d/dmd/declaration.h

/* Compiler implementation of the D programming language
 * Copyright (C) 1999-2021 by The D Language Foundation, All Rights Reserved
 * written by Walter Bright
 * http://www.digitalmars.com
 * Distributed under the Boost Software License, Version 1.0.
 * http://www.boost.org/LICENSE_1_0.txt
 * https://github.com/dlang/dmd/blob/master/src/dmd/declaration.h
 */

#pragma once

#include "dsymbol.h"
#include "mtype.h"
#include "objc.h"

class Expression;
class Statement;
class LabelDsymbol;
class Initializer;
class Module;
class ForeachStatement;
struct Ensure
{
    Identifier *id;
    Statement *ensure;

    Ensure();
    Ensure(Identifier *id, Statement *ensure);
    Ensure syntaxCopy();
    static Ensures *arraySyntaxCopy(Ensures *a);
};
class AliasDeclaration;
class FuncDeclaration;
class ExpInitializer;
class StructDeclaration;
struct InterState;
struct CompiledCtfeFunction;
struct ObjcSelector;
struct IntRange;

enum LINK;
enum TOK;
enum MATCH;
enum PURE;
enum PINLINE;

#define STCundefined    0LL
#define STCstatic       1LL
#define STCextern       2LL
#define STCconst        4LL
#define STCfinal        8LL
#define STCabstract     0x10LL
#define STCparameter    0x20LL
#define STCfield        0x40LL
#define STCoverride     0x80LL
#define STCauto         0x100LL
#define STCsynchronized 0x200LL
#define STCdeprecated   0x400LL
#define STCin           0x800LL         // in parameter
#define STCout          0x1000LL        // out parameter
#define STClazy         0x2000LL        // lazy parameter
#define STCforeach      0x4000LL        // variable for foreach loop
#define STCvariadic     0x10000LL       // the 'variadic' parameter in: T foo(T a, U b, V variadic...)
#define STCctorinit     0x20000LL       // can only be set inside constructor
#define STCtemplateparameter  0x40000LL // template parameter
#define STCscope        0x80000LL
#define STCimmutable    0x100000LL
#define STCref          0x200000LL
#define STCinit         0x400000LL      // has explicit initializer
#define STCmanifest     0x800000LL      // manifest constant
#define STCnodtor       0x1000000LL     // don't run destructor
#define STCnothrow      0x2000000LL     // never throws exceptions
#define STCpure         0x4000000LL     // pure function
#define STCtls          0x8000000LL     // thread local
#define STCalias        0x10000000LL    // alias parameter
#define STCshared       0x20000000LL    // accessible from multiple threads
// accessible from multiple threads
// but not typed as "shared"
#define STCgshared      0x40000000LL
#define STCwild         0x80000000LL    // for "wild" type constructor
#define STC_TYPECTOR    (STCconst | STCimmutable | STCshared | STCwild)
#define STC_FUNCATTR    (STCref | STCnothrow | STCnogc | STCpure | STCproperty | STCsafe | STCtrusted | STCsystem)

#define STCproperty      0x100000000LL
#define STCsafe          0x200000000LL
#define STCtrusted       0x400000000LL
#define STCsystem        0x800000000LL
#define STCctfe          0x1000000000LL  // can be used in CTFE, even if it is static
#define STCdisable       0x2000000000LL  // for functions that are not callable
#define STCresult        0x4000000000LL  // for result variables passed to out contracts
#define STCnodefaultctor 0x8000000000LL  // must be set inside constructor
#define STCtemp          0x10000000000LL // temporary variable
#define STCrvalue        0x20000000000LL // force rvalue for variables
#define STCnogc          0x40000000000LL // @nogc
#define STCvolatile      0x80000000000LL // destined for volatile in the back end
#define STCreturn        0x100000000000LL // 'return ref' or 'return scope' for function parameters
#define STCautoref       0x200000000000LL // Mark for the already deduced 'auto ref' parameter
#define STCinference     0x400000000000LL // do attribute inference
#define STCexptemp       0x800000000000LL // temporary variable that has lifetime restricted to an expression
#define STCmaybescope    0x1000000000000LL // parameter might be 'scope'
#define STCscopeinferred 0x2000000000000LL // 'scope' has been inferred and should not be part of mangling
#define STCfuture        0x4000000000000LL // introducing new base class function
#define STClocal         0x8000000000000LL // do not forward (see ddmd.dsymbol.ForwardingScopeDsymbol).

