cgo: refactor

This is a large refactor of the cgo package. It should fix a number of
smaller problems and be a bit more strict (like upstream CGo): it for
example requires every Go file in a package to include the header files
it needs instead of piggybacking on imports in earlier files.

The main benefit is that it should be a bit more maintainable and easier
to add new features in the future (like static functions).

This breaks the tinygo.org/x/bluetooth package, which should be updated
before this change lands.

9 files changed, 916 insertions, 936 deletions

diff --git a/cgo/cgo.go b/cgo/cgo.go
index 15b388694..42914a11a 100644
--- a/cgo/cgo.go
+++ b/cgo/cgo.go
@@ -18,7 +18,6 @@ import (
 	"go/scanner"
 	"go/token"
 	"path/filepath"
-	"sort"
 	"strconv"
 	"strings"
 
@@ -35,45 +34,19 @@ type cgoPackage struct {
 	packageDir      string // full path to the package to process
 	fset            *token.FileSet
 	tokenFiles      map[string]*token.File
-	missingSymbols  map[string]struct{}
-	constants       map[string]constantInfo
-	functions       map[string]*functionInfo
-	globals         map[string]globalInfo
-	typedefs        map[string]*typedefInfo
-	elaboratedTypes map[string]*elaboratedTypeInfo
-	enums           map[string]enumInfo
-	anonStructNum   int
+	definedGlobally map[string]ast.Node
+	anonDecls       map[interface{}]string
 	cflags          []string // CFlags from #cgo lines
 	ldflags         []string // LDFlags from #cgo lines
 	visitedFiles    map[string][]byte
 }
 
-// constantInfo stores some information about a CGo constant found by libclang
-// and declared in the Go AST.
-type constantInfo struct {
-	expr ast.Expr
-	pos  token.Pos
-}
-
-// functionInfo stores some information about a CGo function found by libclang
-// and declared in the AST.
-type functionInfo struct {
-	args     []paramInfo
-	results  *ast.FieldList
-	pos      token.Pos
-	variadic bool
-}
-
-// paramInfo is a parameter of a CGo function (see functionInfo).
-type paramInfo struct {
-	name     string
-	typeExpr ast.Expr
-}
-
-// typedefInfo contains information about a single typedef in C.
-type typedefInfo struct {
-	typeExpr ast.Expr
-	pos      token.Pos
+// cgoFile holds information only for a single Go file (with one or more
+// `import "C"` statements).
+type cgoFile struct {
+	*cgoPackage
+	defined map[string]ast.Node
+	names   map[string]clangCursor
 }
 
 // elaboratedTypeInfo contains some information about an elaborated type
@@ -97,18 +70,6 @@ type bitfieldInfo struct {
 	endBit   int64 // may be 0 meaning "until the end of the field"
 }
 
-// enumInfo contains information about an enum in the C.
-type enumInfo struct {
-	typeExpr ast.Expr
-	pos      token.Pos
-}
-
-// globalInfo contains information about a declared global variable in C.
-type globalInfo struct {
-	typeExpr ast.Expr
-	pos      token.Pos
-}
-
 // cgoAliases list type aliases between Go and C, for types that are equivalent
 // in both languages. See addTypeAliases.
 var cgoAliases = map[string]string{
@@ -125,24 +86,24 @@ var cgoAliases = map[string]string{
 
 // builtinAliases are handled specially because they only exist on the Go side
 // of CGo, not on the CGo side (they're prefixed with "_Cgo_" there).
-var builtinAliases = map[string]struct{}{
-	"char":      {},
-	"schar":     {},
-	"uchar":     {},
-	"short":     {},
-	"ushort":    {},
-	"int":       {},
-	"uint":      {},
-	"long":      {},
-	"ulong":     {},
-	"longlong":  {},
-	"ulonglong": {},
+var builtinAliases = []string{
+	"char",
+	"schar",
+	"uchar",
+	"short",
+	"ushort",
+	"int",
+	"uint",
+	"long",
+	"ulong",
+	"longlong",
+	"ulonglong",
 }
 
-// cgoTypes lists some C types with ambiguous sizes that must be retrieved
-// somehow from C. This is done by adding some typedefs to get the size of each
-// type.
-const cgoTypes = `
+// builtinAliasTypedefs lists some C types with ambiguous sizes that must be
+// retrieved somehow from C. This is done by adding some typedefs to get the
+// size of each type.
+const builtinAliasTypedefs = `
 # 1 "<cgo>"
 typedef char                _Cgo_char;
 typedef signed char         _Cgo_schar;
@@ -202,13 +163,8 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		currentDir:      dir,
 		fset:            fset,
 		tokenFiles:      map[string]*token.File{},
-		missingSymbols:  map[string]struct{}{},
-		constants:       map[string]constantInfo{},
-		functions:       map[string]*functionInfo{},
-		globals:         map[string]globalInfo{},
-		typedefs:        map[string]*typedefInfo{},
-		elaboratedTypes: map[string]*elaboratedTypeInfo{},
-		enums:           map[string]enumInfo{},
+		definedGlobally: map[string]ast.Node{},
+		anonDecls:       map[interface{}]string{},
 		visitedFiles:    map[string][]byte{},
 	}
 
@@ -238,7 +194,7 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		// This is always a bug in the cgo package.
 		panic("unexpected error: " + err.Error())
 	}
-	// If the Comments field is not set to nil, the fmt package will get
+	// If the Comments field is not set to nil, the go/format package will get
 	// confused about where comments should go.
 	p.generated.Comments = nil
 	// Adjust some of the functions in there.
@@ -254,15 +210,10 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		}
 	}
 	// Patch some types, for example *C.char in C.CString.
-	astutil.Apply(p.generated, p.walker, nil)
-
-	// Find all C.* symbols.
-	for _, f := range files {
-		astutil.Apply(f, p.findMissingCGoNames, nil)
-	}
-	for name := range builtinAliases {
-		p.missingSymbols["_Cgo_"+name] = struct{}{}
-	}
+	cf := p.newCGoFile()
+	astutil.Apply(p.generated, func(cursor *astutil.Cursor) bool {
+		return cf.walker(cursor, nil)
+	}, nil)
 
 	// Find `import "C"` C fragments in the file.
 	cgoHeaders := make([]string, len(files)) // combined CGo header fragment for each file
@@ -337,38 +288,33 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		cflagsForCGo = append(cflagsForCGo, "-isystem", clangHeaders)
 	}
 
+	// Retrieve types such as C.int, C.longlong, etc from C.
+	p.newCGoFile().readNames(builtinAliasTypedefs, cflagsForCGo, "", func(names map[string]clangCursor) {
+		gen := &ast.GenDecl{
+			TokPos: token.NoPos,
+			Tok:    token.TYPE,
+		}
+		for _, name := range builtinAliases {
+			typeSpec := p.getIntegerType("C."+name, names["_Cgo_"+name])
+			gen.Specs = append(gen.Specs, typeSpec)
+		}
+		p.generated.Decls = append(p.generated.Decls, gen)
+	})
+
 	// Process CGo imports for each file.
 	for i, f := range files {
-		p.parseFragment(cgoHeaders[i]+cgoTypes, cflagsForCGo, filepath.Base(fset.File(f.Pos()).Name()))
-	}
-
-	// Declare functions found by libclang.
-	p.addFuncDecls()
-
-	// Declare stub function pointer values found by libclang.
-	p.addFuncPtrDecls()
-
-	// Declare globals found by libclang.
-	p.addConstDecls()
-
-	// Declare globals found by libclang.
-	p.addVarDecls()
-
-	// Forward C types to Go types (like C.uint32_t -> uint32).
-	p.addTypeAliases()
-
-	// Add type declarations for C types, declared using typedef in C.
-	p.addTypedefs()
-
-	// Add elaborated types for C structs and unions.
-	p.addElaboratedTypes()
-
-	// Add enum types and enum constants for C enums.
-	p.addEnumTypes()
-
-	// Patch the AST to use the declared types and functions.
-	for _, f := range files {
-		astutil.Apply(f, p.walker, nil)
+		cf := p.newCGoFile()
+		cf.readNames(cgoHeaders[i], cflagsForCGo, filepath.Base(fset.File(f.Pos()).Name()), func(names map[string]clangCursor) {
+			for _, name := range builtinAliases {
+				// Names such as C.int should not be obtained from C.
+				// This works around an issue in picolibc that has `#define int`
+				// in a header file.
+				delete(names, name)
+			}
+			astutil.Apply(f, func(cursor *astutil.Cursor) bool {
+				return cf.walker(cursor, names)
+			}, nil)
+		})
 	}
 
 	// Print the newly generated in-memory AST, for debugging.
@@ -377,6 +323,14 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	return p.generated, cgoHeaders, p.cflags, p.ldflags, p.visitedFiles, p.errors
 }
 
+func (p *cgoPackage) newCGoFile() *cgoFile {
+	return &cgoFile{
+		cgoPackage: p,
+		defined:    make(map[string]ast.Node),
+		names:      make(map[string]clangCursor),
+	}
+}
+
 // makePathsAbsolute converts some common path compiler flags (-I, -L) from
 // relative flags into absolute flags, if they are relative. This is necessary
 // because the C compiler is usually not invoked from the package path.
@@ -484,365 +438,6 @@ func (p *cgoPackage) parseCGoPreprocessorLines(text string, pos token.Pos) strin
 	return text
 }
 
