Function typecheck

cmd/go-post/typecheck.go:135–215

typecheck type checks the AST f assuming the information in cfg. It returns two maps with type information: typeof maps AST nodes to type information in gofmt string form. assign maps type strings to lists of expressions that were assigned to values of another type that were assigned to that type.

(cfg *TypeConfig, f *ast.File)

// assign maps type strings to lists of expressions that were assigned
// to values of another type that were assigned to that type.
func typecheck(cfg *TypeConfig, f *ast.File) (typeof map[interface{}]string, assign map[string][]interface{}) {
	typeof = make(map[interface{}]string)
	assign = make(map[string][]interface{})
	cfg1 := &TypeConfig{}
	*cfg1 = *cfg // make copy so we can add locally
	copied := false

	// gather function declarations
	for _, decl := range f.Decls {
		fn, ok := decl.(*ast.FuncDecl)
		if !ok {
			continue
		}
		typecheck1(cfg, fn.Type, typeof, assign)
		t := typeof[fn.Type]
		if fn.Recv != nil {
			// The receiver must be a type.
			rcvr := typeof[fn.Recv]
			if !isType(rcvr) {
				if len(fn.Recv.List) != 1 {
					continue
				}
				rcvr = mkType(gofmt(fn.Recv.List[0].Type))
				typeof[fn.Recv.List[0].Type] = rcvr
			}
			rcvr = getType(rcvr)
			if rcvr != "" && rcvr[0] == '*' {
				rcvr = rcvr[1:]
			}
			typeof[rcvr+"."+fn.Name.Name] = t
		} else {
			if isType(t) {
				t = getType(t)
			} else {
				t = gofmt(fn.Type)
			}
			typeof[fn.Name] = t

			// Record typeof[fn.Name.Obj] for future references to fn.Name.
			typeof[fn.Name.Obj] = t
		}
	}

	// gather struct declarations
	for _, decl := range f.Decls {
		d, ok := decl.(*ast.GenDecl)
		if ok {
			for _, s := range d.Specs {
				switch s := s.(type) {
				case *ast.TypeSpec:
					if cfg1.Type[s.Name.Name] != nil {
						break
					}
					if !copied {
						copied = true
						// Copy map lazily: it's time.
						cfg1.Type = make(map[string]*Type)
						for k, v := range cfg.Type {