Doc tests ignore RUSTFLAGS

[crumblingstatue]

(Moved from rust-lang/rust#37330)

I am writing doc examples for the bindings of a C library.
In my RUSTFLAGS, I add a search path for the C library using -L /path/to/lib. (needed because I am using a custom version of the library that's not installed globally)

cargo build/run picks this up fine, and the C library links correctly.
However, doc tests cause a linking error, because RUSTFLAGS seem to be ignored when compiling doc examples.

[alexcrichton]

Ok so as pointed out by @rkruppe I was corrected in that we actually can't do this blindly per se. That is, rustdoc doesn't currently have a feature for "pass these flags to the compiler".

What you can do today, however, is hopefully use RUSTDOCFLAGS!

[carols10cents]

It sounds like using RUSTDOCFLAGS fixes this issue, so I'm going to close this. Please reopen if I'm mistaken! Thank you!