cgo: only include the symbols that are necessary (recursively)
Only try to convert the C symbols to their Go equivalents that are actually referenced by the Go code with C.<somesymbol>. This avoids having to support all possible C types, which is difficult because of oddities like `typedef void` or `__builtin_va_list`. Especially __builtin_va_list, which varies between targets.
Этот коммит содержится в:
Ayke van Laethem
Ron Evans
родитель
35af33ead7
коммит
b1ed8a46b7
3 изменённых файлов: 137 добавлений и 57 удалений
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@ -23,6 +23,7 @@ type fileInfo struct {
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typedefs map[string]*typedefInfo
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elaboratedTypes map[string]ast.Expr
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importCPos token.Pos
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missingSymbols map[string]struct{}
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}
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// functionInfo stores some information about a Cgo function found by libclang
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@ -51,16 +52,31 @@ type globalInfo struct {
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// cgoAliases list type aliases between Go and C, for types that are equivalent
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// in both languages. See addTypeAliases.
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var cgoAliases = map[string]string{
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"C.int8_t": "int8",
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"C.int16_t": "int16",
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"C.int32_t": "int32",
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"C.int64_t": "int64",
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"C.uint8_t": "uint8",
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"C.uint16_t": "uint16",
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"C.uint32_t": "uint32",
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"C.uint64_t": "uint64",
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"C.uintptr_t": "uintptr",
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"C.__builtin_va_list": "uintptr", // dummy value until fully implemented
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"C.int8_t": "int8",
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"C.int16_t": "int16",
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"C.int32_t": "int32",
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"C.int64_t": "int64",
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"C.uint8_t": "uint8",
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"C.uint16_t": "uint16",
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"C.uint32_t": "uint32",
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"C.uint64_t": "uint64",
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"C.uintptr_t": "uintptr",
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}
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// cgoBuiltinAliases are handled specially because they only exist on the Go
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// side of CGo, not on the CGo (they're prefixed with "_Cgo_" there).
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var cgoBuiltinAliases = map[string]struct{}{
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"char": struct{}{},
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"schar": struct{}{},
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"uchar": struct{}{},
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"short": struct{}{},
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"ushort": struct{}{},
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"int": struct{}{},
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"uint": struct{}{},
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"long": struct{}{},
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"ulong": struct{}{},
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"longlong": struct{}{},
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"ulonglong": struct{}{},
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}
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// cgoTypes lists some C types with ambiguous sizes that must be retrieved
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@ -91,6 +107,13 @@ func (p *Package) processCgo(filename string, f *ast.File, cflags []string) []er
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globals: map[string]*globalInfo{},
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typedefs: map[string]*typedefInfo{},
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elaboratedTypes: map[string]ast.Expr{},
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missingSymbols: map[string]struct{}{},
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}
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// Find all C.* symbols.
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f = astutil.Apply(f, info.findMissingCGoNames, nil).(*ast.File)
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for name := range cgoBuiltinAliases {
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info.missingSymbols["_Cgo_"+name] = struct{}{}
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}
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// Find `import "C"` statements in the file.
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@ -222,6 +245,9 @@ func (info *fileInfo) addFuncDecls() {
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// // ...
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// )
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func (info *fileInfo) addFuncPtrDecls() {
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if len(info.functions) == 0 {
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return
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}
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gen := &ast.GenDecl{
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TokPos: info.importCPos,
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Tok: token.VAR,
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@ -270,6 +296,9 @@ func (info *fileInfo) addFuncPtrDecls() {
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// // ...
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// )
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func (info *fileInfo) addVarDecls() {
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if len(info.globals) == 0 {
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return
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}
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gen := &ast.GenDecl{
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TokPos: info.importCPos,
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Tok: token.VAR,
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@ -346,6 +375,9 @@ func (info *fileInfo) addTypeAliases() {
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}
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func (info *fileInfo) addTypedefs() {
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if len(info.typedefs) == 0 {
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return
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}
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gen := &ast.GenDecl{
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TokPos: info.importCPos,
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Tok: token.TYPE,
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@ -394,6 +426,9 @@ func (info *fileInfo) addTypedefs() {
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// See also:
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// https://en.cppreference.com/w/cpp/language/elaborated_type_specifier
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func (info *fileInfo) addElaboratedTypes() {
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if len(info.elaboratedTypes) == 0 {
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return
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}
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gen := &ast.GenDecl{
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TokPos: info.importCPos,
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Tok: token.TYPE,
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@ -424,6 +459,27 @@ func (info *fileInfo) addElaboratedTypes() {
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info.Decls = append(info.Decls, gen)
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}
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// findMissingCGoNames traverses the AST and finds all C.something names. Only
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// these symbols are extracted from the parsed C AST and converted to the Go
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// equivalent.
