mirror of https://go.googlesource.com/go
1031 lines
34 KiB
Go
1031 lines
34 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file implements typechecking of call and selector expressions.
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package types
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import (
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"go/ast"
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"go/internal/typeparams"
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"go/token"
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. "internal/types/errors"
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"strings"
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)
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// funcInst type-checks a function instantiation.
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// The incoming x must be a generic function.
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// If ix != nil, it provides some or all of the type arguments (ix.Indices).
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// If target != nil, it may be used to infer missing type arguments of x, if any.
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// At least one of T or ix must be provided.
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//
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// There are two modes of operation:
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//
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// 1. If infer == true, funcInst infers missing type arguments as needed and
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// instantiates the function x. The returned results are nil.
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//
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// 2. If infer == false and inst provides all type arguments, funcInst
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// instantiates the function x. The returned results are nil.
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// If inst doesn't provide enough type arguments, funcInst returns the
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// available arguments and the corresponding expression list; x remains
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// unchanged.
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//
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// If an error (other than a version error) occurs in any case, it is reported
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// and x.mode is set to invalid.
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func (check *Checker) funcInst(T *target, pos token.Pos, x *operand, ix *typeparams.IndexExpr, infer bool) ([]Type, []ast.Expr) {
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assert(T != nil || ix != nil)
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var instErrPos positioner
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if ix != nil {
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instErrPos = inNode(ix.Orig, ix.Lbrack)
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x.expr = ix.Orig // if we don't have an index expression, keep the existing expression of x
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} else {
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instErrPos = atPos(pos)
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}
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versionErr := !check.verifyVersionf(instErrPos, go1_18, "function instantiation")
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// targs and xlist are the type arguments and corresponding type expressions, or nil.
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var targs []Type
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var xlist []ast.Expr
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if ix != nil {
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xlist = ix.Indices
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targs = check.typeList(xlist)
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if targs == nil {
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x.mode = invalid
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return nil, nil
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}
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assert(len(targs) == len(xlist))
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}
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// Check the number of type arguments (got) vs number of type parameters (want).
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// Note that x is a function value, not a type expression, so we don't need to
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// call under below.
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sig := x.typ.(*Signature)
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got, want := len(targs), sig.TypeParams().Len()
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if got > want {
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// Providing too many type arguments is always an error.
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check.errorf(ix.Indices[got-1], WrongTypeArgCount, "got %d type arguments but want %d", got, want)
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x.mode = invalid
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return nil, nil
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}
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if got < want {
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if !infer {
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return targs, xlist
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}
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// If the uninstantiated or partially instantiated function x is used in
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// an assignment (tsig != nil), infer missing type arguments by treating
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// the assignment
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//
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// var tvar tsig = x
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//
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// like a call g(tvar) of the synthetic generic function g
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//
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// func g[type_parameters_of_x](func_type_of_x)
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//
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var args []*operand
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var params []*Var
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var reverse bool
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if T != nil && sig.tparams != nil {
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if !versionErr && !check.allowVersion(instErrPos, go1_21) {
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if ix != nil {
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check.versionErrorf(instErrPos, go1_21, "partially instantiated function in assignment")
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} else {
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check.versionErrorf(instErrPos, go1_21, "implicitly instantiated function in assignment")
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}
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}
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gsig := NewSignatureType(nil, nil, nil, sig.params, sig.results, sig.variadic)
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params = []*Var{NewVar(x.Pos(), check.pkg, "", gsig)}
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// The type of the argument operand is tsig, which is the type of the LHS in an assignment
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// or the result type in a return statement. Create a pseudo-expression for that operand
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// that makes sense when reported in error messages from infer, below.
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expr := ast.NewIdent(T.desc)
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expr.NamePos = x.Pos() // correct position
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args = []*operand{{mode: value, expr: expr, typ: T.sig}}
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reverse = true
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}
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// Rename type parameters to avoid problems with recursive instantiations.
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// Note that NewTuple(params...) below is (*Tuple)(nil) if len(params) == 0, as desired.
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tparams, params2 := check.renameTParams(pos, sig.TypeParams().list(), NewTuple(params...))