const StorageClass STCStorageClass = (STCauto | STCscope | STCstatic | STCextern | STCconst | STCfinal |
    STCabstract | STCsynchronized | STCdeprecated | STCfuture | STCoverride | STClazy | STCalias |
    STCout | STCin |
    STCmanifest | STCimmutable | STCshared | STCwild | STCnothrow | STCnogc | STCpure | STCref | STCtls |
    STCgshared | STCproperty | STCsafe | STCtrusted | STCsystem | STCdisable | STClocal);

struct Match
{
    int count;                  // number of matches found
    MATCH last;                 // match level of lastf
    FuncDeclaration *lastf;     // last matching function we found
    FuncDeclaration *nextf;     // current matching function
    FuncDeclaration *anyf;      // pick a func, any func, to use for error recovery
};

void functionResolve(Match *m, Dsymbol *fd, Loc loc, Scope *sc, Objects *tiargs, Type *tthis, Expressions *fargs, const char **pMessage = NULL);
int overloadApply(Dsymbol *fstart, void *param, int (*fp)(void *, Dsymbol *));
void aliasSemantic(AliasDeclaration *ds, Scope *sc);

void ObjectNotFound(Identifier *id);

/**************************************************************/

class Declaration : public Dsymbol
{
public:
    Type *type;
    Type *originalType;         // before semantic analysis
    StorageClass storage_class;
    Prot protection;
    LINK linkage;
    int inuse;                  // used to detect cycles
    DString mangleOverride;     // overridden symbol with pragma(mangle, "...")

    Declaration(Identifier *id);
    const char *kind() const;
    d_uns64 size(Loc loc);
    bool checkDisabled(Loc loc, Scope *sc, bool isAliasedDeclaration = false);
    int checkModify(Loc loc, Scope *sc, Type *t, Expression *e1, int flag);

    Dsymbol *search(const Loc &loc, Identifier *ident, int flags = SearchLocalsOnly);

    bool isStatic() { return (storage_class & STCstatic) != 0; }
    virtual bool isDelete();
    virtual bool isDataseg();
    virtual bool isThreadlocal();
    virtual bool isCodeseg() const;
    bool isCtorinit()     { return (storage_class & STCctorinit) != 0; }
    bool isFinal()        { return (storage_class & STCfinal) != 0; }
    bool isAbstract()     { return (storage_class & STCabstract) != 0; }
    bool isConst()        { return (storage_class & STCconst) != 0; }
    bool isImmutable()    { return (storage_class & STCimmutable) != 0; }
    bool isWild()         { return (storage_class & STCwild) != 0; }
    bool isAuto()         { return (storage_class & STCauto) != 0; }
    bool isScope()        { return (storage_class & STCscope) != 0; }
    bool isSynchronized() { return (storage_class & STCsynchronized) != 0; }
    bool isParameter()    { return (storage_class & STCparameter) != 0; }
    bool isDeprecated()   { return (storage_class & STCdeprecated) != 0; }
    bool isDisabled()     { return (storage_class & STCdisable) != 0; }
    bool isOverride()     { return (storage_class & STCoverride) != 0; }
    bool isResult()       { return (storage_class & STCresult) != 0; }
    bool isField()        { return (storage_class & STCfield) != 0; }

    bool isIn()    { return (storage_class & STCin) != 0; }
    bool isOut()   { return (storage_class & STCout) != 0; }
    bool isRef()   { return (storage_class & STCref) != 0; }

    bool isFuture() { return (storage_class & STCfuture) != 0; }

    Prot prot();

    Declaration *isDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

/**************************************************************/

class TupleDeclaration : public Declaration
{
public:
    Objects *objects;
    bool isexp;                 // true: expression tuple

    TypeTuple *tupletype;       // !=NULL if this is a type tuple

    TupleDeclaration(Loc loc, Identifier *ident, Objects *objects);
    Dsymbol *syntaxCopy(Dsymbol *);
    const char *kind() const;
    Type *getType();
    Dsymbol *toAlias2();
    bool needThis();

    TupleDeclaration *isTupleDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

/**************************************************************/

class AliasDeclaration : public Declaration
{
public:
    Dsymbol *aliassym;
    Dsymbol *overnext;          // next in overload list
    Dsymbol *_import;           // !=NULL if unresolved internal alias for selective import

