FieldReport: Upgrading from geo 0.31.x to 0.32.x breaks the build

[martinfrances107]

I see this when building for the browser

The problems is side-effects from changes inside of the getrandom crate.

1. Here is a dependency graph

MyApp -> MyLib -> geo -> rand -> getrandom

getrandom The change here releates to the sourcing of randomness for "supported targets" Here is the relevant quote from the getrandom README

 "wasm32-unknown-unknown" is no longer supported by default. see
(webassembly-support)[<https://crates.io/crates/getrandom#webassembly-support>]

For this PR the summary is

rand must enable the "wasm-js" and the root crate ( MyApp in this example ) must set this enviromment variable

RUSTFLAGS='--cfg getrandom_backend="wasm_js"'

rand takes its own view on this matter

Here is the relevant quote form the rand README

"The WASI and Emscripten targets are directly supported. The wasm32-unknown-unknown target is not automatically supported. To enable support for this target, refer to the getrandom documentation for WebAssembly. Alternatively, the os_rng feature may be disabled."

The best we can do, in geo, I think, is to optionally remove the rand crate, for builds that target the web.

geo = { path ="0.32", features = [ "earcutr", "spade", "multithreading"], default-features = false }

I should empahsise this comes at the cost of removing the kmeans module and its associated functionality.

• [ x] I agree to follow the project's code of conduct.
• I added an entry to CHANGES.md if knowledge of this change could be valuable to users.

---

[dabreegster]

As a workaround, you can add getrandom = { version = "0.2.16", features = ["js"] } to your crate. This was discussed a bit on Discord.

[martinfrances107]

WOW .. thank you, thank you

That works and fixes a problem I have been thinking about for weeks. 😍

Just so I understand you and for other people reading this

in the MyApp Cargo.toml file from above

MyApp -> MyLib -> geo -> rand -> getrandom

When I add this

# Create a shadow dependency on getrandom with the feature "js"
# In effect this will add the "js" feature flag to the real depedency
#  MyApp -> MyLib -> geo -> rand -> genrandom
getrandom = { version = "0.2.16", features = ["js"]}

My response is this is brittle but ok

It needs to be updated with the changing winds from getrandom, which makes me sad.
When I see crazy/sneaky/"Not at all obvious" that is when I document.

I will adjust this PR sometime in this evening... limiting it to just adding a section to to README

[dabreegster]

I think this PR is a nice solution, since it stops downstream users from needing this workaround. Opting into a feature to get kmeans seems much more typical. I'll let other maintainers chime in on the best way forward

[martinfrances107]

I have stripped down the PR to just documentation.

I see that the rand crate needs bumping to the latest version ...
one step at a time .. but just to be here clear here I am leaving a maintenance behind.