internal/lsp: fix fillstruct for structs with unsafe.Pointer

Provide a default value for unsafe.Pointer in fillstruct.

Fixes golang/go#52640

Change-Id: I10a1878fbf53b082f83f44e0ba2788ead14439d6
Reviewed-on: https://go-review.googlesource.com/c/tools/+/403535
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Suzy Mueller <suzmue@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: David Chase <drchase@google.com>

internal/lsp/analysis/fillstruct/fillstruct.go

@@ -368,6 +368,8 @@ func populateValue(fset *token.FileSet, f *ast.File, pkg *types.Package, typ typ
 			return &ast.Ident{Name: "false"}
 		case u.Info()&types.IsString != 0:
 			return &ast.BasicLit{Kind: token.STRING, Value: `""`}
+		case u.Kind() == types.UnsafePointer:
+			return ast.NewIdent("nil")
 		default:
 			panic("unknown basic type")
 		}

internal/lsp/analysis/fillstruct/testdata/src/a/a.go

@@ -8,6 +8,7 @@ import (
 	data "b"
 	"go/ast"
 	"go/token"
+	"unsafe"
 )
 
 type emptyStruct struct{}
@@ -104,3 +105,9 @@ var _ = []ast.BasicLit{
 
 var _ = []ast.BasicLit{{}, // want ""
 }
+
+type unsafeStruct struct {
+	foo unsafe.Pointer
+}
+
+var _ = unsafeStruct{} // want ""

internal/lsp/testdata/fillstruct/fill_struct_unsafe.go

@@ -0,0 +1,12 @@
+package fillstruct
+
+import "unsafe"
+
+type unsafeStruct struct {
+	x int
+	p unsafe.Pointer
+}
+
+func fill() {
+	_ := unsafeStruct{} //@suggestedfix("}", "refactor.rewrite")
+}

internal/lsp/testdata/fillstruct/fill_struct_unsafe.go.golden

@@ -0,0 +1,17 @@
+-- suggestedfix_fill_struct_unsafe_11_20 --
+package fillstruct
+
+import "unsafe"
+
+type unsafeStruct struct {
+	x int
+	p unsafe.Pointer
+}
+
+func fill() {
+	_ := unsafeStruct{
+		x: 0,
+		p: nil,
+	} //@suggestedfix("}", "refactor.rewrite")
+}
+

internal/lsp/testdata/summary.txt.golden

@@ -13,7 +13,7 @@ FoldingRangesCount = 2
 FormatCount = 6
 ImportCount = 8
 SemanticTokenCount = 3
-SuggestedFixCount = 61
+SuggestedFixCount = 62
 FunctionExtractionCount = 25
 MethodExtractionCount = 6
 DefinitionsCount = 95

internal/lsp/testdata/summary_go1.18.txt.golden

@@ -13,7 +13,7 @@ FoldingRangesCount = 2
 FormatCount = 6
 ImportCount = 8
 SemanticTokenCount = 3
-SuggestedFixCount = 62
+SuggestedFixCount = 63
 FunctionExtractionCount = 25
 MethodExtractionCount = 6
 DefinitionsCount = 108