-// addFuncDecls adds the C function declarations found by libclang in the
-// comment above the `import "C"` statement.
-func (p *cgoPackage) addFuncDecls() {
-	names := make([]string, 0, len(p.functions))
-	for name := range p.functions {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-	for _, name := range names {
-		fn := p.functions[name]
-		obj := &ast.Object{
-			Kind: ast.Fun,
-			Name: "C." + name,
-		}
-		args := make([]*ast.Field, len(fn.args))
-		decl := &ast.FuncDecl{
-			Doc: &ast.CommentGroup{
-				List: []*ast.Comment{
-					{
-						Slash: fn.pos - 1,
-						Text:  "//export " + name,
-					},
-				},
-			},
-			Name: &ast.Ident{
-				NamePos: fn.pos,
-				Name:    "C." + name,
-				Obj:     obj,
-			},
-			Type: &ast.FuncType{
-				Func: fn.pos,
-				Params: &ast.FieldList{
-					Opening: fn.pos,
-					List:    args,
-					Closing: fn.pos,
-				},
-				Results: fn.results,
-			},
-		}
-		if fn.variadic {
-			decl.Doc.List = append(decl.Doc.List, &ast.Comment{
-				Slash: fn.pos - 1,
-				Text:  "//go:variadic",
-			})
-		}
-		obj.Decl = decl
-		for i, arg := range fn.args {
-			args[i] = &ast.Field{
-				Names: []*ast.Ident{
-					{
-						NamePos: fn.pos,
-						Name:    arg.name,
-						Obj: &ast.Object{
-							Kind: ast.Var,
-							Name: arg.name,
-							Decl: decl,
-						},
-					},
-				},
-				Type: arg.typeExpr,
-			}
-		}
-		p.generated.Decls = append(p.generated.Decls, decl)
-	}
-}
-
-// addFuncPtrDecls creates stub declarations of function pointer values. These
-// values will later be replaced with the real values in the compiler.
-// It adds code like the following to the AST:
-//
-//     var (
-//         C.add unsafe.Pointer
-//         C.mul unsafe.Pointer
-//         // ...
-//     )
-func (p *cgoPackage) addFuncPtrDecls() {
-	if len(p.functions) == 0 {
-		return
-	}
-	names := make([]string, 0, len(p.functions))
-	for name := range p.functions {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.VAR,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-		}
-		fn := p.functions[name]
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: "C." + name + "$funcaddr",
-		}
-		valueSpec := &ast.ValueSpec{
-			Names: []*ast.Ident{{
-				NamePos: fn.pos,
-				Name:    "C." + name + "$funcaddr",
-				Obj:     obj,
-			}},
-			Type: &ast.SelectorExpr{
-				X: &ast.Ident{
-					NamePos: fn.pos,
-					Name:    "unsafe",
-				},
-				Sel: &ast.Ident{
-					NamePos: fn.pos,
-					Name:    "Pointer",
-				},
-			},
-		}
-		obj.Decl = valueSpec
-		gen.Specs = append(gen.Specs, valueSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
-	}
-}
-
-// addConstDecls declares external C constants in the Go source.
-// It adds code like the following to the AST:
-//
-//     const C.CONST_INT = 5
-//     const C.CONST_FLOAT = 5.8
-//     // ...
-func (p *cgoPackage) addConstDecls() {
-	if len(p.constants) == 0 {
-		return
-	}
-	names := make([]string, 0, len(p.constants))
-	for name := range p.constants {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.CONST,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-		}
-		constVal := p.constants[name]
-		obj := &ast.Object{
-			Kind: ast.Con,
-			Name: "C." + name,
-		}
-		valueSpec := &ast.ValueSpec{
-			Names: []*ast.Ident{{
-				NamePos: constVal.pos,
-				Name:    "C." + name,
-				Obj:     obj,
-			}},
-			Values: []ast.Expr{constVal.expr},
-		}
-		obj.Decl = valueSpec
-		gen.Specs = append(gen.Specs, valueSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
-	}
-}
-
-// addVarDecls declares external C globals in the Go source.
-// It adds code like the following to the AST:
-//
-//     var C.globalInt  int
-//     var C.globalBool bool
-//     // ...
-func (p *cgoPackage) addVarDecls() {
-	if len(p.globals) == 0 {
-		return
-	}
-	names := make([]string, 0, len(p.globals))
-	for name := range p.globals {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-	for _, name := range names {
-		global := p.globals[name]
-		gen := &ast.GenDecl{
-			TokPos: global.pos,
-			Tok:    token.VAR,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-			Doc: &ast.CommentGroup{
-				List: []*ast.Comment{
-					{
-						Slash: global.pos - 1,
-						Text:  "//go:extern " + name,
-					},
-				},
-			},
-		}
-		obj := &ast.Object{
-			Kind: ast.Var,
-			Name: "C." + name,
-		}
-		valueSpec := &ast.ValueSpec{
-			Names: []*ast.Ident{{
-				NamePos: global.pos,
-				Name:    "C." + name,
-				Obj:     obj,
-			}},
-			Type: global.typeExpr,
-		}
-		obj.Decl = valueSpec
-		gen.Specs = append(gen.Specs, valueSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
-	}
-}
-
-// addTypeAliases aliases some built-in Go types with their equivalent C types.
-// It adds code like the following to the AST:
-//
-//     type C.int8_t  = int8
-//     type C.int16_t = int16
-//     // ...
-func (p *cgoPackage) addTypeAliases() {
-	aliasKeys := make([]string, 0, len(cgoAliases))
-	for key := range cgoAliases {
-		aliasKeys = append(aliasKeys, key)
-	}
-	sort.Strings(aliasKeys)
-	for _, typeName := range aliasKeys {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
-			Lparen: token.NoPos,
-			Rparen: token.NoPos,
-		}
-		goTypeName := cgoAliases[typeName]
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: typeName,
-		}
-		typeSpec := &ast.TypeSpec{
-			Name: &ast.Ident{
-				NamePos: token.NoPos,
-				Name:    typeName,
-				Obj:     obj,
-			},
-			Assign: p.generatedPos,
-			Type: &ast.Ident{
-				NamePos: token.NoPos,
-				Name:    goTypeName,
-			},
-		}
-		obj.Decl = typeSpec
-		gen.Specs = append(gen.Specs, typeSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
-	}
-}
-
-func (p *cgoPackage) addTypedefs() {
-	if len(p.typedefs) == 0 {
-		return
-	}
-	names := make([]string, 0, len(p.typedefs))
-	for name := range p.typedefs {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
-		}
-		typedef := p.typedefs[name]
-		typeName := "C." + name
-		isAlias := true
-		if strings.HasPrefix(name, "_Cgo_") {
-			typeName = "C." + name[len("_Cgo_"):]
-			isAlias = false // C.short etc. should not be aliased to the equivalent Go type (not portable)
-		}
-		if _, ok := cgoAliases[typeName]; ok {
-			// This is a type that also exists in Go (defined in stdint.h).
-			continue
-		}
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: typeName,
-		}
-		typeSpec := &ast.TypeSpec{
-			Name: &ast.Ident{
-				NamePos: typedef.pos,
-				Name:    typeName,
-				Obj:     obj,
-			},
-			Type: typedef.typeExpr,
-		}
-		if isAlias {
-			typeSpec.Assign = typedef.pos
-		}
-		obj.Decl = typeSpec
-		gen.Specs = append(gen.Specs, typeSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
-	}
-}
-
-// addElaboratedTypes adds C elaborated types as aliases. These are the "struct
-// foo" or "union foo" types, often used in a typedef.
-//
-// See also:
-// https://en.cppreference.com/w/cpp/language/elaborated_type_specifier
-func (p *cgoPackage) addElaboratedTypes() {
-	if len(p.elaboratedTypes) == 0 {
-		return
-	}
-	names := make([]string, 0, len(p.elaboratedTypes))
-	for name := range p.elaboratedTypes {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
-		}
-		typ := p.elaboratedTypes[name]
-		typeName := "C." + name
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: typeName,
-		}
-		typeExpr := typ.typeExpr
-		if typ.unionSize != 0 {
-			// Create getters/setters.
-			for _, field := range typ.typeExpr.Fields.List {
-				if len(field.Names) != 1 {
-					p.addError(typ.pos, fmt.Sprintf("union must have field with a single name, it has %d names", len(field.Names)))
-					continue
-				}
-				p.createUnionAccessor(field, typeName)
-			}
-			// Convert to a single-field struct type.
-			typeExpr = p.makeUnionField(typ)
-			if typeExpr == nil {
-				// There was an error, that was already added to the list of
-				// errors.
-				continue
-			}
-		}
-		typeSpec := &ast.TypeSpec{
-			Name: &ast.Ident{
-				NamePos: typ.pos,
-				Name:    typeName,
-				Obj:     obj,
-			},
-			Type: typeExpr,
-		}
-		obj.Decl = typeSpec
-		gen.Specs = append(gen.Specs, typeSpec)
-		// If this struct has bitfields, create getters for them.
-		for _, bitfield := range typ.bitfields {
-			p.createBitfieldGetter(bitfield, typeName)
-			p.createBitfieldSetter(bitfield, typeName)
-		}
-		p.generated.Decls = append(p.generated.Decls, gen)
-	}
-}
-
 // makeUnionField creates a new struct from an existing *elaboratedTypeInfo,
 // that has just a single field that must be accessed through special accessors.
 // It returns nil when there is an error. In case of an error, that error has
@@ -1304,80 +899,319 @@ func (p *cgoPackage) createBitfieldSetter(bitfield bitfieldInfo, typeName string
 	p.generated.Decls = append(p.generated.Decls, setter)
 }
 
