@hvitved, would you be able to take a look at this? I think it is mostly what you want (except for the limitations mentioned above).

I have tested the extension with this query, on a Ruby test DB, and that works just fine, except it keeps printing "Rendering graph" even after it has been rendered:

I also tested with this Print CFG query, running the "View CFG" command, but that results in Graph is not available. (an empty graph, I believe).

Thanks again for picking up this task.

Thanks for verifying.

Yes...the rendering graph message is something I need to fix.

And see my point (5) above about why the print ast query is not working. The most correct fix would be from inside of the CLI, which I don't have capacity to do right now. Another work around could be done in vscode itself. I'll see if I can get to that. First priority is getting this feature released internally.

And see my point (5) above about why the print ast query is not working. The most correct fix would be from inside of the CLI, which I don't have capacity to do right now. Another work around could be done in vscode itself. I'll see if I can get to that. First priority is getting this feature released internally.

I agree that this should not be a blocker. I tried changing the ID to rb-print-cfg, but that still produces an empty graph.

Using this variant of the print AST query for cpp, I was able to get a graph to be viewed:

/**
 * @name Print AST
 * @description Outputs a representation of a file's Abstract Syntax Tree. This
 *              query is used by the VS Code extension.
 * @id cpp-print-ast
 * @kind graph
 * @tags ide-contextual-queries/print-ast
 */

import cpp
import semmle.code.cpp.PrintAST
import definitions

/**
 * The source file to generate an AST from.
 */
// external string selectedSourceFile();

class Cfg extends PrintASTConfiguration {
  /**
   * Holds if the AST for `func` should be printed.
   * Print All functions from the selected file.
   */
  override predicate shouldPrintFunction(Function func) {
    func.getFile().getBaseName() = "cpu.c" and func.getName() = "sandbox_read_fdt_from_file"
  }
}

I also removed the Rendering graph... text and got the tests passing (I think).

Lat thing I want to do here is just add a message in the graph viewer itself on what the limitations are and where to go for more support so that if external users do start using this, we can set their expectations appropriately.

OK... finished and ready for a review. This has been fixed:

5. Lastly, there is a small bug in how the @id is interpreted. Any
@id with a / in it will place the .dot in a location that
can't be found by vscode. So, just don't name your queries with any
/.

Also, there is a warning on the results view whenever you view a graph. And I have ensured that this feature is disabled if the canary flag is off.

Here is a sample query that I have been using for the graph:

/**
 * @name Print AST
 * @description Outputs a representation of a file's Abstract Syntax Tree. This
 *              query is used by the VS Code extension.
 * @id id/cpp-print-ast
 * @kind graph
 * @tags ide-contextual-queries/print-ast
 */

import cpp
import semmle.code.cpp.PrintAST
import definitions

class Cfg extends PrintASTConfiguration {
  override predicate shouldPrintFunction(Function func) {
    func.getFile().getBaseName() = "cpu.c" and func.getName() = "sandbox_read_fdt_from_file"
  }
}

It is adapted from the cpp printAST query. Replace the RHS of the getBaseName comparison with a cpp file in a source archive and getName with a name of a function.

If you want to try out the View CFG command, choose any print AST query and add a new tag ide-contextual-queries/print-cfg. Then go to a small source file in a database of the same language, right click and select View CFG.

@shati-patel, @cklin this is ready for your review now. I fixed a race condition that sometimes prevented a graph from appearing. See the second to last commit.

Forgot to mention that if you want to view a graph, you need to regenerate the web view. To do that, run npm run build in the vscode-codeql/extensions/ql-vscode directory.

cc: @cklin since I'm not sure if you're aware of this.