gtsocial-umbx

ast2.go (33778B)

---

 // Copyright 2019 The CC Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package cc // import "modernc.org/cc/v3"
 
 import (
 	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"sort"
 	"strings"
 )
 
 // Source is a named part of a translation unit. If Value is empty, Name is
 // interpreted as a path to file containing the source code.
 type Source struct {
 	Name       string
 	Value      string
 	DoNotCache bool // Disable caching of this source
 }
 
 // Promote returns the type the operands of a binary operation are promoted to
 // or the type and argument passed in a function call is promoted.
 func (n *AssignmentExpression) Promote() Type { return n.promote }
 
 type StructInfo struct {
 	Size uintptr
 
 	Align int
 }
 
 // AST represents a translation unit and its related data.
 type AST struct {
 	Enums       map[StringID]Operand // Enumeration constants declared in file scope.
 	Macros      map[StringID]*Macro  // Macros as defined after parsing.
 	PtrdiffType Type
 	Scope       Scope // File scope.
 	SizeType    Type
 	StructTypes map[StringID]Type // Tagged struct/union types declared in file scope.
 	// Alignment and size of every struct/union defined in the translation
 	// unit. Valid only after Translate.
 	Structs map[StructInfo]struct{}
 	// TLD contains pruned file scope declarators, ie. either the first one
 	// or the first one that has an initializer.
 	TLD               map[*Declarator]struct{}
 	TrailingSeperator StringID // White space and/or comments preceding EOF.
 	TranslationUnit   *TranslationUnit
 	WideCharType      Type
 	cfg               *Config
 	cpp               *cpp
 }
 
 // Eval returns the operand that represents the value of m, if it expands to a
 // valid constant expression other than an identifier, or an error, if any.
 func (n *AST) Eval(m *Macro) (o Operand, err error) {
 	defer func() {
 		if e := recover(); e != nil {
 			o = nil
 			err = fmt.Errorf("%v", e)
 		}
 	}()
 
 	if m.IsFnLike() {
 		return nil, fmt.Errorf("cannot evaluate function-like macro")
 	}
 
 	n.cpp.ctx.cfg.ignoreErrors = true
 	n.cpp.ctx.evalIdentError = true
 	v := n.cpp.eval(m.repl)
 	switch x := v.(type) {
 	case int64:
 		return &operand{abi: &n.cfg.ABI, typ: n.cfg.ABI.Type(LongLong), value: Int64Value(x)}, nil
 	case uint64:
 		return &operand{abi: &n.cfg.ABI, typ: n.cfg.ABI.Type(ULongLong), value: Uint64Value(x)}, nil
 	default:
 		return nil, fmt.Errorf("unexpected value: %T", x)
 	}
 }
 
 // Parse preprocesses and parses a translation unit and returns an *AST or
 // error, if any.
 //
 // Search paths listed in includePaths and sysIncludePaths are used to resolve
 // #include "foo.h" and #include <foo.h> preprocessing directives respectively.
 // A special search path "@" is interpreted as 'the same directory as where the
 // file with the #include directive is'.
 //
 // The sources should typically provide, usually in this particular order:
 //
 // - predefined macros, eg.
 //
 //	#define __SIZE_TYPE__ long unsigned int
 //
 // - built-in declarations, eg.
 //
 //	int __builtin_printf(char *__format, ...);
 //
 // - command-line provided directives, eg.
 //
 //	#define FOO
 //	#define BAR 42
 //	#undef QUX
 //
 // - normal C sources, eg.
 //
 //	int main() {}
 //
 // All search and file paths should be absolute paths.
 //
 // If the preprocessed translation unit is empty, the function may return (nil,
 // nil).
 //
 // The parser does only the minimum declarations/identifier resolving necessary
 // for correct parsing. Redeclarations are not checked.
 //
 // Declarators (*Declarator) and StructDeclarators (*StructDeclarator) are
 // inserted in the appropriate scopes.
 //
 // Tagged struct/union specifier definitions (*StructOrUnionSpecifier) are
 // inserted in the appropriate scopes.
 //
 // Tagged enum specifier definitions (*EnumSpecifier) and enumeration constants
 // (*Enumerator) are inserted in the appropriate scopes.
 //
 // Labels (*LabeledStatement) are inserted in the appropriate scopes.
 func Parse(cfg *Config, includePaths, sysIncludePaths []string, sources []Source) (*AST, error) {
 	return parse(newContext(cfg), includePaths, sysIncludePaths, sources)
 }
 
