Exception while display C/C++ symbols in Project Explorer

[ghentschke]

When a user wants to display the symbols of a C/C++ header or source file in the Project Explorer by clicking on the expand icon:

the icon vanishes:

and no children (symbols of the file) will be displayed.
Reason is this exception:

!ENTRY org.eclipse.lsp4e 4 0 2024-07-26 14:09:22.006
!MESSAGE Error occured during evaluation of enablement expression
!STACK 1
org.eclipse.core.runtime.CoreException: Error evaluating Property [org.eclipse.cdt.lsp.server.enable.hasLanguageServer, type=class java.net.URI, tester=org.eclipse.cdt.lsp.internal.server.HasLanguageServerPropertyTester@50017595]
	at org.eclipse.core.internal.expressions.Property.test(Property.java:68)
	at org.eclipse.core.expressions.TestExpression.evaluate(TestExpression.java:107)
	at org.eclipse.core.expressions.CompositeExpression.evaluateAnd(CompositeExpression.java:54)
	at org.eclipse.core.expressions.WithExpression.evaluate(WithExpression.java:84)
	at org.eclipse.core.expressions.ReferenceExpression.evaluate(ReferenceExpression.java:72)
	at org.eclipse.lsp4e.enablement.EnablementTester.evaluate(EnablementTester.java:90)
	at org.eclipse.lsp4e.ContentTypeToLanguageServerDefinition.isExtensionEnabled(ContentTypeToLanguageServerDefinition.java:52)
	at org.eclipse.lsp4e.ContentTypeToLanguageServerDefinition.isEnabled(ContentTypeToLanguageServerDefinition.java:37)
	at org.eclipse.lsp4e.LanguageServiceAccessor.getLSWrappers(LanguageServiceAccessor.java:303)
	at org.eclipse.lsp4e.LanguageServers$LanguageServerDocumentExecutor.getServers(LanguageServers.java:296)
	at org.eclipse.lsp4e.LanguageServers.executeOnServers(LanguageServers.java:437)
	at org.eclipse.lsp4e.LanguageServers.computeFirst(LanguageServers.java:172)
	at org.eclipse.cdt.lsp.internal.ui.navigator.SymbolsManager.refreshTreeContentFromLS(SymbolsManager.java:247)
	at org.eclipse.cdt.lsp.internal.ui.navigator.SymbolsManager.getCompileUnitElements(SymbolsManager.java:223)
	at org.eclipse.cdt.lsp.internal.ui.navigator.SymbolsManager.fetchDeferredChildren(SymbolsManager.java:129)
	at org.eclipse.ui.progress.DeferredTreeContentManager$1.run(DeferredTreeContentManager.java:215)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)
Caused by: java.lang.IllegalArgumentException: Attempted to beginRule: P/MyCmake, does not match outer scope rule: L/MyCmake/MyCmake.cpp
	at org.eclipse.core.runtime.Assert.isLegal(Assert.java:68)
	at org.eclipse.core.internal.jobs.ThreadJob.illegalPush(ThreadJob.java:144)
	at org.eclipse.core.internal.jobs.ThreadJob.push(ThreadJob.java:416)
	at org.eclipse.core.internal.jobs.ImplicitJobs.begin(ImplicitJobs.java:88)
	at org.eclipse.core.internal.jobs.JobManager.beginRule(JobManager.java:343)
	at org.eclipse.core.internal.resources.WorkManager.checkIn(WorkManager.java:124)
	at org.eclipse.core.internal.resources.Workspace.prepareOperation(Workspace.java:2401)
	at org.eclipse.core.internal.resources.File.create(File.java:129)
	at org.eclipse.core.internal.resources.File.create(File.java:203)
	at org.eclipse.cdt.lsp.clangd.utils.ClangFormatUtils.createFileFromResource(ClangFormatUtils.java:57)
	at org.eclipse.cdt.lsp.clangd.utils.ClangFormatUtils.createClangFormatFile(ClangFormatUtils.java:48)
	at org.eclipse.cdt.lsp.clangd.internal.config.ClangdLanguageServerProvider.preFileOpening(ClangdLanguageServerProvider.java:78)
	at org.eclipse.cdt.lsp.internal.server.HasLanguageServerPropertyTester.preFileOpening(HasLanguageServerPropertyTester.java:99)
	at org.eclipse.cdt.lsp.internal.server.HasLanguageServerPropertyTester.test(HasLanguageServerPropertyTester.java:62)
