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internal/typeparams: fix crash in interface hover with empty type set
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The logic of typeparams.Free.Has was not handling ErrEmptyTypeSet from
InterfaceTermSet, leading to a crash.

Also fix a hover marker in hover/generics.txt that was apparently
missing a '@'.

Fixes golang/go#68213

Change-Id: I0e264b5c5f5ecc0d09a0b8ab381eb7d7c492c18f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/595555
Auto-Submit: Robert Findley <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
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findleyr authored and gopherbot committed Jun 27, 2024
1 parent c0ae6bb commit 72edac2
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Showing 2 changed files with 62 additions and 31 deletions.
90 changes: 61 additions & 29 deletions gopls/internal/test/marker/testdata/hover/generics.txt
Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,11 @@ This file contains tests for hovering over generic Go code.
Requires go1.20+ for the new go/doc/comment package, and a change in Go 1.20
that affected the formatting of constraint interfaces.

Its size expectations assume a 64-bit machine.

-- flags --
-min_go=go1.20
-skip_goarch=386,arm

-- go.mod --
// A go.mod is require for correct pkgsite links.
Expand All @@ -13,10 +16,28 @@ module mod.com

go 1.18

-- issue68213.go --
package generics

// Hovering over an interface with empty type set must not panic.
type empty interface { //@hover("empty", "empty", empty)
int
string
}

-- @empty --
```go
type empty interface { // size=16 (0x10)
int
string
}
```

Hovering over an interface with empty type set must not panic.
-- generics.go --
package generics

type value[T any] struct { //hover("lue", "value", value),hover("T", "T", valueT)
type value[T any] struct { //@hover("lue", "value", value),hover("T", "T", valueT)
val T //@hover("T", "T", valuevalT)
Q int64 //@hover("Q", "Q", valueQ)
}
Expand All @@ -30,51 +51,44 @@ func F[P interface{ ~int | string }]() { //@hover("P", "P", Ptparam)
var _ P //@hover("P","P",Pvar)
}

-- inferred.go --
package generics

func app[S interface{ ~[]E }, E interface{}](s S, e E) S {
return append(s, e)
}

func _() {
_ = app[[]int] //@hover("app", "app", appint)
_ = app[[]int, int] //@hover("app", "app", appint)
_ = app[[]int]([]int{}, 0) //@hover("app", "app", appint), diag("[[]int]", re"unnecessary")
_ = app([]int{}, 0) //@hover("app", "app", appint)
}

-- @ValueQ --
-- @value --
```go
field Q int64 // size=8
type value[T any] struct {
val T //@hover("T", "T", valuevalT)
Q int64 //@hover("Q", "Q", valueQ)
}
```

@hover("Q", "Q", ValueQ)


[`(generics.Value).Q` on pkg.go.dev](https://pkg.go.dev/mod.com#Value.Q)
-- @ValueT --
-- @valueT --
```go
type parameter T any
```
-- @ValuevalT --
-- @valuevalT --
```go
type parameter T any
```
-- @appint --
```go
func app(s []int, e int) []int // func[S interface{~[]E}, E interface{}](s S, e E) S
```
-- @valueQ --
```go
field Q int64 // size=8
```

@hover("Q", "Q", valueQ)
-- @valuevalT --
-- @ValueT --
```go
type parameter T any
```
-- @ValuevalT --
```go
type parameter T any
```
-- @ValueQ --
```go
field Q int64 // size=8
```

@hover("Q", "Q", ValueQ)


[`(generics.Value).Q` on pkg.go.dev](https://pkg.go.dev/mod.com#Value.Q)
-- @Ptparam --
```go
type parameter P interface{~int | string}
Expand All @@ -83,3 +97,21 @@ type parameter P interface{~int | string}
```go
type parameter P interface{~int | string}
```
-- inferred.go --
package generics

func app[S interface{ ~[]E }, E interface{}](s S, e E) S {
return append(s, e)
}

func _() {
_ = app[[]int] //@hover("app", "app", appint)
_ = app[[]int, int] //@hover("app", "app", appint)
_ = app[[]int]([]int{}, 0) //@hover("app", "app", appint), diag("[[]int]", re"unnecessary")
_ = app([]int{}, 0) //@hover("app", "app", appint)
}

-- @appint --
```go
func app(s []int, e int) []int // func[S interface{~[]E}, E interface{}](s S, e E) S
```
3 changes: 1 addition & 2 deletions internal/typeparams/free.go
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,6 @@ type Free struct {

// Has reports whether the specified type has a free type parameter.
func (w *Free) Has(typ types.Type) (res bool) {

// detect cycles
if x, ok := w.seen[typ]; ok {
return x
Expand Down Expand Up @@ -83,7 +82,7 @@ func (w *Free) Has(typ types.Type) (res bool) {
}
terms, err := InterfaceTermSet(t)
if err != nil {
panic(err)
return false // ill typed
}
for _, term := range terms {
if w.Has(term.Type()) {
Expand Down

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