    AliasDeclaration(Loc loc, Identifier *ident, Type *type);
    AliasDeclaration(Loc loc, Identifier *ident, Dsymbol *s);
    static AliasDeclaration *create(Loc loc, Identifier *id, Type *type);
    Dsymbol *syntaxCopy(Dsymbol *);
    bool overloadInsert(Dsymbol *s);
    const char *kind() const;
    Type *getType();
    Dsymbol *toAlias();
    Dsymbol *toAlias2();
    bool isOverloadable();

    AliasDeclaration *isAliasDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

/**************************************************************/

class OverDeclaration : public Declaration
{
public:
    Dsymbol *overnext;          // next in overload list
    Dsymbol *aliassym;
    bool hasOverloads;

    OverDeclaration(Identifier *ident, Dsymbol *s, bool hasOverloads = true);
    const char *kind() const;
    bool equals(RootObject *o);
    bool overloadInsert(Dsymbol *s);

    Dsymbol *toAlias();
    Dsymbol *isUnique();
    bool isOverloadable();

    OverDeclaration *isOverDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

/**************************************************************/

class VarDeclaration : public Declaration
{
public:
    Initializer *_init;
    unsigned offset;
    unsigned sequenceNumber;     // order the variables are declared
    FuncDeclarations nestedrefs; // referenced by these lexically nested functions
    bool isargptr;              // if parameter that _argptr points to
    structalign_t alignment;
    bool ctorinit;              // it has been initialized in a ctor
    bool onstack;               // it is a class that was allocated on the stack
    bool mynew;                 // it is a class new'd with custom operator new
    int canassign;              // it can be assigned to
    bool overlapped;            // if it is a field and has overlapping
    bool overlapUnsafe;         // if it is an overlapping field and the overlaps are unsafe
    bool doNotInferScope;       // do not infer 'scope' for this variable
    unsigned char isdataseg;    // private data for isDataseg
    Dsymbol *aliassym;          // if redone as alias to another symbol
    VarDeclaration *lastVar;    // Linked list of variables for goto-skips-init detection
    unsigned endlinnum;         // line number of end of scope that this var lives in

    // When interpreting, these point to the value (NULL if value not determinable)
    // The index of this variable on the CTFE stack, -1 if not allocated
    int ctfeAdrOnStack;
    Expression *edtor;          // if !=NULL, does the destruction of the variable
    IntRange *range;            // if !NULL, the variable is known to be within the range

    VarDeclaration(Loc loc, Type *t, Identifier *id, Initializer *init);
    static VarDeclaration *create(Loc loc, Type *t, Identifier *id, Initializer *init);
    Dsymbol *syntaxCopy(Dsymbol *);
    void setFieldOffset(AggregateDeclaration *ad, unsigned *poffset, bool isunion);
    const char *kind() const;
    AggregateDeclaration *isThis();
    bool needThis();
    bool isExport() const;
    bool isImportedSymbol() const;
    bool isDataseg();
    bool isThreadlocal();
    bool isCTFE();
    bool isOverlappedWith(VarDeclaration *v);
    bool hasPointers();
    bool canTakeAddressOf();
    bool needsScopeDtor();
    bool enclosesLifetimeOf(VarDeclaration *v) const;
    Expression *callScopeDtor(Scope *sc);
    Expression *getConstInitializer(bool needFullType = true);
    Expression *expandInitializer(Loc loc);
    void checkCtorConstInit();
    bool checkNestedReference(Scope *sc, Loc loc);
    Dsymbol *toAlias();
    // Eliminate need for dynamic_cast
    VarDeclaration *isVarDeclaration() { return (VarDeclaration *)this; }
    void accept(Visitor *v) { v->visit(this); }
};

/**************************************************************/

// This is a shell around a back end symbol

class SymbolDeclaration : public Declaration
{
public:
    StructDeclaration *dsym;

    SymbolDeclaration(Loc loc, StructDeclaration *dsym);

    // Eliminate need for dynamic_cast
    SymbolDeclaration *isSymbolDeclaration() { return (SymbolDeclaration *)this; }
    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoDeclaration : public VarDeclaration
{
public:
    Type *tinfo;

