| // Copyright 2012 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Package types declares the data types and implements |
| // the algorithms for type-checking of Go packages. Use |
| // Config.Check to invoke the type checker for a package. |
| // Alternatively, create a new type checker with NewChecker |
| // and invoke it incrementally by calling Checker.Files. |
| // |
| // Type-checking consists of several interdependent phases: |
| // |
| // Name resolution maps each identifier (ast.Ident) in the program to the |
| // language object (Object) it denotes. |
| // Use Info.{Defs,Uses,Implicits} for the results of name resolution. |
| // |
| // Constant folding computes the exact constant value (constant.Value) |
| // for every expression (ast.Expr) that is a compile-time constant. |
| // Use Info.Types[expr].Value for the results of constant folding. |
| // |
| // Type inference computes the type (Type) of every expression (ast.Expr) |
| // and checks for compliance with the language specification. |
| // Use Info.Types[expr].Type for the results of type inference. |
| // |
| // For a tutorial, see https://golang.org/s/types-tutorial. |
| // |
| package types |
| |
| import ( |
| "bytes" |
| "fmt" |
| "go/ast" |
| "go/constant" |
| "go/token" |
| _ "unsafe" // for go:linkname |
| ) |
| |
| // An Error describes a type-checking error; it implements the error interface. |
| // A "soft" error is an error that still permits a valid interpretation of a |
| // package (such as "unused variable"); "hard" errors may lead to unpredictable |
| // behavior if ignored. |
| type Error struct { |
| Fset *token.FileSet // file set for interpretation of Pos |
| Pos token.Pos // error position |
| Msg string // error message |
| Soft bool // if set, error is "soft" |
| |
| // go116code is a future API, unexported as the set of error codes is large |
| // and likely to change significantly during experimentation. Tools wishing |
| // to preview this feature may read go116code using reflection (see |
| // errorcodes_test.go), but beware that there is no guarantee of future |
| // compatibility. |
| go116code errorCode |
| go116start token.Pos |
| go116end token.Pos |
| } |
| |
| // Error returns an error string formatted as follows: |
| // filename:line:column: message |
| func (err Error) Error() string { |
| return fmt.Sprintf("%s: %s", err.Fset.Position(err.Pos), err.Msg) |
| } |
| |
| // An Importer resolves import paths to Packages. |
| // |
| // CAUTION: This interface does not support the import of locally |
| // vendored packages. See https://golang.org/s/go15vendor. |
| // If possible, external implementations should implement ImporterFrom. |
| type Importer interface { |
| // Import returns the imported package for the given import path. |
| // The semantics is like for ImporterFrom.ImportFrom except that |
| // dir and mode are ignored (since they are not present). |
| Import(path string) (*Package, error) |
| } |
| |
| // ImportMode is reserved for future use. |
| type ImportMode int |
| |
| // An ImporterFrom resolves import paths to packages; it |
| // supports vendoring per https://golang.org/s/go15vendor. |
| // Use go/importer to obtain an ImporterFrom implementation. |
| type ImporterFrom interface { |
| // Importer is present for backward-compatibility. Calling |
| // Import(path) is the same as calling ImportFrom(path, "", 0); |
| // i.e., locally vendored packages may not be found. |
| // The types package does not call Import if an ImporterFrom |
| // is present. |
| Importer |
| |
| // ImportFrom returns the imported package for the given import |
| // path when imported by a package file located in dir. |
| // If the import failed, besides returning an error, ImportFrom |
| // is encouraged to cache and return a package anyway, if one |
| // was created. This will reduce package inconsistencies and |
| // follow-on type checker errors due to the missing package. |
| // The mode value must be 0; it is reserved for future use. |
| // Two calls to ImportFrom with the same path and dir must |
| // return the same package. |
| ImportFrom(path, dir string, mode ImportMode) (*Package, error) |
| } |
| |
