Should theme(palette.* = ) raise a warning when options(ggplot2.* = ) is set?

[yutannihilation]

I read the comments on #5946 and it's for the sake of compatibility that the new theme(palette.* = ) is enabled only when the corresponding palette is NULL. But, I feel it's a bit confusing to see theme(palette.* = ) is silently ignored.

Especially, if I were a theme developer, I will be afraid of inquiries like "Hey, your theme doesn't work on my machine, Why?" from those who set options(ggplot2.*). I think it's a rare case and not a serious issue, but I'm wondering if it's friendlier to show a warning.

library(ggplot2)

p <- ggplot(mpg, aes(displ, hwy)) +
  geom_point(aes(colour = class)) +
  theme(
    palette.colour.discrete = scales::get_palette("mint")
  )

# theme is applied
p

options(ggplot2.discrete.colour = "viridis")

# ignored
p

^{Created on 2025-02-16 with reprex v2.1.1}

[teunbrand]

Mechanically, would you propose to detect this situation whenever theme() is called, or when scale_colour_*() is called?

[yutannihilation]

Oh, I expected the latter, but former should be also fine.