    TypeInfoDeclaration(Type *tinfo);
    static TypeInfoDeclaration *create(Type *tinfo);
    Dsymbol *syntaxCopy(Dsymbol *);
    const char *toChars();

    TypeInfoDeclaration *isTypeInfoDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoStructDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoStructDeclaration(Type *tinfo);
    static TypeInfoStructDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoClassDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoClassDeclaration(Type *tinfo);
    static TypeInfoClassDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoInterfaceDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoInterfaceDeclaration(Type *tinfo);
    static TypeInfoInterfaceDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoPointerDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoPointerDeclaration(Type *tinfo);
    static TypeInfoPointerDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoArrayDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoArrayDeclaration(Type *tinfo);
    static TypeInfoArrayDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoStaticArrayDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoStaticArrayDeclaration(Type *tinfo);
    static TypeInfoStaticArrayDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoAssociativeArrayDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoAssociativeArrayDeclaration(Type *tinfo);
    static TypeInfoAssociativeArrayDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoEnumDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoEnumDeclaration(Type *tinfo);
    static TypeInfoEnumDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoFunctionDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoFunctionDeclaration(Type *tinfo);
    static TypeInfoFunctionDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoDelegateDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoDelegateDeclaration(Type *tinfo);
    static TypeInfoDelegateDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoTupleDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoTupleDeclaration(Type *tinfo);
    static TypeInfoTupleDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoConstDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoConstDeclaration(Type *tinfo);
    static TypeInfoConstDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoInvariantDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoInvariantDeclaration(Type *tinfo);
    static TypeInfoInvariantDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoSharedDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoSharedDeclaration(Type *tinfo);
    static TypeInfoSharedDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoWildDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoWildDeclaration(Type *tinfo);
    static TypeInfoWildDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

class TypeInfoVectorDeclaration : public TypeInfoDeclaration
{
public:
    TypeInfoVectorDeclaration(Type *tinfo);
    static TypeInfoVectorDeclaration *create(Type *tinfo);

    void accept(Visitor *v) { v->visit(this); }
};

/**************************************************************/

class ThisDeclaration : public VarDeclaration
{
public:
    ThisDeclaration(Loc loc, Type *t);
    Dsymbol *syntaxCopy(Dsymbol *);
    ThisDeclaration *isThisDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

enum ILS
{
    ILSuninitialized,   // not computed yet
    ILSno,              // cannot inline
    ILSyes              // can inline
};

/**************************************************************/

enum BUILTIN
{
    BUILTINunknown = 255,   /// not known if this is a builtin
    BUILTINunimp = 0,       /// this is not a builtin
    BUILTINgcc,             /// this is a GCC builtin
    BUILTINllvm,            /// this is an LLVM builtin
    BUILTINsin,
    BUILTINcos,
    BUILTINtan,
    BUILTINsqrt,
    BUILTINfabs,
    BUILTINldexp,
    BUILTINlog,
    BUILTINlog2,
    BUILTINlog10,
    BUILTINexp,
    BUILTINexpm1,
    BUILTINexp2,
    BUILTINround,
    BUILTINfloor,
    BUILTINceil,
    BUILTINtrunc,
    BUILTINcopysign,
    BUILTINpow,
    BUILTINfmin,
    BUILTINfmax,
    BUILTINfma,
    BUILTINisnan,
    BUILTINisinfinity,
    BUILTINisfinite,
    BUILTINbsf,
    BUILTINbsr,
    BUILTINbswap,
    BUILTINpopcnt,
    BUILTINyl2x,
    BUILTINyl2xp1,
    BUILTINtoPrecFloat,
    BUILTINtoPrecDouble,
    BUILTINtoPrecReal
};

Expression *eval_builtin(Loc loc, FuncDeclaration *fd, Expressions *arguments);
BUILTIN isBuiltin(FuncDeclaration *fd);

typedef Expression *(*builtin_fp)(Loc loc, FuncDeclaration *fd, Expressions *arguments);
void add_builtin(const char *mangle, builtin_fp fp);
void builtin_init();