 func parse(ctx *context, includePaths, sysIncludePaths []string, sources []Source) (*AST, error) {
 	if s := ctx.cfg.SharedFunctionDefinitions; s != nil {
 		if s.M == nil {
 			s.M = map[*FunctionDefinition]struct{}{}
 		}
 		if s.m == nil {
 			s.m = map[sharedFunctionDefinitionKey]*FunctionDefinition{}
 		}
 	}
 	if debugWorkingDir || ctx.cfg.DebugWorkingDir {
 		switch wd, err := os.Getwd(); err {
 		case nil:
 			fmt.Fprintf(os.Stderr, "OS working dir: %s\n", wd)
 		default:
 			fmt.Fprintf(os.Stderr, "OS working dir: error %s\n", err)
 		}
 		fmt.Fprintf(os.Stderr, "Config.WorkingDir: %s\n", ctx.cfg.WorkingDir)
 	}
 	if debugIncludePaths || ctx.cfg.DebugIncludePaths {
 		fmt.Fprintf(os.Stderr, "include paths: %v\n", includePaths)
 		fmt.Fprintf(os.Stderr, "system include paths: %v\n", sysIncludePaths)
 	}
 	ctx.includePaths = includePaths
 	ctx.sysIncludePaths = sysIncludePaths
 	var in []source
 	for _, v := range sources {
 		ts, err := cache.get(ctx, v)
 		if err != nil {
 			return nil, err
 		}
 
 		in = append(in, ts)
 	}
 
 	p := newParser(ctx, make(chan *[]Token, 5000)) //DONE benchmark tuned
 	var sep StringID
 	var ssep []byte
 	var seq int32
 	cpp := newCPP(ctx)
 	go func() {
 
 		defer func() {
 			close(p.in)
 			ctx.intMaxWidth = cpp.intMaxWidth()
 		}()
 
 		toks := tokenPool.Get().(*[]Token)
 		*toks = (*toks)[:0]
 		for pline := range cpp.translationPhase4(in) {
 			line := *pline
 			for _, tok := range line {
 				switch tok.char {
 				case ' ', '\n':
 					if ctx.cfg.PreserveOnlyLastNonBlankSeparator {
 						if strings.TrimSpace(tok.value.String()) != "" {
 							sep = tok.value
 						}
 						break
 					}
 
 					switch {
 					case sep != 0:
 						ssep = append(ssep, tok.String()...)
 					default:
 						sep = tok.value
 						ssep = append(ssep[:0], sep.String()...)
 					}
 				default:
 					var t Token
 					t.Rune = tok.char
 					switch {
 					case len(ssep) != 0:
 						t.Sep = dict.id(ssep)
 					default:
 						t.Sep = sep
 					}
 					t.Value = tok.value
 					t.Src = tok.src
 					t.file = tok.file
 					t.macro = tok.macro
 					t.pos = tok.pos
 					seq++
 					t.seq = seq
 					*toks = append(*toks, t)
 					sep = 0
 					ssep = ssep[:0]
 				}
 			}
 			token4Pool.Put(pline)
 			var c rune
 			if n := len(*toks); n != 0 {
 				c = (*toks)[n-1].Rune
 			}
 			switch c {
 			case STRINGLITERAL, LONGSTRINGLITERAL:
 				// nop
 			default:
 				if len(*toks) != 0 {
 					p.in <- translationPhase5(ctx, toks)
 					toks = tokenPool.Get().(*[]Token)
 					*toks = (*toks)[:0]
 				}
 			}
 		}
 		if len(*toks) != 0 {
 			p.in <- translationPhase5(ctx, toks)
 		}
 	}()
 
 	tu := p.translationUnit()
 	if p.errored { // Must drain
 		go func() {
 			for range p.in {
 			}
 		}()
 	}
 
 	if err := ctx.Err(); err != nil {
 		return nil, err
 	}
 
 	if p.errored && !ctx.cfg.ignoreErrors {
 		return nil, fmt.Errorf("%v: syntax error", p.tok.Position())
 	}
 
 	if p.scopes != 0 {
 		panic(internalErrorf("invalid scope nesting but no error reported"))
 	}
 
 	ts := sep
 	if len(ssep) != 0 {
 		ts = dict.id(ssep)
 	}
 	return &AST{
 		Macros:            cpp.macros,
 		Scope:             p.fileScope,
 		TLD:               map[*Declarator]struct{}{},
 		TrailingSeperator: ts,
 		TranslationUnit:   tu,
 		cfg:               ctx.cfg,
 		cpp:               cpp,
 	}, nil
 }
 
 func translationPhase5(ctx *context, toks *[]Token) *[]Token {
 	// [0], 5.1.1.2, 5
 	//
 	// Each source character set member and escape sequence in character
 	// constants and string literals is converted to the corresponding
 	// member of the execution character set; if there is no corresponding
 	// member, it is converted to an implementation- defined member other
 	// than the null (wide) character.
 	for i, tok := range *toks {
 		var cpt cppToken
 		switch tok.Rune {
 		case STRINGLITERAL, LONGSTRINGLITERAL:
 			cpt.char = tok.Rune
 			cpt.value = tok.Value
 			cpt.src = tok.Src
 			cpt.file = tok.file
 			cpt.pos = tok.pos
 			(*toks)[i].Value = dict.sid(stringConst(ctx, cpt))
 		case CHARCONST, LONGCHARCONST:
 			var cpt cppToken
 			cpt.char = tok.Rune
 			cpt.value = tok.Value
 			cpt.src = tok.Src
 			cpt.file = tok.file
 			cpt.pos = tok.pos
 			switch r := charConst(ctx, cpt); {
 			case r <= 255:
 				(*toks)[i].Value = dict.sid(string(r))
 			default:
 				switch cpt.char {
 				case CHARCONST:
 					ctx.err(tok.Position(), "invalid character constant: %s", tok.Value)
 				default:
 					(*toks)[i].Value = dict.sid(string(r))
 				}
 			}
 		}
 	}
 	return toks
 }
 
