Use build-std feature for release build to reduce binary size

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

.github/workflows/build.yml

@@ -105,7 +105,7 @@ jobs:
       run: sudo ./ci-scripts/install-deps.sh
 
     - name: Build
-      run: ${{ env.CTOOL }} build ${{ env.CARGS }}
+      run: ${{ env.CTOOL }} ${{ env.TOOLCHAIN }} build ${{ env.CARGS }}
 
     - name: Get output
       shell: bash

ci-scripts/compile-settings.jq

@@ -1,10 +1,14 @@
 if $for_release then {
   output: "release",
+  toolchain: "+nightly",
   profile: "release",
-  args: ($matrix.release_build_args // ""),
+  # Use build-std to build a std library optimized for size and abort immediately on abort,
+  # so that format string for `unwrap`/`expect`/`unreachable`/`panic` can be optimized out.
+  args: ($matrix.release_build_args // "-Z build-std=std,panic_abort -Z build-std-features=panic_immediate_abort"),
   features: ($matrix.release_features // []),
 } else {
   output: "debug",
+  toolchain: "+stable",
   profile: "dev",
   args: ($matrix.debug_build_args // ""),
   features: ($matrix.debug_features // ["rustls", "fancy-with-backtrace"]),
@@ -19,6 +23,7 @@ if $for_release then {
 {
   CBIN: (if ($matrix.target | test("windows")) then "cargo-binstall.exe" else "cargo-binstall" end),
   CTOOL: (if ($matrix."use-cross" // false) then "cross" else "cargo" end),
+  TOOLCHAIN: .toolchain,
   COUTPUT: .output,
   CARGS: "--target \($matrix.target) --profile \(.profile) \(.features) \(.args)",
 }