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[dev.typeparams] go/types: use a new ast.ListExpr for multi-type instances

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Modify go/parser to consistently represent type instantiation as an
ast.IndexExpr, rather than use an ast.CallExpr (with Brackets:true) for
instantiations with multiple type parameters. To enable this, introduce
a new ast expr type: ListExpr.

This brings go/types in line with types2, with the exception of a small
change to funcInst to eliminate redundant errors if values are
erroneously used as types. In a subsequent CL, call.go and expr.go will
be marked as reviewed.

This also catches some type instance syntax using '()' that was
previously accepted incorrectly. Tests are updated accordingly.

Change-Id: I30cd0181c7608f1be7486a9a8b63df993b412e85
Reviewed-on: https://go-review.googlesource.com/c/go/+/293010
Trust: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Rob Findley 2021-02-16 19:56:38 -05:00 committed by Robert Findley
parent 7b679617f3
commit 5ecb9a7887
14 changed files with 233 additions and 226 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
src/go/ast/ast.go
View File

@ -372,9 +372,13 @@ type (
Args []Expr // function arguments; or nil
Ellipsis token.Pos // position of "..." (token.NoPos if there is no "...")
Rparen token.Pos // position of ")"
// TODO(rFindley) use a new ListExpr type rather than overloading CallExpr
// via Brackets, as is done in the syntax package
Brackets bool // if set, "[" and "]" are used instead of "(" and ")"
}
// A ListExpr node represents a list of expressions separated by commas.
// ListExpr nodes are used as index in IndexExpr nodes representing type
// or function instantiations with more than one type argument.
ListExpr struct {
ElemList []Expr
}
// A StarExpr node represents an expression of the form "*" Expression.
@ -493,12 +497,18 @@ func (x *IndexExpr) Pos() token.Pos { return x.X.Pos() }
func (x *SliceExpr) Pos() token.Pos { return x.X.Pos() }
func (x *TypeAssertExpr) Pos() token.Pos { return x.X.Pos() }
func (x *CallExpr) Pos() token.Pos { return x.Fun.Pos() }
func (x *StarExpr) Pos() token.Pos { return x.Star }
func (x *UnaryExpr) Pos() token.Pos { return x.OpPos }
func (x *BinaryExpr) Pos() token.Pos { return x.X.Pos() }
func (x *KeyValueExpr) Pos() token.Pos { return x.Key.Pos() }
func (x *ArrayType) Pos() token.Pos { return x.Lbrack }
func (x *StructType) Pos() token.Pos { return x.Struct }
func (x *ListExpr) Pos() token.Pos {
if len(x.ElemList) > 0 {
return x.ElemList[0].Pos()
}
return token.NoPos
}
func (x *StarExpr) Pos() token.Pos { return x.Star }
func (x *UnaryExpr) Pos() token.Pos { return x.OpPos }
func (x *BinaryExpr) Pos() token.Pos { return x.X.Pos() }
func (x *KeyValueExpr) Pos() token.Pos { return x.Key.Pos() }
func (x *ArrayType) Pos() token.Pos { return x.Lbrack }
func (x *StructType) Pos() token.Pos { return x.Struct }
func (x *FuncType) Pos() token.Pos {
if x.Func.IsValid() || x.Params == nil { // see issue 3870
return x.Func
@ -526,12 +536,18 @@ func (x *IndexExpr) End() token.Pos { return x.Rbrack + 1 }
func (x *SliceExpr) End() token.Pos { return x.Rbrack + 1 }
func (x *TypeAssertExpr) End() token.Pos { return x.Rparen + 1 }
func (x *CallExpr) End() token.Pos { return x.Rparen + 1 }
func (x *StarExpr) End() token.Pos { return x.X.End() }
func (x *UnaryExpr) End() token.Pos { return x.X.End() }
func (x *BinaryExpr) End() token.Pos { return x.Y.End() }
func (x *KeyValueExpr) End() token.Pos { return x.Value.End() }
func (x *ArrayType) End() token.Pos { return x.Elt.End() }
func (x *StructType) End() token.Pos { return x.Fields.End() }
func (x *ListExpr) End() token.Pos {
if len(x.ElemList) > 0 {
return x.ElemList[len(x.ElemList)-1].End()
}
return token.NoPos
}
func (x *StarExpr) End() token.Pos { return x.X.End() }
func (x *UnaryExpr) End() token.Pos { return x.X.End() }
func (x *BinaryExpr) End() token.Pos { return x.Y.End() }
func (x *KeyValueExpr) End() token.Pos { return x.Value.End() }
func (x *ArrayType) End() token.Pos { return x.Elt.End() }
func (x *StructType) End() token.Pos { return x.Fields.End() }
func (x *FuncType) End() token.Pos {
if x.Results != nil {
return x.Results.End()
@ -557,6 +573,7 @@ func (*IndexExpr) exprNode() {}
func (*SliceExpr) exprNode() {}
func (*TypeAssertExpr) exprNode() {}
func (*CallExpr) exprNode() {}
func (*ListExpr) exprNode() {}
func (*StarExpr) exprNode() {}
func (*UnaryExpr) exprNode() {}
func (*BinaryExpr) exprNode() {}