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err := check.newError(CannotInferTypeArgs)
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targs = check.infer(atPos(pos), tparams, targs, params2.(*Tuple), args, reverse, err)
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if targs == nil {
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if !err.empty() {
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err.report()
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}
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x.mode = invalid
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return nil, nil
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}
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got = len(targs)
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}
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assert(got == want)
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// instantiate function signature
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sig = check.instantiateSignature(x.Pos(), x.expr, sig, targs, xlist)
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x.typ = sig
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x.mode = value
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return nil, nil
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}
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func (check *Checker) instantiateSignature(pos token.Pos, expr ast.Expr, typ *Signature, targs []Type, xlist []ast.Expr) (res *Signature) {
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assert(check != nil)
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assert(len(targs) == typ.TypeParams().Len())
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if check.conf._Trace {
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check.trace(pos, "-- instantiating signature %s with %s", typ, targs)
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check.indent++
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defer func() {
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check.indent--
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check.trace(pos, "=> %s (under = %s)", res, res.Underlying())
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}()
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}
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inst := check.instance(pos, typ, targs, nil, check.context()).(*Signature)
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assert(inst.TypeParams().Len() == 0) // signature is not generic anymore
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check.recordInstance(expr, targs, inst)
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assert(len(xlist) <= len(targs))
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// verify instantiation lazily (was go.dev/issue/50450)
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check.later(func() {
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tparams := typ.TypeParams().list()
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if i, err := check.verify(pos, tparams, targs, check.context()); err != nil {
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// best position for error reporting
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pos := pos
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if i < len(xlist) {
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pos = xlist[i].Pos()
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}
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check.softErrorf(atPos(pos), InvalidTypeArg, "%s", err)
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} else {
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check.mono.recordInstance(check.pkg, pos, tparams, targs, xlist)
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}
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}).describef(atPos(pos), "verify instantiation")
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return inst
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}
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func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
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ix := typeparams.UnpackIndexExpr(call.Fun)
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if ix != nil {
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if check.indexExpr(x, ix) {
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// Delay function instantiation to argument checking,
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// where we combine type and value arguments for type
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// inference.
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assert(x.mode == value)
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} else {
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ix = nil
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}
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x.expr = call.Fun
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check.record(x)
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} else {
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check.exprOrType(x, call.Fun, true)
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}
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// x.typ may be generic
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switch x.mode {
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case invalid:
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check.use(call.Args...)
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x.expr = call
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return statement
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case typexpr:
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// conversion
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check.nonGeneric(nil, x)
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if x.mode == invalid {
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return conversion
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}
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T := x.typ
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x.mode = invalid
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switch n := len(call.Args); n {
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case 0:
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check.errorf(inNode(call, call.Rparen), WrongArgCount, "missing argument in conversion to %s", T)
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case 1:
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check.expr(nil, x, call.Args[0])
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if x.mode != invalid {
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if hasDots(call) {
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check.errorf(call.Args[0], BadDotDotDotSyntax, "invalid use of ... in conversion to %s", T)
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break
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}
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if t, _ := under(T).(*Interface); t != nil && !isTypeParam(T) {
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if !t.IsMethodSet() {
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check.errorf(call, MisplacedConstraintIface, "cannot use interface %s in conversion (contains specific type constraints or is comparable)", T)
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break
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}
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}
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check.conversion(x, T)
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}
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default:
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check.use(call.Args...)
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check.errorf(call.Args[n-1], WrongArgCount, "too many arguments in conversion to %s", T)
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}
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x.expr = call
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return conversion
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case builtin:
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// no need to check for non-genericity here
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id := x.id
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if !check.builtin(x, call, id) {
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x.mode = invalid
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}
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x.expr = call
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// a non-constant result implies a function call
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if x.mode != invalid && x.mode != constant_ {
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check.hasCallOrRecv = true
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}
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return predeclaredFuncs[id].kind
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}
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// ordinary function/method call
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// signature may be generic
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cgocall := x.mode == cgofunc
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// a type parameter may be "called" if all types have the same signature
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sig, _ := coreType(x.typ).(*Signature)
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if sig == nil {
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check.errorf(x, InvalidCall, invalidOp+"cannot call non-function %s", x)
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x.mode = invalid
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x.expr = call
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return statement
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}
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// Capture wasGeneric before sig is potentially instantiated below.
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wasGeneric := sig.TypeParams().Len() > 0
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// evaluate type arguments, if any
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var xlist []ast.Expr
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var targs []Type
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if ix != nil {
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xlist = ix.Indices
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targs = check.typeList(xlist)
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if targs == nil {
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check.use(call.Args...)
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x.mode = invalid
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x.expr = call
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return statement
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}
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assert(len(targs) == len(xlist))
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// check number of type arguments (got) vs number of type parameters (want)
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got, want := len(targs), sig.TypeParams().Len()
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if got > want {
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check.errorf(xlist[want], WrongTypeArgCount, "got %d type arguments but want %d", got, want)
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check.use(call.Args...)
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x.mode = invalid
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x.expr = call
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return statement
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}
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// If sig is generic and all type arguments are provided, preempt function
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// argument type inference by explicitly instantiating the signature. This
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// ensures that we record accurate type information for sig, even if there
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// is an error checking its arguments (for example, if an incorrect number
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// of arguments is supplied).
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if got == want && want > 0 {
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check.verifyVersionf(atPos(ix.Lbrack), go1_18, "function instantiation")
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sig = check.instantiateSignature(ix.Pos(), ix.Orig, sig, targs, xlist)
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// targs have been consumed; proceed with checking arguments of the
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// non-generic signature.
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targs = nil
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xlist = nil
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}
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}
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// evaluate arguments
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args, atargs, atxlist := check.genericExprList(call.Args)
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sig = check.arguments(call, sig, targs, xlist, args, atargs, atxlist)
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if wasGeneric && sig.TypeParams().Len() == 0 {
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// Update the recorded type of call.Fun to its instantiated type.
