"fmt"
"go/ast"
"go/constant"
+ "go/internal/typeparams"
"go/token"
+ . "internal/types/errors"
"sort"
"strconv"
"strings"
type declInfo struct {
file *Scope // scope of file containing this declaration
lhs []*Var // lhs of n:1 variable declarations, or nil
- typ ast.Expr // type, or nil
- init ast.Expr // init/orig expression, or nil
+ vtyp ast.Expr // type, or nil (for const and var declarations only)
+ init ast.Expr // init/orig expression, or nil (for const and var declarations only)
inherited bool // if set, the init expression is inherited from a previous constant declaration
+ tdecl *ast.TypeSpec // type declaration, or nil
fdecl *ast.FuncDecl // func declaration, or nil
- aliasPos token.Pos // If valid, the decl is a type alias and aliasPos is the position of '='.
// The deps field tracks initialization expression dependencies.
deps map[Object]bool // lazily initialized
r = len(init.Values)
}
- const code = _WrongAssignCount
+ const code = WrongAssignCount
switch {
case init == nil && r == 0:
// var decl w/o init expr
if s.Type == nil {
- check.errorf(s, code, "missing type or init expr")
+ check.error(s, code, "missing type or init expr")
}
case l < r:
if l < len(s.Values) {
// init exprs from s
n := s.Values[l]
check.errorf(n, code, "extra init expr %s", n)
- // TODO(gri) avoid declared but not used error here
+ // TODO(gri) avoid declared and not used error here
} else {
// init exprs "inherited"
check.errorf(s, code, "extra init expr at %s", check.fset.Position(init.Pos()))
- // TODO(gri) avoid declared but not used error here
+ // TODO(gri) avoid declared and not used error here
}
case l > r && (init != nil || r != 1):
n := s.Names[r]
// spec: "A package-scope or file-scope identifier with name init
// may only be declared to be a function with this (func()) signature."
if ident.Name == "init" {
- check.errorf(ident, _InvalidInitDecl, "cannot declare init - must be func")
+ check.error(ident, InvalidInitDecl, "cannot declare init - must be func")
return
}
// spec: "The main package must have package name main and declare
// a function main that takes no arguments and returns no value."
if ident.Name == "main" && check.pkg.name == "main" {
- check.errorf(ident, _InvalidMainDecl, "cannot declare main - must be func")
+ check.error(ident, InvalidMainDecl, "cannot declare main - must be func")
return
}
- check.declare(check.pkg.scope, ident, obj, token.NoPos)
+ check.declare(check.pkg.scope, ident, obj, nopos)
check.objMap[obj] = d
obj.setOrder(uint32(len(check.objMap)))
}
return fmt.Sprintf("file[%d]", fileNo)
}
-func (check *Checker) importPackage(pos token.Pos, path, dir string) *Package {
+func (check *Checker) importPackage(at positioner, path, dir string) *Package {
// If we already have a package for the given (path, dir)
// pair, use it instead of doing a full import.
// Checker.impMap only caches packages that are marked Complete
imp = nil // create fake package below
}
if err != nil {
- check.errorf(atPos(pos), _BrokenImport, "could not import %s (%s)", path, err)
+ check.errorf(at, BrokenImport, "could not import %s (%s)", path, err)
if imp == nil {
// create a new fake package
// come up with a sensible package name (heuristic)
// package should be complete or marked fake, but be cautious
if imp.complete || imp.fake {
check.impMap[key] = imp
- check.pkgCnt[imp.name]++
+ // Once we've formatted an error message, keep the pkgPathMap
+ // up-to-date on subsequent imports. It is used for package
+ // qualification in error messages.
+ if check.pkgPathMap != nil {
+ check.markImports(imp)
+ }
return imp
}
pkgImports[imp] = true
}
- var methods []*Func // list of methods with non-blank _ names
+ type methodInfo struct {
+ obj *Func // method
+ ptr bool // true if pointer receiver
+ recv *ast.Ident // receiver type name
+ }
+ var methods []methodInfo // collected methods with valid receivers and non-blank _ names
+ var fileScopes []*Scope
for fileNo, file := range check.files {
// The package identifier denotes the current package,
// but there is no corresponding package object.