33
src/go/ast/example_test.go
View File

@ -119,23 +119,22 @@ func main() {
// 40 . . . . . . . }
// 41 . . . . . . . Ellipsis: -
// 42 . . . . . . . Rparen: 4:25
// 43 . . . . . . . Brackets: false
// 44 . . . . . . }
// 45 . . . . . }
// 46 . . . . }
// 47 . . . . Rbrace: 5:1
// 48 . . . }
// 49 . . }
// 50 . }
// 51 . Scope: *ast.Scope {
// 52 . . Objects: map[string]*ast.Object (len = 1) {
// 53 . . . "main": *(obj @ 11)
// 54 . . }
// 55 . }
// 56 . Unresolved: []*ast.Ident (len = 1) {
// 57 . . 0: *(obj @ 29)
// 58 . }
// 59 }
// 43 . . . . . . }
// 44 . . . . . }
// 45 . . . . }
// 46 . . . . Rbrace: 5:1
// 47 . . . }
// 48 . . }
// 49 . }
// 50 . Scope: *ast.Scope {
// 51 . . Objects: map[string]*ast.Object (len = 1) {
// 52 . . . "main": *(obj @ 11)
// 53 . . }
// 54 . }
// 55 . Unresolved: []*ast.Ident (len = 1) {
// 56 . . 0: *(obj @ 29)
// 57 . }
// 58 }
}
// This example illustrates how to remove a variable declaration

15
src/go/parser/parser.go
View File

@ -754,7 +754,7 @@ func (p *parser) parseArrayFieldOrTypeInstance(x *ast.Ident) (*ast.Ident, ast.Ex
}
// x[P], x[P1, P2], ...
return nil, &ast.CallExpr{Fun: x, Lparen: lbrack, Args: args, Rparen: rbrack, Brackets: true}
return nil, &ast.IndexExpr{X: x, Lbrack: lbrack, Index: &ast.ListExpr{ElemList: args}, Rbrack: rbrack}
}
func (p *parser) parseFieldDecl(scope *ast.Scope) *ast.Field {
@ -1153,7 +1153,7 @@ func (p *parser) parseMethodSpec(scope *ast.Scope) *ast.Field {
p.exprLev--
}
rbrack := p.expectClosing(token.RBRACK, "type argument list")
typ = &ast.CallExpr{Fun: ident, Lparen: lbrack, Args: list, Rparen: rbrack, Brackets: true}
typ = &ast.IndexExpr{X: ident, Lbrack: lbrack, Index: &ast.ListExpr{ElemList: list}, Rbrack: rbrack}
}
case p.tok == token.LPAREN:
// ordinary method
@ -1281,7 +1281,7 @@ func (p *parser) parseTypeInstance(typ ast.Expr) ast.Expr {
closing := p.expectClosing(token.RBRACK, "type argument list")
return &ast.CallExpr{Fun: typ, Lparen: opening, Args: list, Rparen: closing, Brackets: true}
return &ast.IndexExpr{X: typ, Lbrack: opening, Index: &ast.ListExpr{ElemList: list}, Rbrack: closing}
}
// If the result is an identifier, it is not resolved.
@ -1557,7 +1557,7 @@ func (p *parser) parseIndexOrSliceOrInstance(x ast.Expr) ast.Expr {
}
// instance expression
return &ast.CallExpr{Fun: x, Lparen: lbrack, Args: args, Rparen: rbrack, Brackets: true}
return &ast.IndexExpr{X: x, Lbrack: lbrack, Index: &ast.ListExpr{ElemList: args}, Rbrack: rbrack}
}
func (p *parser) parseCallOrConversion(fun ast.Expr) *ast.CallExpr {
@ -1773,17 +1773,12 @@ func (p *parser) parsePrimaryExpr(lhs bool) (x ast.Expr) {
// type; accept it but complain if we have a complit
t := unparen(x)
// determine if '{' belongs to a composite literal or a block statement
switch t := t.(type) {
switch t.(type) {
case *ast.BadExpr, *ast.Ident, *ast.SelectorExpr:
if p.exprLev < 0 {
return
}
// x is possibly a composite literal type
case *ast.CallExpr:
if !t.Brackets || p.exprLev < 0 {
return
}
// x is possibly a composite literal type
case *ast.IndexExpr:
if p.exprLev < 0 {
return

