allow aarch64 as an alias for arm64 when associating a platform with …

…a derivation

cli/src/main.rs

@@ -285,7 +285,7 @@ OPTIONS for --save:
 --multiplatform        Treat the entrypoint VALUE as a nix expression returning an attrset of
                        `platform: derivation`. Use this when cross-compiling for multiple
                        platforms. Implies `--expr`.
---platforms PLATFORMS  Re-evaluate VALUE for each of the passe-in platforms (comma-separated).
+--platforms PLATFORMS  Re-evaluate VALUE for each of the passed-in platforms (comma-separated).
                        Unlike `--multiplatform`, this is used when you have built the same
                        expression natively on multiple platforms.
 "#);

cli/src/platform.rs

@@ -51,7 +51,12 @@ impl FromStr for Arch {
 	fn from_str(s: &str) -> Result<Self, Self::Err> {
 		match s {
 			"x86_64" => Ok(Self::x86_64),
+
+			// uname reports `arm64`, so that's what we use for bootstrapping and
+			// CLI. But we also support `aarch64` since that's what we get from
+			// `drv.system` of a nix build.
 			"arm64" => Ok(Self::arm64),
+			"aarch64" => Ok(Self::arm64),
 			other => Err(anyhow!("Unknown arch: {}", other))
 		}
 	}