Stop hardcoding the Swift toolchain version in the Multithreading example

Author: kateinoigakukun

Examples/Multithreading/README.md

@@ -1,9 +1,21 @@
 # Multithreading example
 
-Install Development Snapshot toolchain `DEVELOPMENT-SNAPSHOT-2024-07-08-a` from [swift.org/install](https://www.swift.org/install/) and run the following commands:
+Install Development Snapshot toolchain `DEVELOPMENT-SNAPSHOT-2024-07-08-a` or later from [swift.org/install](https://www.swift.org/install/) and run the following commands:
 
 ```sh
-$ swift sdk install https://github.com/swiftwasm/swift/releases/download/swift-wasm-DEVELOPMENT-SNAPSHOT-2024-07-09-a/swift-wasm-DEVELOPMENT-SNAPSHOT-2024-07-09-a-wasm32-unknown-wasip1-threads.artifactbundle.zip
+$ (
+  set -eo pipefail; \
+  V="$(swiftc --version | head -n1)"; \
+  TAG="$(curl -sL "https://raw.githubusercontent.com/swiftwasm/swift-sdk-index/refs/heads/main/v1/tag-by-version.json" | jq -e -r --arg v "$V" '.[$v] | .[-1]')"; \
+  curl -sL "https://raw.githubusercontent.com/swiftwasm/swift-sdk-index/refs/heads/main/v1/builds/$TAG.json" | \
+  jq -r '.["swift-sdks"]["wasm32-unknown-wasip1-threads"] | "swift sdk install \"\(.url)\" --checksum \"\(.checksum)\""' | sh -x
+)
+$ export SWIFT_SDK_ID=$(
+  V="$(swiftc --version | head -n1)"; \
+  TAG="$(curl -sL "https://raw.githubusercontent.com/swiftwasm/swift-sdk-index/refs/heads/main/v1/tag-by-version.json" | jq -e -r --arg v "$V" '.[$v] | .[-1]')"; \
+  curl -sL "https://raw.githubusercontent.com/swiftwasm/swift-sdk-index/refs/heads/main/v1/builds/$TAG.json" | \
+  jq -r '.["swift-sdks"]["wasm32-unknown-wasip1-threads"]["id"]'
+)
 $ ./build.sh
 $ npx serve
 ```

Examples/Multithreading/build.sh

@@ -1 +1 @@
-swift build --swift-sdk DEVELOPMENT-SNAPSHOT-2024-07-09-a-wasm32-unknown-wasip1-threads -Xswiftc -Xclang-linker -Xswiftc -mexec-model=reactor -Xlinker --export=__main_argc_argv -c release -Xswiftc -g
+swift build --swift-sdk "${SWIFT_SDK_ID:-wasm32-unknown-wasip1-threads}" -Xswiftc -Xclang-linker -Xswiftc -mexec-model=reactor -Xlinker --export=__main_argc_argv -c release -Xswiftc -g