This test exercises basic tests for signature help.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests

go 1.18

-- signature/signature.go --
// Package signature has tests for signature help.
package signature

import (
	"bytes"
	"encoding/json"
	"math/big"
	"fmt"
)

func Foo(a string, b int) (c bool) {
	return
}

func Bar(float64, ...byte) {
}

type myStruct struct{}

func (*myStruct) foo(e *json.Decoder) (*big.Int, error) {
	return nil, nil
}

type MyType struct{}

type MyFunc func(foo int) string

type Alias = int
type OtherAlias = int
type StringAlias = string

func AliasSlice(a []*Alias) (b Alias)                                 { return 0 }
func AliasMap(a map[*Alias]StringAlias) (b, c map[*Alias]StringAlias) { return nil, nil }
func OtherAliasMap(a, b map[Alias]OtherAlias) map[Alias]OtherAlias    { return nil }

func Qux() {
	Foo("foo", 123) //@signature("(", "Foo(a string, b int) (c bool)", 0)
	Foo("foo", 123) //@signature("123", "Foo(a string, b int) (c bool)", 1)
	Foo("foo", 123) //@signature(",", "Foo(a string, b int) (c bool)", 0)
	Foo("foo", 123) //@signature(" 1", "Foo(a string, b int) (c bool)", 1)
	Foo("foo", 123) //@signature(")", "Foo(a string, b int) (c bool)", 1)
	Foo("foo", 123) //@signature("o", "Foo(a string, b int) (c bool)", 0)
	_ = Foo //@signature("o", "Foo(a string, b int) (c bool)", 0)
	Foo //@signature("o", "Foo(a string, b int) (c bool)", 0)

	Bar(13.37, 0x13)       //@signature("13.37", "Bar(float64, ...byte)", 0)
	Bar(13.37, 0x37)       //@signature("0x37", "Bar(float64, ...byte)", 1)
	Bar(13.37, 1, 2, 3, 4) //@signature("4", "Bar(float64, ...byte)", 1)

	fn := func(hi, there string) func(i int) rune {
		return func(int) rune { return 0 }
	}

	fn("hi", "there")    //@signature("hi", "", 0)
	fn("hi", "there")    //@signature(",", "fn(hi string, there string) func(i int) rune", 0)
	fn("hi", "there")(1) //@signature("1", "func(i int) rune", 0)

	fnPtr := &fn
	(*fnPtr)("hi", "there") //@signature(",", "func(hi string, there string) func(i int) rune", 0)

	var fnIntf interface{} = Foo
	fnIntf.(func(string, int) bool)("hi", 123) //@signature("123", "func(string, int) bool", 1)

	(&bytes.Buffer{}).Next(2) //@signature("2", "Next(n int) []byte", 0)

	myFunc := MyFunc(func(n int) string { return "" })
	myFunc(123) //@signature("123", "myFunc(foo int) string", 0)

	var ms myStruct
	ms.foo(nil) //@signature("nil", "foo(e *json.Decoder) (*big.Int, error)", 0)

	_ = make([]int, 1, 2) //@signature("2", "make(t Type, size ...int) Type", 1)

	Foo(myFunc(123), 456) //@signature("o(", "Foo(a string, b int) (c bool)", 0)
	Foo(myFunc(123), 456) //@signature("(m", "Foo(a string, b int) (c bool)", 0)
	Foo( myFunc(123), 456) //@signature(" m", "Foo(a string, b int) (c bool)", 0)
	Foo(myFunc(123), 456) //@signature(", ", "Foo(a string, b int) (c bool)", 0)
	Foo(myFunc(123), 456) //@signature("456", "Foo(a string, b int) (c bool)", 1)
	Foo(myFunc) //@signature(")", "Foo(a string, b int) (c bool)", 0)
	Foo(myFunc(123), 456) //@signature("(1", "myFunc(foo int) string", 0)
	Foo(myFunc(123), 456) //@signature("123", "myFunc(foo int) string", 0)

	fmt.Println //@signature("ln", "Println(a ...any) (n int, err error)", 0)
	fmt.Println(myFunc) //@signature("ln", "Println(a ...any) (n int, err error)", 0)
	fmt.Println(myFunc) //@signature("Func", "myFunc(foo int) string", 0)

	var hi string = "hello"
	var wl string = " world: %s"
	fmt.Println(fmt.Sprintf(wl, myFunc)) //@signature("Func", "myFunc(foo int) string", 0)
	fmt.Println(fmt.Sprintf(wl, myFunc)) //@signature("wl", "Sprintf(format string, a ...any) string", 0)
	fmt.Println(fmt.Sprintf(wl, myFunc)) //@signature(" m", "Sprintf(format string, a ...any) string", 1)
	fmt.Println(hi, fmt.Sprintf(wl, myFunc)) //@signature("Sprint", "Sprintf(format string, a ...any) string", 0)
	fmt.Println(hi, fmt.Sprintf(wl, myFunc)) //@signature(" fmt", "Println(a ...any) (n int, err error)", 0)
	fmt.Println(hi, fmt.Sprintf(wl, myFunc)) //@signature("hi", "Println(a ...any) (n int, err error)", 0)

	panic("oops!")            //@signature(")", "panic(v any)", 0)
	println("hello", "world") //@signature(",", "println(args ...Type)", 0)

