[Rd] --as-cran / BuildVignettes: false

[Paul Gilbert]

I have packages where I know CRAN and other test platforms do not have 
all the resources to build the vignettes, for example, access to 
databases. Previously I think putting

  BuildVignettes: false

in the DESCRIPTION file resolved this, by preventing CRAN checks from 
attempting to run the vignette code. (If it was not this, then there was 
some other magic I don't understand.)

Now, when I specify --as-cran, the checks fail when attempting to check 
R code from vignettes, even though I have "BuildVignettes: false" in the 
DESCRIPTION file.

What is the mechanism for indicating that CRAN should not attempt to 
check this code?  Perhaps it is intentionally difficult - I can see an 
argument for that.  (For running tests there are environment variables, 
e.g._R_CHECK_HAVE_MYSQL_, but using these really clutters up a vignette, 
and it did not seem necessary to use them before.)

(The difficult also occurs on R-forge, possibly because it is using 
--as-cran like settings.)

Paul