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check.recordTypeAndValue(call.Fun, value, sig, nil)
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}
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// determine result
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switch sig.results.Len() {
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case 0:
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x.mode = novalue
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case 1:
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if cgocall {
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x.mode = commaerr
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} else {
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x.mode = value
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}
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x.typ = sig.results.vars[0].typ // unpack tuple
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default:
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x.mode = value
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x.typ = sig.results
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}
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x.expr = call
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check.hasCallOrRecv = true
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// if type inference failed, a parameterized result must be invalidated
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// (operands cannot have a parameterized type)
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if x.mode == value && sig.TypeParams().Len() > 0 && isParameterized(sig.TypeParams().list(), x.typ) {
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x.mode = invalid
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}
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return statement
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}
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// exprList evaluates a list of expressions and returns the corresponding operands.
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// A single-element expression list may evaluate to multiple operands.
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func (check *Checker) exprList(elist []ast.Expr) (xlist []*operand) {
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if n := len(elist); n == 1 {
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xlist, _ = check.multiExpr(elist[0], false)
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} else if n > 1 {
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// multiple (possibly invalid) values
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xlist = make([]*operand, n)
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for i, e := range elist {
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var x operand
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check.expr(nil, &x, e)
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xlist[i] = &x
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}
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}
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return
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}
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// genericExprList is like exprList but result operands may be uninstantiated or partially
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// instantiated generic functions (where constraint information is insufficient to infer
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// the missing type arguments) for Go 1.21 and later.
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// For each non-generic or uninstantiated generic operand, the corresponding targsList and
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// xlistList elements do not exist (targsList and xlistList are nil) or the elements are nil.
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// For each partially instantiated generic function operand, the corresponding targsList and
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// xlistList elements are the operand's partial type arguments and type expression lists.
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func (check *Checker) genericExprList(elist []ast.Expr) (resList []*operand, targsList [][]Type, xlistList [][]ast.Expr) {
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if debug {
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defer func() {
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// targsList and xlistList must have matching lengths
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assert(len(targsList) == len(xlistList))
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// type arguments must only exist for partially instantiated functions
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for i, x := range resList {
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if i < len(targsList) {
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if n := len(targsList[i]); n > 0 {
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// x must be a partially instantiated function
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assert(n < x.typ.(*Signature).TypeParams().Len())
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}
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}
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}
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}()
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}
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// Before Go 1.21, uninstantiated or partially instantiated argument functions are
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// nor permitted. Checker.funcInst must infer missing type arguments in that case.
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infer := true // for -lang < go1.21
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n := len(elist)
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if n > 0 && check.allowVersion(elist[0], go1_21) {
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infer = false
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}
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if n == 1 {
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// single value (possibly a partially instantiated function), or a multi-valued expression
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e := elist[0]
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var x operand
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if ix := typeparams.UnpackIndexExpr(e); ix != nil && check.indexExpr(&x, ix) {
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// x is a generic function.
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targs, xlist := check.funcInst(nil, x.Pos(), &x, ix, infer)
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if targs != nil {
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// x was not instantiated: collect the (partial) type arguments.
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targsList = [][]Type{targs}
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xlistList = [][]ast.Expr{xlist}
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// Update x.expr so that we can record the partially instantiated function.
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x.expr = ix.Orig
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} else {
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// x was instantiated: we must record it here because we didn't
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// use the usual expression evaluators.
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check.record(&x)
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}
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resList = []*operand{&x}
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} else {
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// x is not a function instantiation (it may still be a generic function).
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check.rawExpr(nil, &x, e, nil, true)
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check.exclude(&x, 1<<novalue|1<<builtin|1<<typexpr)
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if t, ok := x.typ.(*Tuple); ok && x.mode != invalid {
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// x is a function call returning multiple values; it cannot be generic.
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resList = make([]*operand, t.Len())
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for i, v := range t.vars {
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resList[i] = &operand{mode: value, expr: e, typ: v.typ}
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}
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} else {
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// x is exactly one value (possibly invalid or uninstantiated generic function).
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resList = []*operand{&x}
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}
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}
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} else if n > 1 {
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// multiple values
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resList = make([]*operand, n)
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targsList = make([][]Type, n)
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xlistList = make([][]ast.Expr, n)
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for i, e := range elist {
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var x operand
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if ix := typeparams.UnpackIndexExpr(e); ix != nil && check.indexExpr(&x, ix) {
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// x is a generic function.
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targs, xlist := check.funcInst(nil, x.Pos(), &x, ix, infer)
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if targs != nil {
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// x was not instantiated: collect the (partial) type arguments.
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targsList[i] = targs
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xlistList[i] = xlist
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// Update x.expr so that we can record the partially instantiated function.
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x.expr = ix.Orig
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} else {
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// x was instantiated: we must record it here because we didn't
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// use the usual expression evaluators.
