I'm going to
       // write down in cc_tcheck which one this is
       public(xml) bool isNewSize = false;
     }

  -> D_bitfield {
       // type checker stashes the bitfield size in bits here
       public(xml) int numBits = 0;
     }
}


class ExceptionSpec {
  public FunctionType::ExnSpec *tcheck(Env &env);
}


class OperatorName {
  public void tcheck(Env &env);
}


class Statement {
  // typecheck, and return which Statement is selected from among
  // syntactically ambiguous choices
  public /*no_ignore*/ Statement *tcheck(Env &env);

  public void mid_tcheck(Env &env, int &);
  pure_virtual void itcheck(Env &env);

  -> S_case {
       // the case label must be an integer; this its value
       public(xml) int labelVal = 0;
     }
}


class Condition {
  // typecheck, and return which Condition is selected from among
  // syntactically ambiguous choices
  public /*no_ignore*/ Condition *tcheck(Env &env);
  public void mid_tcheck(Env &env, int &) { itcheck(env); };
  pure_virtual void itcheck(Env &env);

  // can use after calling 'tcheck'
  pure_virtual Type *getType() const;
}


class Handler {
  public void tcheck(Env &env);
}


class Expression {
  // type check and yield the type of the expression; this type
  // gets automatically stored in the 'type' field; the return
  // value specifies which of possibly ambiguous alternatives
  // was selected for retention
  public void tcheck(Env &env, Expression *&ptr);
  public void mid_tcheck(Env &env, Expression *&replacement);

  // per-type checker; return type this expression eval's to; if
  // this Expression would like to rewrite itself, then it can put
  // the new Expression into 'replacement' and the parent AST node
  // will be updated accordingly; the caller should always put the
  // receiver object pointer into 'replacement' initially
  //
  // the "_x" is for grepping value; think of it as standing for 'eXpression'
  pure_virtual Type *itcheck_x(Env &env, Expression *&replacement);

  // type computed for this expression; might be a SimpleType for
  // ST_ERROR, in which case a subsequent attempt to typecheck the
  // same expression should stop and look for an ambiguous alt.
  public(xml_TY) Type *type = NULL;

  // this is a violation of the cloning invariant, but it gets fixed
  // with CloneExprTypesVisitor after the AST has been fully cloned
  custom clone {
    ret->type = type;
  }

  // make the API for getting the type identical to that of FullExpression
  public Type *getType() { return type; };

  // const-eval; will add an error message to the environment if this
  // expression is not a constant (and also return false); can only
  // call this after tchecking; result must be an integer
  public bool constEval(Env &env, int &result) const;

  // if the function returns true and 'dependent' returns as true, the
  // expression *is* constant but the precise value is dependent on
  // template parameters
  public bool constEval(Env &env, int &result, bool &dependent) const;

  // more control: all info returned in the return value
  public CValue constEval(ConstEval &env) const;
  public CValue iconstEval(ConstEval &env) const;
  public virtual CValue extConstEval(ConstEval &env) const;

  // this attempts to evaluate the expression's address
  public CValue constEvalAddr(ConstEval &env) const;

  // shared by E_cast and E_keywordCast
  public CValue constEvalCast(ConstEval &env, ASTTypeId const *ctype,
                              Expression const *expr) const;

  // return true if this expression has any greater-than operators
  // that are not buried under an E_grouping; this may modify 'expr'
  // if it filters out certain ambiguous alternatives
  public static bool hasUnparenthesizedGT(Expression *&expr);
  public bool ihasUnparenthesizedGT();
  public virtual bool extHasUnparenthesizedGT();

  // return what kind of special expression this is, if any
  public SpecialExpr getSpecial(const ellcc::LangOptions& LO) const;

  public void printExtras(std::ostream &os, int indent) const;
  custom debugPrint { printExtras(os, indent); }

  // interpretations of literals
  -> E_intLit      { public unsigned long long i = 0; }
  -> E_floatLit    { public llvm::APFloat v = 0.0; }

  -> E_stringLit   {
       // The decoded string contents, including the contents from
       // continuations, and a final NUL character.  If this is a wide
       // string literal, then the data block contains wchar_ts.  The
       // exact number of characters, including the NUL, and the
       // character type (and hence width), are available from the
       // ArrayType attached to this Expression.
       //
       // This is NULL only until it has been type checked.
       public DataBlock *data = NULL;
     }