if f := check.fset.File(file.Pos()); f != nil {
pos, end = token.Pos(f.Base()), token.Pos(f.Base()+f.Size())
}
- fileScope := NewScope(check.pkg.scope, pos, end, check.filename(fileNo))
+ fileScope := NewScope(pkg.scope, pos, end, check.filename(fileNo))
+ fileScopes = append(fileScopes, fileScope)
check.recordScope(file, fileScope)
// determine file directory, necessary to resolve imports
switch d := d.(type) {
case importDecl:
// import package
+ if d.spec.Path.Value == "" {
+ return // error reported by parser
+ }
path, err := validatedImportPath(d.spec.Path.Value)
if err != nil {
- check.errorf(d.spec.Path, _BadImportPath, "invalid import path (%s)", err)
+ check.errorf(d.spec.Path, BadImportPath, "invalid import path (%s)", err)
return
}
- imp := check.importPackage(d.spec.Path.Pos(), path, fileDir)
+ imp := check.importPackage(d.spec.Path, path, fileDir)
if imp == nil {
return
}
if d.spec.Name != nil {
name = d.spec.Name.Name
if path == "C" {
- // match cmd/compile (not prescribed by spec)
- check.errorf(d.spec.Name, _ImportCRenamed, `cannot rename import "C"`)
+ // match 1.17 cmd/compile (not prescribed by spec)
+ check.error(d.spec.Name, ImportCRenamed, `cannot rename import "C"`)
return
}
}
if name == "init" {
- check.errorf(d.spec.Name, _InvalidInitDecl, "cannot import package as init - init must be a func")
+ check.error(d.spec, InvalidInitDecl, "cannot import package as init - init must be a func")
return
}
check.recordImplicit(d.spec, pkgName)
}
- if path == "C" {
- // match cmd/compile (not prescribed by spec)
+ if imp.fake {
+ // match 1.17 cmd/compile (not prescribed by spec)
pkgName.used = true
}
check.dotImportMap = make(map[dotImportKey]*PkgName)
}
// merge imported scope with file scope
- for _, obj := range imp.scope.elems {
+ for name, obj := range imp.scope.elems {
+ // Note: Avoid eager resolve(name, obj) here, so we only
+ // resolve dot-imported objects as needed.
+
// A package scope may contain non-exported objects,
// do not import them!
- if obj.Exported() {
+ if token.IsExported(name) {
// declare dot-imported object
// (Do not use check.declare because it modifies the object
// via Object.setScopePos, which leads to a race condition;
// the object may be imported into more than one file scope
- // concurrently. See issue #32154.)
- if alt := fileScope.Insert(obj); alt != nil {
- check.errorf(d.spec.Name, _DuplicateDecl, "%s redeclared in this block", obj.Name())
+ // concurrently. See go.dev/issue/32154.)
+ if alt := fileScope.Lookup(name); alt != nil {
+ check.errorf(d.spec.Name, DuplicateDecl, "%s redeclared in this block", alt.Name())
check.reportAltDecl(alt)
} else {
- check.dotImportMap[dotImportKey{fileScope, obj}] = pkgName
+ fileScope.insert(name, obj)
+ check.dotImportMap[dotImportKey{fileScope, name}] = pkgName
}
}
}
} else {
// declare imported package object in file scope
// (no need to provide s.Name since we called check.recordDef earlier)
- check.declare(fileScope, nil, pkgName, token.NoPos)
+ check.declare(fileScope, nil, pkgName, nopos)
}
case constDecl:
// declare all constants
init = d.init[i]
}
- d := &declInfo{file: fileScope, typ: d.typ, init: init, inherited: d.inherited}
+ d := &declInfo{file: fileScope, vtyp: d.typ, init: init, inherited: d.inherited}
check.declarePkgObj(name, obj, d)
}
// The lhs elements are only set up after the for loop below,
// but that's ok because declareVar only collects the declInfo
// for a later phase.