45
src/go/printer/nodes.go
View File

@ -870,7 +870,11 @@ func (p *printer) expr1(expr ast.Expr, prec1, depth int) {
// TODO(gri): should treat[] like parentheses and undo one level of depth
p.expr1(x.X, token.HighestPrec, 1)
p.print(x.Lbrack, token.LBRACK)
p.expr0(x.Index, depth+1)
if e, _ := x.Index.(*ast.ListExpr); e != nil {
p.exprList(x.Lbrack, e.ElemList, depth+1, commaTerm, x.Rbrack, false)
} else {
p.expr0(x.Index, depth+1)
}
p.print(x.Rbrack, token.RBRACK)
case *ast.SliceExpr:
@ -919,32 +923,25 @@ func (p *printer) expr1(expr ast.Expr, prec1, depth int) {
depth++
}
var wasIndented bool
if x.Brackets {
if _, ok := x.Fun.(*ast.FuncType); ok {
// conversions to literal function types require parentheses around the type
p.print(token.LPAREN)
wasIndented = p.possibleSelectorExpr(x.Fun, token.HighestPrec, depth)
p.print(x.Lparen, token.LBRACK)
p.exprList(x.Lparen, x.Args, depth, commaTerm, x.Rparen, false)
p.print(x.Rparen, token.RBRACK)
p.print(token.RPAREN)
} else {
if _, ok := x.Fun.(*ast.FuncType); ok {
// conversions to literal function types require parentheses around the type
p.print(token.LPAREN)
wasIndented = p.possibleSelectorExpr(x.Fun, token.HighestPrec, depth)
p.print(token.RPAREN)
} else {
wasIndented = p.possibleSelectorExpr(x.Fun, token.HighestPrec, depth)
}
p.print(x.Lparen, token.LPAREN)
if x.Ellipsis.IsValid() {
p.exprList(x.Lparen, x.Args, depth, 0, x.Ellipsis, false)
p.print(x.Ellipsis, token.ELLIPSIS)
if x.Rparen.IsValid() && p.lineFor(x.Ellipsis) < p.lineFor(x.Rparen) {
p.print(token.COMMA, formfeed)
}
} else {
p.exprList(x.Lparen, x.Args, depth, commaTerm, x.Rparen, false)
}
p.print(x.Rparen, token.RPAREN)
wasIndented = p.possibleSelectorExpr(x.Fun, token.HighestPrec, depth)
}
p.print(x.Lparen, token.LPAREN)
if x.Ellipsis.IsValid() {
p.exprList(x.Lparen, x.Args, depth, 0, x.Ellipsis, false)
p.print(x.Ellipsis, token.ELLIPSIS)
if x.Rparen.IsValid() && p.lineFor(x.Ellipsis) < p.lineFor(x.Rparen) {
p.print(token.COMMA, formfeed)
}
} else {
p.exprList(x.Lparen, x.Args, depth, commaTerm, x.Rparen, false)
}
p.print(x.Rparen, token.RPAREN)
if wasIndented {
p.print(unindent)
}