-// addEnumTypes adds C enums to the AST. For example, the following C code:
-//
-//     enum option {
-//         optionA,
-//         optionB = 5,
-//     };
-//
-// is translated to the following Go code equivalent:
-//
-//     type C.enum_option int32
-//
-// The constants are treated just like macros so are inserted into the AST by
-// addConstDecls.
-// See also: https://en.cppreference.com/w/c/language/enum
-func (p *cgoPackage) addEnumTypes() {
-	if len(p.enums) == 0 {
-		return
+// isEquivalentAST returns whether the given two AST nodes are equivalent as far
+// as CGo is concerned. This is used to check that C types, globals, etc defined
+// in different CGo header snippets are actually the same type (and probably
+// even defined in the same header file, just in different translation units).
+func (p *cgoPackage) isEquivalentAST(a, b ast.Node) bool {
+	switch node := a.(type) {
+	case *ast.ArrayType:
+		b, ok := b.(*ast.ArrayType)
+		if !ok {
+			return false
+		}
+		if !p.isEquivalentAST(node.Len, b.Len) {
+			return false
+		}
+		return p.isEquivalentAST(node.Elt, b.Elt)
+	case *ast.BasicLit:
+		b, ok := b.(*ast.BasicLit)
+		if !ok {
+			return false
+		}
+		// Note: this comparison is not correct in general ("1e2" equals "100"),
+		// but is correct for its use in the cgo package.
+		return node.Value == b.Value
+	case *ast.CommentGroup:
+		b, ok := b.(*ast.CommentGroup)
+		if !ok {
+			return false
+		}
+		if len(node.List) != len(b.List) {
+			return false
+		}
+		for i, c := range node.List {
+			if c.Text != b.List[i].Text {
+				return false
+			}
+		}
+		return true
+	case *ast.FieldList:
+		b, ok := b.(*ast.FieldList)
+		if !ok {
+			return false
+		}
+		if len(node.List) != len(b.List) {
+			return false
+		}
+		for i, f := range node.List {
+			if !p.isEquivalentAST(f, b.List[i]) {
+				return false
+			}
+		}
+		return true
+	case *ast.Field:
+		b, ok := b.(*ast.Field)
+		if !ok {
+			return false
+		}
+		if !p.isEquivalentAST(node.Type, b.Type) {
+			return false
+		}
+		if len(node.Names) != len(b.Names) {
+			return false
+		}
+		for i, name := range node.Names {
+			if name.Name != b.Names[i].Name {
+				return false
+			}
+		}
+		return true
+	case *ast.FuncDecl:
+		b, ok := b.(*ast.FuncDecl)
+		if !ok {
+			return false
+		}
+		if node.Name.Name != b.Name.Name {
+			return false
+		}
+		if node.Doc != b.Doc {
+			if !p.isEquivalentAST(node.Doc, b.Doc) {
+				return false
+			}
+		}
+		if node.Recv != b.Recv {
+			if !p.isEquivalentAST(node.Recv, b.Recv) {
+				return false
+			}
+		}
+		if !p.isEquivalentAST(node.Type.Params, b.Type.Params) {
+			return false
+		}
+		return p.isEquivalentAST(node.Type.Results, b.Type.Results)
+	case *ast.GenDecl:
+		b, ok := b.(*ast.GenDecl)
+		if !ok {
+			return false
+		}
+		if node.Doc != b.Doc {
+			if !p.isEquivalentAST(node.Doc, b.Doc) {
+				return false
+			}
+		}
+		if len(node.Specs) != len(b.Specs) {
+			return false
+		}
+		for i, s := range node.Specs {
+			if !p.isEquivalentAST(s, b.Specs[i]) {
+				return false
+			}
+		}
+		return true
+	case *ast.Ident:
+		b, ok := b.(*ast.Ident)
+		if !ok {
+			return false
+		}
+		return node.Name == b.Name
+	case *ast.SelectorExpr:
+		b, ok := b.(*ast.SelectorExpr)
+		if !ok {
+			return false
+		}
+		if !p.isEquivalentAST(node.Sel, b.Sel) {
+			return false
+		}
+		return p.isEquivalentAST(node.X, b.X)
+	case *ast.StarExpr:
+		b, ok := b.(*ast.StarExpr)
+		if !ok {
+			return false
+		}
+		return p.isEquivalentAST(node.X, b.X)
+	case *ast.StructType:
+		b, ok := b.(*ast.StructType)
+		if !ok {
+			return false
+		}
+		return p.isEquivalentAST(node.Fields, b.Fields)
+	case *ast.TypeSpec:
+		b, ok := b.(*ast.TypeSpec)
+		if !ok {
+			return false
+		}
+		if node.Name.Name != b.Name.Name {
+			return false
+		}
+		if node.Assign.IsValid() != b.Assign.IsValid() {
+			return false
+		}
+		return p.isEquivalentAST(node.Type, b.Type)
+	case *ast.ValueSpec:
+		b, ok := b.(*ast.ValueSpec)
+		if !ok {
+			return false
+		}
+		if len(node.Names) != len(b.Names) {
+			return false
+		}
+		for i, name := range node.Names {
+			if name.Name != b.Names[i].Name {
+				return false
+			}
+		}
+		if node.Type != b.Type && !p.isEquivalentAST(node.Type, b.Type) {
+			return false
+		}
+		if len(node.Values) != len(b.Values) {
+			return false
+		}
+		for i, value := range node.Values {
+			if !p.isEquivalentAST(value, b.Values[i]) {
+				return false
+			}
+		}
+		return true
+	case nil:
+		p.addError(token.NoPos, "internal error: AST node is nil")
+		return true
+	default:
+		p.addError(a.Pos(), fmt.Sprintf("internal error: unknown AST node: %T", a))
+		return true
 	}
-	names := make([]string, 0, len(p.enums))
-	for name := range p.enums {
-		names = append(names, name)
+}
+
+// getPos returns node.Pos(), and tries to obtain a closely related position if
+// that fails.
+func getPos(node ast.Node) token.Pos {
+	pos := node.Pos()
+	if pos.IsValid() {
+		return pos
 	}
-	sort.Strings(names)
-	for _, name := range names {
-		gen := &ast.GenDecl{
-			TokPos: token.NoPos,
-			Tok:    token.TYPE,
+	if decl, ok := node.(*ast.GenDecl); ok {
+		// *ast.GenDecl often doesn't have TokPos defined, so look at the first
+		// spec.
+		return getPos(decl.Specs[0])
+	}
+	return token.NoPos
+}
+
+// getUnnamedDeclName creates a name (with the given prefix) for the given C
+// declaration. This is used for structs, unions, and enums that are often
+// defined without a name and used in a typedef.
+func (p *cgoPackage) getUnnamedDeclName(prefix string, itf interface{}) string {
+	if name, ok := p.anonDecls[itf]; ok {
+		return name
+	}
+	name := prefix + strconv.Itoa(len(p.anonDecls))
+	p.anonDecls[itf] = name
+	return name
+}
+
+// getASTDeclName will declare the given C AST node (if not already defined) and
+// will return its name, in the form of C.foo.
+func (f *cgoFile) getASTDeclName(name string, found clangCursor, iscall bool) string {
+	// Some types are defined in stdint.h and map directly to a particular Go
+	// type.
+	if alias := cgoAliases["C."+name]; alias != "" {
+		return alias
+	}
+	node := f.getASTDeclNode(name, found, iscall)
+	if _, ok := node.(*ast.FuncDecl); ok && !iscall {
+		return "C." + name + "$funcaddr"
+	}
+	return "C." + name
+}
+
+// getASTDeclNode will declare the given C AST node (if not already defined) and
+// returns it.
+func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) ast.Node {
+	if node, ok := f.defined[name]; ok {
+		// Declaration was found in the current file, so return it immediately.
+		return node
+	}
+
+	if node, ok := f.definedGlobally[name]; ok {
+		// Declaration was previously created, but not for the current file. It
+		// may be different (because it comes from a different CGo snippet), so
+		// we need to check whether the AST for this definition is equivalent.
+		f.defined[name] = nil
+		newNode, _ := f.createASTNode(name, found)
+		if !f.isEquivalentAST(node, newNode) {
+			// It's not. Return a nice error with both locations.
+			// Original cgo reports an error like
+			//   cgo: inconsistent definitions for C.myint
+			// which is far less helpful.
+			f.addError(getPos(node), "defined previously at "+f.fset.Position(getPos(newNode)).String()+" with a different type")
 		}
-		typ := p.enums[name]
-		typeName := "C.enum_" + name
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: typeName,
-		}
-		typeSpec := &ast.TypeSpec{
-			Name: &ast.Ident{
-				NamePos: typ.pos,
-				Name:    typeName,
-				Obj:     obj,
+		f.defined[name] = node
+		return node
+	}
+
+	// The declaration has no AST node. Create it now.
+	f.defined[name] = nil
+	node, elaboratedType := f.createASTNode(name, found)
+	f.defined[name] = node
+	f.definedGlobally[name] = node
+	switch node := node.(type) {
+	case *ast.FuncDecl:
+		f.generated.Decls = append(f.generated.Decls, node)
+		// Also add a declaration like the following:
+		//   var C.foo$funcaddr unsafe.Pointer
+		f.generated.Decls = append(f.generated.Decls, &ast.GenDecl{
+			Tok: token.VAR,
+			Specs: []ast.Spec{
+				&ast.ValueSpec{
+					Names: []*ast.Ident{{Name: "C." + name + "$funcaddr"}},
+					Type: &ast.SelectorExpr{
+						X:   &ast.Ident{Name: "unsafe"},
+						Sel: &ast.Ident{Name: "Pointer"},
+					},
+				},
 			},
-			Type: typ.typeExpr,
-		}
-		obj.Decl = typeSpec
-		gen.Specs = append(gen.Specs, typeSpec)
-		p.generated.Decls = append(p.generated.Decls, gen)
+		})
+	case *ast.GenDecl:
+		f.generated.Decls = append(f.generated.Decls, node)
+	case *ast.TypeSpec:
+		f.generated.Decls = append(f.generated.Decls, &ast.GenDecl{
+			Tok:   token.TYPE,
+			Specs: []ast.Spec{node},
+		})
+	case nil:
+		// Node may be nil in case of an error. In that case, just don't add it
+		// as a declaration.
+	default:
+		panic("unexpected AST node")
 	}
-}
 
-// findMissingCGoNames traverses the AST and finds all C.something names. Only
-// these symbols are extracted from the parsed C AST and converted to the Go
-// equivalent.
-func (p *cgoPackage) findMissingCGoNames(cursor *astutil.Cursor) bool {
-	switch node := cursor.Node().(type) {
-	case *ast.SelectorExpr:
-		x, ok := node.X.(*ast.Ident)
-		if !ok {
-			return true
+	// If this is a struct or union it may need bitfields or union accessor
+	// methods.
+	if elaboratedType != nil {
+		// Add struct bitfields.
+		for _, bitfield := range elaboratedType.bitfields {
+			f.createBitfieldGetter(bitfield, "C."+name)
+			f.createBitfieldSetter(bitfield, "C."+name)
 		}
-		if x.Name == "C" {
-			name := node.Sel.Name
-			if _, ok := builtinAliases[name]; ok {
-				name = "_Cgo_" + name
+		if elaboratedType.unionSize != 0 {
+			// Create union getters/setters.
+			for _, field := range elaboratedType.typeExpr.Fields.List {
+				if len(field.Names) != 1 {
+					f.addError(elaboratedType.pos, fmt.Sprintf("union must have field with a single name, it has %d names", len(field.Names)))
+					continue
+				}
+				f.createUnionAccessor(field, "C."+name)
 			}
-			p.missingSymbols[name] = struct{}{}
 		}
 	}
-	return true
+
+	return node
 }
 