 // Preprocess preprocesses a translation unit and outputs the result to w.
 //
 // Please see Parse for the documentation of the other parameters.
 func Preprocess(cfg *Config, includePaths, sysIncludePaths []string, sources []Source, w io.Writer) error {
 	ctx := newContext(cfg)
 	if debugWorkingDir || ctx.cfg.DebugWorkingDir {
 		switch wd, err := os.Getwd(); err {
 		case nil:
 			fmt.Fprintf(os.Stderr, "OS working dir: %s\n", wd)
 		default:
 			fmt.Fprintf(os.Stderr, "OS working dir: error %s\n", err)
 		}
 		fmt.Fprintf(os.Stderr, "Config.WorkingDir: %s\n", ctx.cfg.WorkingDir)
 	}
 	if debugIncludePaths || ctx.cfg.DebugIncludePaths {
 		fmt.Fprintf(os.Stderr, "include paths: %v\n", includePaths)
 		fmt.Fprintf(os.Stderr, "system include paths: %v\n", sysIncludePaths)
 	}
 	ctx.includePaths = includePaths
 	ctx.sysIncludePaths = sysIncludePaths
 	var in []source
 	for _, v := range sources {
 		ts, err := cache.get(ctx, v)
 		if err != nil {
 			return err
 		}
 
 		in = append(in, ts)
 	}
 
 	var sep StringID
 	cpp := newCPP(ctx)
 	toks := tokenPool.Get().(*[]Token)
 	*toks = (*toks)[:0]
 	for pline := range cpp.translationPhase4(in) {
 		line := *pline
 		for _, tok := range line {
 			switch tok.char {
 			case ' ', '\n':
 				if ctx.cfg.PreserveOnlyLastNonBlankSeparator {
 					if strings.TrimSpace(tok.value.String()) != "" {
 						sep = tok.value
 					}
 					break
 				}
 
 				switch {
 				case sep != 0:
 					sep = dict.sid(sep.String() + tok.String())
 				default:
 					sep = tok.value
 				}
 			default:
 				var t Token
 				t.Rune = tok.char
 				t.Sep = sep
 				t.Value = tok.value
 				t.Src = tok.src
 				t.file = tok.file
 				t.pos = tok.pos
 				*toks = append(*toks, t)
 				sep = 0
 			}
 		}
 		token4Pool.Put(pline)
 		var c rune
 		if n := len(*toks); n != 0 {
 			c = (*toks)[n-1].Rune
 		}
 		switch c {
 		case STRINGLITERAL, LONGSTRINGLITERAL:
 			// nop
 		default:
 			if len(*toks) != 0 {
 				for _, v := range *translationPhase5(ctx, toks) {
 					if err := wTok(w, v); err != nil {
 						return err
 					}
 				}
 				toks = tokenPool.Get().(*[]Token)
 				*toks = (*toks)[:0]
 			}
 		}
 	}
 	if len(*toks) != 0 {
 		for _, v := range *translationPhase5(ctx, toks) {
 			if err := wTok(w, v); err != nil {
 				return err
 			}
 		}
 	}
 	if _, err := fmt.Fprintln(w); err != nil {
 		return err
 	}
 	return ctx.Err()
 }
 
 func wTok(w io.Writer, tok Token) (err error) {
 	switch tok.Rune {
 	case STRINGLITERAL, LONGSTRINGLITERAL:
 		_, err = fmt.Fprintf(w, `%s"%s"`, tok.Sep, cQuotedString(tok.String(), true))
 	case CHARCONST, LONGCHARCONST:
 		_, err = fmt.Fprintf(w, `%s'%s'`, tok.Sep, cQuotedString(tok.String(), false))
 	default:
 		_, err = fmt.Fprintf(w, "%s%s", tok.Sep, tok)
 	}
 	return err
 }
 
 func cQuotedString(s string, isString bool) []byte {
 	var b []byte
 	for i := 0; i < len(s); i++ {
 		c := s[i]
 		switch c {
 		case '\b':
 			b = append(b, '\\', 'b')
 			continue
 		case '\f':
 			b = append(b, '\\', 'f')
 			continue
 		case '\n':
 			b = append(b, '\\', 'n')
 			continue
 		case '\r':
 			b = append(b, '\\', 'r')
 			continue
 		case '\t':
 			b = append(b, '\\', 't')
 			continue
 		case '\\':
 			b = append(b, '\\', '\\')
 			continue
 		case '"':
 			switch {
 			case isString:
 				b = append(b, '\\', '"')
 			default:
 				b = append(b, '"')
 			}
 			continue
 		case '\'':
 			switch {
 			case isString:
 				b = append(b, '\'')
 			default:
 				b = append(b, '\\', '\'')
 			}
 			continue
 		}
 
 		switch {
 		case c < ' ' || c >= 0x7f:
 			b = append(b, '\\', octal(c>>6), octal(c>>3), octal(c))
 		default:
 			b = append(b, c)
 		}
 	}
 	return b
 }
 
 func octal(b byte) byte { return '0' + b&7 }
 
 var trcSource = Source{"<builtin-trc>", `
 extern void *stderr;
 int fflush(void *stream);
 int fprintf(void *stream, const char *format, ...);
 `, false}
 