- d1 = &declInfo{file: fileScope, lhs: lhs, typ: d.spec.Type, init: d.spec.Values[0]}
+ d1 = &declInfo{file: fileScope, lhs: lhs, vtyp: d.spec.Type, init: d.spec.Values[0]}
}
// declare all variables
if i < len(d.spec.Values) {
init = d.spec.Values[i]
}
- di = &declInfo{file: fileScope, typ: d.spec.Type, init: init}
+ di = &declInfo{file: fileScope, vtyp: d.spec.Type, init: init}
}
check.declarePkgObj(name, obj, di)
}
case typeDecl:
+ _ = d.spec.TypeParams.NumFields() != 0 && check.verifyVersionf(d.spec.TypeParams.List[0], go1_18, "type parameter")
obj := NewTypeName(d.spec.Name.Pos(), pkg, d.spec.Name.Name, nil)
- check.declarePkgObj(d.spec.Name, obj, &declInfo{file: fileScope, typ: d.spec.Type, aliasPos: d.spec.Assign})
+ check.declarePkgObj(d.spec.Name, obj, &declInfo{file: fileScope, tdecl: d.spec})
case funcDecl:
- info := &declInfo{file: fileScope, fdecl: d.decl}
name := d.decl.Name.Name
obj := NewFunc(d.decl.Name.Pos(), pkg, name, nil)
- if d.decl.Recv == nil {
+ hasTParamError := false // avoid duplicate type parameter errors
+ if d.decl.Recv.NumFields() == 0 {
// regular function
+ if d.decl.Recv != nil {
+ check.error(d.decl.Recv, BadRecv, "method has no receiver")
+ // treat as function
+ }
+ if name == "init" || (name == "main" && check.pkg.name == "main") {
+ code := InvalidInitDecl
+ if name == "main" {
+ code = InvalidMainDecl
+ }
+ if d.decl.Type.TypeParams.NumFields() != 0 {
+ check.softErrorf(d.decl.Type.TypeParams.List[0], code, "func %s must have no type parameters", name)
+ hasTParamError = true
+ }
+ if t := d.decl.Type; t.Params.NumFields() != 0 || t.Results != nil {
+ // TODO(rFindley) Should this be a hard error?
+ check.softErrorf(d.decl.Name, code, "func %s must have no arguments and no return values", name)
+ }
+ }
if name == "init" {
// don't declare init functions in the package scope - they are invisible
obj.parent = pkg.scope
check.recordDef(d.decl.Name, obj)
// init functions must have a body
if d.decl.Body == nil {
- check.softErrorf(obj, _MissingInitBody, "missing function body")
+ // TODO(gri) make this error message consistent with the others above
+ check.softErrorf(obj, MissingInitBody, "missing function body")
}
} else {
- check.declare(pkg.scope, d.decl.Name, obj, token.NoPos)
+ check.declare(pkg.scope, d.decl.Name, obj, nopos)
}
} else {
// method
- // (Methods with blank _ names are never found; no need to collect
- // them for later type association. They will still be type-checked
- // with all the other functions.)
- if name != "_" {
- methods = append(methods, obj)
+
+ // TODO(rFindley) earlier versions of this code checked that methods
+ // have no type parameters, but this is checked later
+ // when type checking the function type. Confirm that
+ // we don't need to check tparams here.
+
+ ptr, recv, _ := check.unpackRecv(d.decl.Recv.List[0].Type, false)
+ // (Methods with invalid receiver cannot be associated to a type, and
+ // methods with blank _ names are never found; no need to collect any
+ // of them. They will still be type-checked with all the other functions.)
+ if recv != nil && name != "_" {
+ methods = append(methods, methodInfo{obj, ptr, recv})
}
check.recordDef(d.decl.Name, obj)
}
+ _ = d.decl.Type.TypeParams.NumFields() != 0 && !hasTParamError && check.verifyVersionf(d.decl.Type.TypeParams.List[0], go1_18, "type parameter")
+ info := &declInfo{file: fileScope, fdecl: d.decl}
// Methods are not package-level objects but we still track them in the
// object map so that we can handle them like regular functions (if the
// receiver is invalid); also we need their fdecl info when associating
}
// verify that objects in package and file scopes have different names
- for _, scope := range check.pkg.scope.children /* file scopes */ {
- for _, obj := range scope.elems {
- if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
+ for _, scope := range fileScopes {
+ for name, obj := range scope.elems {
+ if alt := pkg.scope.Lookup(name); alt != nil {
+ obj = resolve(name, obj)
if pkg, ok := obj.(*PkgName); ok {
- check.errorf(alt, _DuplicateDecl, "%s already declared through import of %s", alt.Name(), pkg.Imported())
+ check.errorf(alt, DuplicateDecl, "%s already declared through import of %s", alt.Name(), pkg.Imported())
check.reportAltDecl(pkg)
} else {
- check.errorf(alt, _DuplicateDecl, "%s already declared through dot-import of %s", alt.Name(), obj.Pkg())
+ check.errorf(alt, DuplicateDecl, "%s already declared through dot-import of %s", alt.Name(), obj.Pkg())
// TODO(gri) dot-imported objects don't have a position; reportAltDecl won't print anything
check.reportAltDecl(obj)
}
return // nothing to do
}
check.methods = make(map[*TypeName][]*Func)
- for _, f := range methods {
- fdecl := check.objMap[f].fdecl
- if list := fdecl.Recv.List; len(list) > 0 {
- // f is a method.
