wip

demos/vc_issuer/Cargo.toml

@@ -30,6 +30,9 @@ strfmt = "0.2"
 lazy_static = "1.4"
 include_dir = "0.7"
 
+[target.'cfg(all(target_arch = "wasm32", target_vendor = "unknown", target_os = "unknown"))'.dependencies]
+getrandom = { version = "0.2", features = ["custom"] }
+
 [dev-dependencies]
 assert_matches = "1.5.0"
 candid_parser = "0.1"

demos/vc_issuer/src/lib.rs

@@ -0,0 +1,8 @@
+/// A small module that makes get_random work on wasm32-unknown-unknown.
+/// The dependency on get_random comes from the captcha library.
+#[cfg(all(
+    target_arch = "wasm32",
+    target_vendor = "unknown",
+    target_os = "unknown"
+))]
+mod wasm_get_random;

demos/vc_issuer/src/wasm_get_random.rs

@@ -0,0 +1,21 @@
+//! This module exists to work around a problem with `getrandom` 0.2, which is a dependency
+//! of `rand` 0.8
+//!
+//! For the `wasm32-unknown-unknown` target, `getrandom` 0.2 will refuse to compile. This is an
+//! intentional policy decision on the part of the getrandom developers. As a consequence, it
+//! would not be possible to compile anything which depends on `rand` 0.8 to wasm for use in
+//! canister code.
+//!
+//! Depending on this crate converts the compile time error into a runtime error, by
+//! registering a custom `getrandom` implementation which always fails. This matches the
+//! behavior of `getrandom` 0.1.
+//!
+//! See the [getrandom
+//! documentation](https://docs.rs/getrandom/latest/getrandom/macro.register_custom_getrandom.html)
+//! for more details on custom implementations.
+
+/// A getrandom implementation that always fails
+pub fn always_fail(_buf: &mut [u8]) -> Result<(), getrandom::Error> {
+    Err(getrandom::Error::UNSUPPORTED)
+}
+getrandom::register_custom_getrandom!(always_fail);