#define FUNCFLAGpurityInprocess    1    // working on determining purity
#define FUNCFLAGsafetyInprocess    2    // working on determining safety
#define FUNCFLAGnothrowInprocess   4    // working on determining nothrow
#define FUNCFLAGnogcInprocess      8    // working on determining @nogc
#define FUNCFLAGreturnInprocess 0x10    // working on inferring 'return' for parameters
#define FUNCFLAGinlineScanned   0x20    // function has been scanned for inline possibilities
#define FUNCFLAGinferScope      0x40    // infer 'scope' for parameters
#define FUNCFLAGprintf          0x200   // is a printf-like function
#define FUNCFLAGscanf           0x400   // is a scanf-like function

class FuncDeclaration : public Declaration
{
public:
    Types *fthrows;                     // Array of Type's of exceptions (not used)
    Statements *frequires;              // in contracts
    Ensures *fensures;                  // out contracts
    Statement *frequire;                // lowered in contract
    Statement *fensure;                 // lowered out contract
    Statement *fbody;

    FuncDeclarations foverrides;        // functions this function overrides
    FuncDeclaration *fdrequire;         // function that does the in contract
    FuncDeclaration *fdensure;          // function that does the out contract

    const char *mangleString;           // mangled symbol created from mangleExact()

    VarDeclaration *vresult;            // result variable for out contracts
    LabelDsymbol *returnLabel;          // where the return goes

    // used to prevent symbols in different
    // scopes from having the same name
    DsymbolTable *localsymtab;
    VarDeclaration *vthis;              // 'this' parameter (member and nested)
    VarDeclaration *v_arguments;        // '_arguments' parameter
    ObjcSelector* selector;             // Objective-C method selector (member function only)
    VarDeclaration *v_argptr;           // '_argptr' variable
    VarDeclarations *parameters;        // Array of VarDeclaration's for parameters
    DsymbolTable *labtab;               // statement label symbol table
    Dsymbol *overnext;                  // next in overload list
    FuncDeclaration *overnext0;         // next in overload list (only used during IFTI)
    Loc endloc;                         // location of closing curly bracket
    int vtblIndex;                      // for member functions, index into vtbl[]
    bool naked;                         // true if naked
    bool generated;                     // true if function was generated by the compiler rather than
                                        // supplied by the user
    ILS inlineStatusStmt;
    ILS inlineStatusExp;
    PINLINE inlining;

    CompiledCtfeFunction *ctfeCode;     // Compiled code for interpreter
    int inlineNest;                     // !=0 if nested inline
    bool isArrayOp;                     // true if array operation
    // true if errors in semantic3 this function's frame ptr
    bool semantic3Errors;
    ForeachStatement *fes;              // if foreach body, this is the foreach
    BaseClass* interfaceVirtual;        // if virtual, but only appears in interface vtbl[]
    bool introducing;                   // true if 'introducing' function
    // if !=NULL, then this is the type
    // of the 'introducing' function
    // this one is overriding
    Type *tintro;
    bool inferRetType;                  // true if return type is to be inferred
    StorageClass storage_class2;        // storage class for template onemember's

    // Things that should really go into Scope

    // 1 if there's a return exp; statement
    // 2 if there's a throw statement
    // 4 if there's an assert(0)
    // 8 if there's inline asm
    // 16 if there are multiple return statements
    int hasReturnExp;

    // Support for NRVO (named return value optimization)
    bool nrvo_can;                      // true means we can do it
    VarDeclaration *nrvo_var;           // variable to replace with shidden
    Symbol *shidden;                    // hidden pointer passed to function

    ReturnStatements *returns;

    GotoStatements *gotos;              // Gotos with forward references

    // set if this is a known, builtin function we can evaluate at compile time
    BUILTIN builtin;

    // set if someone took the address of this function
    int tookAddressOf;
    bool requiresClosure;               // this function needs a closure

    // local variables in this function which are referenced by nested functions
    VarDeclarations closureVars;
    // Sibling nested functions which called this one
    FuncDeclarations siblingCallers;