 // walker replaces all "C".<something> expressions to literal "C.<something>"
 // expressions. Such expressions are impossible to write in Go (a dot cannot be
 // used in the middle of a name) so in practice all C identifiers live in a
 // separate namespace (no _Cgo_ hacks like in gc).
-func (p *cgoPackage) walker(cursor *astutil.Cursor) bool {
+func (f *cgoFile) walker(cursor *astutil.Cursor, names map[string]clangCursor) bool {
 	switch node := cursor.Node().(type) {
 	case *ast.CallExpr:
 		fun, ok := node.Fun.(*ast.SelectorExpr)
@@ -1388,10 +1222,10 @@ func (p *cgoPackage) walker(cursor *astutil.Cursor) bool {
 		if !ok {
 			return true
 		}
-		if _, ok := p.functions[fun.Sel.Name]; ok && x.Name == "C" {
+		if found, ok := names[fun.Sel.Name]; ok && x.Name == "C" {
 			node.Fun = &ast.Ident{
 				NamePos: x.NamePos,
-				Name:    "C." + fun.Sel.Name,
+				Name:    f.getASTDeclName(fun.Sel.Name, found, true),
 			}
 		}
 	case *ast.SelectorExpr:
@@ -1401,8 +1235,8 @@ func (p *cgoPackage) walker(cursor *astutil.Cursor) bool {
 		}
 		if x.Name == "C" {
 			name := "C." + node.Sel.Name
-			if _, ok := p.functions[node.Sel.Name]; ok {
-				name += "$funcaddr"
+			if found, ok := names[node.Sel.Name]; ok {
+				name = f.getASTDeclName(node.Sel.Name, found, false)
 			}
 			cursor.Replace(&ast.Ident{
 				NamePos: x.NamePos,
diff --git a/cgo/libclang.go b/cgo/libclang.go
index f0663794f..f7aca9689 100644
--- a/cgo/libclang.go
+++ b/cgo/libclang.go
@@ -72,7 +72,11 @@ var diagnosticSeverity = [...]string{
 	C.CXDiagnostic_Fatal:   "fatal",
 }
 
-func (p *cgoPackage) parseFragment(fragment string, cflags []string, filename string) {
+// Alias so that cgo.go (which doesn't import Clang related stuff and is in
+// theory decoupled from Clang) can also use this type.
+type clangCursor = C.GoCXCursor
+
+func (f *cgoFile) readNames(fragment string, cflags []string, filename string, callback func(map[string]clangCursor)) {
 	index := C.clang_createIndex(0, 0)
 	defer C.clang_disposeIndex(index)
 
@@ -119,8 +123,8 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, filename st
 			spelling := getString(C.clang_getDiagnosticSpelling(diagnostic))
 			severity := diagnosticSeverity[C.clang_getDiagnosticSeverity(diagnostic)]
 			location := C.clang_getDiagnosticLocation(diagnostic)
-			pos := p.getClangLocationPosition(location, unit)
-			p.addError(pos, severity+": "+spelling)
+			pos := f.getClangLocationPosition(location, unit)
+			f.addError(pos, severity+": "+spelling)
 		}
 		for i := 0; i < numDiagnostics; i++ {
 			diagnostic := C.clang_getDiagnostic(unit, C.uint(i))
@@ -135,7 +139,7 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, filename st
 	}
 
 	// Extract information required by CGo.
-	ref := storedRefs.Put(p)
+	ref := storedRefs.Put(f)
 	defer storedRefs.Remove(ref)
 	cursor := C.tinygo_clang_getTranslationUnitCursor(unit)
 	C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_globals_visitor), C.CXClientData(ref))
@@ -155,35 +159,64 @@ func (p *cgoPackage) parseFragment(fragment string, cflags []string, filename st
 		data := (*[1 << 24]byte)(unsafe.Pointer(rawData))[:size]
 
 		// Hash the contents if it isn't hashed yet.
-		if _, ok := p.visitedFiles[path]; !ok {
+		if _, ok := f.visitedFiles[path]; !ok {
 			// already stored
 			sum := sha512.Sum512_224(data)
-			p.visitedFiles[path] = sum[:]
+			f.visitedFiles[path] = sum[:]
 		}
 	}
 	inclusionCallbackRef := storedRefs.Put(inclusionCallback)
 	defer storedRefs.Remove(inclusionCallbackRef)
 	C.clang_getInclusions(unit, C.CXInclusionVisitor(C.tinygo_clang_inclusion_visitor), C.CXClientData(inclusionCallbackRef))
+
+	// Do all the C AST operations inside a callback. This makes sure that
+	// libclang related memory is only freed after it is not necessary anymore.
+	callback(f.names)
 }
 
-//export tinygo_clang_globals_visitor
-func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClientData) C.int {
-	p := storedRefs.Get(unsafe.Pointer(client_data)).(*cgoPackage)
+// Convert the AST node under the given Clang cursor to a Go AST node and return
+// it.
+func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, *elaboratedTypeInfo) {
 	kind := C.tinygo_clang_getCursorKind(c)
-	pos := p.getCursorPosition(c)
+	pos := f.getCursorPosition(c)
 	switch kind {
 	case C.CXCursor_FunctionDecl:
-		name := getString(C.tinygo_clang_getCursorSpelling(c))
-		if _, required := p.missingSymbols[name]; !required {
-			return C.CXChildVisit_Continue
-		}
 		cursorType := C.tinygo_clang_getCursorType(c)
 		numArgs := int(C.tinygo_clang_Cursor_getNumArguments(c))
-		fn := &functionInfo{
-			pos:      pos,
-			variadic: C.clang_isFunctionTypeVariadic(cursorType) != 0,
+		obj := &ast.Object{
+			Kind: ast.Fun,
+			Name: "C." + name,
+		}
+		args := make([]*ast.Field, numArgs)
+		decl := &ast.FuncDecl{
+			Doc: &ast.CommentGroup{
+				List: []*ast.Comment{
+					{
+						Slash: pos - 1,
+						Text:  "//export " + name,
+					},
+				},
+			},
+			Name: &ast.Ident{
+				NamePos: pos,
+				Name:    "C." + name,
+				Obj:     obj,
+			},
+			Type: &ast.FuncType{
+				Func: pos,
+				Params: &ast.FieldList{
+					Opening: pos,
+					List:    args,
+					Closing: pos,
+				},
+			},
+		}
+		if C.clang_isFunctionTypeVariadic(cursorType) != 0 {
+			decl.Doc.List = append(decl.Doc.List, &ast.Comment{
+				Slash: pos - 1,
+				Text:  "//go:variadic",
+			})
 		}
-		p.functions[name] = fn
 		for i := 0; i < numArgs; i++ {
 			arg := C.tinygo_clang_Cursor_getArgument(c, C.uint(i))
 			argName := getString(C.tinygo_clang_getCursorSpelling(arg))
@@ -191,50 +224,108 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 			if argName == "" {
 				argName = "$" + strconv.Itoa(i)
 			}
-			fn.args = append(fn.args, paramInfo{
-				name:     argName,
-				typeExpr: p.makeDecayingASTType(argType, pos),
-			})
+			args[i] = &ast.Field{
+				Names: []*ast.Ident{
+					{
+						NamePos: pos,
+						Name:    argName,
+						Obj: &ast.Object{
+							Kind: ast.Var,
+							Name: argName,
+							Decl: decl,
+						},
+					},
+				},
+				Type: f.makeDecayingASTType(argType, pos),
+			}
 		}
 		resultType := C.tinygo_clang_getCursorResultType(c)
 		if resultType.kind != C.CXType_Void {
-			fn.results = &ast.FieldList{
+			decl.Type.Results = &ast.FieldList{
 				List: []*ast.Field{
 					{
-						Type: p.makeASTType(resultType, pos),
+						Type: f.makeASTType(resultType, pos),
 					},
 				},
 			}
 		}
-	case C.CXCursor_StructDecl:
-		typ := C.tinygo_clang_getCursorType(c)
-		name := getString(C.tinygo_clang_getCursorSpelling(c))
-		if _, required := p.missingSymbols["struct_"+name]; !required {
-			return C.CXChildVisit_Continue
+		obj.Decl = decl
+		return decl, nil
+	case C.CXCursor_StructDecl, C.CXCursor_UnionDecl:
+		typ := f.makeASTRecordType(c, pos)
+		typeName := "C." + name
+		typeExpr := typ.typeExpr
+		if typ.unionSize != 0 {
+			// Convert to a single-field struct type.
+			typeExpr = f.makeUnionField(typ)
+		}
+		obj := &ast.Object{
+			Kind: ast.Typ,
+			Name: typeName,
 		}
-		p.makeASTType(typ, pos)
+		typeSpec := &ast.TypeSpec{
+			Name: &ast.Ident{
+				NamePos: typ.pos,
+				Name:    typeName,
+				Obj:     obj,
+			},
+			Type: typeExpr,
+		}
+		obj.Decl = typeSpec
+		return typeSpec, typ
 	case C.CXCursor_TypedefDecl:
-		typedefType := C.tinygo_clang_getCursorType(c)
-		name := getString(C.clang_getTypedefName(typedefType))
-		if _, required := p.missingSymbols[name]; !required {
-			return C.CXChildVisit_Continue
+		typeName := "C." + name
+		underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(c)
+		obj := &ast.Object{
+			Kind: ast.Typ,
+			Name: typeName,
 		}
-		p.makeASTType(typedefType, pos)
-	case C.CXCursor_VarDecl:
-		name := getString(C.tinygo_clang_getCursorSpelling(c))
-		if _, required := p.missingSymbols[name]; !required {
-			return C.CXChildVisit_Continue
+		typeSpec := &ast.TypeSpec{
+			Name: &ast.Ident{
+				NamePos: pos,
+				Name:    typeName,
+				Obj:     obj,
+			},
+			Type: f.makeASTType(underlyingType, pos),
 		}
+		if underlyingType.kind != C.CXType_Enum {
+			typeSpec.Assign = pos
+		}
+		obj.Decl = typeSpec
+		return typeSpec, nil
+	case C.CXCursor_VarDecl:
 		cursorType := C.tinygo_clang_getCursorType(c)
-		p.globals[name] = globalInfo{
-			typeExpr: p.makeASTType(cursorType, pos),
-			pos:      pos,
+		typeExpr := f.makeASTType(cursorType, pos)
+		gen := &ast.GenDecl{
+			TokPos: pos,
+			Tok:    token.VAR,
+			Lparen: token.NoPos,
+			Rparen: token.NoPos,
+			Doc: &ast.CommentGroup{
+				List: []*ast.Comment{
+					{
+						Slash: pos - 1,
+						Text:  "//go:extern " + name,
+					},
+				},
+			},
 		}
-	case C.CXCursor_MacroDefinition:
-		name := getString(C.tinygo_clang_getCursorSpelling(c))
-		if _, required := p.missingSymbols[name]; !required {
-			return C.CXChildVisit_Continue
+		obj := &ast.Object{
+			Kind: ast.Var,
+			Name: "C." + name,
 		}
+		valueSpec := &ast.ValueSpec{
+			Names: []*ast.Ident{{
+				NamePos: pos,
+				Name:    "C." + name,
+				Obj:     obj,
+			}},
+			Type: typeExpr,
+		}
+		obj.Decl = valueSpec
+		gen.Specs = append(gen.Specs, valueSpec)
+		return gen, nil
+	case C.CXCursor_MacroDefinition:
 		sourceRange := C.tinygo_clang_getCursorExtent(c)
 		start := C.clang_getRangeStart(sourceRange)
 		end := C.clang_getRangeEnd(sourceRange)
@@ -242,17 +333,17 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 		var startOffset, endOffset C.unsigned
 		C.clang_getExpansionLocation(start, &file, nil, nil, &startOffset)
 		if file == nil {
-			p.addError(pos, "internal error: could not find file where macro is defined")
-			break
+			f.addError(pos, "internal error: could not find file where macro is defined")
+			return nil, nil
 		}
 		C.clang_getExpansionLocation(end, &endFile, nil, nil, &endOffset)
 		if file != endFile {
-			p.addError(pos, "internal error: expected start and end location of a macro to be in the same file")
-			break
+			f.addError(pos, "internal error: expected start and end location of a macro to be in the same file")
+			return nil, nil
 		}
 		if startOffset > endOffset {
-			p.addError(pos, "internal error: start offset of macro is after end offset")
-			break
+			f.addError(pos, "internal error: start offset of macro is after end offset")
+			return nil, nil
 		}
 
