Ask before clearing out out-dir

[llimllib]

• Don't clear out-dir unless user agrees
  • as per discussion in go build -out-dir $(pwd) will delete your working directory #74

[paulsmith]

Now that I'm seeing it in action locally I realize I didn't fully understand the behavior discussed in #74. My feeling was that pushup build would behave like zig build or cargo build, which AFAIK don't prompt each time, because it's assumed the build dir is under full control of the build tool.

Can you explain more about the use-case of needed to check first before clearing the build dir? In normal usage users shouldn't be putting files in there unless via the Pushup tool.

[llimllib]

Neither of those tools delete everything in the build dir, which is a very dangerous operation.

My worry is the first user who says "oh output-dir? I want my output in /usr/bin".

If you run zig build file.zig --cache-dir /usr/bin, what you'll get is a few new directories in /usr/bin that you probably don't want.

On the other hand, if you run pushup -out-dir /usr/bin <etc etc>, you'll silently erase your entire /usr/bin directory

Here's what a zig cache folder looks like after building two different binaries:

$ tree zig-cache/
zig-cache/
├── h
├── o
│   ├── 44d1925c83e24fb5b66ebebff916ac77
│   │   └── builtin.zig
│   └── 776651cd8468fc28abb2062cf0f1827e
│       └── builtin.zig
└── z
    ├── 1a8ca814016384106f75c92ca78ed220
    └── d35b7c44b39ce30aa92d0a5fd4c85e00

It creates two directories with a guid for each different binary that you build, and never deletes anything

[llimllib]

(updating the tool to not warn the user but to be safely non-destructive would be a fine alternative)

[paulsmith]

I wonder if the best thing to do in the short term is just emulate the zig cache behavior and not try to delete anything. Tests are a different story.

[llimllib]

Cool, I'll close this PR and we can aim for a nondestructive strategy - will update the issue