4
src/go/types/api_test.go
View File

@ -325,8 +325,8 @@ func TestTypesInfo(t *testing.T) {
{broken + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string][-1]int`},
// parameterized functions
{genericPkg + `p0; func f[T any](T); var _ = f(int)`, `f`, `func[T₁ interface{}](T₁)`},
{genericPkg + `p1; func f[T any](T); var _ = f(int)`, `f(int)`, `func(int)`},
{genericPkg + `p0; func f[T any](T); var _ = f[int]`, `f`, `func[T₁ interface{}](T₁)`},
{genericPkg + `p1; func f[T any](T); var _ = f[int]`, `f[int]`, `func(int)`},
{genericPkg + `p2; func f[T any](T); func _() { f(42) }`, `f`, `func[T₁ interface{}](T₁)`},
{genericPkg + `p3; func f[T any](T); func _() { f(42) }`, `f(42)`, `()`},

14
src/go/types/assignments.go
View File

@ -303,6 +303,20 @@ func (check *Checker) assignVars(lhs, origRHS []ast.Expr) {
}
}
// unpack unpacks an *ast.ListExpr into a list of ast.Expr.
// TODO(gri) Should find a more efficient solution that doesn't
// require introduction of a new slice for simple
// expressions.
func unpackExpr(x ast.Expr) []ast.Expr {
if x, _ := x.(*ast.ListExpr); x != nil {
return x.ElemList
}
if x != nil {
return []ast.Expr{x}
}
return nil
}
func (check *Checker) shortVarDecl(pos positioner, lhs, rhs []ast.Expr) {
top := len(check.delayed)
scope := check.scope