 		// read file contents and extract the relevant byte range
@@ -260,31 +351,94 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
 		var size C.size_t
 		sourcePtr := C.clang_getFileContents(tu, file, &size)
 		if endOffset >= C.uint(size) {
-			p.addError(pos, "internal error: end offset of macro lies after end of file")
-			break
+			f.addError(pos, "internal error: end offset of macro lies after end of file")
+			return nil, nil
 		}
 		source := string(((*[1 << 28]byte)(unsafe.Pointer(sourcePtr)))[startOffset:endOffset:endOffset])
 		if !strings.HasPrefix(source, name) {
-			p.addError(pos, fmt.Sprintf("internal error: expected macro value to start with %#v, got %#v", name, source))
-			break
+			f.addError(pos, fmt.Sprintf("internal error: expected macro value to start with %#v, got %#v", name, source))
+			return nil, nil
 		}
 		value := source[len(name):]
 		// Try to convert this #define into a Go constant expression.
-		expr, scannerError := parseConst(pos+token.Pos(len(name)), p.fset, value)
+		expr, scannerError := parseConst(pos+token.Pos(len(name)), f.fset, value)
 		if scannerError != nil {
-			p.errors = append(p.errors, *scannerError)
+			f.errors = append(f.errors, *scannerError)
+			return nil, nil
+		}
+
+		gen := &ast.GenDecl{
+			TokPos: token.NoPos,
+			Tok:    token.CONST,
+			Lparen: token.NoPos,
+			Rparen: token.NoPos,
 		}
-		if expr != nil {
-			// Parsing was successful.
-			p.constants[name] = constantInfo{expr, pos}
+		obj := &ast.Object{
+			Kind: ast.Con,
+			Name: "C." + name,
 		}
+		valueSpec := &ast.ValueSpec{
+			Names: []*ast.Ident{{
+				NamePos: pos,
+				Name:    "C." + name,
+				Obj:     obj,
+			}},
+			Values: []ast.Expr{expr},
+		}
+		obj.Decl = valueSpec
+		gen.Specs = append(gen.Specs, valueSpec)
+		return gen, nil
 	case C.CXCursor_EnumDecl:
-		// Visit all enums, because the fields may be used even when the enum
-		// type itself is not.
-		typ := C.tinygo_clang_getCursorType(c)
-		p.makeASTType(typ, pos)
+		obj := &ast.Object{
+			Kind: ast.Typ,
+			Name: "C." + name,
+		}
+		underlying := C.tinygo_clang_getEnumDeclIntegerType(c)
+		// TODO: gc's CGo implementation uses types such as `uint32` for enums
+		// instead of types such as C.int, which are used here.
+		typeSpec := &ast.TypeSpec{
+			Name: &ast.Ident{
+				NamePos: pos,
+				Name:    "C." + name,
+				Obj:     obj,
+			},
+			Assign: pos,
+			Type:   f.makeASTType(underlying, pos),
+		}
+		obj.Decl = typeSpec
+		return typeSpec, nil
+	case C.CXCursor_EnumConstantDecl:
+		value := C.tinygo_clang_getEnumConstantDeclValue(c)
+		expr := &ast.BasicLit{
+			ValuePos: pos,
+			Kind:     token.INT,
+			Value:    strconv.FormatInt(int64(value), 10),
+		}
+		gen := &ast.GenDecl{
+			TokPos: token.NoPos,
+			Tok:    token.CONST,
+			Lparen: token.NoPos,
+			Rparen: token.NoPos,
+		}
+		obj := &ast.Object{
+			Kind: ast.Con,
+			Name: "C." + name,
+		}
+		valueSpec := &ast.ValueSpec{
+			Names: []*ast.Ident{{
+				NamePos: pos,
+				Name:    "C." + name,
+				Obj:     obj,
+			}},
+			Values: []ast.Expr{expr},
+		}
+		obj.Decl = valueSpec
+		gen.Specs = append(gen.Specs, valueSpec)
+		return gen, nil
+	default:
+		f.addError(pos, fmt.Sprintf("internal error: unknown cursor type: %d", kind))
+		return nil, nil
 	}
-	return C.CXChildVisit_Continue
 }
 
 func getString(clangString C.CXString) (s string) {
@@ -294,6 +448,49 @@ func getString(clangString C.CXString) (s string) {
 	return
 }
 
+//export tinygo_clang_globals_visitor
+func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClientData) C.int {
+	f := storedRefs.Get(unsafe.Pointer(client_data)).(*cgoFile)
+	switch C.tinygo_clang_getCursorKind(c) {
+	case C.CXCursor_FunctionDecl:
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		f.names[name] = c
+	case C.CXCursor_StructDecl:
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		if name != "" {
+			f.names["struct_"+name] = c
+		}
+	case C.CXCursor_UnionDecl:
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		if name != "" {
+			f.names["union_"+name] = c
+		}
+	case C.CXCursor_TypedefDecl:
+		typedefType := C.tinygo_clang_getCursorType(c)
+		name := getString(C.clang_getTypedefName(typedefType))
+		f.names[name] = c
+	case C.CXCursor_VarDecl:
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		f.names[name] = c
+	case C.CXCursor_MacroDefinition:
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		f.names[name] = c
+	case C.CXCursor_EnumDecl:
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		if name != "" {
+			// Named enum, which can be referenced from Go using C.enum_foo.
+			f.names["enum_"+name] = c
+		}
+		// The enum fields are in global scope, so recurse to visit them.
+		return C.CXChildVisit_Recurse
+	case C.CXCursor_EnumConstantDecl:
+		// We arrive here because of the "Recurse" above.
+		name := getString(C.tinygo_clang_getCursorSpelling(c))
+		f.names[name] = c
+	}
+	return C.CXChildVisit_Continue
+}
+
 // getCursorPosition returns a usable token.Pos from a libclang cursor.
 func (p *cgoPackage) getCursorPosition(cursor C.GoCXCursor) token.Pos {
 	return p.getClangLocationPosition(C.tinygo_clang_getCursorLocation(cursor), C.tinygo_clang_Cursor_getTranslationUnit(cursor))
@@ -391,7 +588,7 @@ func (p *cgoPackage) addErrorAt(position token.Position, msg string) {
 // makeDecayingASTType does the same as makeASTType but takes care of decaying
 // types (arrays in function parameters, etc). It is otherwise identical to
 // makeASTType.
-func (p *cgoPackage) makeDecayingASTType(typ C.CXType, pos token.Pos) ast.Expr {
+func (f *cgoFile) makeDecayingASTType(typ C.CXType, pos token.Pos) ast.Expr {
 	// Strip typedefs, if any.
 	underlyingType := typ
 	if underlyingType.kind == C.CXType_Typedef {
@@ -417,15 +614,15 @@ func (p *cgoPackage) makeDecayingASTType(typ C.CXType, pos token.Pos) ast.Expr {
 		pointeeType := C.clang_getElementType(underlyingType)
 		return &ast.StarExpr{
 			Star: pos,
-			X:    p.makeASTType(pointeeType, pos),
+			X:    f.makeASTType(pointeeType, pos),
 		}
 	}
-	return p.makeASTType(typ, pos)
+	return f.makeASTType(typ, pos)
 }
 
