typescript-go icon indicating copy to clipboard operation
typescript-go copied to clipboard
Published 2 weeks ago • verified publisher icon microsoft

Fix panic by restricting @overload to legal contexts in JSDoc

Open Copilot opened this issue 3 weeks ago • 7 comments

Panic when type-checking JavaScript files with JSDoc @overload annotations, caused by invalid AST structures created by the reparser.

Root Cause

The reparser was creating synthetic MethodDeclaration nodes for ALL @overload JSDoc tags, including those on object literal methods. This created invalid AST structures where a MethodDeclaration was a direct child of SourceFile (e.g., for methods in object literals), resulting in the panic:

KindStringKeyword -> KindParameter -> KindMethodDeclaration -> KindSourceFile

Changes

  • Modified reparseUnhosted() to only create synthetic overload declarations for legal contexts:
    • Function declarations (KindFunctionDeclaration)
    • Class methods (KindMethodDeclaration when not in PCObjectLiteralMembers parsing context)
    • Interface methods (KindMethodSignature)
  • Reports parsing error TS8110 for @overload tags on object literal methods
  • Added nil check in getConditionalFlowTypeOfType to prevent panic when nodes have nil parents
  • Added new diagnostic message TS8110: "A JSDoc '@overload' tag is not allowed in this context."
  • Added regression test case with JSDoc overloads that previously panicked

Example

The following JavaScript now reports a parsing error instead of panicking:

const foo = {
	/**
	 * @overload
	 * @param {string} termCode
	 * @param {string[]} crnList
	 * @returns {Record<string, string>}
	 */
	/**
	 * @param {string} termCode
	 * @param {string | string[]} crnList
	 * @returns {string | Record<string, string>}
	 */
	getStatus(termCode, crnList) {},
};

Error: error TS8110: A JSDoc '@overload' tag is not allowed in this context.

Function declarations and class methods with @overload continue to work correctly with proper overload declarations generated in .d.ts files.

Impact

This fix properly addresses the panic while maintaining full support for legal @overload use cases in function and class/interface method declarations. Object literal methods with @overload tags now receive appropriate parsing errors.

Original prompt

This section details on the original issue you should resolve

<issue_title>Panic on initial attempt of existing JavaScript + JSDoc project</issue_title> <issue_description>## Stack trace

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x0 pc=0x102a8783c]

goroutine 1 [running]:
github.com/microsoft/typescript-go/internal/ast.IsParameter(...)
	github.com/microsoft/typescript-go/internal/ast/ast.go:3976
github.com/microsoft/typescript-go/internal/checker.(*Checker).getConditionalFlowTypeOfType(0x14003eb4c08, 0x140043b8410, 0x14006a85658?)
	github.com/microsoft/typescript-go/internal/checker/checker.go:24330 +0xac
github.com/microsoft/typescript-go/internal/checker.(*Checker).getTypeFromTypeNode(0x14003eb4c08, 0x14002531fc8)
	github.com/microsoft/typescript-go/internal/checker/checker.go:22257 +0x34
github.com/microsoft/typescript-go/internal/checker.(*Checker).tryGetTypeFromTypeNode(0x14003eb4c08, 0x102a634bc?)
	github.com/microsoft/typescript-go/internal/checker/checker.go:22251 +0x34
github.com/microsoft/typescript-go/internal/checker.(*Checker).getTypeForVariableLikeDeclaration(0x14003eb4c08, 0x14002563468, 0x0?, 0x0)
	github.com/microsoft/typescript-go/internal/checker/checker.go:16187 +0x17c
github.com/microsoft/typescript-go/internal/checker.(*Checker).getWidenedTypeForVariableLikeDeclaration(0x14003eb4c08, 0x14002563468, 0x1)
	github.com/microsoft/typescript-go/internal/checker/checker.go:16158 +0x30
github.com/microsoft/typescript-go/internal/checker.(*Checker).getTypeOfVariableOrParameterOrPropertyWorker(0x14003eb4c08, 0x14003d68a18)
	github.com/microsoft/typescript-go/internal/checker/checker.go:16118 +0x24c
github.com/microsoft/typescript-go/internal/checker.(*Checker).getTypeOfVariableOrParameterOrProperty(0x14003eb4c08, 0x14003d68a18)
	github.com/microsoft/typescript-go/internal/checker/checker.go:16055 +0x50
github.com/microsoft/typescript-go/internal/checker.(*Checker).getTypeOfSymbol(0x14003eb4c08?, 0x14002563468?)
	github.com/microsoft/typescript-go/internal/checker/checker.go:16015 +0xa8
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkVariableLikeDeclaration(0x14003eb4c08, 0x14002563468)
	github.com/microsoft/typescript-go/internal/checker/checker.go:5703 +0x258
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkParameter(0x14003eb4c08, 0x14002563468)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2559 +0x30
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSourceElementWorker(0x14003eb4c08, 0x14002563468)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2179 +0xa0
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSourceElement(0x14003eb4c08, 0x102a1f250?)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2150 +0x58
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSourceElements(0x14003eb4c08, {0x1400211ce40, 0x3, 0x0?})
	github.com/microsoft/typescript-go/internal/checker/checker.go:2140 +0x34
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSignatureDeclaration(0x14003eb4c08, 0x140025126e0)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2631 +0x100
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkFunctionOrMethodDeclaration(0x14003eb4c08, 0x140025126e0)
	github.com/microsoft/typescript-go/internal/checker/checker.go:3297 +0x30
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkMethodDeclaration(0x14003eb4c08, 0x140025126e0)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2694 +0x14c
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSourceElementWorker(0x14003eb4c08, 0x140025126e0)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2187 +0xb8
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSourceElement(0x14003eb4c08, 0x140046fb5f0?)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2150 +0x58
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSourceElements(0x14003eb4c08, {0x140017bcc58, 0x1c, 0x140019fedc0?})
	github.com/microsoft/typescript-go/internal/checker/checker.go:2140 +0x34
github.com/microsoft/typescript-go/internal/checker.(*Checker).checkSourceFile(0x14003eb4c08, {0x1032a1600, 0x10391c860}, 0x14002521508)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2112 +0xf4
github.com/microsoft/typescript-go/internal/checker.(*Checker).CheckSourceFile(0x14003eb4c08, {0x1032a1600, 0x10391c860}, 0x14002521508)
	github.com/microsoft/typescript-go/internal/checker/checker.go:2101 +0x64
github.com/microsoft/typescript-go/internal/checker.(*Checker).getDiagnostics(0x14003eb4c08, {0x1032a1600, 0x10391c860}, 0x14002521508, 0x14003eb4df0)
	github.com/microsoft/typescript-go/internal/checker/checker.go:13516 +0xac
github.com/microsoft/typescript-go/internal/checker.(*Checker).GetDiagno...

</details>

- Fixes microsoft/typescript-go#2218

<!-- START COPILOT CODING AGENT TIPS -->
---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more [Copilot coding agent tips](https://gh.io/copilot-coding-agent-tips) in the docs.

Copilot avatar Dec 04 '25 17:12 Copilot