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func (info *fileInfo) findMissingCGoNames(cursor *astutil.Cursor) bool {
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switch node := cursor.Node().(type) {
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case *ast.SelectorExpr:
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x, ok := node.X.(*ast.Ident)
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if !ok {
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return true
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}
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if x.Name == "C" {
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name := node.Sel.Name
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if _, ok := cgoBuiltinAliases[name]; ok {
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name = "_Cgo_" + name
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}
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info.missingSymbols[name] = struct{}{}
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}
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}
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return true
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}
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// walker replaces all "C".<something> expressions to literal "C.<something>"
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// expressions. Such expressions are impossible to write in Go (a dot cannot be
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// used in the middle of a name) so in practice all C identifiers live in a
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@ -168,6 +168,9 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
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switch kind {
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case C.CXCursor_FunctionDecl:
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name := getString(C.tinygo_clang_getCursorSpelling(c))
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if _, required := info.missingSymbols[name]; !required {
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return C.CXChildVisit_Continue
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}
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cursorType := C.tinygo_clang_getCursorType(c)
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if C.clang_isFunctionTypeVariadic(cursorType) != 0 {
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return C.CXChildVisit_Continue // not supported
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@ -199,58 +202,23 @@ func tinygo_clang_globals_visitor(c, parent C.GoCXCursor, client_data C.CXClient
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}
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case C.CXCursor_StructDecl:
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typ := C.tinygo_clang_getCursorType(c)
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name := getString(C.tinygo_clang_getCursorSpelling(c))
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if _, required := info.missingSymbols["struct_"+name]; !required {
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return C.CXChildVisit_Continue
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}
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info.makeASTType(typ, pos)
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case C.CXCursor_TypedefDecl:
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typedefType := C.tinygo_clang_getCursorType(c)
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name := getString(C.clang_getTypedefName(typedefType))
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underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(c)
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expr := info.makeASTType(underlyingType, pos)
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if strings.HasPrefix(name, "_Cgo_") {
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expr := expr.(*ast.Ident)
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typeSize := C.clang_Type_getSizeOf(underlyingType)
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switch expr.Name {
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case "C.char":
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if typeSize != 1 {
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// This happens for some very special purpose architectures
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// (DSPs etc.) that are not currently targeted.
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// https://www.embecosm.com/2017/04/18/non-8-bit-char-support-in-clang-and-llvm/
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panic("unknown char width")
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}
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switch underlyingType.kind {
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case C.CXType_Char_S:
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expr.Name = "int8"
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case C.CXType_Char_U:
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expr.Name = "uint8"
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}
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case "C.schar", "C.short", "C.int", "C.long", "C.longlong":
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switch typeSize {
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case 1:
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expr.Name = "int8"
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case 2:
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expr.Name = "int16"
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case 4:
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expr.Name = "int32"
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case 8:
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expr.Name = "int64"
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}
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case "C.uchar", "C.ushort", "C.uint", "C.ulong", "C.ulonglong":
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switch typeSize {
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case 1:
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expr.Name = "uint8"
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case 2:
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expr.Name = "uint16"
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case 4:
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expr.Name = "uint32"
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case 8:
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expr.Name = "uint64"
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}
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}
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}
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info.typedefs[name] = &typedefInfo{
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typeExpr: expr,
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if _, required := info.missingSymbols[name]; !required {
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return C.CXChildVisit_Continue
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}
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info.makeASTType(typedefType, pos)
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case C.CXCursor_VarDecl:
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name := getString(C.tinygo_clang_getCursorSpelling(c))
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if _, required := info.missingSymbols[name]; !required {
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return C.CXChildVisit_Continue
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}
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cursorType := C.tinygo_clang_getCursorType(c)
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info.globals[name] = &globalInfo{
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typeExpr: info.makeASTType(cursorType, pos),
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@ -394,10 +362,60 @@ func (info *fileInfo) makeASTType(typ C.CXType, pos token.Pos) ast.Expr {
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},
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}
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case C.CXType_Typedef:
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typedefName := getString(C.clang_getTypedefName(typ))
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name := getString(C.clang_getTypedefName(typ))
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if _, ok := info.typedefs[name]; !ok {
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info.typedefs[name] = nil // don't recurse
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c := C.tinygo_clang_getTypeDeclaration(typ)
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underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(c)
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expr := info.makeASTType(underlyingType, pos)
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if strings.HasPrefix(name, "_Cgo_") {
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expr := expr.(*ast.Ident)
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typeSize := C.clang_Type_getSizeOf(underlyingType)
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switch expr.Name {
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case "C.char":
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if typeSize != 1 {
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// This happens for some very special purpose architectures
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// (DSPs etc.) that are not currently targeted.
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// https://www.embecosm.com/2017/04/18/non-8-bit-char-support-in-clang-and-llvm/
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panic("unknown char width")
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}
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switch underlyingType.kind {
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case C.CXType_Char_S:
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expr.Name = "int8"
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case C.CXType_Char_U:
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expr.Name = "uint8"
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}
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case "C.schar", "C.short", "C.int", "C.long", "C.longlong":
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switch typeSize {
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case 1:
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expr.Name = "int8"
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case 2:
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expr.Name = "int16"
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case 4:
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expr.Name = "int32"
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case 8:
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expr.Name = "int64"
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}
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case "C.uchar", "C.ushort", "C.uint", "C.ulong", "C.ulonglong":
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switch typeSize {
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case 1:
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expr.Name = "uint8"
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case 2:
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expr.Name = "uint16"
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case 4:
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expr.Name = "uint32"
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case 8:
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expr.Name = "uint64"
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}
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}
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}
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info.typedefs[name] = &typedefInfo{
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typeExpr: expr,
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}
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}
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return &ast.Ident{
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NamePos: pos,
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Name: "C." + typedefName,
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Name: "C." + name,
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}
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case C.CXType_Elaborated:
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underlying := C.clang_Type_getNamedType(typ)
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6
testdata/cgo/main.h
предоставленный
6
testdata/cgo/main.h
предоставленный
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@ -2,12 +2,17 @@
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#include <stdint.h>
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typedef short myint;
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typedef short unusedTypedef;
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int add(int a, int b);
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int unusedFunction(void);
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typedef int (*binop_t) (int, int);
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int doCallback(int a, int b, binop_t cb);
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typedef int * intPointer;
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void store(int value, int *ptr);
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// this signature should not be included by CGo
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void unusedFunction2(int x, __builtin_va_list args);
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typedef struct collection {
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short s;
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long l;
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@ -37,6 +42,7 @@ void unionSetData(short f0, short f1, short f2);
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// test globals and datatypes
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extern int global;
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extern int unusedGlobal;
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extern bool globalBool;
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extern bool globalBool2;
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extern float globalFloat;
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