 // makeASTType return the ast.Expr for the given libclang type. In other words,
 // it converts a libclang type to a type in the Go AST.
-func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
+func (f *cgoFile) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 	var typeName string
 	switch typ.kind {
 	case C.CXType_Char_S, C.CXType_Char_U:
@@ -486,7 +683,7 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 		}
 		return &ast.StarExpr{
 			Star: pos,
-			X:    p.makeASTType(pointeeType, pos),
+			X:    f.makeASTType(pointeeType, pos),
 		}
 	case C.CXType_ConstantArray:
 		return &ast.ArrayType{
@@ -496,7 +693,7 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 				Kind:     token.INT,
 				Value:    strconv.FormatInt(int64(C.clang_getArraySize(typ)), 10),
 			},
-			Elt: p.makeASTType(C.clang_getElementType(typ), pos),
+			Elt: f.makeASTType(C.clang_getElementType(typ), pos),
 		}
 	case C.CXType_FunctionProto:
 		// Be compatible with gc, which uses the *[0]byte type for function
@@ -517,71 +714,21 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 		}
 	case C.CXType_Typedef:
 		name := getString(C.clang_getTypedefName(typ))
-		if _, ok := p.typedefs[name]; !ok {
-			p.typedefs[name] = nil // don't recurse
-			c := C.tinygo_clang_getTypeDeclaration(typ)
-			underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(c)
-			expr := p.makeASTType(underlyingType, pos)
-			if strings.HasPrefix(name, "_Cgo_") {
-				expr := expr.(*ast.Ident)
-				typeSize := C.clang_Type_getSizeOf(underlyingType)
-				switch expr.Name {
-				case "C.char":
-					if typeSize != 1 {
-						// This happens for some very special purpose architectures
-						// (DSPs etc.) that are not currently targeted.
-						// https://www.embecosm.com/2017/04/18/non-8-bit-char-support-in-clang-and-llvm/
-						p.addError(pos, fmt.Sprintf("unknown char width: %d", typeSize))
-					}
-					switch underlyingType.kind {
-					case C.CXType_Char_S:
-						expr.Name = "int8"
-					case C.CXType_Char_U:
-						expr.Name = "uint8"
-					}
-				case "C.schar", "C.short", "C.int", "C.long", "C.longlong":
-					switch typeSize {
-					case 1:
-						expr.Name = "int8"
-					case 2:
-						expr.Name = "int16"
-					case 4:
-						expr.Name = "int32"
-					case 8:
-						expr.Name = "int64"
-					}
-				case "C.uchar", "C.ushort", "C.uint", "C.ulong", "C.ulonglong":
-					switch typeSize {
-					case 1:
-						expr.Name = "uint8"
-					case 2:
-						expr.Name = "uint16"
-					case 4:
-						expr.Name = "uint32"
-					case 8:
-						expr.Name = "uint64"
-					}
-				}
-			}
-			p.typedefs[name] = &typedefInfo{
-				typeExpr: expr,
-				pos:      pos,
-			}
-		}
+		c := C.tinygo_clang_getTypeDeclaration(typ)
 		return &ast.Ident{
 			NamePos: pos,
-			Name:    "C." + name,
+			Name:    f.getASTDeclName(name, c, false),
 		}
 	case C.CXType_Elaborated:
 		underlying := C.clang_Type_getNamedType(typ)
 		switch underlying.kind {
 		case C.CXType_Record:
-			return p.makeASTType(underlying, pos)
+			return f.makeASTType(underlying, pos)
 		case C.CXType_Enum:
-			return p.makeASTType(underlying, pos)
+			return f.makeASTType(underlying, pos)
 		default:
 			typeKindSpelling := getString(C.clang_getTypeKindSpelling(underlying.kind))
-			p.addError(pos, fmt.Sprintf("unknown elaborated type (libclang type kind %s)", typeKindSpelling))
+			f.addError(pos, fmt.Sprintf("unknown elaborated type (libclang type kind %s)", typeKindSpelling))
 			typeName = "<unknown>"
 		}
 	case C.CXType_Record:
@@ -599,63 +746,46 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 		}
 		if name == "" {
 			// Anonymous record, probably inside a typedef.
-			typeInfo := p.makeASTRecordType(cursor, pos)
-			if typeInfo.bitfields != nil || typeInfo.unionSize != 0 {
-				// This record is a union or is a struct with bitfields, so we
-				// have to declare it as a named type (for getters/setters to
-				// work).
-				p.anonStructNum++
-				cgoName := cgoRecordPrefix + strconv.Itoa(p.anonStructNum)
-				p.elaboratedTypes[cgoName] = typeInfo
-				return &ast.Ident{
-					NamePos: pos,
-					Name:    "C." + cgoName,
-				}
+			clangLocation := C.tinygo_clang_getCursorLocation(cursor)
+			var file C.CXFile
+			var line C.unsigned
+			var column C.unsigned
+			C.clang_getFileLocation(clangLocation, &file, &line, &column, nil)
+			location := token.Position{
+				Filename: getString(C.clang_getFileName(file)),
+				Line:     int(line),
+				Column:   int(column),
 			}
-			return typeInfo.typeExpr
-		} else {
-			cgoName := cgoRecordPrefix + name
-			if _, ok := p.elaboratedTypes[cgoName]; !ok {
-				p.elaboratedTypes[cgoName] = nil // predeclare (to avoid endless recursion)
-				p.elaboratedTypes[cgoName] = p.makeASTRecordType(cursor, pos)
-			}
-			return &ast.Ident{
-				NamePos: pos,
-				Name:    "C." + cgoName,
+			if location.Filename == "" || location.Line == 0 {
+				// Not sure when this would happen, but protect from it anyway.
+				f.addError(pos, "could not find file/line information")
 			}
+			name = f.getUnnamedDeclName("_Ctype_"+cgoRecordPrefix+"__", location)
+		} else {
+			name = cgoRecordPrefix + name
+		}
+		return &ast.Ident{
+			NamePos: pos,
+			Name:    f.getASTDeclName(name, cursor, false),
 		}
 	case C.CXType_Enum:
 		cursor := C.tinygo_clang_getTypeDeclaration(typ)
 		name := getString(C.tinygo_clang_getCursorSpelling(cursor))
-		underlying := C.tinygo_clang_getEnumDeclIntegerType(cursor)
 		if name == "" {
-			// anonymous enum
-			ref := storedRefs.Put(p)
-			defer storedRefs.Remove(ref)
-			C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_enum_visitor), C.CXClientData(ref))
-			return p.makeASTType(underlying, pos)
+			name = f.getUnnamedDeclName("_Ctype_enum___", cursor)
 		} else {
-			// named enum
-			if _, ok := p.enums[name]; !ok {
-				ref := storedRefs.Put(p)
-				defer storedRefs.Remove(ref)
-				C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_enum_visitor), C.CXClientData(ref))
-				p.enums[name] = enumInfo{
-					typeExpr: p.makeASTType(underlying, pos),
-					pos:      pos,
-				}
-			}
-			return &ast.Ident{
-				NamePos: pos,
-				Name:    "C.enum_" + name,
-			}
+			name = "enum_" + name
+		}
+		return &ast.Ident{
+			NamePos: pos,
+			Name:    f.getASTDeclName(name, cursor, false),
 		}
 	}
 	if typeName == "" {
 		// Report this as an error.
 		typeSpelling := getString(C.clang_getTypeSpelling(typ))
 		typeKindSpelling := getString(C.clang_getTypeKindSpelling(typ.kind))
-		p.addError(pos, fmt.Sprintf("unknown C type: %v (libclang type kind %s)", typeSpelling, typeKindSpelling))
+		f.addError(pos, fmt.Sprintf("unknown C type: %v (libclang type kind %s)", typeSpelling, typeKindSpelling))
 		typeName = "C.<unknown>"
 	}
 	return &ast.Ident{
@@ -664,9 +794,80 @@ func (p *cgoPackage) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
 	}
 }
 