    FuncDeclarations *inlinedNestedCallees;

    unsigned flags;                     // FUNCFLAGxxxxx

    FuncDeclaration(Loc loc, Loc endloc, Identifier *id, StorageClass storage_class, Type *type);
    static FuncDeclaration *create(Loc loc, Loc endloc, Identifier *id, StorageClass storage_class, Type *type);
    Dsymbol *syntaxCopy(Dsymbol *);
    bool functionSemantic();
    bool functionSemantic3();
    bool checkForwardRef(Loc loc);
    // called from semantic3
    VarDeclaration *declareThis(Scope *sc, AggregateDeclaration *ad);
    bool equals(RootObject *o);

    int overrides(FuncDeclaration *fd);
    int findVtblIndex(Dsymbols *vtbl, int dim, bool fix17349 = true);
    BaseClass *overrideInterface();
    bool overloadInsert(Dsymbol *s);
    FuncDeclaration *overloadExactMatch(Type *t);
    FuncDeclaration *overloadModMatch(Loc loc, Type *tthis, bool &hasOverloads);
    TemplateDeclaration *findTemplateDeclRoot();
    bool inUnittest();
    MATCH leastAsSpecialized(FuncDeclaration *g);
    LabelDsymbol *searchLabel(Identifier *ident);
    int getLevel(Loc loc, Scope *sc, FuncDeclaration *fd); // lexical nesting level difference
    const char *toPrettyChars(bool QualifyTypes = false);
    const char *toFullSignature();  // for diagnostics, e.g. 'int foo(int x, int y) pure'
    bool isMain();
    bool isCMain();
    bool isWinMain();
    bool isDllMain();
    bool isExport() const;
    bool isImportedSymbol() const;
    bool isCodeseg() const;
    bool isOverloadable();
    PURE isPure();
    PURE isPureBypassingInference();
    bool setImpure();
    bool isSafe();
    bool isSafeBypassingInference();
    bool isTrusted();
    bool setUnsafe();

    bool isNogc();
    bool isNogcBypassingInference();
    bool setGC();

    void printGCUsage(Loc loc, const char *warn);
    bool isolateReturn();
    bool parametersIntersect(Type *t);
    virtual bool isNested();
    AggregateDeclaration *isThis();
    bool needThis();
    bool isVirtualMethod();
    virtual bool isVirtual();
    virtual bool isFinalFunc();
    virtual bool addPreInvariant();
    virtual bool addPostInvariant();
    const char *kind() const;
    FuncDeclaration *isUnique();
    bool checkNestedReference(Scope *sc, Loc loc);
    bool needsClosure();
    bool checkClosure();
    bool hasNestedFrameRefs();
    void buildResultVar(Scope *sc, Type *tret);
    Statement *mergeFrequire(Statement *);
    static bool needsFensure(FuncDeclaration *fd);
    void buildEnsureRequire();
    Statement *mergeFensure(Statement *, Identifier *oid);
    ParameterList getParameterList();

    static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, const char *name, StorageClass stc=0);
    static FuncDeclaration *genCfunc(Parameters *args, Type *treturn, Identifier *id, StorageClass stc=0);
    void checkDmain();
    bool checkNRVO();

    FuncDeclaration *isFuncDeclaration() { return this; }

    virtual FuncDeclaration *toAliasFunc() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

FuncDeclaration *resolveFuncCall(Loc loc, Scope *sc, Dsymbol *s,
        Objects *tiargs,
        Type *tthis,
        Expressions *arguments,
        int flags = 0);

class FuncAliasDeclaration : public FuncDeclaration
{
public:
    FuncDeclaration *funcalias;
    bool hasOverloads;

    FuncAliasDeclaration(Identifier *ident, FuncDeclaration *funcalias, bool hasOverloads = true);

    FuncAliasDeclaration *isFuncAliasDeclaration() { return this; }
    const char *kind() const;

    FuncDeclaration *toAliasFunc();
    void accept(Visitor *v) { v->visit(this); }
};

class FuncLiteralDeclaration : public FuncDeclaration
{
public:
    TOK tok;                       // TOKfunction or TOKdelegate
    Type *treq;                         // target of return type inference

    // backend
    bool deferToObj;

    FuncLiteralDeclaration(Loc loc, Loc endloc, Type *type, TOK tok,
        ForeachStatement *fes, Identifier *id = NULL);
    Dsymbol *syntaxCopy(Dsymbol *);
    bool isNested();
    AggregateDeclaration *isThis();
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();

    void modifyReturns(Scope *sc, Type *tret);

    FuncLiteralDeclaration *isFuncLiteralDeclaration() { return this; }
    const char *kind() const;
    const char *toPrettyChars(bool QualifyTypes = false);
    void accept(Visitor *v) { v->visit(this); }
};

class CtorDeclaration : public FuncDeclaration
{
public:
    CtorDeclaration(Loc loc, Loc endloc, StorageClass stc, Type *type);
    Dsymbol *syntaxCopy(Dsymbol *);
    const char *kind() const;
    const char *toChars();
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();

