Content from tags inside pre is missing whitespace characters

[johannesegger]

When emitting a parsed document whitespace characters are usually preserved for pre tags. The following test checks this.

https://github.com/fsharp/FSharp.Data/blob/33e6e825bc2978eb9ce6dd880f31d9e60d452699/tests/FSharp.Data.Tests/HtmlParser.fs#L763-L772

However that's not the case when there are child tags within the pre tag. As soon as the parser encounters a different tag, whitespace characters are removed. So e.g. when emitting the parsed document from the following snippet, whitespace characters after the span tag are missing. Whitespace before the span tag is not missing.

<pre>\r\n        This <span>code</span> should be indented and\r\n        have line feeds in it</pre>

The code that's responsible for "normalizing" whitespace characters is the following:

https://github.com/fsharp/FSharp.Data/blob/33e6e825bc2978eb9ce6dd880f31d9e60d452699/src/Html/HtmlParser.fs#L373-L382

And x.InsertionMode is calculated as follows:

https://github.com/fsharp/FSharp.Data/blob/49a3bfb22a8955463d7536af1d2df86449e335c6/src/Html/HtmlParser.fs#L353-L356

x.IsFormattedTag is only true if the last parsed tag is pre or code. It should check if it's currently inside a formatted tag, shouldn't it?

[hcoona]

Report a related behavior with minimal reproduce steps:

[<EntryPoint>]
let main argv =
    let n = List.exactlyOne (HtmlNode.Parse("""<pre>
%module graphics
%{
#include &lt;GL/gl.h&gt;
#include &lt;GL/glu.h&gt;
%}
    
// Put the rest of the declarations here
...
</pre>"""))
    printfn "%s" (n.InnerText())

would produce:

%module graphics
%{
#include <GL/gl.h> #include <GL/glu.h> %} // Put the rest of the declarations here ...

instead of (expected):

%module graphics
%{
#include <GL/gl.h>
#include <GL/glu.h>
%}
    
// Put the rest of the declarations here
...

[github-actions]

🤖 This is an automated response from Repo Assist, the repository's AI assistant.

This bug is still present in the current code, but a fix has recently been proposed. PR #1605 addresses exactly this issue by propagating an insidePre flag through the serialize function in HtmlNode.fs, ensuring that whitespace-normalisation is skipped for all content nested inside <pre> (or <code>) elements — not just for the immediate text children.

The root cause you identified is correct: x.InsertionMode / x.IsFormattedTag in HtmlParser.fs only tests whether the last parsed tag is pre/code, rather than whether the serialiser is currently inside a formatted block. PR #1605 fixes this at the serialisation layer.

If you'd like to follow along or test the fix, please see PR #1605.

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[dsyme]

Fix merged