Enable AddressSanitizer for rustc in CI

Just running AddressSanitizer may not be enough; it needs to be explicitly enabled
for Rust in addition to C++.

External resources:
* https://rustc-dev-guide.rust-lang.org/sanitizers.html#how-to-use-the-sanitizers
* https://doc.rust-lang.org/beta/unstable-book/compiler-flags/sanitizer.html

Author: Bromeon

.github/composite/godot-itest/action.yml

@@ -45,6 +45,11 @@ inputs:
     default: ''
     description: "Extra values for the RUSTFLAGS env var"
 
+  rust-target:
+    required: false
+    default: ''
+    description: "If provided, acts as an argument for '--target', and results in output files written to ./target/{target}"
+
   with-llvm:
     required: false
     default: ''
@@ -118,11 +123,23 @@ runs:
       shell: bash
 
     - name: "Build gdext (itest)"
-      run: |
-        cargo build -p itest ${{ inputs.rust-extra-args }}
-      shell: bash
       env:
         RUSTFLAGS: ${{ inputs.rust-env-rustflags }}
+        TARGET: ${{ inputs.rust-target }}
+      run: |
+        targetArgs=""
+        if [[ -n "$TARGET" ]]; then
+          targetArgs="--target $TARGET"
+        fi
+        
+        cargo build -p itest ${{ inputs.rust-extra-args }} $targetArgs
+        
+        # Instead of modifying .gdextension, rename the output directory
+        if [[ -n "$TARGET" ]]; then
+          rm -rf target/debug
+          mv target/$TARGET/debug target
+        fi
+      shell: bash
 
     # This step no longer fails if there's a diff, as we expect header to be forward-compatible; instead issues a warning
     # However, still fails if patch cannot be applied (conflict).

.github/composite/rust/action.yml

@@ -31,11 +31,11 @@ runs:
   steps:
     - name: "Configure"
       id: configure
+      env:
+        CS: ${{ inputs.components }}
       run: |
         echo "Rust cache shared-key: '${{ runner.os }}-${{ inputs.rust }}${{ inputs.cache-key }}'"
-        echo "components=$( for c in ${cs//,/ }; do echo -n ' --component' $c; done )" >> $GITHUB_OUTPUT
-      env:
-        cs: ${{ inputs.components }}
+        echo "components=$( for c in ${CS//,/ }; do echo -n ' --component' $c; done )" >> $GITHUB_OUTPUT
       shell: bash
 
     - name: "Rustup"

.github/workflows/full-ci.yml

@@ -202,17 +202,22 @@ jobs:
             godot-prebuilt-patch: '4.1'
 
           # Special Godot binaries compiled with AddressSanitizer/LeakSanitizer to detect UB/leaks.
+          # See also https://rustc-dev-guide.rust-lang.org/sanitizers.html.
+          #
           # Additionally, the Godot source is patched to make dlclose() a no-op, as unloading dynamic libraries loses stacktrace and
           # cause false positives like println!. See https://github.com/google/sanitizers/issues/89.
-          # The gcc version can possibly be removed later, as it is slower and needs a larger artifact than the clang one.
+          #
+          # There is also a gcc variant besides clang, which is currently not used.
           - name: linux-memcheck-nightly
             os: ubuntu-20.04
             artifact-name: linux-memcheck-clang-nightly
             godot-binary: godot.linuxbsd.editor.dev.x86_64.llvm.san
             godot-args: -- --disallow-focus
             rust-toolchain: nightly
-            rust-env-rustflags: -Zrandomize-layout
+            rust-env-rustflags: -Zrandomize-layout -Zsanitizer=address
             rust-extra-args: --features godot/custom-godot
+            # Sanitizers can't build proc-macros and build scripts; with --target, cargo ignores RUSTFLAGS for those two.
+            rust-target: x86_64-unknown-linux-gnu
             godot-prebuilt-patch: '4.1'
 
           # Linux under Godot 4.0.x
@@ -246,8 +251,9 @@ jobs:
             godot-binary: godot.linuxbsd.editor.dev.x86_64.llvm.san
             godot-args: -- --disallow-focus
             rust-toolchain: nightly
-            rust-env-rustflags: -Zrandomize-layout
-
+            rust-env-rustflags: -Zrandomize-layout -Zsanitizer=address
+            # Sanitizers can't build proc-macros and build scripts; with --target, cargo ignores RUSTFLAGS for those two.
+            rust-target: x86_64-unknown-linux-gnu
 
     steps:
       - uses: actions/checkout@v3
@@ -262,6 +268,7 @@ jobs:
           rust-extra-args: ${{ matrix.rust-extra-args }}
           rust-toolchain: ${{ matrix.rust-toolchain || 'stable' }}
           rust-env-rustflags: ${{ matrix.rust-env-rustflags }}
+          rust-target: ${{ matrix.rust-target }}
           with-llvm: ${{ contains(matrix.name, 'macos') && contains(matrix.rust-extra-args, 'custom-godot') }}
           godot-check-header: ${{ matrix.godot-check-header }}