| // A Config specifies the configuration for type checking. |
| // The zero value for Config is a ready-to-use default configuration. |
| type Config struct { |
| // goVersion describes the accepted Go language version. The string |
| // must follow the format "go%d.%d" (e.g. "go1.12") or it must be |
| // empty; an empty string indicates the latest language version. |
| // If the format is invalid, invoking the type checker will cause a |
| // panic. |
| goVersion string |
| |
| // If IgnoreFuncBodies is set, function bodies are not |
| // type-checked. |
| IgnoreFuncBodies bool |
| |
| // If FakeImportC is set, `import "C"` (for packages requiring Cgo) |
| // declares an empty "C" package and errors are omitted for qualified |
| // identifiers referring to package C (which won't find an object). |
| // This feature is intended for the standard library cmd/api tool. |
| // |
| // Caution: Effects may be unpredictable due to follow-on errors. |
| // Do not use casually! |
| FakeImportC bool |
| |
| // If go115UsesCgo is set, the type checker expects the |
| // _cgo_gotypes.go file generated by running cmd/cgo to be |
| // provided as a package source file. Qualified identifiers |
| // referring to package C will be resolved to cgo-provided |
| // declarations within _cgo_gotypes.go. |
| // |
| // It is an error to set both FakeImportC and go115UsesCgo. |
| go115UsesCgo bool |
| |
| // If Error != nil, it is called with each error found |
| // during type checking; err has dynamic type Error. |
| // Secondary errors (for instance, to enumerate all types |
| // involved in an invalid recursive type declaration) have |
| // error strings that start with a '\t' character. |
| // If Error == nil, type-checking stops with the first |
| // error found. |
| Error func(err error) |
| |
| // An importer is used to import packages referred to from |
| // import declarations. |
| // If the installed importer implements ImporterFrom, the type |
| // checker calls ImportFrom instead of Import. |
| // The type checker reports an error if an importer is needed |
| // but none was installed. |
| Importer Importer |
| |
| // If Sizes != nil, it provides the sizing functions for package unsafe. |
| // Otherwise SizesFor("gc", "amd64") is used instead. |
| Sizes Sizes |
| |
| // If DisableUnusedImportCheck is set, packages are not checked |
| // for unused imports. |
| DisableUnusedImportCheck bool |
| } |
| |
| //go:linkname srcimporter_setUsesCgo |
| func srcimporter_setUsesCgo(conf *Config) { |
| conf.go115UsesCgo = true |
| } |
| |
| // The Info struct is found in api_notypeparams.go and api_typeparams.go. |
| |
| // TypeOf returns the type of expression e, or nil if not found. |
| // Precondition: the Types, Uses and Defs maps are populated. |
| // |
| func (info *Info) TypeOf(e ast.Expr) Type { |
| if t, ok := info.Types[e]; ok { |
| return t.Type |
| } |
| if id, _ := e.(*ast.Ident); id != nil { |
| if obj := info.ObjectOf(id); obj != nil { |
| return obj.Type() |
| } |
| } |
| return nil |
| } |
| |
| // ObjectOf returns the object denoted by the specified id, |
| // or nil if not found. |
| // |
| // If id is an embedded struct field, ObjectOf returns the field (*Var) |
| // it defines, not the type (*TypeName) it uses. |
| // |
| // Precondition: the Uses and Defs maps are populated. |
| // |
| func (info *Info) ObjectOf(id *ast.Ident) Object { |
| if obj := info.Defs[id]; obj != nil { |
| return obj |
| } |
| return info.Uses[id] |
| } |
| |
| // TypeAndValue reports the type and value (for constants) |
| // of the corresponding expression. |
| type TypeAndValue struct { |
| mode operandMode |
| Type Type |
| Value constant.Value |
| } |
| |
| // IsVoid reports whether the corresponding expression |
| // is a function call without results. |
| func (tv TypeAndValue) IsVoid() bool { |
| return tv.mode == novalue |
| } |
| |
| // IsType reports whether the corresponding expression specifies a type. |
| func (tv TypeAndValue) IsType() bool { |
| return tv.mode == typexpr |
| } |
| |
| // IsBuiltin reports whether the corresponding expression denotes |
| // a (possibly parenthesized) built-in function. |
| func (tv TypeAndValue) IsBuiltin() bool { |
| return tv.mode == builtin |