	Hello(func() {
		//@signature("//", "", 0)
	})

	AliasSlice()    //@signature(")", "AliasSlice(a []*Alias) (b Alias)", 0)
	AliasMap()      //@signature(")", "AliasMap(a map[*Alias]StringAlias) (b map[*Alias]StringAlias, c map[*Alias]StringAlias)", 0)
	OtherAliasMap() //@signature(")", "OtherAliasMap(a map[Alias]OtherAlias, b map[Alias]OtherAlias) map[Alias]OtherAlias", 0)
}

func Hello(func()) {}

-- signature/signature2.go --
package signature

func _() {
	Foo(//@signature("//", "Foo(a string, b int) (c bool)", 0)
	Foo.//@signature("//", "Foo(a string, b int) (c bool)", 0)
	Foo.//@signature("oo", "Foo(a string, b int) (c bool)", 0)
}

-- signature/signature3.go --
package signature

func _() {
	Foo("hello",//@signature("//", "Foo(a string, b int) (c bool)", 1)
}

-- signature/nonsignature.go --
package signature

var x = (1) //@signature("1)", "", 0)

-- signature/signature_test.go --
package signature_test

import (
	"testing"

	sig "golang.org/lsptests/signature"
)

func TestSignature(t *testing.T) {
	sig.AliasSlice()    //@signature(")", "AliasSlice(a []*sig.Alias) (b sig.Alias)", 0)
	sig.AliasMap()      //@signature(")", "AliasMap(a map[*sig.Alias]sig.StringAlias) (b map[*sig.Alias]sig.StringAlias, c map[*sig.Alias]sig.StringAlias)", 0)
	sig.OtherAliasMap() //@signature(")", "OtherAliasMap(a map[sig.Alias]sig.OtherAlias, b map[sig.Alias]sig.OtherAlias) map[sig.Alias]sig.OtherAlias", 0)
}

-- snippets/snippets.go --
package snippets

import (
	"golang.org/lsptests/signature"
)

type CoolAlias = int //@item(CoolAlias, "CoolAlias", "int", "type")

type structy struct {
	x signature.MyType
}

func X(_ map[signature.Alias]CoolAlias) (map[signature.Alias]CoolAlias) {
	return nil
}

func _() {
	X() //@signature(")", "X(_ map[signature.Alias]CoolAlias) map[signature.Alias]CoolAlias", 0)
	_ = signature.MyType{} //@item(literalMyType, "signature.MyType{}", "", "var")
	s := structy{
		x: //@snippet(" //", literalMyType, "signature.MyType{\\}")
	}
}

-- importedcomplit/importedcomplit.go --
package importedcomplit

import (
	// TODO(rfindley): re-enable after moving to new framework
	// "golang.org/lsptests/foo"

	// import completions (separate blocks to avoid comment alignment)
	"crypto/elli" //@complete("\" //", cryptoImport)

	"fm" //@complete("\" //", fmtImport)

	"go/pars" //@complete("\" //", parserImport)

	namedParser "go/pars" //@complete("\" //", parserImport)

	"golang.org/lspte" //@complete("\" //", lsptestsImport)

	"golang.org/lsptests/sign" //@complete("\" //", signatureImport)

	"golang.org/lsptests/sign" //@complete("ests", lsptestsImport)

	"golang.org/lsptests/signa" //@complete("na\" //", signatureImport)
)

func _() {
	var V int //@item(icVVar, "V", "int", "var")

	// TODO(rfindley): re-enable after moving to new framework
	// _ = foo.StructFoo{V} // complete("}", Value, icVVar)
}

func _() {
	var (
		aa string //@item(icAAVar, "aa", "string", "var")
		ab int    //@item(icABVar, "ab", "int", "var")
	)

	// TODO(rfindley): re-enable after moving to new framework
	// _ = foo.StructFoo{a} // complete("}", abVar, aaVar)

	var s struct {
		AA string //@item(icFieldAA, "AA", "string", "field")
		AB int    //@item(icFieldAB, "AB", "int", "field")
	}

	// TODO(rfindley): re-enable after moving to new framework
	//_ = foo.StructFoo{s.} // complete("}", icFieldAB, icFieldAA)
}

/* "fmt" */ //@item(fmtImport, "fmt", "\"fmt\"", "package")
/* "go/parser" */ //@item(parserImport, "parser", "\"go/parser\"", "package")
/* "golang.org/lsptests/signature" */ //@item(signatureImport, "signature", "\"golang.org/lsptests/signature\"", "package")
/* "golang.org/lsptests/" */ //@item(lsptestsImport, "lsptests/", "\"golang.org/lsptests/\"", "package")
/* "crypto/elliptic" */ //@item(cryptoImport, "elliptic", "\"crypto/elliptic\"", "package")