 // Translate parses and typechecks a translation unit  and returns an *AST or
 // error, if any.
 //
 // Please see Parse for the documentation of the parameters.
 func Translate(cfg *Config, includePaths, sysIncludePaths []string, sources []Source) (*AST, error) {
 	if cfg.InjectTracingCode {
 		for i, v := range sources {
 			if filepath.Ext(v.Name) == ".c" {
 				sources = append(append(append([]Source(nil), sources[:i]...), trcSource), sources[i:]...)
 			}
 		}
 	}
 	return translate(newContext(cfg), includePaths, sysIncludePaths, sources)
 }
 
 func translate(ctx *context, includePaths, sysIncludePaths []string, sources []Source) (*AST, error) {
 	ast, err := parse(ctx, includePaths, sysIncludePaths, sources)
 	if err != nil {
 		return nil, err
 	}
 
 	if ctx, err = ast.typecheck(); err != nil {
 		return nil, err
 	}
 
 	ast.PtrdiffType = ptrdiffT(ctx, ast.Scope, Token{})
 	ast.SizeType = sizeT(ctx, ast.Scope, Token{})
 	ast.WideCharType = wcharT(ctx, ast.Scope, Token{})
 	return ast, nil
 }
 
 // Typecheck determines types of objects and expressions and verifies types are
 // valid in the context they are used.
 func (n *AST) Typecheck() error {
 	_, err := n.typecheck()
 	return err
 }
 
 func (n *AST) typecheck() (*context, error) {
 	ctx := newContext(n.cfg)
 	if err := ctx.cfg.ABI.sanityCheck(ctx, int(ctx.intMaxWidth), n.Scope); err != nil {
 		return nil, err
 	}
 
 	ctx.intBits = int(ctx.cfg.ABI.Types[Int].Size) * 8
 	ctx.ast = n
 	n.TranslationUnit.check(ctx)
 	n.Structs = ctx.structs
 	var a []int
 	for k := range n.Scope {
 		a = append(a, int(k))
 	}
 	sort.Ints(a)
 	for _, v := range a {
 		nm := StringID(v)
 		defs := n.Scope[nm]
 		var r, w int
 		for _, v := range defs {
 			switch x := v.(type) {
 			case *Declarator:
 				r += x.Read
 				w += x.Write
 			}
 		}
 		for _, v := range defs {
 			switch x := v.(type) {
 			case *Declarator:
 				x.Read = r
 				x.Write = w
 			}
 		}
 		var pruned *Declarator
 		for _, v := range defs {
 			switch x := v.(type) {
 			case *Declarator:
 				//TODO check compatible types
 				switch {
 				case x.IsExtern() && !x.fnDef:
 					// nop
 				case pruned == nil:
 					pruned = x
 				case pruned.hasInitializer && x.hasInitializer:
 					ctx.errNode(x, "multiple initializers for the same symbol")
 					continue
 				case pruned.fnDef && x.fnDef:
 					ctx.errNode(x, "multiple function definitions")
 					continue
 				case x.hasInitializer || x.fnDef:
 					pruned = x
 				}
 			}
 		}
 		if pruned == nil {
 			continue
 		}
 
 		n.TLD[pruned] = struct{}{}
 	}
 	n.Enums = ctx.enums
 	n.StructTypes = ctx.structTypes
 	return ctx, ctx.Err()
 }
 
 func (n *AlignmentSpecifier) align() int {
 	switch n.Case {
 	case AlignmentSpecifierAlignasType: // "_Alignas" '(' TypeName ')'
 		return n.TypeName.Type().Align()
 	case AlignmentSpecifierAlignasExpr: // "_Alignas" '(' ConstantExpression ')'
 		return n.ConstantExpression.Operand.Type().Align()
 	default:
 		panic(internalError())
 	}
 }
 
 // Closure reports the variables closed over by a nested function (case
 // BlockItemFuncDef).
 func (n *BlockItem) Closure() map[StringID]struct{} { return n.closure }
 
 // FunctionDefinition returns the nested function (case BlockItemFuncDef).
 func (n *BlockItem) FunctionDefinition() *FunctionDefinition { return n.fn }
 
 func (n *Declarator) IsStatic() bool { return n.td != nil && n.td.static() }
 
 // IsImplicit reports whether n was not declared nor defined, only inferred.
 func (n *Declarator) IsImplicit() bool { return n.implicit }
 
 func (n *Declarator) isVisible(at int32) bool { return at == 0 || n.DirectDeclarator.ends() < at }
 
 func (n *Declarator) setLHS(lhs *Declarator) {
 	if n == nil {
 		return
 	}
 
 	if n.lhs == nil {
 		n.lhs = map[*Declarator]struct{}{}
 	}
 	n.lhs[lhs] = struct{}{}
 }
 
