"Literal cannot be cast Identifier" when processing new ECMAScript/TypeScript export/import syntax

[jakebailey]

Description of the issue

In the TypeScript repo, we have tests which include very new ECMAScript syntax; in particular https://github.com/microsoft/TypeScript/blob/56a08250f3516b3f5bc120d6c7ab4450a9a69352/tests/cases/conformance/es2022/arbitraryModuleNamespaceIdentifiers/arbitraryModuleNamespaceIdentifiers_module.ts contains a new syntax for imports/exports that uses string literals instead of identifiers.

CodeQL scans our tests (depending on our config), and then crashes when encountering this code:

[2024-12-17 17:54:44] [build-stdout] Extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2021/logicalAssignment/logicalAssignment9.ts
[2024-12-17 17:54:44] [build-stdout] Done extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2021/logicalAssignment/logicalAssignment9.ts (0 ms)
[2024-12-17 17:54:44] [build-stdout] Extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2022/arbitraryModuleNamespaceIdentifiers/arbitraryModuleNamespaceIdentifiers_exportEmpty.ts
[2024-12-17 17:54:44] [build-stdout] Done extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2022/arbitraryModuleNamespaceIdentifiers/arbitraryModuleNamespaceIdentifiers_exportEmpty.ts (1 ms)
[2024-12-17 17:54:44] [build-stdout] Extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2022/arbitraryModuleNamespaceIdentifiers/arbitraryModuleNamespaceIdentifiers_importEmpty.ts
[2024-12-17 17:54:44] [build-stdout] Done extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2022/arbitraryModuleNamespaceIdentifiers/arbitraryModuleNamespaceIdentifiers_importEmpty.ts (1 ms)
[2024-12-17 17:54:44] [build-stdout] Extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2022/arbitraryModuleNamespaceIdentifiers/arbitraryModuleNamespaceIdentifiers_module.ts
[2024-12-17 17:54:44] [build-stderr] Exception while extracting /mnt/vss/_work/1/s/tests/cases/conformance/es2022/arbitraryModuleNamespaceIdentifiers/arbitraryModuleNamespaceIdentifiers_module.ts.
[2024-12-17 17:54:44] [build-stderr] java.lang.ClassCastException: class com.semmle.js.ast.Literal cannot be cast to class com.semmle.js.ast.Identifier (com.semmle.js.ast.Literal and com.semmle.js.ast.Identifier are in unnamed module of loader 'app')
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertExportSpecifier(TypeScriptASTConverter.java:1220)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNodeUntyped(TypeScriptASTConverter.java:416)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNode(TypeScriptASTConverter.java:318)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNode(TypeScriptASTConverter.java:310)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNodes(TypeScriptASTConverter.java:709)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertChildren(TypeScriptASTConverter.java:777)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertChildren(TypeScriptASTConverter.java:756)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertExportDeclaration(TypeScriptASTConverter.java:1212)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNodeUntyped(TypeScriptASTConverter.java:414)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNode(TypeScriptASTConverter.java:318)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNode(TypeScriptASTConverter.java:310)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNodes(TypeScriptASTConverter.java:709)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNodes(TypeScriptASTConverter.java:697)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertSourceFile(TypeScriptASTConverter.java:2161)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNodeUntyped(TypeScriptASTConverter.java:563)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNode(TypeScriptASTConverter.java:318)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertNode(TypeScriptASTConverter.java:310)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptASTConverter.convertAST(TypeScriptASTConverter.java:217)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.ts.extractor.TypeScriptParser.parse(TypeScriptParser.java:440)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.TypeScriptExtractor.extract(TypeScriptExtractor.java:24)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.FileExtractor.extractContents(FileExtractor.java:553)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.FileExtractor.extract(FileExtractor.java:460)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.AutoBuild.doExtract(AutoBuild.java:1255)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.AutoBuild.extract(AutoBuild.java:1241)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.AutoBuild.extractTypeScriptFiles(AutoBuild.java:1194)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.AutoBuild.extractTypeScript(AutoBuild.java:1091)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.AutoBuild.extractSource(AutoBuild.java:758)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.AutoBuild.run(AutoBuild.java:464)
[2024-12-17 17:54:44] [build-stderr] 	at com.semmle.js.extractor.AutoBuild.main(AutoBuild.java:1360)

I don't think this syntax is supported yet, but the crash seems to halt database generation, which means that any files after a file with the bad syntax are entirely skipped.

For TypeScript, we can theoretically just ignore these paths, but this syntax will eventually make its way into user code and npm, where it will also cause crashes.

[erik-krogh]

Thanks for the detailed report.

The issue should be fixed with #18336.
That fix should land with CodeQL 2.20.2, which should release at the end of the month.