don't fill plain shaped nodes

[makelinux]

for configuration with
DOT_NODE_ATTR = shape=plaintext

because filling is intended for record or box shaped Graphviz nodes.
Plain shaped root node is already highlighted with bold font
and Truncated is already marked with italic font
in function DotNode::writeLabel.

Mark Undefined with dark gray color.

The legend before:

The legend after:

This PR continues #9463

[albert-github]

The gray fill color is to indicate a special feature (see the explanation with the legend graph).

• A filled gray box represents the struct or class for which the graph is generated.

So when using this it would also be necessary to adjust the first line of text.

• I assume you explicitly set the shape to plain, what is the reason?

• In the graphviz documentation we see (https://graphviz.org/doc/info/shapes.html):

  As the figures suggest, the shapes rect and rectangle are synonyms for box, and none is a synonym for plaintext. The shape plain is similar to these two, except that it also enforces width=0 height=0 margin=0, which guarantees that the actual size of the node is entirely determined by the label. This is useful, for example, when using HTML-like labels. Also, unlike the rest, we have shown these three, as well as underline, without style=filled to indicate the normal use. If fill were turned on, the label text would appear in a filled rectangle.

  I don't see from this that it is not allowed to use the fill (it might not be intended but that doesn't mean it is not allowed).

• why is the "undocumented" box in your example still gray? Due to the "plain" change shouldn't this loose the gray filling as well? (due to the cut-off I cannot see what happens here with the "Truncated" filled box)

[makelinux]

I've updated the patch and the description.

Fill is allowed for shapes in Graphviz. Boxes can be removed for aesthetic purposes accordingly subjective taste with my accepted PR: #9463

[makelinux]

@albert-github , would you like please to review?

[albert-github]

Does this mean that the "legend" is in the "old" stile even when using "shape=plain" and thus having an inconsistent "legend" with the images?
The "legend" should follow the current status (there might also be some places already where the color description doesn't fit).

[makelinux]

Do you mean legend text? For default configuration the legend image is consistent with legend text. For another style configuration legend images are inconsistent with the hard-coded legend text.
What do you suggest?

[albert-github]

I think that the legend (and its texts) should express the the way the graphs are generated (i.e. colors, shapes and texts).

[makelinux]

We have contradiction between flexible graph generation rigid text description on many languages.

Hypothetically it is possible to translate arbitrary graph style to description to all languages with help of AI.

[albert-github]

I already expressed my opinion before and now placed a, small, review as well.