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check.record(&x)
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}
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} else {
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// x is exactly one value (possibly invalid or uninstantiated generic function).
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check.genericExpr(&x, e)
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}
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resList[i] = &x
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}
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}
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return
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}
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// arguments type-checks arguments passed to a function call with the given signature.
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// The function and its arguments may be generic, and possibly partially instantiated.
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// targs and xlist are the function's type arguments (and corresponding expressions).
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// args are the function arguments. If an argument args[i] is a partially instantiated
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// generic function, atargs[i] and atxlist[i] are the corresponding type arguments
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// (and corresponding expressions).
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// If the callee is variadic, arguments adjusts its signature to match the provided
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// arguments. The type parameters and arguments of the callee and all its arguments
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// are used together to infer any missing type arguments, and the callee and argument
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// functions are instantiated as necessary.
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// The result signature is the (possibly adjusted and instantiated) function signature.
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// If an error occurred, the result signature is the incoming sig.
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func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type, xlist []ast.Expr, args []*operand, atargs [][]Type, atxlist [][]ast.Expr) (rsig *Signature) {
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rsig = sig
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// Function call argument/parameter count requirements
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//
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// | standard call | dotdotdot call |
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// --------------+------------------+----------------+
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// standard func | nargs == npars | invalid |
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// --------------+------------------+----------------+
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// variadic func | nargs >= npars-1 | nargs == npars |
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// --------------+------------------+----------------+
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nargs := len(args)
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npars := sig.params.Len()
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ddd := hasDots(call)
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// set up parameters
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sigParams := sig.params // adjusted for variadic functions (may be nil for empty parameter lists!)
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adjusted := false // indicates if sigParams is different from sig.params
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if sig.variadic {
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if ddd {
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// variadic_func(a, b, c...)
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if len(call.Args) == 1 && nargs > 1 {
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// f()... is not permitted if f() is multi-valued
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check.errorf(inNode(call, call.Ellipsis), InvalidDotDotDot, "cannot use ... with %d-valued %s", nargs, call.Args[0])
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return
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}
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} else {
|
|
// variadic_func(a, b, c)
|
|
if nargs >= npars-1 {
|
|
// Create custom parameters for arguments: keep
|
|
// the first npars-1 parameters and add one for
|
|
// each argument mapping to the ... parameter.
|
|
vars := make([]*Var, npars-1) // npars > 0 for variadic functions
|
|
copy(vars, sig.params.vars)
|
|
last := sig.params.vars[npars-1]
|
|
typ := last.typ.(*Slice).elem
|
|
for len(vars) < nargs {
|
|
vars = append(vars, NewParam(last.pos, last.pkg, last.name, typ))
|
|
}
|
|
sigParams = NewTuple(vars...) // possibly nil!
|
|
adjusted = true
|
|
npars = nargs
|
|
} else {
|
|
// nargs < npars-1
|
|
npars-- // for correct error message below
|
|
}
|
|
}
|
|
} else {
|
|
if ddd {
|
|
// standard_func(a, b, c...)
|
|
check.errorf(inNode(call, call.Ellipsis), NonVariadicDotDotDot, "cannot use ... in call to non-variadic %s", call.Fun)
|
|
return
|
|
}
|
|
// standard_func(a, b, c)
|
|
}
|
|
|
|
// check argument count
|
|
if nargs != npars {
|
|
var at positioner = call
|
|
qualifier := "not enough"
|
|
if nargs > npars {
|
|
at = args[npars].expr // report at first extra argument
|
|
qualifier = "too many"
|
|
} else {
|
|
at = atPos(call.Rparen) // report at closing )
|
|
}
|
|
// take care of empty parameter lists represented by nil tuples
|
|
var params []*Var
|
|
if sig.params != nil {
|
|
params = sig.params.vars
|
|
}
|
|
err := check.newError(WrongArgCount)
|
|
err.addf(at, "%s arguments in call to %s", qualifier, call.Fun)
|
|
err.addf(noposn, "have %s", check.typesSummary(operandTypes(args), false))
|
|
err.addf(noposn, "want %s", check.typesSummary(varTypes(params), sig.variadic))
|
|
err.report()
|
|
return
|
|
}
|
|
|
|
// collect type parameters of callee and generic function arguments
|
|
var tparams []*TypeParam
|
|
|
|
// collect type parameters of callee
|
|
n := sig.TypeParams().Len()
|
|
if n > 0 {
|
|
if !check.allowVersion(call, go1_18) {
|
|
switch call.Fun.(type) {
|
|
case *ast.IndexExpr, *ast.IndexListExpr:
|
|
ix := typeparams.UnpackIndexExpr(call.Fun)
|
|
check.versionErrorf(inNode(call.Fun, ix.Lbrack), go1_18, "function instantiation")
|
|
default:
|
|
check.versionErrorf(inNode(call, call.Lparen), go1_18, "implicit function instantiation")
|
|
}
|
|
}
|
|
// rename type parameters to avoid problems with recursive calls
|
|
var tmp Type
|
|
tparams, tmp = check.renameTParams(call.Pos(), sig.TypeParams().list(), sigParams)
|
|
sigParams = tmp.(*Tuple)
|
|
// make sure targs and tparams have the same length
|
|
for len(targs) < len(tparams) {
|
|
targs = append(targs, nil)
|
|
}
|
|
}
|
|
assert(len(tparams) == len(targs))
|
|
|
|
// collect type parameters from generic function arguments
|
|
var genericArgs []int // indices of generic function arguments
|
|
if enableReverseTypeInference {
|
|
for i, arg := range args {
|
|
// generic arguments cannot have a defined (*Named) type - no need for underlying type below
|
|
if asig, _ := arg.typ.(*Signature); asig != nil && asig.TypeParams().Len() > 0 {
|
|
// The argument type is a generic function signature. This type is
|
|
// pointer-identical with (it's copied from) the type of the generic
|
|
// function argument and thus the function object.
