Improve .Position for included content rendered with RenderShortcodes

[bep]

While the work in #14664 certainly significantly improves this situation, the failing test below illustrates a potential improvement. I think most people would expect the output below (useful for "Edit this title" links). Note that if you replace RenderShortcodes with Content the test passes, but that has other unwanted side effects.

With Goldmark now having source positions for all nodes, I think it should be possible to calculate offsets in nested structures similar to the below. Not trivial, but possible. I think.

func TestRenderHooksPositionNested(t *testing.T) {
	t.Parallel()

	files := `
-- hugo.toml --
-- layouts/_markup/render-heading.html --
{{ $pos := .Position }}
{{ $pos.Filename }}|{{ printf "%d:%d" $pos.LineNumber $pos.ColumnNumber }}|{{ $.Ordinal }}|
-- layouts/_shortcodes/include.html --
{{ $p := site.GetPage (.Get 0) }}
{{ $p.RenderShortcodes }}
-- layouts/all.html --
{{ .Content }}
-- content/p1.md --
---
title: "p1"
---

## My Heading 2
{{% include "headings" %}}
-- content/headings.md --
## My Heading 3
## My Heading 4

`

	b := hugolib.Test(t, files)
	b.AssertFileContent("public/p1/index.html", `
 content/p1.md|5:1|
 content/headings.md|1:1|
 content/headings.md|2:1|
	`)
}

/cc @jmooring

[jmooring]

the failing test below

I haven't spent any time looking at the details here, but my first question is, "Would this test fail for render hooks that already had Position in context prior to your work in #14664?"

I can't recall any forum topics related to Position problems when calling RenderShortcodes so it either works or is a low priority.

[bep]

"Would this test fail for render hooks that already had Position in context prior to your work in #14664?"

• In the release version of Hugo we do a text search in the entry source file (content/p1.md) which didn't resolve anything in the test case above.
• In Improve the render hooks .Position #14664 you will always get a position; in the shortcode example above you will get the position of the shortcode inclusion point {{% include "headings" %}}.