205
src/go/types/call.go
View File

@ -14,25 +14,103 @@ import (
"unicode"
)
// TODO(rFindley) this has diverged a bit from types2. Bring it up to date.
// If call == nil, the "call" was an index expression, and orig is of type *ast.IndexExpr.
func (check *Checker) call(x *operand, call *ast.CallExpr, orig ast.Expr) exprKind {
assert(orig != nil)
if call != nil {
assert(call == orig)
check.exprOrType(x, call.Fun)
} else {
// We must have an index expression.
// x has already been set up (evaluation of orig.X).
// Set up fake call so we can use its fields below.
expr := orig.(*ast.IndexExpr)
call = &ast.CallExpr{Fun: expr.X, Lparen: expr.Lbrack, Args: []ast.Expr{expr.Index}, Rparen: expr.Rbrack, Brackets: true}
// funcInst type-checks a function instantiaton inst and returns the result in x.
// The operand x must be the evaluation of inst.X and its type must be a signature.
func (check *Checker) funcInst(x *operand, inst *ast.IndexExpr) {
args, ok := check.exprOrTypeList(unpackExpr(inst.Index))
if !ok {
x.mode = invalid
x.expr = inst
return
}
if len(args) > 0 && args[0].mode != typexpr {
check.errorf(args[0], _NotAType, "%s is not a type", args[0])
ok = false
}
// check number of type arguments
n := len(args)
sig := x.typ.(*Signature)
if n > len(sig.tparams) {
check.errorf(args[n-1], _Todo, "got %d type arguments but want %d", n, len(sig.tparams))
x.mode = invalid
x.expr = inst
return
}
// collect types
targs := make([]Type, n)
// TODO(rFindley) use a positioner here? instantiate would need to be
// updated accordingly.
poslist := make([]token.Pos, n)
for i, a := range args {
if a.mode != typexpr {
// error was reported earlier
x.mode = invalid
x.expr = inst
return
}
targs[i] = a.typ
poslist[i] = a.Pos()
}
// if we don't have enough type arguments, use constraint type inference
var inferred bool
if n < len(sig.tparams) {
var failed int
targs, failed = check.inferB(sig.tparams, targs)
if targs == nil {
// error was already reported
x.mode = invalid
x.expr = inst
return
}
if failed >= 0 {
// at least one type argument couldn't be inferred
assert(targs[failed] == nil)
tpar := sig.tparams[failed]
check.errorf(inNode(inst, inst.Rbrack), 0, "cannot infer %s (%v) (%s)", tpar.name, tpar.pos, targs)
x.mode = invalid
x.expr = inst
return
}
// all type arguments were inferred sucessfully
if debug {
for _, targ := range targs {
assert(targ != nil)
}
}
n = len(targs)
inferred = true
}
assert(n == len(sig.tparams))
// instantiate function signature
for i, typ := range targs {
// some positions may be missing if types are inferred
var pos token.Pos
if i < len(poslist) {
pos = poslist[i]
}
check.ordinaryType(atPos(pos), typ)
}
res := check.instantiate(x.Pos(), sig, targs, poslist).(*Signature)
assert(res.tparams == nil) // signature is not generic anymore
if inferred {
check.recordInferred(inst, targs, res)
}
x.typ = res
x.mode = value
x.expr = inst
}
func (check *Checker) call(x *operand, call *ast.CallExpr) exprKind {
check.exprOrType(x, call.Fun)
switch x.mode {
case invalid:
check.use(call.Args...)
x.expr = orig
x.expr = call
return statement
case typexpr:
@ -72,7 +150,7 @@ func (check *Checker) call(x *operand, call *ast.CallExpr, orig ast.Expr) exprKi
check.use(call.Args...)
check.errorf(call.Args[n-1], _WrongArgCount, "too many arguments in conversion to %s", T)
}
x.expr = orig
x.expr = call
return conversion
case builtin:
@ -80,7 +158,7 @@ func (check *Checker) call(x *operand, call *ast.CallExpr, orig ast.Expr) exprKi
if !check.builtin(x, call, id) {
x.mode = invalid
}
x.expr = orig
x.expr = call
// a non-constant result implies a function call
if x.mode != invalid && x.mode != constant_ {
check.hasCallOrRecv = true
@ -95,109 +173,18 @@ func (check *Checker) call(x *operand, call *ast.CallExpr, orig ast.Expr) exprKi
if sig == nil {
check.invalidOp(x, _InvalidCall, "cannot call non-function %s", x)
x.mode = invalid
x.expr = orig
x.expr = call
return statement
}
// evaluate arguments
args, ok := check.exprOrTypeList(call.Args)
if ok && call.Brackets && len(args) > 0 && args[0].mode != typexpr {
check.errorf(args[0], _NotAType, "%s is not a type", args[0])
ok = false
}
if !ok {
x.mode = invalid
x.expr = orig
x.expr = call
return expression
}
// instantiate function if needed
if n := len(args); n > 0 && len(sig.tparams) > 0 && args[0].mode == typexpr {
// If the first argument is a type, assume we have explicit type arguments.
// check number of type arguments
if n > len(sig.tparams) {
check.errorf(args[n-1], _Todo, "got %d type arguments but want %d", n, len(sig.tparams))
x.mode = invalid
x.expr = orig
return expression
}
// collect types
targs := make([]Type, n)
// TODO(rFindley) use a positioner here? instantiate would need to be
// updated accordingly.
poslist := make([]token.Pos, n)
for i, a := range args {
if a.mode != typexpr {
// error was reported earlier
x.mode = invalid
x.expr = orig
return expression
}
targs[i] = a.typ
poslist[i] = a.Pos()
}
// if we don't have enough type arguments, use constraint type inference
var inferred bool
if n < len(sig.tparams) {
var failed int
targs, failed = check.inferB(sig.tparams, targs)
if targs == nil {
// error was already reported
x.mode = invalid
x.expr = orig
return expression
}
if failed >= 0 {
// at least one type argument couldn't be inferred
assert(targs[failed] == nil)
tpar := sig.tparams[failed]
ppos := check.fset.Position(tpar.pos).String()
check.errorf(inNode(call, call.Rparen), 0, "cannot infer %s (%s) (%s)", tpar.name, ppos, targs)
x.mode = invalid
x.expr = orig
return expression
}
// all type arguments were inferred sucessfully
if debug {
for _, targ := range targs {
assert(targ != nil)
}
}
n = len(targs)
inferred = true
}
assert(n == len(sig.tparams))
// instantiate function signature
for i, typ := range targs {
// some positions may be missing if types are inferred
var pos token.Pos
if i < len(poslist) {
pos = poslist[i]
}
check.ordinaryType(atPos(pos), typ)
}
res := check.instantiate(x.Pos(), sig, targs, poslist).(*Signature)
assert(res.tparams == nil) // signature is not generic anymore
if inferred {
check.recordInferred(orig, targs, res)
}
x.typ = res
x.mode = value
x.expr = orig
return expression
}
// If we reach here, orig must have been a regular call, not an index
// expression.
// TODO(rFindley) with a manually constructed AST it is possible to reach
// this assertion. We should return an invalidAST error here
// rather than panicking.
assert(!call.Brackets)
sig = check.arguments(call, sig, args)
// determine result