    CtorDeclaration *isCtorDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class PostBlitDeclaration : public FuncDeclaration
{
public:
    PostBlitDeclaration(Loc loc, Loc endloc, StorageClass stc, Identifier *id);
    Dsymbol *syntaxCopy(Dsymbol *);
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();
    bool overloadInsert(Dsymbol *s);

    PostBlitDeclaration *isPostBlitDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class DtorDeclaration : public FuncDeclaration
{
public:
    DtorDeclaration(Loc loc, Loc endloc);
    DtorDeclaration(Loc loc, Loc endloc, StorageClass stc, Identifier *id);
    Dsymbol *syntaxCopy(Dsymbol *);
    const char *kind() const;
    const char *toChars();
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();
    bool overloadInsert(Dsymbol *s);

    DtorDeclaration *isDtorDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class StaticCtorDeclaration : public FuncDeclaration
{
public:
    StaticCtorDeclaration(Loc loc, Loc endloc, StorageClass stc);
    StaticCtorDeclaration(Loc loc, Loc endloc, const char *name, StorageClass stc);
    Dsymbol *syntaxCopy(Dsymbol *);
    AggregateDeclaration *isThis();
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();
    bool hasStaticCtorOrDtor();

    StaticCtorDeclaration *isStaticCtorDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class SharedStaticCtorDeclaration : public StaticCtorDeclaration
{
public:
    SharedStaticCtorDeclaration(Loc loc, Loc endloc, StorageClass stc);
    Dsymbol *syntaxCopy(Dsymbol *);

    SharedStaticCtorDeclaration *isSharedStaticCtorDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class StaticDtorDeclaration : public FuncDeclaration
{
public:
    VarDeclaration *vgate;      // 'gate' variable

    StaticDtorDeclaration(Loc loc, Loc endloc, StorageClass stc);
    StaticDtorDeclaration(Loc loc, Loc endloc, const char *name, StorageClass stc);
    Dsymbol *syntaxCopy(Dsymbol *);
    AggregateDeclaration *isThis();
    bool isVirtual();
    bool hasStaticCtorOrDtor();
    bool addPreInvariant();
    bool addPostInvariant();

    StaticDtorDeclaration *isStaticDtorDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class SharedStaticDtorDeclaration : public StaticDtorDeclaration
{
public:
    SharedStaticDtorDeclaration(Loc loc, Loc endloc, StorageClass stc);
    Dsymbol *syntaxCopy(Dsymbol *);

    SharedStaticDtorDeclaration *isSharedStaticDtorDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class InvariantDeclaration : public FuncDeclaration
{
public:
    InvariantDeclaration(Loc loc, Loc endloc, StorageClass stc, Identifier *id = NULL);
    Dsymbol *syntaxCopy(Dsymbol *);
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();

    InvariantDeclaration *isInvariantDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class UnitTestDeclaration : public FuncDeclaration
{
public:
    char *codedoc; /** For documented unittest. */

    // toObjFile() these nested functions after this one
    FuncDeclarations deferredNested;

    UnitTestDeclaration(Loc loc, Loc endloc, StorageClass stc, char *codedoc);
    Dsymbol *syntaxCopy(Dsymbol *);
    AggregateDeclaration *isThis();
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();

    UnitTestDeclaration *isUnitTestDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};

class NewDeclaration : public FuncDeclaration
{
public:
    Parameters *parameters;
    VarArg varargs;

    NewDeclaration(Loc loc, Loc endloc, StorageClass stc, Parameters *arguments, VarArg varargs);
    Dsymbol *syntaxCopy(Dsymbol *);
    const char *kind() const;
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();

    NewDeclaration *isNewDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};


class DeleteDeclaration : public FuncDeclaration
{
public:
    Parameters *parameters;

    DeleteDeclaration(Loc loc, Loc endloc, StorageClass stc, Parameters *arguments);
    Dsymbol *syntaxCopy(Dsymbol *);
    const char *kind() const;
    bool isDelete();
    bool isVirtual();
    bool addPreInvariant();
    bool addPostInvariant();

    DeleteDeclaration *isDeleteDeclaration() { return this; }
    void accept(Visitor *v) { v->visit(this); }
};