|
|
// Before we change the type (type parameter renaming, below), make
|
|
// a clone of it as otherwise we implicitly modify the object's type
|
|
// (go.dev/issues/63260).
|
|
asig = clone(asig)
|
|
// Rename type parameters for cases like f(g, g); this gives each
|
|
// generic function argument a unique type identity (go.dev/issues/59956).
|
|
// TODO(gri) Consider only doing this if a function argument appears
|
|
// multiple times, which is rare (possible optimization).
|
|
atparams, tmp := check.renameTParams(call.Pos(), asig.TypeParams().list(), asig)
|
|
asig = tmp.(*Signature)
|
|
asig.tparams = &TypeParamList{atparams} // renameTParams doesn't touch associated type parameters
|
|
arg.typ = asig // new type identity for the function argument
|
|
tparams = append(tparams, atparams...)
|
|
// add partial list of type arguments, if any
|
|
if i < len(atargs) {
|
|
targs = append(targs, atargs[i]...)
|
|
}
|
|
// make sure targs and tparams have the same length
|
|
for len(targs) < len(tparams) {
|
|
targs = append(targs, nil)
|
|
}
|
|
genericArgs = append(genericArgs, i)
|
|
}
|
|
}
|
|
}
|
|
assert(len(tparams) == len(targs))
|
|
|
|
// at the moment we only support implicit instantiations of argument functions
|
|
_ = len(genericArgs) > 0 && check.verifyVersionf(args[genericArgs[0]], go1_21, "implicitly instantiated function as argument")
|
|
|
|
// tparams holds the type parameters of the callee and generic function arguments, if any:
|
|
// the first n type parameters belong to the callee, followed by mi type parameters for each
|
|
// of the generic function arguments, where mi = args[i].typ.(*Signature).TypeParams().Len().
|
|
|
|
// infer missing type arguments of callee and function arguments
|
|
if len(tparams) > 0 {
|
|
err := check.newError(CannotInferTypeArgs)
|
|
targs = check.infer(call, tparams, targs, sigParams, args, false, err)
|
|
if targs == nil {
|
|
// TODO(gri) If infer inferred the first targs[:n], consider instantiating
|
|
// the call signature for better error messages/gopls behavior.
|
|
// Perhaps instantiate as much as we can, also for arguments.
|
|
// This will require changes to how infer returns its results.
|
|
if !err.empty() {
|
|
check.errorf(err.posn(), CannotInferTypeArgs, "in call to %s, %s", call.Fun, err.msg())
|
|
}
|
|
return
|
|
}
|
|
|
|
// update result signature: instantiate if needed
|
|
if n > 0 {
|
|
rsig = check.instantiateSignature(call.Pos(), call.Fun, sig, targs[:n], xlist)
|
|
// If the callee's parameter list was adjusted we need to update (instantiate)
|
|
// it separately. Otherwise we can simply use the result signature's parameter
|
|
// list.
|
|
if adjusted {
|
|
sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(tparams[:n], targs[:n]), nil, check.context()).(*Tuple)
|
|
} else {
|
|
sigParams = rsig.params
|
|
}
|
|
}
|
|
|
|
// compute argument signatures: instantiate if needed
|
|
j := n
|
|
for _, i := range genericArgs {
|
|
arg := args[i]
|
|
asig := arg.typ.(*Signature)
|
|
k := j + asig.TypeParams().Len()
|
|
// targs[j:k] are the inferred type arguments for asig
|
|
arg.typ = check.instantiateSignature(call.Pos(), arg.expr, asig, targs[j:k], nil) // TODO(gri) provide xlist if possible (partial instantiations)
|
|
check.record(arg) // record here because we didn't use the usual expr evaluators
|
|
j = k
|
|
}
|
|
}
|
|
|
|
// check arguments
|
|
if len(args) > 0 {
|
|
context := check.sprintf("argument to %s", call.Fun)
|
|
for i, a := range args {
|
|
check.assignment(a, sigParams.vars[i].typ, context)
|
|
}
|
|
}
|
|
|
|
return
|
|
}
|
|
|
|
var cgoPrefixes = [...]string{
|
|
"_Ciconst_",
|
|
"_Cfconst_",
|
|
"_Csconst_",
|
|
"_Ctype_",
|
|
"_Cvar_", // actually a pointer to the var
|
|
"_Cfpvar_fp_",
|
|
"_Cfunc_",
|
|
"_Cmacro_", // function to evaluate the expanded expression
|
|
}
|
|
|
|
func (check *Checker) selector(x *operand, e *ast.SelectorExpr, def *TypeName, wantType bool) {
|
|
// these must be declared before the "goto Error" statements
|
|
var (
|
|
obj Object
|
|
index []int
|
|
indirect bool
|
|
)
|
|
|
|
sel := e.Sel.Name
|
|
// If the identifier refers to a package, handle everything here
|
|
// so we don't need a "package" mode for operands: package names
|
|
// can only appear in qualified identifiers which are mapped to
|
|
// selector expressions.
