Merge pull request #256 from NobodyXu/optimize-release-build

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

.github/workflows/build.yml

@@ -73,6 +73,10 @@ jobs:
       if: "!matrix.use-cross"
       run: rustup target add ${{ matrix.target }}
 
+    - name: Install rust-src
+      if: inputs.for_release
+      run: rustup component add rust-src
+
     - name: Select compile settings
       shell: bash
       run: |
@@ -106,6 +110,8 @@ jobs:
 
     - name: Build
       run: ${{ env.CTOOL }} build ${{ env.CARGS }}
+      env:
+        RUSTFLAGS: ${{ env.RUSTFLAGS }}
 
     - name: Get output
       shell: bash

ci-scripts/compile-settings.jq

@@ -1,7 +1,9 @@
 if $for_release then {
   output: "release",
   profile: "release",
-  args: ($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",
@@ -10,6 +12,12 @@ if $for_release then {
   features: ($matrix.debug_features // ["rustls", "fancy-with-backtrace"]),
 } end
 |
+.rustflags = (
+  if $for_release and $matrix.target == "aarch64-unknown-linux-musl" or $matrix.target == "armv7-unknown-linux-musleabihf"
+  then "-C link-arg=-lgcc -Clink-arg=-static-libgcc"
+  else "" end
+)
+|
 .features = (
   if (.features | length > 0)
   then "--no-default-features --features \(.features | join(","))"
@@ -21,6 +29,7 @@ if $for_release then {
   CTOOL: (if ($matrix."use-cross" // false) then "cross" else "cargo" end),
   COUTPUT: .output,
   CARGS: "--target \($matrix.target) --profile \(.profile) \(.features) \(.args)",
+  RUSTFLAGS: .rustflags,
 }
 |
 to_entries[] | "\(.key)=\(.value)"