Add LTO test

Author: antoyo

.github/workflows/release.yml

@@ -55,6 +55,11 @@ jobs:
         ./y.sh prepare --only-libcore
         EMBED_LTO_BITCODE=1 ./y.sh build --sysroot --release --release-sysroot
         cargo test
+
+    - name: Run y.sh cargo build
+      run: |
+        CHANNEL="release" ./y.sh cargo build --release --manifest-path tests/hello-world/Cargo.toml
+        # TODO: grep the asm output for "call my_func" and fail if it is found.
         ./y.sh clean all
 
     - name: Prepare dependencies

tests/hello-world/Cargo.toml

@@ -7,3 +7,6 @@ mylib = { path = "mylib" }
 
 [profile.dev]
 lto = "thin"
+
+[profile.release]
+lto = "fat"