go/ast/astutil: update PathEnclosingInterval to handle type parameters

Add support for the new generic syntax to PathEnclosingInterval, notably
the new IndexListExpr node and FuncDecl.Type.TypeParams.

Change-Id: I013a916a1617e5f08c8d1cb30501bf2bf253c742
Reviewed-on: https://go-review.googlesource.com/c/tools/+/353150
Trust: Robert Findley <[email protected]>
Run-TryBot: Robert Findley <[email protected]>
gopls-CI: kokoro <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>

Author: findleyr

go/ast/astutil/enclosing.go

@@ -11,6 +11,8 @@ import (
 	"go/ast"
 	"go/token"
 	"sort"
+
+	"golang.org/x/tools/internal/typeparams"
 )
 
 // PathEnclosingInterval returns the node that encloses the source
@@ -294,8 +296,8 @@ func childrenOf(n ast.Node) []ast.Node {
 
 	case *ast.FieldList:
 		children = append(children,
-			tok(n.Opening, len("(")),
-			tok(n.Closing, len(")")))
+			tok(n.Opening, len("(")), // or len("[")
+			tok(n.Closing, len(")"))) // or len("]")
 
 	case *ast.File:
 		// TODO test: Doc
@@ -322,6 +324,9 @@ func childrenOf(n ast.Node) []ast.Node {
 			children = append(children, n.Recv)
 		}
 		children = append(children, n.Name)
+		if tparams := typeparams.ForFuncType(n.Type); tparams != nil {
+			children = append(children, tparams)
+		}
 		if n.Type.Params != nil {
 			children = append(children, n.Type.Params)
 		}
@@ -371,8 +376,13 @@ func childrenOf(n ast.Node) []ast.Node {
 
 	case *ast.IndexExpr:
 		children = append(children,
-			tok(n.Lbrack, len("{")),
-			tok(n.Rbrack, len("}")))
+			tok(n.Lbrack, len("[")),
+			tok(n.Rbrack, len("]")))
+
+	case *typeparams.IndexListExpr:
+		children = append(children,
+			tok(n.Lbrack, len("[")),
+			tok(n.Rbrack, len("]")))
 
 	case *ast.InterfaceType:
 		children = append(children,
@@ -581,6 +591,8 @@ func NodeDescription(n ast.Node) string {
 		return "decrement statement"
 	case *ast.IndexExpr:
 		return "index expression"
+	case *typeparams.IndexListExpr:
+		return "index list expression"
 	case *ast.InterfaceType:
 		return "interface type"
 	case *ast.KeyValueExpr:

go/ast/astutil/enclosing_test.go

@@ -19,6 +19,7 @@ import (
 	"testing"
 
 	"golang.org/x/tools/go/ast/astutil"
+	"golang.org/x/tools/internal/typeparams"
 )
 
 // pathToString returns a string containing the concrete types of the
@@ -59,7 +60,10 @@ func findInterval(t *testing.T, fset *token.FileSet, input, substr string) (f *a
 }
 
 // Common input for following tests.
-const input = `
+var input = makeInput()
+
+func makeInput() string {
+	src := `
 // Hello.
 package main
 import "fmt"
@@ -70,52 +74,88 @@ func main() {
 }
 `
 