|
|
if ident, ok := e.X.(*ast.Ident); ok {
|
|
obj := check.lookup(ident.Name)
|
|
if pname, _ := obj.(*PkgName); pname != nil {
|
|
assert(pname.pkg == check.pkg)
|
|
check.recordUse(ident, pname)
|
|
pname.used = true
|
|
pkg := pname.imported
|
|
|
|
var exp Object
|
|
funcMode := value
|
|
if pkg.cgo {
|
|
// cgo special cases C.malloc: it's
|
|
// rewritten to _CMalloc and does not
|
|
// support two-result calls.
|
|
if sel == "malloc" {
|
|
sel = "_CMalloc"
|
|
} else {
|
|
funcMode = cgofunc
|
|
}
|
|
for _, prefix := range cgoPrefixes {
|
|
// cgo objects are part of the current package (in file
|
|
// _cgo_gotypes.go). Use regular lookup.
|
|
_, exp = check.scope.LookupParent(prefix+sel, check.pos)
|
|
if exp != nil {
|
|
break
|
|
}
|
|
}
|
|
if exp == nil {
|
|
check.errorf(e.Sel, UndeclaredImportedName, "undefined: %s", ast.Expr(e)) // cast to ast.Expr to silence vet
|
|
goto Error
|
|
}
|
|
check.objDecl(exp, nil)
|
|
} else {
|
|
exp = pkg.scope.Lookup(sel)
|
|
if exp == nil {
|
|
if !pkg.fake {
|
|
check.errorf(e.Sel, UndeclaredImportedName, "undefined: %s", ast.Expr(e))
|
|
}
|
|
goto Error
|
|
}
|
|
if !exp.Exported() {
|
|
check.errorf(e.Sel, UnexportedName, "name %s not exported by package %s", sel, pkg.name)
|
|
// ok to continue
|
|
}
|
|
}
|
|
check.recordUse(e.Sel, exp)
|
|
|
|
// Simplified version of the code for *ast.Idents:
|
|
// - imported objects are always fully initialized
|
|
switch exp := exp.(type) {
|
|
case *Const:
|
|
assert(exp.Val() != nil)
|
|
x.mode = constant_
|
|
x.typ = exp.typ
|
|
x.val = exp.val
|
|
case *TypeName:
|
|
x.mode = typexpr
|
|
x.typ = exp.typ
|
|
case *Var:
|
|
x.mode = variable
|
|
x.typ = exp.typ
|
|
if pkg.cgo && strings.HasPrefix(exp.name, "_Cvar_") {
|
|
x.typ = x.typ.(*Pointer).base
|
|
}
|
|
case *Func:
|
|
x.mode = funcMode
|
|
x.typ = exp.typ
|
|
if pkg.cgo && strings.HasPrefix(exp.name, "_Cmacro_") {
|
|
x.mode = value
|
|
x.typ = x.typ.(*Signature).results.vars[0].typ
|
|
}
|
|
case *Builtin:
|
|
x.mode = builtin
|
|
x.typ = exp.typ
|
|
x.id = exp.id
|
|
default:
|
|
check.dump("%v: unexpected object %v", e.Sel.Pos(), exp)
|
|
panic("unreachable")
|
|
}
|
|
x.expr = e
|
|
return
|
|
}
|
|
}
|
|
|
|
check.exprOrType(x, e.X, false)
|
|
switch x.mode {
|
|
case typexpr:
|
|
// don't crash for "type T T.x" (was go.dev/issue/51509)
|
|
if def != nil && def.typ == x.typ {
|
|
check.cycleError([]Object{def}, 0)
|
|
goto Error
|
|
}
|
|
case builtin:
|
|
// types2 uses the position of '.' for the error
|
|
check.errorf(e.Sel, UncalledBuiltin, "cannot select on %s", x)
|
|
goto Error
|
|
case invalid:
|
|
goto Error
|
|
}
|
|
|
|
// Avoid crashing when checking an invalid selector in a method declaration
|
|
// (i.e., where def is not set):
|
|
//
|
|
// type S[T any] struct{}
|
|
// type V = S[any]
|
|
// func (fs *S[T]) M(x V.M) {}
|
|
//
|
|
// All codepaths below return a non-type expression. If we get here while
|
|
// expecting a type expression, it is an error.