 // LHS reports which declarators n is used in assignment RHS or which function
 // declarators n is used in a function argument. To collect this information,
 // TrackAssignments in Config must be set during type checking.
 // The returned map may contain a nil key. That means that n is assigned to a
 // declarator not known at typechecking time.
 func (n *Declarator) LHS() map[*Declarator]struct{} { return n.lhs }
 
 // Called reports whether n is involved in expr in expr(callArgs).
 func (n *Declarator) Called() bool { return n.called }
 
 // FunctionDefinition returns the function definition associated with n, if any.
 func (n *Declarator) FunctionDefinition() *FunctionDefinition {
 	return n.funcDefinition
 }
 
 // NameTok returns n's declaring name token.
 func (n *Declarator) NameTok() (r Token) {
 	if n == nil || n.DirectDeclarator == nil {
 		return r
 	}
 
 	return n.DirectDeclarator.NameTok()
 }
 
 // LexicalScope returns the lexical scope of n.
 func (n *Declarator) LexicalScope() Scope { return n.DirectDeclarator.lexicalScope }
 
 // Name returns n's declared name.
 func (n *Declarator) Name() StringID {
 	if n == nil || n.DirectDeclarator == nil {
 		return 0
 	}
 
 	return n.DirectDeclarator.Name()
 }
 
 // ParamScope returns the scope in which n's function parameters are declared
 // if the underlying type of n is a function or nil otherwise. If n is part of
 // a function definition the scope is the same as the scope of the function
 // body.
 func (n *Declarator) ParamScope() Scope {
 	if n == nil {
 		return nil
 	}
 
 	return n.DirectDeclarator.ParamScope()
 }
 
 // Type returns the type of n.
 func (n *Declarator) Type() Type { return n.typ }
 
 // IsExtern reports whether n was declared with storage class specifier 'extern'.
 func (n *Declarator) IsExtern() bool { return n.td != nil && n.td.extern() }
 
 func (n *DeclarationSpecifiers) auto() bool        { return n != nil && n.class&fAuto != 0 }
 func (n *DeclarationSpecifiers) extern() bool      { return n != nil && n.class&fExtern != 0 }
 func (n *DeclarationSpecifiers) register() bool    { return n != nil && n.class&fRegister != 0 }
 func (n *DeclarationSpecifiers) static() bool      { return n != nil && n.class&fStatic != 0 }
 func (n *DeclarationSpecifiers) threadLocal() bool { return n != nil && n.class&fThreadLocal != 0 }
 func (n *DeclarationSpecifiers) typedef() bool     { return n != nil && n.class&fTypedef != 0 }
 
 func (n *DirectAbstractDeclarator) TypeQualifier() Type { return n.typeQualifiers }
 
 func (n *DirectDeclarator) ends() int32 {
 	switch n.Case {
 	case DirectDeclaratorIdent: // IDENTIFIER
 		return n.Token.seq
 	case DirectDeclaratorDecl: // '(' Declarator ')'
 		return n.Token2.seq
 	case DirectDeclaratorArr: // DirectDeclarator '[' TypeQualifierList AssignmentExpression ']'
 		return n.Token2.seq
 	case DirectDeclaratorStaticArr: // DirectDeclarator '[' "static" TypeQualifierList AssignmentExpression ']'
 		return n.Token3.seq
 	case DirectDeclaratorArrStatic: // DirectDeclarator '[' TypeQualifierList "static" AssignmentExpression ']'
 		return n.Token3.seq
 	case DirectDeclaratorStar: // DirectDeclarator '[' TypeQualifierList '*' ']'
 		return n.Token3.seq
 	case DirectDeclaratorFuncParam: // DirectDeclarator '(' ParameterTypeList ')'
 		return n.Token2.seq
 	case DirectDeclaratorFuncIdent: // DirectDeclarator '(' IdentifierList ')'
 		return n.Token2.seq
 	default:
 		panic(internalError())
 	}
 }
 
 func (n *DirectDeclarator) TypeQualifier() Type { return n.typeQualifiers }
 
 // NameTok returns n's declarin name token.
 func (n *DirectDeclarator) NameTok() (r Token) {
 	for {
 		if n == nil {
 			return r
 		}
 
 		switch n.Case {
 		case DirectDeclaratorIdent: // IDENTIFIER
 			return n.Token
 		case DirectDeclaratorDecl: // '(' Declarator ')'
 			return n.Declarator.NameTok()
 		default:
 			n = n.DirectDeclarator
 		}
 	}
 }
 
 // Name returns n's declared name.
 func (n *DirectDeclarator) Name() StringID {
 	for {
 		if n == nil {
 			return 0
 		}
 
 		switch n.Case {
 		case DirectDeclaratorIdent: // IDENTIFIER
 			return n.Token.Value
 		case DirectDeclaratorDecl: // '(' Declarator ')'
 			return n.Declarator.Name()
 		default:
 			n = n.DirectDeclarator
 		}
 	}
 }
 
