ResourceException when ' Save As...' on text file in workspace

[ghentschke]

A ResourceException exception will be thrown when a Save As... will be performed on a opened text file wihin the workspace:

!ENTRY org.eclipse.cdt.lsp 4 0 2023-08-17 13:51:54.974
!MESSAGE Resource '/Cmk1/.clangdNew' does not exist.
!STACK 1
org.eclipse.core.internal.resources.ResourceException(/Cmk1/.clangdNew)[368]: java.lang.Exception: Resource '/Cmk1/.clangdNew' does not exist.
	at org.eclipse.core.internal.resources.ResourceException.provideStackTrace(ResourceException.java:42)
	at org.eclipse.core.internal.resources.ResourceException.<init>(ResourceException.java:38)
	at org.eclipse.core.internal.resources.Resource.checkExists(Resource.java:330)
	at org.eclipse.core.internal.resources.Resource.checkAccessible(Resource.java:204)
	at org.eclipse.core.internal.resources.File.getContentDescription(File.java:255)
	at org.eclipse.core.internal.filebuffers.ResourceTextFileBuffer.getContentType(ResourceTextFileBuffer.java:201)
	at org.eclipse.cdt.lsp.ui.navigator.CSymbolsContentProvider$1.dirtyStateChanged(CSymbolsContentProvider.java:72)

It's caused by a IFileBuffer.getContentType() call in org.eclipse.cdt.lsp.ui.navigator.CSymbolsContentProvider.fileBufferListener.new FileBufferListenerAdapter() {...}.dirtyStateChanged(IFileBuffer, boolean)

It seems to be that dirtyStateChanged gets called before the file creation has been finished. May be it should be fixed in org.eclipse.core.internal.filebuffers.ResourceTextFileBuffer.getContentType() as well:

@Override
public IContentType getContentType() throws CoreException {
try {
	if (isDirty()) {
		try(Reader reader = new DocumentReader(getDocument())) {
			IContentDescription desc= Platform.getContentTypeManager().getDescriptionFor(reader, fFile.getName(), NO_PROPERTIES);
			if (desc != null && desc.getContentType() != null)
				return desc.getContentType();
		}
	}
	IContentDescription desc= fFile.getContentDescription();
	if (desc != null && desc.getContentType() != null)
		return desc.getContentType();
	return null;
} catch (IOException x) {
	throw new CoreException(new Status(IStatus.ERROR, FileBuffersPlugin.PLUGIN_ID, IStatus.OK, NLSUtility.format(FileBuffersMessages.FileBuffer_error_queryContentDescription, fFile.getFullPath().toOSString()), x));
}
}

The exception will be triggered in the call fFile.getContentDescription();
A check fFile.exists() prior to the call would fix it.

Steps to reproduce

Start Eclipse IDE with cdt and cdt-lsp plugin runnning. Then:

1. Open a text file (i.e. .clangd) form workspace project in the editor.
2. Set focus on that editor tab
3. Select File -> Save As..
4. Save file with new name in other workspace project
5. See the stack trace as above in the log