|
|
//
|
|
// See go.dev/issue/57522 for more details.
|
|
//
|
|
// TODO(rfindley): We should do better by refusing to check selectors in all cases where
|
|
// x.typ is incomplete.
|
|
if wantType {
|
|
check.errorf(e.Sel, NotAType, "%s is not a type", ast.Expr(e))
|
|
goto Error
|
|
}
|
|
|
|
obj, index, indirect = lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel, false)
|
|
if obj == nil {
|
|
// Don't report another error if the underlying type was invalid (go.dev/issue/49541).
|
|
if !isValid(under(x.typ)) {
|
|
goto Error
|
|
}
|
|
|
|
if index != nil {
|
|
// TODO(gri) should provide actual type where the conflict happens
|
|
check.errorf(e.Sel, AmbiguousSelector, "ambiguous selector %s.%s", x.expr, sel)
|
|
goto Error
|
|
}
|
|
|
|
if indirect {
|
|
if x.mode == typexpr {
|
|
check.errorf(e.Sel, InvalidMethodExpr, "invalid method expression %s.%s (needs pointer receiver (*%s).%s)", x.typ, sel, x.typ, sel)
|
|
} else {
|
|
check.errorf(e.Sel, InvalidMethodExpr, "cannot call pointer method %s on %s", sel, x.typ)
|
|
}
|
|
goto Error
|
|
}
|
|
|
|
var why string
|
|
if isInterfacePtr(x.typ) {
|
|
why = check.interfacePtrError(x.typ)
|
|
} else {
|
|
alt, _, _ := lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel, true)
|
|
why = check.lookupError(x.typ, sel, alt, false)
|
|
}
|
|
check.errorf(e.Sel, MissingFieldOrMethod, "%s.%s undefined (%s)", x.expr, sel, why)
|
|
goto Error
|
|
}
|
|
|
|
// methods may not have a fully set up signature yet
|
|
if m, _ := obj.(*Func); m != nil {
|
|
check.objDecl(m, nil)
|
|
}
|
|
|
|
if x.mode == typexpr {
|
|
// method expression
|
|
m, _ := obj.(*Func)
|
|
if m == nil {
|
|
check.errorf(e.Sel, MissingFieldOrMethod, "%s.%s undefined (type %s has no method %s)", x.expr, sel, x.typ, sel)
|
|
goto Error
|
|
}
|
|
|
|
check.recordSelection(e, MethodExpr, x.typ, m, index, indirect)
|
|
|
|
sig := m.typ.(*Signature)
|
|
if sig.recv == nil {
|
|
check.error(e, InvalidDeclCycle, "illegal cycle in method declaration")
|
|
goto Error
|
|
}
|
|
|
|
// the receiver type becomes the type of the first function
|
|
// argument of the method expression's function type
|
|
var params []*Var
|
|
if sig.params != nil {
|
|
params = sig.params.vars
|
|
}
|
|
// Be consistent about named/unnamed parameters. This is not needed
|
|
// for type-checking, but the newly constructed signature may appear
|
|
// in an error message and then have mixed named/unnamed parameters.
|
|
// (An alternative would be to not print parameter names in errors,
|
|
// but it's useful to see them; this is cheap and method expressions
|
|
// are rare.)
|
|
name := ""
|
|
if len(params) > 0 && params[0].name != "" {
|
|
// name needed
|
|
name = sig.recv.name
|
|
if name == "" {
|
|
name = "_"
|
|
}
|
|
}
|
|
params = append([]*Var{NewVar(sig.recv.pos, sig.recv.pkg, name, x.typ)}, params...)
|
|
x.mode = value
|
|
x.typ = &Signature{
|
|
tparams: sig.tparams,
|
|
params: NewTuple(params...),
|
|
results: sig.results,
|
|
variadic: sig.variadic,
|
|
}
|
|
|
|
check.addDeclDep(m)
|
|
|
|
} else {
|
|
// regular selector
|
|
switch obj := obj.(type) {
|
|
case *Var:
|
|
check.recordSelection(e, FieldVal, x.typ, obj, index, indirect)
|
|
if x.mode == variable || indirect {
|
|
x.mode = variable
|
|
} else {
|
|
x.mode = value
|
|
}
|
|
x.typ = obj.typ
|
|
|
|
case *Func:
|
|
// TODO(gri) If we needed to take into account the receiver's
|
|
// addressability, should we report the type &(x.typ) instead?
|
|
check.recordSelection(e, MethodVal, x.typ, obj, index, indirect)
|
|
|
|
// TODO(gri) The verification pass below is disabled for now because
|
|
// method sets don't match method lookup in some cases.
