Fix go-to-definition functionality at JS JSX tag edge (microsoft/typescript-go#4909)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: DanielRosenwasser <972891+DanielRosenwasser@users.noreply.github.com>
Co-authored-by: andrewbranch <3277153+andrewbranch@users.noreply.github.com>

Author: 3 people

tsc/_packages/native-preview/src/ast/astnav.ts

@@ -130,8 +130,19 @@ function getTokenAtPositionImpl(
         left: 0,
     };
 
+    const getIncludedPrecedingToken = (subtree: Node): Node | undefined => {
+        const child = findPrecedingTokenImpl(sourceFile, position, subtree);
+        if (child !== undefined && child.end === position && includePrecedingTokenAtEndPosition!(child)) {
+            return child;
+        }
+        return undefined;
+    };
+
     const testNode = (node: Node): number => {
         if (node.kind !== SyntaxKind.EndOfFile && node.end === position && includePrecedingTokenAtEndPosition !== undefined) {
+            if (state.prevSubtree !== undefined && getIncludedPrecedingToken(state.prevSubtree) !== undefined) {
+                return 0;
+            }
             state.prevSubtree = node;
         }
         // A node "contains" the position if position < end, except nodes at the file end
@@ -243,8 +254,8 @@ function getTokenAtPositionImpl(
 
         // If prevSubtree was set, check if the rightmost token of prevSubtree should be returned.
         if (state.prevSubtree !== undefined) {
-            const child = findPrecedingTokenImpl(sourceFile, position, state.prevSubtree);
-            if (child !== undefined && child.end === position && includePrecedingTokenAtEndPosition!(child)) {
+            const child = getIncludedPrecedingToken(state.prevSubtree);
+            if (child !== undefined) {
                 return child;
             }
             state.prevSubtree = undefined;

tsc/internal/astnav/tokens.go

@@ -63,9 +63,20 @@ func getTokenAtPosition(
 	// When scanning in between nodes for token, we should only scan up to the start of `nodeAfterLeft`.
 	var nodeAfterLeft *ast.Node
 
+	getIncludedPrecedingToken := func(subtree *ast.Node) *ast.Node {
+		child := FindPrecedingTokenEx(sourceFile, position, subtree, false /*excludeJSDoc*/)
+		if child != nil && child.End() == position && includePrecedingTokenAtEndPosition(child) {
+			return child
+		}
+		return nil
+	}
+
 	testNode := func(node *ast.Node) int {
 		if node.Kind != ast.KindEndOfFile && node.End() == position &&
 			includePrecedingTokenAtEndPosition != nil && node.Flags&ast.NodeFlagsReparsed == 0 {
+			if prevSubtree != nil && getIncludedPrecedingToken(prevSubtree) != nil {
+				return 0
+			}
 			prevSubtree = node
 		}
 
@@ -191,8 +202,7 @@ func getTokenAtPosition(
 		// Check if the rightmost token of prevSubtree should be returned based on the
 		// `includePrecedingTokenAtEndPosition` callback.
 		if prevSubtree != nil {
-			child := FindPrecedingTokenEx(sourceFile, position, prevSubtree, false /*excludeJSDoc*/)
-			if child != nil && child.End() == position && includePrecedingTokenAtEndPosition(child) {
+			if child := getIncludedPrecedingToken(prevSubtree); child != nil {
 				// Optimization: includePrecedingTokenAtEndPosition only ever returns true
 				// for real AST nodes, so we don't run the scanner here.
 				return child

tsc/internal/fourslash/tests/goToDefinitionJsxTagNameRightEdge_test.go

@@ -0,0 +1,26 @@
+package fourslash_test
+
+import (
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/fourslash"
+	"github.com/microsoft/typescript-go/internal/testutil"
+)
+
+func TestGoToDefinitionJsxTagNameRightEdge(t *testing.T) {
+	t.Parallel()
+	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
+	const content = `// @allowJs: true
+// @jsx: react-jsx
+// @filename: /a.jsx
+export function Component() {
+    return null;
+}
+
+export function App() {
+    return <Component/*use*/ />
+}`
+	f, done := fourslash.NewFourslash(t, nil /*capabilities*/, content)
+	defer done()
+	f.VerifyBaselineGoToDefinition(t, true, "use")
+}

tsc/testdata/baselines/reference/fourslash/goToDefinition/goToDefinitionJsxTagNameRightEdge.baseline.jsonc

@@ -0,0 +1,9 @@
+// === goToDefinition ===
+// === /a.jsx ===
+// <|export function [|Component|]() {
+//     return null;
+// }|>
+// 
+// export function App() {
+//     return <Component/*GOTO DEF*/ />
+// }