(Potential) bug with theme within guide_* call

[kylebutts]

It is very possible that I'm misunderstanding how to use the theme object within guide_*, but applying themes does not seem to work for me. I am using the most recent development version of ggplot2.

Edit: After some more testing, only the legend.x options are not working

library(ggplot2)
ggplot() +
  geom_point(
    aes(x = mpg, y = hp, color = as.factor(cyl)),
    data = mtcars
  ) +
  scale_color_manual(
    values = c("red", "blue", "green"),
    guide = guide_legend(
      theme = theme(legend.position = "bottom")
    )
  )

ggplot() +
  geom_point(
    aes(x = mpg, y = hp, color = as.factor(cyl)),
    data = mtcars
  ) +
  scale_color_manual(
    values = c("red", "blue", "green"),
    guide = guide_legend()
  ) +
  theme(legend.position = "bottom")

^{Created on 2024-09-12 with reprex v2.1.0}

[teunbrand]

Thanks for the report!
The issue mirrors #5712 (comment) very closely, so I'll close the discussion here in favour of that issue.
In any case; it is not a bug, but ggplot2 should probably do a better job at making clear which theme elements are in scope and which ones aren't.