 // ParamScope returns the innermost scope in which function parameters are
 // declared for Case DirectDeclaratorFuncParam or DirectDeclaratorFuncIdent or
 // nil otherwise.
 func (n *DirectDeclarator) ParamScope() Scope {
 	if n == nil {
 		return nil
 	}
 
 	switch n.Case {
 	case DirectDeclaratorIdent: // IDENTIFIER
 		return nil
 	case DirectDeclaratorDecl: // '(' Declarator ')'
 		return n.Declarator.ParamScope()
 	case DirectDeclaratorArr: // DirectDeclarator '[' TypeQualifierList AssignmentExpression ']'
 		return n.DirectDeclarator.ParamScope()
 	case DirectDeclaratorStaticArr: // DirectDeclarator '[' "static" TypeQualifierList AssignmentExpression ']'
 		return n.DirectDeclarator.ParamScope()
 	case DirectDeclaratorArrStatic: // DirectDeclarator '[' TypeQualifierList "static" AssignmentExpression ']'
 		return n.DirectDeclarator.ParamScope()
 	case DirectDeclaratorStar: // DirectDeclarator '[' TypeQualifierList '*' ']'
 		return n.DirectDeclarator.ParamScope()
 	case DirectDeclaratorFuncParam: // DirectDeclarator '(' ParameterTypeList ')'
 		if s := n.DirectDeclarator.ParamScope(); s != nil {
 			return s
 		}
 
 		return n.paramScope
 	case DirectDeclaratorFuncIdent: // DirectDeclarator '(' IdentifierList ')'
 		if s := n.DirectDeclarator.ParamScope(); s != nil {
 			return s
 		}
 
 		return n.paramScope
 	default:
 		panic(internalError())
 	}
 }
 
 func (n *Enumerator) isVisible(at int32) bool { return n.Token.seq < at }
 
 func (n *EnumSpecifier) Type() Type { return n.typ }
 
 // Promote returns the type the operands of the binary operation are promoted to.
 func (n *EqualityExpression) Promote() Type { return n.promote }
 
 // Promote returns the type the operands of the binary operation are promoted to.
 func (n *AdditiveExpression) Promote() Type { return n.promote }
 
 // Promote returns the type the operands of the binary operation are promoted to.
 func (n *MultiplicativeExpression) Promote() Type { return n.promote }
 
 // Promote returns the type the operands of the binary operation are promoted to.
 func (n *InclusiveOrExpression) Promote() Type { return n.promote }
 
 // Promote returns the type the operands of the binary operation are promoted to.
 func (n *ExclusiveOrExpression) Promote() Type { return n.promote }
 
 // Promote returns the type the operands of the binary operation are promoted to.
 func (n *AndExpression) Promote() Type { return n.promote }
 
 func (n *InitDeclarator) Value() *InitializerValue { return n.initializer }
 
 // FirstDesignatorField returns the first field a designator of an union type
 // denotes, if any.
 func (n *Initializer) FirstDesignatorField() Field { return n.field0 }
 
 // TrailingComma returns the comma token following n, if any.
 func (n *Initializer) TrailingComma() *Token { return n.trailingComma }
 
 // IsConst reports whether n is constant.
 func (n *Initializer) IsConst() bool { return n == nil || n.isConst }
 
 // IsZero reports whether n is a zero value.
 func (n *Initializer) IsZero() bool { return n == nil || n.isZero }
 
 // List returns n as a flattened list of all items that are case
 // InitializerExpr.
 func (n *Initializer) List() []*Initializer { return n.list }
 
 // Parent returns the parent of n, if any.
 func (n *Initializer) Parent() *Initializer { return n.parent }
 
 // Type returns the type this initializer initializes.
 func (n *Initializer) Type() Type { return n.typ }
 
 // IsConst reports whether n is constant.
 func (n *InitializerList) IsConst() bool { return n == nil || n.isConst }
 
 // IsZero reports whether n is a zero value.
 func (n *InitializerList) IsZero() bool { return n == nil || n.isZero }
 
 // List returns n as a flattened list of all items that are case
 // InitializerExpr.
 func (n *InitializerList) List() []*Initializer {
 	if n == nil {
 		return nil
 	}
 
 	return n.list
 }
 
 // IsEmpty reprts whether n is an empty list.
 func (n *InitializerList) IsEmpty() bool { return len(n.list) == 0 }
 
 // LexicalScope returns the lexical scope of n.
 func (n *JumpStatement) LexicalScope() Scope { return n.lexicalScope }
 
 // LexicalScope returns the lexical scope of n.
 func (n *LabeledStatement) LexicalScope() Scope { return n.lexicalScope }
 
 func (n *ParameterDeclaration) Type() Type { return n.typ }
 
 func (n *Pointer) TypeQualifier() Type { return n.typeQualifiers }
 
 // ResolvedIn reports which scope the identifier of cases
 // PrimaryExpressionIdent, PrimaryExpressionEnum were resolved in, if any.
 func (n *PrimaryExpression) ResolvedIn() Scope { return n.resolvedIn }
 
