Panic on initial attempt of existing JavaScript + JSDoc project

[jbrimeyer-leepfrog]

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).GetDiagnostics(...)
	github.com/microsoft/typescript-go/internal/checker/checker.go:13499
github.com/microsoft/typescript-go/internal/compiler.(*Program).getBindAndCheckDiagnosticsForFile(0x14000173400, {0x1032a1600, 0x10391c860}, 0x14002521508)
	github.com/microsoft/typescript-go/internal/compiler/program.go:1052 +0xd4
github.com/microsoft/typescript-go/internal/compiler.(*Program).getSemanticDiagnosticsForFile(0x14000173400, {0x1032a1600?, 0x10391c860?}, 0x14002521508)
	github.com/microsoft/typescript-go/internal/compiler/program.go:1034 +0x2c
github.com/microsoft/typescript-go/internal/compiler.(*Program).collectDiagnostics(0x26a85cc000037fe8?, {0x1032a1600, 0x10391c860}, 0x1027aad2c?, 0x14006a85fd8)
	github.com/microsoft/typescript-go/internal/compiler/program.go:429 +0x10c
github.com/microsoft/typescript-go/internal/compiler.(*Program).GetSemanticDiagnostics(0x0?, {0x1032a1600?, 0x10391c860?}, 0x102b904b4?)
	github.com/microsoft/typescript-go/internal/compiler/program.go:453 +0x34
github.com/microsoft/typescript-go/internal/execute/tsc.EmitFilesAndReportErrors.func2({0x1032a1600, 0x10391c860}, 0x0)
	github.com/microsoft/typescript-go/internal/execute/tsc/emit.go:91 +0x68
github.com/microsoft/typescript-go/internal/compiler.GetDiagnosticsOfAnyProgram({0x1032a1600, 0x10391c860}, {0x1032a8958, 0x14000173400}, 0x0, 0x0, 0x14000038270, 0x140000381e8)
	github.com/microsoft/typescript-go/internal/compiler/program.go:1468 +0x364
github.com/microsoft/typescript-go/internal/execute/tsc.EmitFilesAndReportErrors({{0x1032a6458, 0x1400007acc0}, {0x1032a8958, 0x14000173400}, 0x14000173400, 0x140002222c0, 0x140002f8120, 0x140002f8140, {0x10329cd68, 0x14000060020}, ...})
	github.com/microsoft/typescript-go/internal/execute/tsc/emit.go:75 +0x13c
github.com/microsoft/typescript-go/internal/execute/tsc.EmitAndReportStatistics({{0x1032a6458, 0x1400007acc0}, {0x1032a8958, 0x1
4000173400}, 0x14000173400, 0x140002222c0, 0x140002f8120, 0x140002f8140, {0x10329cd68, 0x14000060020}, ...})
	github.com/microsoft/typescript-go/internal/execute/tsc/emit.go:45 +0x104
github.com/microsoft/typescript-go/internal/execute.performCompilation({0x1032a6458, 0x1400007acc0}, 0x140002222c0, 0x140002f8120, 0x140002f8140, {0x10329d380, 0x14000021c50}, 0x1400002d740, {0x0, 0x0})
	github.com/microsoft/typescript-go/internal/execute/tsc.go:318 +0x30c
github.com/microsoft/typescript-go/internal/execute.tscCompilation({0x1032a6458, 0x1400007acc0}, 0x14000222000, {0x0, 0x0})
	github.com/microsoft/typescript-go/internal/execute/tsc.go:228 +0xbd0
github.com/microsoft/typescript-go/internal/execute.CommandLine({0x1032a6458, 0x1400007acc0}, {0x14000020130, 0x2, 0x2}, {0x0, 0x0})
	github.com/microsoft/typescript-go/internal/execute/tsc.go:35 +0x18c
main.runMain()
	github.com/microsoft/typescript-go/cmd/tsgo/main.go:23 +0x120
main.main()
	github.com/microsoft/typescript-go/cmd/tsgo/main.go:10 +0x1c

tsconfig.json

{
	"compilerOptions": {
		"strict": true,
		"noEmit": true,
		"noUnusedLocals": true,
		"noUnusedParameters": true,
		"forceConsistentCasingInFileNames": true,
		"allowJs": true,
		"checkJs": true,
		"target": "ES2020",
		"module": "ES2020",
		"lib": [
			"es2021"
		]
	},
	"include": [
		"typings/server/**/*",
		"**/*.js",
		"**/types.d.ts",
		"test/**/*"
	]
}

[jakebailey]

I don't think this is enough information for us to investigate. Do you have the code?

[jbrimeyer-leepfrog]

I do, but I cannot provide the source here. Suggestions on how to provide more information to track this down?

[jakebailey]

You'll probably need to start deleting code out of your project until you find the code that's breaking things.

[jbrimeyer-leepfrog]

In a file test.js:

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

Run npx tsgo --allowJs --noEmit test.js to get the panic.

tsgo version: Version 7.0.0-dev.20251204.1

[jakebailey]

@ahejlsberg you self assigned this, not sure if you saw #2221 (comment) but we are dumping method overloads into the source file for these object method overloads, and I am not even sure if one can write these legally in TS. i.e. you can't do

const foo = {
	getStatus(termCode: string, crnList: string[], sis: string): Record<string, string>;
	getStatus(termCode: string, crnList: string, sis: string): string;
	getStatus(termCode: string, crnList: string | string[], sis: string): string | Record<string, string> {},
};

I do not think we can do this without either allowing new TS syntax, or adding back more hacks in the checker to deal with this.

[sandersn]

I am against hacks. It should be added as a TS language feature in 7.1 if it's important enough of a feature, and then the jsdoc reparsing can be fixed up as needed then for it to work in JS.

[ahejlsberg]

Right, the fix I'm going to put up will be to ignore @overload tags unless they occur on function, method, or constructor declarations outside object literals (because then we can reparse as overload declarations).