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go/parser: allow method type parameters 

Controlled via methodTypeParamsOk (internal flag).

Change-Id: I821a303f897f5a99ac42f667a3f592cbd1e98d0c
This commit is contained in:
Robert Griesemer 2020-01-06 10:02:02 -08:00
parent a9c105c1d7
commit 464fb5c1e7
2 changed files with 26 additions and 4 deletions
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8
src/go/parser/parser.go
View File

@ -26,6 +26,8 @@ import (
"unicode"
)
const methodTypeParamsOk = typeParamsOk // set this to 0 to disallow type params in methods
// The parser structure holds the parser's internal state.
type parser struct {
file *token.File
@ -1132,7 +1134,7 @@ func (p *parser) parseMethodSpec(scope *ast.Scope) *ast.Field {
// method
idents = []*ast.Ident{ident}
scope := ast.NewScope(nil) // method scope
_, params := p.parseParameters(scope, variadicOk, "method")
_, params := p.parseParameters(scope, methodTypeParamsOk|variadicOk, "method")
results := p.parseResult(scope, true)
typ = &ast.FuncType{Func: token.NoPos, Params: params, Results: results}
} else {
@ -1254,7 +1256,7 @@ func (p *parser) parseConstraint() *ast.Constraint {
// method
mname = ident
scope := ast.NewScope(nil) // method scope
_, params := p.parseParameters(scope, variadicOk, "method")
_, params := p.parseParameters(scope, methodTypeParamsOk|variadicOk, "method")
results := p.parseResult(scope, true)
typ = &ast.FuncType{Func: token.NoPos, Params: params, Results: results}
}
@ -2785,7 +2787,7 @@ func (p *parser) parseFuncDecl() *ast.FuncDecl {
ident := p.parseIdent()
tparams, params := p.parseParameters(scope, mode, "method") // context string only used in methods
tparams, params := p.parseParameters(scope, mode|methodTypeParamsOk, "method") // context string only used in methods
results := p.parseResult(scope, true)
var body *ast.BlockStmt

22
src/go/parser/short_test.go
View File

@ -49,10 +49,13 @@ var valids = []string{
`package p; type T = int`,
`package p; type (T = p.T; _ = struct{}; x = *T)`,
`package p; type T (*int)`,
// type parameters
`package p; type T(type P) struct { P }`,
`package p; type T(type P comparable) struct { P }`,
`package p; type T(type P comparable(P)) struct { P }`,
`package p; type T(type P1, P2) struct { P1; f []P2 }`,
`package p; var _ = [](T(int)){}`,
`package p; var _ = func()T(nil)`,
`package p; func _(type)()`,
@ -63,9 +66,19 @@ var valids = []string{
`package p; func _(T [P]E)`,
`package p; func _(x T(P1, P2, P3))`,
`package p; func _((T(P1, P2, P3)))`,
// method type parameters (if methodTypeParamsOk)
`package p; func _(type A, B)(a A) B`,
`package p; func _(type A, B C)(a A) B`,
`package p; func _(type A, B C(A, B))(a A) B`,
`package p; func (T) _(type A, B)(a A) B`,
`package p; func (T) _(type A, B C)(a A) B`,
`package p; func (T) _(type A, B C(A, B))(a A) B`,
`package p; type _ interface { _(type A, B)(a A) B }`,
`package p; type _ interface { _(type A, B C)(a A) B }`,
`package p; type _ interface { _(type A, B C(A, B))(a A) B }`,
// contracts
`package p; contract C(){}`,
`package p; contract C(T, S, R,){}`,
`package p; contract C(T){ T (m(x, int)); }`,
@ -82,7 +95,7 @@ var valids = []string{
`package p; func _(type T1, T2 interface{})(x T1) T2`,
`package p; func _(type T1 interface{ m() }, T2, T3 interface{})(x T1, y T3) T2`,
// interfaces as contracts (experimental)
// interfaces with (contract) type lists
`package p; type _ interface{type int}`,
`package p; type _ interface{type int, float32; type bool; m(); type string;}`,
}
@ -146,6 +159,13 @@ var invalids = []string{
`package p; func f() { defer func() {} /* ERROR HERE "function must be invoked" */ }`,
`package p; func f() { go func() { func() { f(x func /* ERROR "missing ','" */ (){}) } } }`,
//`package p; func f(x func(), u v func /* ERROR "missing ','" */ ()){}`,
// type parameters
`package p; var _ func( /* ERROR "no type parameters" */ type T)(T)`,
`package p; func _() ( /* ERROR "no type parameters" */ type T)(T)`,
`package p; func ( /* ERROR "no type parameters" */ type T)(T) _()`,
// contracts
`package p; contract C(T, T /* ERROR "T redeclared" */ ) {}`,
`package p; contract C(T) { imported /* ERROR "expected type parameter name" */ .T int }`,