|
|
// For instance, if we made a copy above when creating a
|
|
// custom method for a parameterized received type, the
|
|
// method set method doesn't match (no copy there). There
|
|
/// may be other situations.
|
|
disabled := true
|
|
if !disabled && debug {
|
|
// Verify that LookupFieldOrMethod and MethodSet.Lookup agree.
|
|
// TODO(gri) This only works because we call LookupFieldOrMethod
|
|
// _before_ calling NewMethodSet: LookupFieldOrMethod completes
|
|
// any incomplete interfaces so they are available to NewMethodSet
|
|
// (which assumes that interfaces have been completed already).
|
|
typ := x.typ
|
|
if x.mode == variable {
|
|
// If typ is not an (unnamed) pointer or an interface,
|
|
// use *typ instead, because the method set of *typ
|
|
// includes the methods of typ.
|
|
// Variables are addressable, so we can always take their
|
|
// address.
|
|
if _, ok := typ.(*Pointer); !ok && !IsInterface(typ) {
|
|
typ = &Pointer{base: typ}
|
|
}
|
|
}
|
|
// If we created a synthetic pointer type above, we will throw
|
|
// away the method set computed here after use.
|
|
// TODO(gri) Method set computation should probably always compute
|
|
// both, the value and the pointer receiver method set and represent
|
|
// them in a single structure.
|
|
// TODO(gri) Consider also using a method set cache for the lifetime
|
|
// of checker once we rely on MethodSet lookup instead of individual
|
|
// lookup.
|
|
mset := NewMethodSet(typ)
|
|
if m := mset.Lookup(check.pkg, sel); m == nil || m.obj != obj {
|
|
check.dump("%v: (%s).%v -> %s", e.Pos(), typ, obj.name, m)
|
|
check.dump("%s\n", mset)
|
|
// Caution: MethodSets are supposed to be used externally
|
|
// only (after all interface types were completed). It's
|
|
// now possible that we get here incorrectly. Not urgent
|
|
// to fix since we only run this code in debug mode.
|
|
// TODO(gri) fix this eventually.
|
|
panic("method sets and lookup don't agree")
|
|
}
|
|
}
|
|
|
|
x.mode = value
|
|
|
|
// remove receiver
|
|
sig := *obj.typ.(*Signature)
|
|
sig.recv = nil
|
|
x.typ = &sig
|
|
|
|
check.addDeclDep(obj)
|
|
|
|
default:
|
|
panic("unreachable")
|
|
}
|
|
}
|
|
|
|
// everything went well
|
|
x.expr = e
|
|
return
|
|
|
|
Error:
|
|
x.mode = invalid
|
|
x.expr = e
|
|
}
|
|
|
|
// use type-checks each argument.
|
|
// Useful to make sure expressions are evaluated
|
|
// (and variables are "used") in the presence of
|
|
// other errors. Arguments may be nil.
|
|
// Reports if all arguments evaluated without error.
|
|
func (check *Checker) use(args ...ast.Expr) bool { return check.useN(args, false) }
|
|
|
|
// useLHS is like use, but doesn't "use" top-level identifiers.
|
|
// It should be called instead of use if the arguments are
|
|
// expressions on the lhs of an assignment.
|
|
func (check *Checker) useLHS(args ...ast.Expr) bool { return check.useN(args, true) }
|
|
|
|
func (check *Checker) useN(args []ast.Expr, lhs bool) bool {
|
|
ok := true
|
|
for _, e := range args {
|
|
if !check.use1(e, lhs) {
|
|
ok = false
|
|
}
|
|
}
|
|
return ok
|
|
}
|
|
|
|
func (check *Checker) use1(e ast.Expr, lhs bool) bool {
|
|
var x operand
|
|
x.mode = value // anything but invalid
|
|
switch n := ast.Unparen(e).(type) {
|
|
case nil:
|
|
// nothing to do
|
|
case *ast.Ident:
|
|
// don't report an error evaluating blank
|
|
if n.Name == "_" {
|
|
break
|
|
}
|
|
// If the lhs is an identifier denoting a variable v, this assignment
|
|
// is not a 'use' of v. Remember current value of v.used and restore
|
|
// after evaluating the lhs via check.rawExpr.
|
|
var v *Var
|
|
var v_used bool
|
|
if lhs {
|
|
if _, obj := check.scope.LookupParent(n.Name, nopos); obj != nil {
|
|
// It's ok to mark non-local variables, but ignore variables
|
|
// from other packages to avoid potential race conditions with
|
|
// dot-imported variables.
|
|
if w, _ := obj.(*Var); w != nil && w.pkg == check.pkg {
|
|
v = w
|
|
v_used = v.used
|
|
}
|
|
}
|
|
}
|
|
check.exprOrType(&x, n, true)
|
|
if v != nil {
|
|
v.used = v_used // restore v.used
|
|
}
|
|
default:
|
|
check.rawExpr(nil, &x, e, nil, true)
|
|
}
|
|
return x.mode != invalid
|
|
}
|