Changing a file in the middle of a build causes rustc to not pick up latest changes

[bfops]

If I change a file partway through a build then the final executable doesn't include that change. However, when I run cargo build again it thinks there have been no changes since the last build.

To have the build incorporate the most recent changes, I need to change the file again, build, change it back, and rebuild.

[nikomatsakis]

cc @alexcrichton

[nikomatsakis]

This is probably not, strictly speaking, a compiler bug, but rather a cargo bug?

[nikomatsakis]

(FWIW, I've also observed this behavior.)

[alexcrichton]

I believe this is probably rust-lang/cargo#2426, so closing in favor of that.

[bfops]

Oh of course, no wonder I couldn't find an existing report - I was looking in the wrong place!