 // ResolvedTo reports which Node the identifier of cases
 // PrimaryExpressionIdent, PrimaryExpressionEnum resolved to, if any.
 func (n *PrimaryExpression) ResolvedTo() Node { return n.resolvedTo }
 
 // Promote returns the type the operands of the binary operation are promoted to.
 func (n *RelationalExpression) Promote() Type { return n.promote }
 
 // Cases returns the cases a switch statement consist of, in source order.
 func (n *SelectionStatement) Cases() []*LabeledStatement { return n.cases }
 
 // Promote returns the type the shift count operand is promoted to.
 func (n *ShiftExpression) Promote() Type { return n.promote }
 
 func (n *StructOrUnionSpecifier) Type() Type { return n.typ }
 
 // Promote returns the type the type the switch expression is promoted to.
 func (n *SelectionStatement) Promote() Type { return n.promote }
 
 // Type returns the type of n.
 func (n *TypeName) Type() Type { return n.typ }
 
 // // LexicalScope returns the lexical scope of n.
 // func (n *AttributeValue) LexicalScope() Scope { return n.lexicalScope }
 
 // // Scope returns n's scope.
 // func (n *CompoundStatement) Scope() Scope { return n.scope }
 
 // // LexicalScope returns the lexical scope of n.
 // func (n *Designator) LexicalScope() Scope { return n.lexicalScope }
 
 // // LexicalScope returns the lexical scope of n.
 // func (n *DirectDeclarator) LexicalScope() Scope { return n.lexicalScope }
 
 // LexicalScope returns the lexical scope of n.
 func (n *EnumSpecifier) LexicalScope() Scope { return n.lexicalScope }
 
 // // LexicalScope returns the lexical scope of n.
 // func (n *IdentifierList) LexicalScope() Scope { return n.lexicalScope }
 
 // // LexicalScope returns the lexical scope of n.
 // func (n *PrimaryExpression) LexicalScope() Scope { return n.lexicalScope }
 
 // // LexicalScope returns the lexical scope of n.
 // func (n *StructOrUnionSpecifier) LexicalScope() Scope { return n.lexicalScope }
 
 // // ResolvedIn reports which scope the identifier of case
 // // TypeSpecifierTypedefName was resolved in, if any.
 // func (n *TypeSpecifier) ResolvedIn() Scope { return n.resolvedIn }
 
 func (n *TypeSpecifier) list() (r []*TypeSpecifier) {
 	switch n.Case {
 	case TypeSpecifierAtomic:
 		return n.AtomicTypeSpecifier.list
 	default:
 		return []*TypeSpecifier{n}
 	}
 }
 
 // // LexicalScope returns the lexical scope of n.
 // func (n *UnaryExpression) LexicalScope() Scope { return n.lexicalScope }
 
 func (n *UnaryExpression) Declarator() *Declarator {
 	switch n.Case {
 	case UnaryExpressionPostfix: // PostfixExpression
 		return n.PostfixExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *PostfixExpression) Declarator() *Declarator {
 	switch n.Case {
 	case PostfixExpressionPrimary: // PrimaryExpression
 		return n.PrimaryExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *PrimaryExpression) Declarator() *Declarator {
 	switch n.Case {
 	case PrimaryExpressionIdent: // IDENTIFIER
 		if n.Operand != nil {
 			return n.Operand.Declarator()
 		}
 
 		return nil
 	case PrimaryExpressionExpr: // '(' Expression ')'
 		return n.Expression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *Expression) Declarator() *Declarator {
 	switch n.Case {
 	case ExpressionAssign: // AssignmentExpression
 		return n.AssignmentExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *AssignmentExpression) Declarator() *Declarator {
 	switch n.Case {
 	case AssignmentExpressionCond: // ConditionalExpression
 		return n.ConditionalExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *ConditionalExpression) Declarator() *Declarator {
 	switch n.Case {
 	case ConditionalExpressionLOr: // LogicalOrExpression
 		return n.LogicalOrExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *LogicalOrExpression) Declarator() *Declarator {
 	switch n.Case {
 	case LogicalOrExpressionLAnd: // LogicalAndExpression
 		return n.LogicalAndExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *LogicalAndExpression) Declarator() *Declarator {
 	switch n.Case {
 	case LogicalAndExpressionOr: // InclusiveOrExpression
 		return n.InclusiveOrExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *InclusiveOrExpression) Declarator() *Declarator {
 	switch n.Case {
 	case InclusiveOrExpressionXor: // ExclusiveOrExpression
 		return n.ExclusiveOrExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *ExclusiveOrExpression) Declarator() *Declarator {
 	switch n.Case {
 	case ExclusiveOrExpressionAnd: // AndExpression
 		return n.AndExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *AndExpression) Declarator() *Declarator {
 	switch n.Case {
 	case AndExpressionEq: // EqualityExpression
 		return n.EqualityExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *EqualityExpression) Declarator() *Declarator {
 	switch n.Case {
 	case EqualityExpressionRel: // RelationalExpression
 		return n.RelationalExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *RelationalExpression) Declarator() *Declarator {
 	switch n.Case {
 	case RelationalExpressionShift: // ShiftExpression
 		return n.ShiftExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *ShiftExpression) Declarator() *Declarator {
 	switch n.Case {
 	case ShiftExpressionAdd: // AdditiveExpression
 		return n.AdditiveExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *AdditiveExpression) Declarator() *Declarator {
 	switch n.Case {
 	case AdditiveExpressionMul: // MultiplicativeExpression
 		return n.MultiplicativeExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *MultiplicativeExpression) Declarator() *Declarator {
 	switch n.Case {
 	case MultiplicativeExpressionCast: // CastExpression
 		return n.CastExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 func (n *CastExpression) Declarator() *Declarator {
 	switch n.Case {
 	case CastExpressionUnary: // UnaryExpression
 		return n.UnaryExpression.Declarator()
 	default:
 		return nil
 	}
 }
 