4
src/go/types/examples/functions.go2
View File

@ -50,7 +50,7 @@ func new[T any]() *T {
// result type from the assignment to keep things simple and
// easy to understand.
var _ = new[int]()
var _ *float64 = new(float64)() // the result type is indeed *float64
var _ *float64 = new[float64]() // the result type is indeed *float64
// A function may have multiple type parameters, of course.
func foo[A, B, C any](a A, b []B, c *C) B {
@ -59,7 +59,7 @@ func foo[A, B, C any](a A, b []B, c *C) B {
}
// As before, we can pass type parameters explicitly.
var s = foo[int, string, float64](1, []string{"first"}, new(float64)())
var s = foo[int, string, float64](1, []string{"first"}, new[float64]())
// Or we can use type inference.
var _ float64 = foo(42, []float64{1.0}, &s)

5
src/go/types/expr.go
View File

@ -1459,7 +1459,8 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
if x.mode == value {
if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
return check.call(x, nil, e)
check.funcInst(x, e)
return expression
}
}
@ -1739,7 +1740,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
x.typ = T
case *ast.CallExpr:
return check.call(x, e, e)
return check.call(x, e)
case *ast.StarExpr:
check.exprOrType(x, e.X)

16
src/go/types/exprstring.go
View File

@ -72,6 +72,14 @@ func WriteExpr(buf *bytes.Buffer, x ast.Expr) {
WriteExpr(buf, x.Index)
buf.WriteByte(']')
case *ast.ListExpr:
for i, e := range x.ElemList {
if i > 0 {
buf.WriteString(", ")
}
WriteExpr(buf, e)
}
case *ast.SliceExpr:
WriteExpr(buf, x.X)
buf.WriteByte('[')
@ -98,16 +106,12 @@ func WriteExpr(buf *bytes.Buffer, x ast.Expr) {
case *ast.CallExpr:
WriteExpr(buf, x.Fun)
var l, r byte = '(', ')'
if x.Brackets {
l, r = '[', ']'
}
buf.WriteByte(l)
buf.WriteByte('(')
writeExprList(buf, x.Args)
if x.Ellipsis.IsValid() {
buf.WriteString("...")
}
buf.WriteByte(r)
buf.WriteByte(')')
case *ast.StarExpr:
buf.WriteByte('*')

9
src/go/types/resolver.go
View File

@ -494,13 +494,10 @@ L: // unpack receiver type
}
// unpack type parameters, if any
switch ptyp := rtyp.(type) {
case *ast.IndexExpr:
panic("unimplemented")
case *ast.CallExpr:
rtyp = ptyp.Fun
if ptyp, _ := rtyp.(*ast.IndexExpr); ptyp != nil {
rtyp = ptyp.X
if unpackParams {
for _, arg := range ptyp.Args {
for _, arg := range unpackExpr(ptyp.Index) {
var par *ast.Ident
switch arg := arg.(type) {
case *ast.Ident:

8
src/go/types/testdata/issues.go2 vendored
View File

@ -21,7 +21,7 @@ func _() {
eql(x, x)
eql(y, y)
eql(y, nil)
eql(io.Reader)(nil, nil)
eql[io.Reader](nil, nil)
}
// If we have a receiver of pointer type (below: *T) we must ignore
@ -55,8 +55,8 @@ func (T) m1()
func (*T) m2()
func _() {
f2(T /* ERROR wrong method signature */ )()
f2(*T)()
f2[T /* ERROR wrong method signature */]()
f2[*T]()
}
// When a type parameter is used as an argument to instantiate a parameterized
@ -244,7 +244,7 @@ func append[T interface{}, S sliceOf[T], T2 interface{ type T }](s S, t ...T2) S
var f func()
var cancelSlice []context.CancelFunc
var _ = append(context.CancelFunc, []context.CancelFunc, context.CancelFunc)(cancelSlice, f)
var _ = append[context.CancelFunc, []context.CancelFunc, context.CancelFunc](cancelSlice, f)
// A generic function must be instantiated with a type, not a value.

