Method funcType

syntax/parser.go:1361–1395

If context != "", type parameters are not permitted.

(context string, tparamList *[]*Field)

// If context != "", type parameters are not permitted.
func (p *parser) funcType(context string, tparamList *[]*Field) *FuncType {
	if trace {
		defer p.trace("funcType")()
	}

	typ := new(FuncType)
	typ.pos = p.pos()

	if p.allowGenerics() && p.tok == _Lbrack {
		p.async(func() {
			p.next()
			if context != "" {
				// accept but complain
				p.syntaxErrorAt(typ.pos, context+" must have no type parameters")
			}
			if p.tok == _Rbrack {
				p.syntaxError("empty type parameter list")
				p.next()
			} else {
				list := p.paramList(nil, nil, _Rbrack, true)
				if tparamList != nil {
					*tparamList = list
				}
			}
		})
	}

	p.async(func() {
		p.want(_Lparen)
		typ.ParamList = p.paramList(nil, nil, _Rparen, false)
	})
	typ.ResultList = p.funcResult()

	return typ
}

// "[" has already been consumed, and pos is its position, and open is its tape index.
// If len != nil it is the already consumed array length.