Fix nightly sdk compatibility build, again (#242)

The previous attempt to fix the nightly `latest-matrix-sdk-crypto` job failed,
because the version of the rust-sdk in git was 0.12.0, whereas our Cargo.lock
required 0.11.0.

It seems like we have to edit the Cargo.toml. Editing a toml isn't something I
want to do from a script, so I've made it an xtask.

Author: richvdh

.cargo/config.toml

@@ -1,5 +1,5 @@
-[build]
-target = "wasm32-unknown-unknown"
+[alias]
+xtask = "run --manifest-path xtask/Cargo.toml --"
 
 [target.wasm32-unknown-unknown]
 rustflags = ['--cfg', 'getrandom_backend="wasm_js"']

.github/workflows/ci.yml

@@ -36,6 +36,7 @@ jobs:
       - name: Check formatting
         run: |
           cargo fmt -- --check
+          (cd xtask && cargo fmt -- --check)
 
       - name: Install Node.js
         uses: actions/setup-node@v3

.github/workflows/latest-matrix-sdk-crypto.yml

@@ -53,16 +53,7 @@ jobs:
 
       - name: Update to the latest matrix-sdk-crypto version
         run: |
-           tee >> .cargo/config.toml << EOF
-           [patch.crates-io]
-           matrix-sdk-common = { git = "https://github.com/matrix-org/matrix-rust-sdk" }
-           matrix-sdk-crypto = { git = "https://github.com/matrix-org/matrix-rust-sdk" }
-           matrix-sdk-indexeddb = { git = "https://github.com/matrix-org/matrix-rust-sdk" }
-           matrix-sdk-qrcode = { git = "https://github.com/matrix-org/matrix-rust-sdk" }
-           matrix-sdk-store-encryption = { git = "https://github.com/matrix-org/matrix-rust-sdk" }
-           EOF
-
-           cargo update matrix-sdk-crypto
+           cargo xtask unstable-rust-sdk
 
       - name: Install Node.js
         uses: actions/setup-node@v3

xtask/.gitignore

@@ -0,0 +1 @@
+/target