12
src/go/types/testdata/typeparams.go2 vendored
View File

@ -38,7 +38,7 @@ var _ = f(0 /* ERROR cannot use 0 .* as \[\]chan int */ )
func swap[A, B any](a A, b B) (B, A) { return b, a }
var _ = swap /* ERROR single value is expected */ [int, float32](1, 2)
var f32, i = swap[int, float32](swap(float32, int)(1, 2))
var f32, i = swap[int, float32](swap[float32, int](1, 2))
var _ float32 = f32
var _ int = i
@ -76,11 +76,11 @@ var _ *int = new[int]()
func _[T any](map[T /* ERROR incomparable map key type T \(missing comparable constraint\) */]int) // w/o constraint we don't know if T is comparable
func f1[T1 any](struct{T1}) int
var _ = f1(int)(struct{T1}{})
var _ = f1[int](struct{T1}{})
type T1 = int
func f2[t1 any](struct{t1; x float32}) int
var _ = f2(t1)(struct{t1; x float32}{})
var _ = f2[t1](struct{t1; x float32}{})
type t1 = int
@ -216,9 +216,9 @@ var _ = f8(1) /* ERROR not enough arguments */
var _ = f8(1, 2.3)
var _ = f8(1, 2.3, 3.4, 4.5)
var _ = f8(1, 2.3, 3.4, 4 /* ERROR does not match */ )
var _ = f8(int, float64)(1, 2.3, 3.4, 4)
var _ = f8[int, float64](1, 2.3, 3.4, 4)
var _ = f8(int, float64)(0, 0, nil...) // test case for #18268
var _ = f8[int, float64](0, 0, nil...) // test case for #18268
// init functions cannot have type parameters
@ -271,7 +271,7 @@ type A[T any] T
func (a A[T]) m() A[T]
func _[T any]() {
f12(A[T])()
f12[A[T]]()
}
// method expressions

42
src/go/types/typexpr.go
View File

@ -208,21 +208,28 @@ func isubst(x ast.Expr, smap map[*ast.Ident]*ast.Ident) ast.Expr {
new.X = X
return &new
}
case *ast.CallExpr:
var args []ast.Expr
for i, arg := range n.Args {
new := isubst(arg, smap)
if new != arg {
if args == nil {
args = make([]ast.Expr, len(n.Args))
copy(args, n.Args)
case *ast.IndexExpr:
index := isubst(n.Index, smap)
if index != n.Index {
new := *n
new.Index = index
return &new
}
case *ast.ListExpr:
var elems []ast.Expr
for i, elem := range n.ElemList {
new := isubst(elem, smap)
if new != elem {
if elems == nil {
elems = make([]ast.Expr, len(n.ElemList))
copy(elems, n.ElemList)
}
args[i] = new
elems[i] = new
}
}
if args != nil {
if elems != nil {
new := *n
new.Args = args
new.ElemList = elems
return &new
}
case *ast.ParenExpr:
@ -460,14 +467,7 @@ func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
}
case *ast.IndexExpr:
return check.instantiatedType(e.X, []ast.Expr{e.Index}, def)
case *ast.CallExpr:
if e.Brackets {
return check.instantiatedType(e.Fun, e.Args, def)
} else {
check.errorf(e0, _NotAType, "%s is not a type", e0)
}
return check.instantiatedType(e.X, unpackExpr(e.Index), def)
case *ast.ParenExpr:
// Generic types must be instantiated before they can be used in any form.
@ -1158,10 +1158,6 @@ func embeddedFieldIdent(e ast.Expr) *ast.Ident {
return e.Sel
case *ast.IndexExpr:
return embeddedFieldIdent(e.X)
case *ast.CallExpr:
if e.Brackets {
return embeddedFieldIdent(e.Fun)
}
}
return nil // invalid embedded field
}