Blender Version
Broken: 2.8x, 2.9

Short description of error
Wireframe mode has solid shading when X-Ray is turned off and ( X-ray value is greater than 0 or outline is turned on).

Exact steps for others to reproduce the error
Open default cube.
Change to Wireframe Shading.
Open the shading dropdown.
Turn off Outline.
Turn off X-ray.
Turn on Outline. The shading will be solid filled with the background color.
Turn off Outline. The shading won't be solid
Now with both Outline and X-Ray off, change the X-ray slider up and down. Even though it's toggled off, changing it still influences shading. A value off 0 makes it shade correctly, and greater values makes it solid.