  -> E_charLit     { public unsigned int c = 0; }

  -> E_this {
       // the receiver parameter to which this 'this' refers; NOTE
       // that 'receiver' is a *reference* whereas E_this is a
       // *pointer* (it's like taking the address of 'receiver')
       public(xml_TY,xmlShouldSerialize) Variable *receiver = NULL;
       custom clone { ret->receiver = receiver; }
     }

  -> E_variable {
       public(xml_TY,xmlShouldSerialize) Variable *var = NULL; // (serf) binding introduction of this name
       public Type *itcheck_var(Env &env, Expression *&replacement, LookupFlags flags);
       custom clone { ret->var = var; }

       // extended tcheck interface for lookups that yield sets
       public Type *itcheck_var_set(Env &env, Expression *&replacement,
                                    LookupFlags flags, LookupSet &set);

       // similar to TS_name::nondependentVar
       public(xml_TY,xmlShouldSerialize) Variable *nondependentVar = NULL;
       custom clone { ret->nondependentVar = nondependentVar; }
     }

  // these two kinds have their tcheck further split into two stages
  // so I can use a more specialized disambiguation procedure; the
  // first stage is sufficient to disambiguate between the two
  -> E_funCall {
       public void inner1_itcheck(Env &env, LookupSet &candidates);
       public Type *inner2_itcheck(Env &env, LookupSet &candidates);
     }
  -> E_constructor {
       public void inner1_itcheck(Env &env);
       public Type *inner2_itcheck(Env &env, Expression *&replacement);

       // The constructor function being called.  If this is NULL, it
       // means the constructor is "trivial"; for a no-arg ctor this
       // means a no-op, and for a copy ctor it means member-wise
       // assignment implementable with a memcpy.  (This is a
       // generalization of the Standard's notion of "trivial"; see
       // cppstd 12.1p5,6.)
       public(xml_TY,xmlShouldSerialize) Variable *ctorVar = NULL;
       custom clone { ret->ctorVar = ctorVar; }
     }

  -> E_fieldAcc {
       public(xml_TY,xmlShouldSerialize) Variable *field = NULL;
       public Type *itcheck_fieldAcc(Env &env, LookupFlags flags);
       public Type *itcheck_fieldAcc_set(Env &env, LookupFlags flags,
                                         LookupSet &candidates);

       custom clone { ret->field = field; }
     }

  -> E_sizeof {
       public(xml) int size = -1; // size of the type of expr
       custom clone { ret->size = size; }
     }

  -> E_cast {
       // idempotency for type definitions in casts
       public(xml) bool tcheckedType = false;
     }

  -> E_sizeofType {
       public(xml) int size = -1; // size of the type
       custom clone { ret->size = size; }

       // This flag is used in some circumstances in C mode to ensure
       // a given type expression is only tchecked one time, despite
       // possible ambiguities.  (See the tcheck method.)
       public(xml) bool tchecked = false;
     }

  // Q: should I manually clone all the annotation fields?  Do I
  // need them all?  Should I make a new mechanism in astgen to do
  // this automatically?

  -> E_new {
       // if this is non-NULL, it's the number of elements to allocate via new[]
       //
       // 2005-08-07: Don't traverse this!  It is a non-tree pointer.
       // That is why it says "serf".
       public(xml_AST) Expression /*nullable serf*/ *arraySize = NULL;

       // constructor being called to initialize the storage
       public(xml_TY,xmlShouldSerialize) Variable *ctorVar = NULL;
       custom debugPrint { ind(os,indent) << "ctorVar: " << refersTo(ctorVar) << "\n"; }
       custom clone { ret->ctorVar = ctorVar; }
     }

  // extended tcheck interface for lookups that yield sets; see
  // tcheckExpression_set() in cc_tcheck.cc
  -> E_addrOf {
       public Type *itcheck_addrOf_set(Env &env, Expression *&replacement,
                                       LookupFlags flags, LookupSet &set);
     }
  -> E_grouping {
       public Type *itcheck_grouping_set(Env &env, Expression *&replacement,
                                         LookupFlags flags, LookupSet &set);
     }
  -> E_arrow {
       public Type *itcheck_arrow_set(Env &env, Expression *&replacement,
                                      LookupFlags flags, LookupSet &set);
     }
     
