build.rs is not run after src/main.rs changed, when using cargo:rerun-if-env-changed

[ghost]

I made this simple project illustrate the issue: https://github.com/xftroxgpx/buildrs_not_updated
(just run ./go)

In simple terms:

1. touch src/main.rs
2. cargo build
   will not recompile build.rs because it used cargo:rerun-if-env-changed (doc)
   thus src/main.rs will use stale build.rs ...../output !
3. remove the use of cargo:rerun-if-env-changed
4. repeat steps 1 and 2.
   that recompiles build.rs every time you do step 4. now.

tested two versions of cargo:
cargo 0.26.0
release: 0.26.0
and
cargo 0.25.0-nightly (a88fbac 2017-12-29)
release: 0.25.0
commit-hash: a88fbac
commit-date: 2017-12-29

with rust:
rustc 1.24.0-dev (687d3d15b 2018-01-02)
binary: rustc
commit-hash: 687d3d15ba726dbb1ac6b85223ebe0e98c6820cc
commit-date: 2018-01-02
host: x86_64-unknown-linux-gnu
release: 1.24.0-dev
LLVM version: 4.0

[alexcrichton]

Thanks for the report! Is this perhaps the same bug as #4587?

[ghost]

Exactly! Thank you for spotting that! I forgot to search first, for some reason :)

I guess I'll close this in favor of that one