+// getIntegerType returns an AST node that defines types such as C.int.
+func (p *cgoPackage) getIntegerType(name string, cursor clangCursor) *ast.TypeSpec {
+	pos := p.getCursorPosition(cursor)
+
+	// Find a Go type that matches the size and signedness of the given C type.
+	underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(cursor)
+	var goName string
+	typeSize := C.clang_Type_getSizeOf(underlyingType)
+	switch name {
+	case "C.char":
+		if typeSize != 1 {
+			// This happens for some very special purpose architectures
+			// (DSPs etc.) that are not currently targeted.
+			// https://www.embecosm.com/2017/04/18/non-8-bit-char-support-in-clang-and-llvm/
+			p.addError(pos, fmt.Sprintf("unknown char width: %d", typeSize))
+		}
+		switch underlyingType.kind {
+		case C.CXType_Char_S:
+			goName = "int8"
+		case C.CXType_Char_U:
+			goName = "uint8"
+		}
+	case "C.schar", "C.short", "C.int", "C.long", "C.longlong":
+		switch typeSize {
+		case 1:
+			goName = "int8"
+		case 2:
+			goName = "int16"
+		case 4:
+			goName = "int32"
+		case 8:
+			goName = "int64"
+		}
+	case "C.uchar", "C.ushort", "C.uint", "C.ulong", "C.ulonglong":
+		switch typeSize {
+		case 1:
+			goName = "uint8"
+		case 2:
+			goName = "uint16"
+		case 4:
+			goName = "uint32"
+		case 8:
+			goName = "uint64"
+		}
+	}
+
+	if goName == "" { // should not happen
+		p.addError(pos, "internal error: did not find Go type for C type "+name)
+		goName = "int"
+	}
+
+	// Construct an *ast.TypeSpec for this type.
+	obj := &ast.Object{
+		Kind: ast.Typ,
+		Name: name,
+	}
+	spec := &ast.TypeSpec{
+		Name: &ast.Ident{
+			NamePos: pos,
+			Name:    name,
+			Obj:     obj,
+		},
+		Type: &ast.Ident{
+			NamePos: pos,
+			Name:    goName,
+		},
+	}
+	obj.Decl = spec
+	return spec
+}
+
 // makeASTRecordType parses a C record (struct or union) and translates it into
 // a Go struct type.
-func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elaboratedTypeInfo {
+func (f *cgoFile) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elaboratedTypeInfo {
 	fieldList := &ast.FieldList{
 		Opening: pos,
 		Closing: pos,
@@ -676,11 +877,11 @@ func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elab
 	bitfieldNum := 0
 	ref := storedRefs.Put(struct {
 		fieldList    *ast.FieldList
-		pkg          *cgoPackage
+		file         *cgoFile
 		inBitfield   *bool
 		bitfieldNum  *int
 		bitfieldList *[]bitfieldInfo
-	}{fieldList, p, &inBitfield, &bitfieldNum, &bitfieldList})
+	}{fieldList, f, &inBitfield, &bitfieldNum, &bitfieldList})
 	defer storedRefs.Remove(ref)
 	C.tinygo_clang_visitChildren(cursor, C.CXCursorVisitor(C.tinygo_clang_struct_visitor), C.CXClientData(ref))
 	renameFieldKeywords(fieldList)
@@ -709,13 +910,13 @@ func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elab
 		}
 		if bitfieldList != nil {
 			// This is valid C... but please don't do this.
-			p.addError(pos, "bitfield in a union is not supported")
+			f.addError(pos, "bitfield in a union is not supported")
 		}
 		typ := C.tinygo_clang_getCursorType(cursor)
 		alignInBytes := int64(C.clang_Type_getAlignOf(typ))
 		sizeInBytes := int64(C.clang_Type_getSizeOf(typ))
 		if sizeInBytes == 0 {
-			p.addError(pos, "zero-length union is not supported")
+			f.addError(pos, "zero-length union is not supported")
 		}
 		typeInfo.unionSize = sizeInBytes
 		typeInfo.unionAlign = alignInBytes
@@ -723,7 +924,7 @@ func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elab
 	default:
 		cursorKind := C.tinygo_clang_getCursorKind(cursor)
 		cursorKindSpelling := getString(C.clang_getCursorKindSpelling(cursorKind))
-		p.addError(pos, fmt.Sprintf("expected StructDecl or UnionDecl, not %s", cursorKindSpelling))
+		f.addError(pos, fmt.Sprintf("expected StructDecl or UnionDecl, not %s", cursorKindSpelling))
 		return &elaboratedTypeInfo{
 			typeExpr: &ast.StructType{
 				Struct: pos,
@@ -737,17 +938,17 @@ func (p *cgoPackage) makeASTRecordType(cursor C.GoCXCursor, pos token.Pos) *elab
 func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientData) C.int {
 	passed := storedRefs.Get(unsafe.Pointer(client_data)).(struct {
 		fieldList    *ast.FieldList
-		pkg          *cgoPackage
+		file         *cgoFile
 		inBitfield   *bool
 		bitfieldNum  *int
 		bitfieldList *[]bitfieldInfo
 	})
 	fieldList := passed.fieldList
-	p := passed.pkg
+	f := passed.file
 	inBitfield := passed.inBitfield
 	bitfieldNum := passed.bitfieldNum
 	bitfieldList := passed.bitfieldList
-	pos := p.getCursorPosition(c)
+	pos := f.getCursorPosition(c)
 	switch cursorKind := C.tinygo_clang_getCursorKind(c); cursorKind {
 	case C.CXCursor_FieldDecl:
 		// Expected. This is a regular field.
@@ -756,7 +957,7 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 		return C.CXChildVisit_Continue
 	default:
 		cursorKindSpelling := getString(C.clang_getCursorKindSpelling(cursorKind))
-		p.addError(pos, fmt.Sprintf("expected FieldDecl in struct or union, not %s", cursorKindSpelling))
+		f.addError(pos, fmt.Sprintf("expected FieldDecl in struct or union, not %s", cursorKindSpelling))
 		return C.CXChildVisit_Continue
 	}
 	name := getString(C.tinygo_clang_getCursorSpelling(c))
@@ -767,14 +968,14 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 	}
 	typ := C.tinygo_clang_getCursorType(c)
 	field := &ast.Field{
-		Type: p.makeASTType(typ, p.getCursorPosition(c)),
+		Type: f.makeASTType(typ, f.getCursorPosition(c)),
 	}
 	offsetof := int64(C.clang_Type_getOffsetOf(C.tinygo_clang_getCursorType(parent), C.CString(name)))
 	alignOf := int64(C.clang_Type_getAlignOf(typ) * 8)
 	bitfieldOffset := offsetof % alignOf
 	if bitfieldOffset != 0 {
 		if C.tinygo_clang_Cursor_isBitField(c) != 1 {
-			p.addError(pos, "expected a bitfield")
+			f.addError(pos, "expected a bitfield")
 			return C.CXChildVisit_Continue
 		}
 		if !*inBitfield {
@@ -821,23 +1022,6 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 	return C.CXChildVisit_Continue
 }
 
-//export tinygo_clang_enum_visitor
-func tinygo_clang_enum_visitor(c, parent C.GoCXCursor, client_data C.CXClientData) C.int {
-	p := storedRefs.Get(unsafe.Pointer(client_data)).(*cgoPackage)
-	name := getString(C.tinygo_clang_getCursorSpelling(c))
-	pos := p.getCursorPosition(c)
-	value := C.tinygo_clang_getEnumConstantDeclValue(c)
-	p.constants[name] = constantInfo{
-		expr: &ast.BasicLit{
-			ValuePos: pos,
-			Kind:     token.INT,
-			Value:    strconv.FormatInt(int64(value), 10),
-		},
-		pos: pos,
-	}
-	return C.CXChildVisit_Continue
-}
-
 //export tinygo_clang_inclusion_visitor
 func tinygo_clang_inclusion_visitor(includedFile C.CXFile, inclusionStack *C.CXSourceLocation, includeLen C.unsigned, clientData C.CXClientData) {
 	callback := storedRefs.Get(unsafe.Pointer(clientData)).(func(C.CXFile))
diff --git a/cgo/testdata/basic.out.go b/cgo/testdata/basic.out.go
index 125605de8..f2daa78da 100644
--- a/cgo/testdata/basic.out.go
+++ b/cgo/testdata/basic.out.go
@@ -24,23 +24,16 @@ func C.GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 	return C.__GoBytes(ptr, uintptr(length))
 }
 
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
+type (
+	C.char      uint8
+	C.schar     int8
+	C.uchar     uint8
+	C.short     int16
+	C.ushort    uint16
+	C.int       int32
+	C.uint      uint32
+	C.long      int32
+	C.ulong     uint32
+	C.longlong  int64
+	C.ulonglong uint64
+)
diff --git a/cgo/testdata/const.out.go b/cgo/testdata/const.out.go
index e12cded4f..4a5f5fd5b 100644
--- a/cgo/testdata/const.out.go
+++ b/cgo/testdata/const.out.go
@@ -24,26 +24,19 @@ func C.GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 	return C.__GoBytes(ptr, uintptr(length))
 }
 
-const C.bar = C.foo
-const C.foo = 3
+type (
+	C.char      uint8
+	C.schar     int8
+	C.uchar     uint8
+	C.short     int16
+	C.ushort    uint16
+	C.int       int32
+	C.uint      uint32
+	C.long      int32
+	C.ulong     uint32
+	C.longlong  int64
+	C.ulonglong uint64
+)
 
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
+const C.foo = 3
+const C.bar = C.foo
diff --git a/cgo/testdata/errors.go b/cgo/testdata/errors.go
index 8724caf73..7ca5b7960 100644
--- a/cgo/testdata/errors.go
+++ b/cgo/testdata/errors.go
@@ -27,7 +27,7 @@ import "C"
 //line errors.go:100
 var (
 	// constant too large
-	_ C.uint8_t = 2 << 10
+	_ C.char = 2 << 10
 
 	// z member does not exist
 	_ C.point_t = C.point_t{z: 3}
diff --git a/cgo/testdata/errors.out.go b/cgo/testdata/errors.out.go
index 8200a459f..b15a26b66 100644
--- a/cgo/testdata/errors.out.go
+++ b/cgo/testdata/errors.out.go
@@ -6,7 +6,7 @@
 //     testdata/errors.go:19:26: unexpected token ), expected end of expression
 
 // Type checking errors after CGo processing:
-//     testdata/errors.go:102: cannot use 2 << 10 (untyped int constant 2048) as uint8 value in variable declaration (overflows)
+//     testdata/errors.go:102: cannot use 2 << 10 (untyped int constant 2048) as C.char value in variable declaration (overflows)
 //     testdata/errors.go:105: unknown field z in struct literal
 //     testdata/errors.go:108: undeclared name: C.SOME_CONST_1
 //     testdata/errors.go:110: cannot use C.SOME_CONST_3 (untyped int constant 1234) as byte value in variable declaration (overflows)
@@ -38,29 +38,23 @@ func C.GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 	return C.__GoBytes(ptr, uintptr(length))
 }
 
-const C.SOME_CONST_3 = 1234
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
-type C.point_t = struct {
+type (
+	C.char      uint8
+	C.schar     int8
+	C.uchar     uint8
+	C.short     int16
+	C.ushort    uint16
+	C.int       int32
+	C.uint      uint32
+	C.long      int32
+	C.ulong     uint32
+	C.longlong  int64
+	C.ulonglong uint64
+)
+type C._Ctype_struct___0 struct {
 	x C.int
 	y C.int
 }
+type C.point_t = C._Ctype_struct___0
+
+const C.SOME_CONST_3 = 1234
diff --git a/cgo/testdata/flags.out.go b/cgo/testdata/flags.out.go
index 920778655..72520ab6d 100644
--- a/cgo/testdata/flags.out.go
+++ b/cgo/testdata/flags.out.go
@@ -29,26 +29,19 @@ func C.GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 	return C.__GoBytes(ptr, uintptr(length))
 }
 
+type (
+	C.char      uint8
+	C.schar     int8
+	C.uchar     uint8
+	C.short     int16
+	C.ushort    uint16
+	C.int       int32
+	C.uint      uint32
+	C.long      int32
+	C.ulong     uint32
+	C.longlong  int64
+	C.ulonglong uint64
+)
+
 const C.BAR = 3
 const C.FOO_H = 1
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
diff --git a/cgo/testdata/symbols.out.go b/cgo/testdata/symbols.out.go
index 53ec4f0b0..6791999ad 100644
--- a/cgo/testdata/symbols.out.go
+++ b/cgo/testdata/symbols.out.go
@@ -24,41 +24,36 @@ func C.GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 	return C.__GoBytes(ptr, uintptr(length))
 }
 