+	if typeparams.Enabled {
+		src += `
+func g[A any, P interface{ctype1| ~ctype2}](a1 A, p1 P) {}
+
+type PT[T constraint] struct{ t T }
+
+var v GT[targ1]
+
+var h = g[ targ2, targ3]
+`
+	}
+	return src
+}
+
 func TestPathEnclosingInterval_Exact(t *testing.T) {
-	// For the exact tests, we check that a substring is mapped to
-	// the canonical string for the node it denotes.
-	tests := []struct {
+	type testCase struct {
 		substr string // first occurrence of this string indicates interval
 		node   string // complete text of expected containing node
-	}{
+	}
+
+	dup := func(s string) testCase { return testCase{s, s} }
+	// For the exact tests, we check that a substring is mapped to
+	// the canonical string for the node it denotes.
+	tests := []testCase{
 		{"package",
 			input[11 : len(input)-1]},
 		{"\npack",
 			input[11 : len(input)-1]},
-		{"main",
-			"main"},
+		dup("main"),
 		{"import",
 			"import \"fmt\""},
-		{"\"fmt\"",
-			"\"fmt\""},
+		dup("\"fmt\""),
 		{"\nfunc f() {}\n",
 			"func f() {}"},
 		{"x ",
 			"x"},
 		{" y",
 			"y"},
-		{"z",
-			"z"},
+		dup("z"),
 		{" + ",
 			"x + y"},
 		{" :=",
 			"z := (x + y)"},
-		{"x + y",
-			"x + y"},
-		{"(x + y)",
-			"(x + y)"},
+		dup("x + y"),
+		dup("(x + y)"),
 		{" (x + y) ",
 			"(x + y)"},
 		{" (x + y) // add",
 			"(x + y)"},
 		{"func",
 			"func f() {}"},
-		{"func f() {}",
-			"func f() {}"},
+		dup("func f() {}"),
 		{"\nfun",
 			"func f() {}"},
 		{" f",
 			"f"},
 	}
+	if typeparams.Enabled {
+		tests = append(tests, []testCase{
+			dup("[A any, P interface{ctype1| ~ctype2}]"),
+			{"[", "[A any, P interface{ctype1| ~ctype2}]"},
+			dup("A"),
+			{" any", "any"},
+			dup("ctype1"),
+			{"|", "ctype1| ~ctype2"},
+			dup("ctype2"),
+			{"~", "~ctype2"},
+			dup("~ctype2"),
+			{" ~ctype2", "~ctype2"},
+			{"]", "[A any, P interface{ctype1| ~ctype2}]"},
+			dup("a1"),
+			dup("a1 A"),
+			dup("(a1 A, p1 P)"),
+			dup("type PT[T constraint] struct{ t T }"),
+			dup("PT"),
+			dup("[T constraint]"),
+			dup("constraint"),
+			dup("targ1"),
+			{" targ2", "targ2"},
+			dup("g[ targ2, targ3]"),
+		}...)
+	}
 	for _, test := range tests {
 		f, start, end := findInterval(t, new(token.FileSet), input, test.substr)
 		if f == nil {
@@ -145,13 +185,14 @@ func TestPathEnclosingInterval_Exact(t *testing.T) {
 }
 
 func TestPathEnclosingInterval_Paths(t *testing.T) {
+	type testCase struct {
+		substr string // first occurrence of this string indicates interval
+		path   string // the pathToString(),exact of the expected path
+	}
 	// For these tests, we check only the path of the enclosing
 	// node, but not its complete text because it's often quite
 	// large when !exact.
-	tests := []struct {
-		substr string // first occurrence of this string indicates interval
-		path   string // the pathToString(),exact of the expected path
-	}{
+	tests := []testCase{
 		{"// add",
 			"[BlockStmt FuncDecl File],false"},
 		{"(x + y",
@@ -179,6 +220,18 @@ func TestPathEnclosingInterval_Paths(t *testing.T) {
 		{"f() // NB",
 			"[CallExpr ExprStmt BlockStmt FuncDecl File],true"},
 	}
+	if typeparams.Enabled {
+		tests = append(tests, []testCase{
+			{" any", "[Ident Field FieldList FuncDecl File],true"},
+			{"|", "[BinaryExpr Field FieldList InterfaceType Field FieldList FuncDecl File],true"},
+			{"ctype2",
+				"[Ident UnaryExpr BinaryExpr Field FieldList InterfaceType Field FieldList FuncDecl File],true"},
+			{"a1", "[Ident Field FieldList FuncDecl File],true"},
+			{"PT[T constraint]", "[TypeSpec GenDecl File],false"},
+			{"[T constraint]", "[FieldList TypeSpec GenDecl File],true"},
+			{"targ2", "[Ident IndexListExpr ValueSpec GenDecl File],true"},
+		}...)
+	}
 	for _, test := range tests {
 		f, start, end := findInterval(t, new(token.FileSet), input, test.substr)
 		if f == nil {