- // Determine the receiver base type and associate f with it.
- ptr, base := check.resolveBaseTypeName(list[0].Type)
- if base != nil {
- f.hasPtrRecv = ptr
- check.methods[base] = append(check.methods[base], f)
+ for i := range methods {
+ m := &methods[i]
+ // Determine the receiver base type and associate m with it.
+ ptr, base := check.resolveBaseTypeName(m.ptr, m.recv, fileScopes)
+ if base != nil {
+ m.obj.hasPtrRecv_ = ptr
+ check.methods[base] = append(check.methods[base], m.obj)
+ }
+ }
+}
+
+// unpackRecv unpacks a receiver type and returns its components: ptr indicates whether
+// rtyp is a pointer receiver, rname is the receiver type name, and tparams are its
+// type parameters, if any. The type parameters are only unpacked if unpackParams is
+// set. If rname is nil, the receiver is unusable (i.e., the source has a bug which we
+// cannot easily work around).
+func (check *Checker) unpackRecv(rtyp ast.Expr, unpackParams bool) (ptr bool, rname *ast.Ident, tparams []*ast.Ident) {
+L: // unpack receiver type
+ // This accepts invalid receivers such as ***T and does not
+ // work for other invalid receivers, but we don't care. The
+ // validity of receiver expressions is checked elsewhere.
+ for {
+ switch t := rtyp.(type) {
+ case *ast.ParenExpr:
+ rtyp = t.X
+ case *ast.StarExpr:
+ ptr = true
+ rtyp = t.X
+ default:
+ break L
+ }
+ }
+
+ // unpack type parameters, if any
+ switch rtyp.(type) {
+ case *ast.IndexExpr, *ast.IndexListExpr:
+ ix := typeparams.UnpackIndexExpr(rtyp)
+ rtyp = ix.X
+ if unpackParams {
+ for _, arg := range ix.Indices {
+ var par *ast.Ident
+ switch arg := arg.(type) {
+ case *ast.Ident:
+ par = arg
+ case *ast.BadExpr:
+ // ignore - error already reported by parser
+ case nil:
+ check.error(ix.Orig, InvalidSyntaxTree, "parameterized receiver contains nil parameters")
+ default:
+ check.errorf(arg, BadDecl, "receiver type parameter %s must be an identifier", arg)
+ }
+ if par == nil {
+ par = &ast.Ident{NamePos: arg.Pos(), Name: "_"}
+ }
+ tparams = append(tparams, par)
}
}
}
+
+ // unpack receiver name
+ if name, _ := rtyp.(*ast.Ident); name != nil {
+ rname = name
+ }
+
+ return
}
// resolveBaseTypeName returns the non-alias base type name for typ, and whether
// there was a pointer indirection to get to it. The base type name must be declared
// in package scope, and there can be at most one pointer indirection. If no such type
// name exists, the returned base is nil.
-func (check *Checker) resolveBaseTypeName(typ ast.Expr) (ptr bool, base *TypeName) {
+func (check *Checker) resolveBaseTypeName(seenPtr bool, typ ast.Expr, fileScopes []*Scope) (ptr bool, base *TypeName) {
// Algorithm: Starting from a type expression, which may be a name,
// we follow that type through alias declarations until we reach a
// non-alias type name. If we encounter anything but pointer types or
// parentheses we're done. If we encounter more than one pointer type
// we're done.
+ ptr = seenPtr
var seen map[*TypeName]bool
for {
+ // Note: this differs from types2, but is necessary. The syntax parser
+ // strips unnecessary parens.
typ = unparen(typ)
// check if we have a pointer type
typ = unparen(pexpr.X) // continue with pointer base type
}
- // typ must be a name
- name, _ := typ.(*ast.Ident)
- if name == nil {
+ // typ must be a name, or a C.name cgo selector.
+ var name string
+ switch typ := typ.(type) {
+ case *ast.Ident:
+ name = typ.Name
+ case *ast.SelectorExpr:
+ // C.struct_foo is a valid type name for packages using cgo.
+ //
+ // Detect this case, and adjust name so that the correct TypeName is
+ // resolved below.
+ if ident, _ := typ.X.(*ast.Ident); ident != nil && ident.Name == "C" {
+ // Check whether "C" actually resolves to an import of "C", by looking
+ // in the appropriate file scope.