| } |
| |
| // IsValue reports whether the corresponding expression is a value. |
| // Builtins are not considered values. Constant values have a non- |
| // nil Value. |
| func (tv TypeAndValue) IsValue() bool { |
| switch tv.mode { |
| case constant_, variable, mapindex, value, commaok, commaerr: |
| return true |
| } |
| return false |
| } |
| |
| // IsNil reports whether the corresponding expression denotes the |
| // predeclared value nil. |
| func (tv TypeAndValue) IsNil() bool { |
| return tv.mode == value && tv.Type == Typ[UntypedNil] |
| } |
| |
| // Addressable reports whether the corresponding expression |
| // is addressable (https://golang.org/ref/spec#Address_operators). |
| func (tv TypeAndValue) Addressable() bool { |
| return tv.mode == variable |
| } |
| |
| // Assignable reports whether the corresponding expression |
| // is assignable to (provided a value of the right type). |
| func (tv TypeAndValue) Assignable() bool { |
| return tv.mode == variable || tv.mode == mapindex |
| } |
| |
| // HasOk reports whether the corresponding expression may be |
| // used on the rhs of a comma-ok assignment. |
| func (tv TypeAndValue) HasOk() bool { |
| return tv.mode == commaok || tv.mode == mapindex |
| } |
| |
| // _Inferred reports the _Inferred type arguments and signature |
| // for a parameterized function call that uses type inference. |
| type _Inferred struct { |
| Targs []Type |
| Sig *Signature |
| } |
| |
| // An Initializer describes a package-level variable, or a list of variables in case |
| // of a multi-valued initialization expression, and the corresponding initialization |
| // expression. |
| type Initializer struct { |
| Lhs []*Var // var Lhs = Rhs |
| Rhs ast.Expr |
| } |
| |
| func (init *Initializer) String() string { |
| var buf bytes.Buffer |
| for i, lhs := range init.Lhs { |
| if i > 0 { |
| buf.WriteString(", ") |
| } |
| buf.WriteString(lhs.Name()) |
| } |
| buf.WriteString(" = ") |
| WriteExpr(&buf, init.Rhs) |
| return buf.String() |
| } |
| |
| // Check type-checks a package and returns the resulting package object and |
| // the first error if any. Additionally, if info != nil, Check populates each |
| // of the non-nil maps in the Info struct. |
| // |
| // The package is marked as complete if no errors occurred, otherwise it is |
| // incomplete. See Config.Error for controlling behavior in the presence of |
| // errors. |
| // |
| // The package is specified by a list of *ast.Files and corresponding |
| // file set, and the package path the package is identified with. |
| // The clean path must not be empty or dot ("."). |
| func (conf *Config) Check(path string, fset *token.FileSet, files []*ast.File, info *Info) (*Package, error) { |
| pkg := NewPackage(path, "") |
| return pkg, NewChecker(conf, fset, pkg, info).Files(files) |
| } |
| |
| // AssertableTo reports whether a value of type V can be asserted to have type T. |
| func AssertableTo(V *Interface, T Type) bool { |
| m, _ := (*Checker)(nil).assertableTo(V, T) |
| return m == nil |
| } |
| |
| // AssignableTo reports whether a value of type V is assignable to a variable of type T. |
| func AssignableTo(V, T Type) bool { |
| x := operand{mode: value, typ: V} |
| ok, _ := x.assignableTo(nil, T, nil) // check not needed for non-constant x |
| return ok |
| } |
| |
| // ConvertibleTo reports whether a value of type V is convertible to a value of type T. |
| func ConvertibleTo(V, T Type) bool { |
| x := operand{mode: value, typ: V} |
| return x.convertibleTo(nil, T, nil) // check not needed for non-constant x |
| } |
| |
| // Implements reports whether type V implements interface T. |
| func Implements(V Type, T *Interface) bool { |
| f, _ := MissingMethod(V, T, true) |
| return f == nil |
| } |
| |
| // Identical reports whether x and y are identical types. |
| // Receivers of Signature types are ignored. |
| func Identical(x, y Type) bool { |
| return (*Checker)(nil).identical(x, y) |
| } |
| |
| // IdenticalIgnoreTags reports whether x and y are identical types if tags are ignored. |
| // Receivers of Signature types are ignored. |
| func IdenticalIgnoreTags(x, y Type) bool { |
| return (*Checker)(nil).identicalIgnoreTags(x, y) |
| } |