 // Has reports whether n has any of attributes in key.
 func (n *AttributeSpecifier) Has(key ...StringID) (*ExpressionList, bool) {
 	if n == nil {
 		return nil, false
 	}
 
 	for list := n.AttributeValueList; list != nil; list = list.AttributeValueList {
 		av := list.AttributeValue
 		for _, k := range key {
 			if av.Token.Value == k {
 				switch av.Case {
 				case AttributeValueIdent: // IDENTIFIER
 					return nil, true
 				case AttributeValueExpr: // IDENTIFIER '(' ExpressionList ')'
 					return av.ExpressionList, true
 				}
 			}
 		}
 	}
 	return nil, false
 }
 
 // Has reports whether n has any of attributes in key.
 func (n *AttributeSpecifierList) Has(key ...StringID) (*ExpressionList, bool) {
 	for ; n != nil; n = n.AttributeSpecifierList {
 		if exprList, ok := n.AttributeSpecifier.Has(key...); ok {
 			return exprList, ok
 		}
 	}
 	return nil, false
 }
 
 // Parent returns the CompoundStatement that contains n, if any.
 func (n *CompoundStatement) Parent() *CompoundStatement { return n.parent }
 
 // IsJumpTarget returns whether n or any of its children contain a named
 // labeled statement.
 func (n *CompoundStatement) IsJumpTarget() bool { return n.isJumpTarget }
 
 func (n *CompoundStatement) hasLabel() {
 	for ; n != nil; n = n.parent {
 		n.isJumpTarget = true
 	}
 }
 
 // Declarations returns the list of declarations in n.
 func (n *CompoundStatement) Declarations() []*Declaration { return n.declarations }
 
 // Children returns the list of n's children.
 func (n *CompoundStatement) Children() []*CompoundStatement { return n.children }
 
 // CompoundStatements returns the list of compound statements in n.
 func (n *FunctionDefinition) CompoundStatements() []*CompoundStatement { return n.compoundStatements }
 
 // CompoundStatement returns the block containing n.
 func (n *LabeledStatement) CompoundStatement() *CompoundStatement { return n.block }
 
 // LabeledStatements returns labeled statements of n.
 func (n *CompoundStatement) LabeledStatements() []*LabeledStatement { return n.labeledStmts }
 
 // HasInitializer reports whether d has an initializator.
 func (n *Declarator) HasInitializer() bool { return n.hasInitializer }
 
 // Context reports the statement, if any, a break or continue belongs to. Valid
 // only after typecheck and for n.Case == JumpStatementBreak or
 // JumpStatementContinue.
 func (n *JumpStatement) Context() Node { return n.context }
 
 // IsFunctionPrototype reports whether n is a function prototype.
 func (n *Declarator) IsFunctionPrototype() bool {
 	return n != nil && n.Type() != nil && n.Type().Kind() == Function && !n.fnDef && !n.IsParameter
 }
 
 // DeclarationSpecifiers returns the declaration specifiers associated with n or nil.
 func (n *Declarator) DeclarationSpecifiers() *DeclarationSpecifiers {
 	if x, ok := n.td.(*DeclarationSpecifiers); ok {
 		return x
 	}
 
 	return nil
 }
 
 // SpecifierQualifierList returns the specifier qualifer list associated with n or nil.
 func (n *Declarator) SpecifierQualifierList() *SpecifierQualifierList {
 	if x, ok := n.td.(*SpecifierQualifierList); ok {
 		return x
 	}
 
 	return nil
 }
 
 // TypeQualifier returns the type qualifiers associated with n or nil.
 func (n *Declarator) TypeQualifiers() *TypeQualifiers {
 	if x, ok := n.td.(*TypeQualifiers); ok {
 		return x
 	}
 
 	return nil
 }
 
 // StructDeclaration returns the struct declaration associated with n.
 func (n *StructDeclarator) StructDeclaration() *StructDeclaration { return n.decl }