  // Carry an implicit standard conversion.  The reason I do not
  // re-use E_cast is that E_cast wants to carry a syntactic name for
  // the destination type, but I don't want to waste space by
  // constructing it (nor do I want to make E_cast::type nullable).
  //
  // 'stdConv' is the overall description of the conversion; it is
  // never SC_ERROR nor SC_IDENTITY.  The exact conversion is
  // 'expr->type' being converted to 'this->type'.
  -> E_stdConv(Expression expr, StandardConversion stdConv) {
       ctor {
         xassert(stdConv != SC_ERROR && stdConv != SC_IDENTITY);
       };
     }
}


class FullExpression {
  public void tcheck(Env &env);

  // duplicate the API of Expression and delegate all the calls down
  // to the Expression *expr member
  public Type *getType() const
    { return expr->type; };
  public bool constEval(Env &env, int &result) const
    { return expr->constEval(env, result); };
  public CValue constEval(ConstEval &env) const
    { return expr->constEval(env); };
  public CValue iconstEval(ConstEval &env) const
    { return expr->iconstEval(env); };
}


class ArgExpression {
  // repeat some of Expression's interface so I can avoid adding
  // lots of annoying "expr->expr" clutter
  public Type *getType() const
    { return expr->type; };
  public bool constEval(Env &env, int &result) const
    { return expr->constEval(env, result); };
  public CValue constEval(ConstEval &env) const
    { return expr->constEval(env); };
  public CValue iconstEval(ConstEval &env) const
    { return expr->iconstEval(env); };
  public bool hasUnparenthesizedGT()
    { return Expression::hasUnparenthesizedGT(expr); };
  public SpecialExpr getSpecial(const ellcc::LangOptions& LO) const
    { return expr->getSpecial(LO); };

  public ArgExpression *tcheck(Env &env, ArgumentInfo &);
  public void mid_tcheck(Env &env, ArgumentInfo &);
}


class Initializer {
  // check that the initializer is well-typed, given the type of
  // the thing it initializes
  pure_virtual void tcheck(Env &env, Type *type);

  -> IN_ctor() {
       // constructor function being called
       public(xml_TY,xmlShouldSerialize) Variable *ctorVar = NULL;
       custom debugPrint { ind(os,indent) << "ctorVar: " << refersTo(ctorVar) << "\n"; }

       // true if this was originally an IN_expr that the type
       // checker rewrote as IN_ctor; needed to implement 8.5p14
       public(xml,field) bool was_IN_expr = false;

       custom clone {
         ret->ctorVar = ctorVar;
         ret->was_IN_expr = was_IN_expr;
       }
     }
}


class TemplateDeclaration {
  public void tcheck(Env &env);
  pure_virtual void itcheck(Env &env);

  // oy, I wanted 'preemptTraverse' to affect all TemplateDeclarations
  // at once, but that's a little difficult, so I have to copy it..

  -> TD_func {
       custom preemptTraverse {
         // we are now in a template if we already were, or if this
         // declaration is not a complete specialization
         Restorer<bool> r(vis.inTemplate, vis.inTemplate || params!=NULL);
       }
     }

  -> TD_decl {
       custom preemptTraverse {
         Restorer<bool> r(vis.inTemplate, vis.inTemplate || params!=NULL);
       }
     }

  -> TD_tmember {
       custom preemptTraverse {
         Restorer<bool> r(vis.inTemplate, vis.inTemplate || params!=NULL);
       }
     }
}


class TemplateParameter {
  public /*no_ignore*/ TemplateParameter *tcheck(Env &env);
  public void mid_tcheck(Env &env, int &dummy);
  pure_virtual void itcheck(Env &env, int &dummy);

  // parameter Variable
  public(xml_TY,xmlShouldSerialize) Variable *var = NULL;
}


class TemplateArgument {
  public /*no_ignore*/ TemplateArgument *tcheck(Env &env, STemplateArgument &sarg);
  public void mid_tcheck(Env &env, STemplateArgument &sarg);
  pure_virtual void itcheck(Env &env, STemplateArgument &sarg);
}


class NamespaceDecl {
  pure_virtual void tcheck(Env &env);
}

// EOF