+ var obj Object
+ for _, scope := range fileScopes {
+ if scope.Contains(ident.Pos()) {
+ obj = scope.Lookup(ident.Name)
+ }
+ }
+ // If Config.go115UsesCgo is set, the typechecker will resolve Cgo
+ // selectors to their cgo name. We must do the same here.
+ if pname, _ := obj.(*PkgName); pname != nil {
+ if pname.imported.cgo { // only set if Config.go115UsesCgo is set
+ name = "_Ctype_" + typ.Sel.Name
+ }
+ }
+ }
+ if name == "" {
+ return false, nil
+ }
+ default:
return false, nil
}
// name must denote an object found in the current package scope
// (note that dot-imported objects are not in the package scope!)
- obj := check.pkg.scope.Lookup(name.Name)
+ obj := check.pkg.scope.Lookup(name)
if obj == nil {
return false, nil
}
// we're done if tdecl defined tname as a new type
// (rather than an alias)
- tdecl := check.objMap[tname] // must exist for objects in package scope
- if !tdecl.aliasPos.IsValid() {
+ tdecl := check.objMap[tname].tdecl // must exist for objects in package scope
+ if !tdecl.Assign.IsValid() {
return ptr, tname
}
// otherwise, continue resolving
- typ = tdecl.typ
+ typ = tdecl.Type
if seen == nil {
seen = make(map[*TypeName]bool)
}
// add new methods to already type-checked types (from a prior Checker.Files call)
for _, obj := range objList {
if obj, _ := obj.(*TypeName); obj != nil && obj.typ != nil {
- check.addMethodDecls(obj)
+ check.collectMethods(obj)
}
}
- // We process non-alias declarations first, in order to avoid situations where
- // the type of an alias declaration is needed before it is available. In general
- // this is still not enough, as it is possible to create sufficiently convoluted
- // recursive type definitions that will cause a type alias to be needed before it
- // is available (see issue #25838 for examples).
- // As an aside, the cmd/compiler suffers from the same problem (#25838).
- var aliasList []*TypeName
- // phase 1
- for _, obj := range objList {
- // If we have a type alias, collect it for the 2nd phase.
- if tname, _ := obj.(*TypeName); tname != nil && check.objMap[tname].aliasPos.IsValid() {
- aliasList = append(aliasList, tname)
- continue
+ if check.conf._EnableAlias {
+ // With _Alias nodes we can process declarations in any order.
+ for _, obj := range objList {
+ check.objDecl(obj, nil)
+ }
+ } else {
+ // Without _Alias nodes, we process non-alias type declarations first, followed by
+ // alias declarations, and then everything else. This appears to avoid most situations
+ // where the type of an alias is needed before it is available.
+ // There may still be cases where this is not good enough (see also go.dev/issue/25838).
+ // In those cases Checker.ident will report an error ("invalid use of type alias").
+ var aliasList []*TypeName
+ var othersList []Object // everything that's not a type
+ // phase 1: non-alias type declarations
+ for _, obj := range objList {
+ if tname, _ := obj.(*TypeName); tname != nil {
+ if check.objMap[tname].tdecl.Assign.IsValid() {
+ aliasList = append(aliasList, tname)
+ } else {
+ check.objDecl(obj, nil)
+ }
+ } else {
+ othersList = append(othersList, obj)
+ }
+ }
+ // phase 2: alias type declarations
+ for _, obj := range aliasList {
+ check.objDecl(obj, nil)
+ }
+ // phase 3: all other declarations
+ for _, obj := range othersList {
+ check.objDecl(obj, nil)
}
-
- check.objDecl(obj, nil)
- }
- // phase 2
- for _, obj := range aliasList {
- check.objDecl(obj, nil)
}
// At this point we may have a non-empty check.methods map; this means that not all
// unusedImports checks for unused imports.
func (check *Checker) unusedImports() {
- // if function bodies are not checked, packages' uses are likely missing - don't check
+ // If function bodies are not checked, packages' uses are likely missing - don't check.
if check.conf.IgnoreFuncBodies {
return
}
elem = elem[i+1:]
}
if obj.name == "" || obj.name == "." || obj.name == elem {
- check.softErrorf(obj, _UnusedImport, "%q imported but not used", path)
+ check.softErrorf(obj, UnusedImport, "%q imported and not used", path)
} else {
- check.softErrorf(obj, _UnusedImport, "%q imported but not used as %s", path, obj.name)
+ check.softErrorf(obj, UnusedImport, "%q imported as %s and not used", path, obj.name)
}
}