+type (
+	C.char      uint8
+	C.schar     int8
+	C.uchar     uint8
+	C.short     int16
+	C.ushort    uint16
+	C.int       int32
+	C.uint      uint32
+	C.long      int32
+	C.ulong     uint32
+	C.longlong  int64
+	C.ulonglong uint64
+)
+
 //export foo
 func C.foo(a C.int, b C.int) C.int
 
+var C.foo$funcaddr unsafe.Pointer
+
 //export variadic0
 //go:variadic
 func C.variadic0()
 
+var C.variadic0$funcaddr unsafe.Pointer
+
 //export variadic2
 //go:variadic
 func C.variadic2(x C.int, y C.int)
 
-var C.foo$funcaddr unsafe.Pointer
-var C.variadic0$funcaddr unsafe.Pointer
 var C.variadic2$funcaddr unsafe.Pointer
 
 //go:extern someValue
 var C.someValue C.int
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
diff --git a/cgo/testdata/types.out.go b/cgo/testdata/types.out.go
index 639d1f4f3..bd7b3fc42 100644
--- a/cgo/testdata/types.out.go
+++ b/cgo/testdata/types.out.go
@@ -24,132 +24,126 @@ func C.GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 	return C.__GoBytes(ptr, uintptr(length))
 }
 
-const C.option2A = 20
-const C.optionA = 0
-const C.optionB = 1
-const C.optionC = -5
-const C.optionD = -4
-const C.optionE = 10
-const C.optionF = 11
-const C.optionG = 12
-const C.unused1 = 5
-
-type C.int16_t = int16
-type C.int32_t = int32
-type C.int64_t = int64
-type C.int8_t = int8
-type C.uint16_t = uint16
-type C.uint32_t = uint32
-type C.uint64_t = uint64
-type C.uint8_t = uint8
-type C.uintptr_t = uintptr
-type C.char uint8
-type C.int int32
-type C.long int32
-type C.longlong int64
-type C.schar int8
-type C.short int16
-type C.uchar uint8
-type C.uint uint32
-type C.ulong uint32
-type C.ulonglong uint64
-type C.ushort uint16
-type C.bitfield_t = C.struct_4
-type C.myIntArray = [10]C.int
+type (
+	C.char      uint8
+	C.schar     int8
+	C.uchar     uint8
+	C.short     int16
+	C.ushort    uint16
+	C.int       int32
+	C.uint      uint32
+	C.long      int32
+	C.ulong     uint32
+	C.longlong  int64
+	C.ulonglong uint64
+)
 type C.myint = C.int
-type C.option2_t = C.uint
-type C.option_t = C.enum_option
-type C.point2d_t = struct {
+type C._Ctype_struct___0 struct {
 	x C.int
 	y C.int
 }
-type C.point3d_t = C.struct_point3d
-type C.struct_nested_t = struct {
-	begin C.point2d_t
-	end   C.point2d_t
-	tag   C.int
-
-	coord C.union_2
-}
-type C.types_t = struct {
-	f   float32
-	d   float64
-	ptr *C.int
-}
-type C.union1_t = struct{ i C.int }
-type C.union2d_t = C.union_union2d
-type C.union3_t = C.union_1
-type C.union_nested_t = C.union_3
-type C.unionarray_t = struct{ arr [10]C.uchar }
-
-func (s *C.struct_4) bitfield_a() C.uchar { return s.__bitfield_1 & 0x1f }
-func (s *C.struct_4) set_bitfield_a(value C.uchar) {
-	s.__bitfield_1 = s.__bitfield_1&^0x1f | value&0x1f<<0
-}
-func (s *C.struct_4) bitfield_b() C.uchar {
-	return s.__bitfield_1 >> 5 & 0x1
-}
-func (s *C.struct_4) set_bitfield_b(value C.uchar) {
-	s.__bitfield_1 = s.__bitfield_1&^0x20 | value&0x1<<5
-}
-func (s *C.struct_4) bitfield_c() C.uchar {
-	return s.__bitfield_1 >> 6
-}
-func (s *C.struct_4) set_bitfield_c(value C.uchar,
-
-) { s.__bitfield_1 = s.__bitfield_1&0x3f | value<<6 }
-
-type C.struct_4 struct {
-	start        C.uchar
-	__bitfield_1 C.uchar
-
-	d C.uchar
-	e C.uchar
-}
+type C.point2d_t = C._Ctype_struct___0
 type C.struct_point3d struct {
 	x C.int
 	y C.int
 	z C.int
 }
+type C.point3d_t = C.struct_point3d
 type C.struct_type1 struct {
 	_type   C.int
 	__type  C.int
 	___type C.int
 }
 type C.struct_type2 struct{ _type C.int }
+type C._Ctype_union___1 struct{ i C.int }
+type C.union1_t = C._Ctype_union___1
+type C._Ctype_union___2 struct{ $union uint64 }
 
-func (union *C.union_1) unionfield_i() *C.int   { return (*C.int)(unsafe.Pointer(&union.$union)) }
-func (union *C.union_1) unionfield_d() *float64 { return (*float64)(unsafe.Pointer(&union.$union)) }
-func (union *C.union_1) unionfield_s() *C.short { return (*C.short)(unsafe.Pointer(&union.$union)) }
+func (union *C._Ctype_union___2) unionfield_i() *C.int {
+	return (*C.int)(unsafe.Pointer(&union.$union))
+}
+func (union *C._Ctype_union___2) unionfield_d() *float64 {
+	return (*float64)(unsafe.Pointer(&union.$union))
+}
+func (union *C._Ctype_union___2) unionfield_s() *C.short {
+	return (*C.short)(unsafe.Pointer(&union.$union))
+}
 
-type C.union_1 struct{ $union uint64 }
+type C.union3_t = C._Ctype_union___2
+type C.union_union2d struct{ $union [2]uint64 }
 
-func (union *C.union_2) unionfield_area() *C.point2d_t {
+func (union *C.union_union2d) unionfield_i() *C.int { return (*C.int)(unsafe.Pointer(&union.$union)) }
+func (union *C.union_union2d) unionfield_d() *[2]float64 {
+	return (*[2]float64)(unsafe.Pointer(&union.$union))
+}
+
+type C.union2d_t = C.union_union2d
+type C._Ctype_union___3 struct{ arr [10]C.uchar }
+type C.unionarray_t = C._Ctype_union___3
+type C._Ctype_union___5 struct{ $union [3]uint32 }
+
+func (union *C._Ctype_union___5) unionfield_area() *C.point2d_t {
 	return (*C.point2d_t)(unsafe.Pointer(&union.$union))
 }
-func (union *C.union_2) unionfield_solid() *C.point3d_t {
+func (union *C._Ctype_union___5) unionfield_solid() *C.point3d_t {
 	return (*C.point3d_t)(unsafe.Pointer(&union.$union))
 }
 
-type C.union_2 struct{ $union [3]uint32 }
+type C._Ctype_struct___4 struct {
+	begin C.point2d_t
+	end   C.point2d_t
+	tag   C.int
+
+	coord C._Ctype_union___5
+}
+type C.struct_nested_t = C._Ctype_struct___4
+type C._Ctype_union___6 struct{ $union [2]uint64 }
 
-func (union *C.union_3) unionfield_point() *C.point3d_t {
+func (union *C._Ctype_union___6) unionfield_point() *C.point3d_t {
 	return (*C.point3d_t)(unsafe.Pointer(&union.$union))
 }
-func (union *C.union_3) unionfield_array() *C.unionarray_t {
+func (union *C._Ctype_union___6) unionfield_array() *C.unionarray_t {
 	return (*C.unionarray_t)(unsafe.Pointer(&union.$union))
 }
-func (union *C.union_3) unionfield_thing() *C.union3_t {
+func (union *C._Ctype_union___6) unionfield_thing() *C.union3_t {
 	return (*C.union3_t)(unsafe.Pointer(&union.$union))
 }
 
-type C.union_3 struct{ $union [2]uint64 }
+type C.union_nested_t = C._Ctype_union___6
+type C.enum_option = C.int
+type C.option_t = C.enum_option
+type C._Ctype_enum___7 = C.uint
+type C.option2_t = C._Ctype_enum___7
+type C._Ctype_struct___8 struct {
+	f   float32
+	d   float64
+	ptr *C.int
+}
+type C.types_t = C._Ctype_struct___8
+type C.myIntArray = [10]C.int
+type C._Ctype_struct___9 struct {
+	start        C.uchar
+	__bitfield_1 C.uchar
+
+	d C.uchar
+	e C.uchar
+}
 
-func (union *C.union_union2d) unionfield_i() *C.int { return (*C.int)(unsafe.Pointer(&union.$union)) }
-func (union *C.union_union2d) unionfield_d() *[2]float64 {
-	return (*[2]float64)(unsafe.Pointer(&union.$union))
+func (s *C._Ctype_struct___9) bitfield_a() C.uchar { return s.__bitfield_1 & 0x1f }
+func (s *C._Ctype_struct___9) set_bitfield_a(value C.uchar) {
+	s.__bitfield_1 = s.__bitfield_1&^0x1f | value&0x1f<<0
 }
+func (s *C._Ctype_struct___9) bitfield_b() C.uchar {
+	return s.__bitfield_1 >> 5 & 0x1
+}
+func (s *C._Ctype_struct___9) set_bitfield_b(value C.uchar) {
+	s.__bitfield_1 = s.__bitfield_1&^0x20 | value&0x1<<5
+}
+func (s *C._Ctype_struct___9) bitfield_c() C.uchar {
+	return s.__bitfield_1 >> 6
+}
+func (s *C._Ctype_struct___9) set_bitfield_c(value C.uchar,
 
-type C.union_union2d struct{ $union [2]uint64 }
-type C.enum_option C.int
-type C.enum_unused C.uint
+) { s.__bitfield_1 = s.__bitfield_1&0x3f | value<<6 }
+
+type C.bitfield_t = C._Ctype_struct___9