	at org.eclipse.core.internal.expressions.Property.test(Property.java:65)
	... 16 more
!SUBENTRY 1 org.eclipse.core.expressions 4 0 2024-07-26 14:09:22.006
!MESSAGE Error evaluating Property [org.eclipse.cdt.lsp.server.enable.hasLanguageServer, type=class java.net.URI, tester=org.eclipse.cdt.lsp.internal.server.HasLanguageServerPropertyTester@50017595]
!STACK 0
java.lang.IllegalArgumentException: Attempted to beginRule: P/MyCmake, does not match outer scope rule: L/MyCmake/MyCmake.cpp
	at org.eclipse.core.runtime.Assert.isLegal(Assert.java:68)
	at org.eclipse.core.internal.jobs.ThreadJob.illegalPush(ThreadJob.java:144)
	at org.eclipse.core.internal.jobs.ThreadJob.push(ThreadJob.java:416)
	at org.eclipse.core.internal.jobs.ImplicitJobs.begin(ImplicitJobs.java:88)
	at org.eclipse.core.internal.jobs.JobManager.beginRule(JobManager.java:343)
	at org.eclipse.core.internal.resources.WorkManager.checkIn(WorkManager.java:124)
	at org.eclipse.core.internal.resources.Workspace.prepareOperation(Workspace.java:2401)
	at org.eclipse.core.internal.resources.File.create(File.java:129)
	at org.eclipse.core.internal.resources.File.create(File.java:203)
	at org.eclipse.cdt.lsp.clangd.utils.ClangFormatUtils.createFileFromResource(ClangFormatUtils.java:57)
	at org.eclipse.cdt.lsp.clangd.utils.ClangFormatUtils.createClangFormatFile(ClangFormatUtils.java:48)
	at org.eclipse.cdt.lsp.clangd.internal.config.ClangdLanguageServerProvider.preFileOpening(ClangdLanguageServerProvider.java:78)
	at org.eclipse.cdt.lsp.internal.server.HasLanguageServerPropertyTester.preFileOpening(HasLanguageServerPropertyTester.java:99)
	at org.eclipse.cdt.lsp.internal.server.HasLanguageServerPropertyTester.test(HasLanguageServerPropertyTester.java:62)
	at org.eclipse.core.internal.expressions.Property.test(Property.java:65)
	at org.eclipse.core.expressions.TestExpression.evaluate(TestExpression.java:107)
	at org.eclipse.core.expressions.CompositeExpression.evaluateAnd(CompositeExpression.java:54)
	at org.eclipse.core.expressions.WithExpression.evaluate(WithExpression.java:84)
	at org.eclipse.core.expressions.ReferenceExpression.evaluate(ReferenceExpression.java:72)
	at org.eclipse.lsp4e.enablement.EnablementTester.evaluate(EnablementTester.java:90)
	at org.eclipse.lsp4e.ContentTypeToLanguageServerDefinition.isExtensionEnabled(ContentTypeToLanguageServerDefinition.java:52)
	at org.eclipse.lsp4e.ContentTypeToLanguageServerDefinition.isEnabled(ContentTypeToLanguageServerDefinition.java:37)
	at org.eclipse.lsp4e.LanguageServiceAccessor.getLSWrappers(LanguageServiceAccessor.java:303)
	at org.eclipse.lsp4e.LanguageServers$LanguageServerDocumentExecutor.getServers(LanguageServers.java:296)
	at org.eclipse.lsp4e.LanguageServers.executeOnServers(LanguageServers.java:437)
	at org.eclipse.lsp4e.LanguageServers.computeFirst(LanguageServers.java:172)
	at org.eclipse.cdt.lsp.internal.ui.navigator.SymbolsManager.refreshTreeContentFromLS(SymbolsManager.java:247)
	at org.eclipse.cdt.lsp.internal.ui.navigator.SymbolsManager.getCompileUnitElements(SymbolsManager.java:223)
	at org.eclipse.cdt.lsp.internal.ui.navigator.SymbolsManager.fetchDeferredChildren(SymbolsManager.java:129)
	at org.eclipse.ui.progress.DeferredTreeContentManager$1.run(DeferredTreeContentManager.java:215)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

Steps to reproduce:

1. Create a C/C++ project with no .clang-format file in the project root folder.
2. Ensure that the project contains a C/C++ source file.
3. Ensure that no C/C++ file is opened in the new LSP based editor.
4. Enable the LSP Editor for this project
5. Try to Expand the children of the C/C++ project as described above