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go/internal/lsp/testdata/snippets/literal_snippets.go.in
Muir Manders 0c330b00b1 internal/lsp: improve literal func completion candidates
Previously we were erroneously suggesting a "func() {}" literal in
cases like:

http.Handle("/", <>)

This was happening because saw that the http.HandlerFunc type
satisfied the http.Handler interface, and that http.HandlerFunc is a
function type. However, of course, you can't pass a function literal
to http.Handle().

Make a few tweaks to address the problem:

1. Don't suggest literal "func () {}" candidates if the expected type
   is an interface type.

2. Suggest named function types that implement an interface. This
   causes us to suggest "http.HandlerFunc()" in the above example.

3. Suggest a func literal candidate inside named function type
   conversions. This will suggest "func() {}" when completing
   "http.HandlerFunc(<>)".

This way the false positive func literal is gone, and you still get
literal candidates that help you use an http.HandlerFunc as an
http.Handler. Note that this particular example is not very compelling
in light of http.HandleFunc() which can take a func literal directly,
but such a convenience function may not exist in other analogous
situations.

Change-Id: Ia68097b9a5b8351921349340d18acd8876554691
Reviewed-on: https://go-review.googlesource.com/c/tools/+/205137
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-11-07 21:18:00 +00:00

153 lines
4.7 KiB
Go

package snippets
import (
"net/http"
"sort"
"golang.org/x/tools/internal/lsp/foo"
)
func _() {
[]int{} //@item(litIntSlice, "[]int{}", "", "var")
make([]int, 0) //@item(makeIntSlice, "make([]int, 0)", "", "func")
var slice []int
slice = i //@snippet(" //", litIntSlice, "[]int{$0\\}", "[]int{$0\\}")
slice = m //@snippet(" //", makeIntSlice, "make([]int, ${1:})", "make([]int, ${1:0})")
}
func _() {
type namedInt []int
namedInt{} //@item(litNamedSlice, "namedInt{}", "", "var")
make(namedInt, 0) //@item(makeNamedSlice, "make(namedInt, 0)", "", "func")
var namedSlice namedInt
namedSlice = n //@snippet(" //", litNamedSlice, "namedInt{$0\\}", "namedInt{$0\\}")
namedSlice = m //@snippet(" //", makeNamedSlice, "make(namedInt, ${1:})", "make(namedInt, ${1:0})")
}
func _() {
make(chan int) //@item(makeChan, "make(chan int)", "", "func")
var ch chan int
ch = m //@snippet(" //", makeChan, "make(chan int)", "make(chan int)")
}
func _() {
map[string]struct{}{} //@item(litMap, "map[string]struct{}{}", "", "var")
make(map[string]struct{}) //@item(makeMap, "make(map[string]struct{})", "", "func")
var m map[string]struct{}
m = m //@snippet(" //", litMap, "map[string]struct{\\}{$0\\}", "map[string]struct{\\}{$0\\}")
m = m //@snippet(" //", makeMap, "make(map[string]struct{\\})", "make(map[string]struct{\\})")
struct{}{} //@item(litEmptyStruct, "struct{}{}", "", "var")
m["hi"] = s //@snippet(" //", litEmptyStruct, "struct{\\}{\\}", "struct{\\}{\\}")
}
func _() {
type myStruct struct{ i int }
myStruct{} //@item(litStruct, "myStruct{}", "", "var")
&myStruct{} //@item(litStructPtr, "&myStruct{}", "", "var")
var ms myStruct
ms = m //@snippet(" //", litStruct, "myStruct{$0\\}", "myStruct{$0\\}")
var msPtr *myStruct
msPtr = m //@snippet(" //", litStructPtr, "&myStruct{$0\\}", "&myStruct{$0\\}")
msPtr = &m //@snippet(" //", litStruct, "myStruct{$0\\}", "myStruct{$0\\}")
}
type myImpl struct{}
func (myImpl) foo() {}
func (*myImpl) bar() {}
type myBasicImpl string
func (myBasicImpl) foo() {}
func _() {
type myIntf interface {
foo()
}
myImpl{} //@item(litImpl, "myImpl{}", "", "var")
var mi myIntf
mi = m //@snippet(" //", litImpl, "myImpl{\\}", "myImpl{\\}")
myBasicImpl() //@item(litBasicImpl, "myBasicImpl()", "string", "var")
mi = m //@snippet(" //", litBasicImpl, "myBasicImpl($0)", "myBasicImpl($0)")
// only satisfied by pointer to myImpl
type myPtrIntf interface {
bar()
}
&myImpl{} //@item(litImplPtr, "&myImpl{}", "", "var")
var mpi myPtrIntf
mpi = m //@snippet(" //", litImplPtr, "&myImpl{\\}", "&myImpl{\\}")
}
func _() {
var s struct{ i []int } //@item(litSliceField, "i", "[]int", "field")
var foo []int
// no literal completions after selector
foo = s.i //@complete(" //", litSliceField)
}
func _() {
type myStruct struct{ i int } //@item(litStructType, "myStruct", "struct{...}", "struct")
foo := func(s string, args ...myStruct) {}
// Don't give literal slice candidate for variadic arg.
foo("", myStruct) //@complete(")", litStructType)
}
func _() {
_ = "func(...) {}" //@item(litFunc, "func(...) {}", "", "var")
sort.Slice(nil, f) //@snippet(")", litFunc, "func(i, j int) bool {$0\\}", "func(i, j int) bool {$0\\}")
http.HandleFunc("", f) //@snippet(")", litFunc, "", "func(${1:rw} http.ResponseWriter, ${2:r} *http.Request) {$0\\}")
// no literal "func" completions
http.Handle("", fun) //@complete(")")
http.HandlerFunc() //@item(handlerFunc, "http.HandlerFunc()", "", "var")
http.Handle("", h) //@snippet(")", handlerFunc, "http.HandlerFunc($0)", "http.HandlerFunc($0)")
http.Handle("", http.HandlerFunc()) //@snippet("))", litFunc, "", "func(${1:rw} http.ResponseWriter, ${2:r} *http.Request) {$0\\}")
var namedReturn func(s string) (b bool)
namedReturn = f //@snippet(" //", litFunc, "func(s string) (b bool) {$0\\}", "func(s string) (b bool) {$0\\}")
var multiReturn func() (bool, int)
multiReturn = f //@snippet(" //", litFunc, "func() (bool, int) {$0\\}", "func() (bool, int) {$0\\}")
var multiNamedReturn func() (b bool, i int)
multiNamedReturn = f //@snippet(" //", litFunc, "func() (b bool, i int) {$0\\}", "func() (b bool, i int) {$0\\}")
var duplicateParams func(myImpl, int, myImpl)
duplicateParams = f //@snippet(" //", litFunc, "", "func(${1:mi} myImpl, ${2:_} int, ${3:_} myImpl) {$0\\}")
}
func _() {
StructFoo{} //@item(litStructFoo, "StructFoo{}", "struct{...}", "struct")
var sfp *foo.StructFoo
// Don't insert the "&" before "StructFoo{}".
sfp = foo.Str //@snippet(" //", litStructFoo, "StructFoo{$0\\}", "StructFoo{$0\\}")
var sf foo.StructFoo
sf = foo.Str //@snippet(" //", litStructFoo, "StructFoo{$0\\}", "StructFoo{$0\\}")
sf = foo. //@snippet(" //", litStructFoo, "StructFoo{$0\\}", "StructFoo{$0\\}")
}