fix Unity 6.5 built-in mimalloc conflict

Author: ruccho

.github/scripts/localize-apple-staticlib.sh

@@ -0,0 +1,76 @@
+#!/usr/bin/env bash
+# Localize all non-exported symbols in an Apple static library so that its
+# bundled mimalloc does not coalesce with Unity 6.5's built-in mimalloc when the
+# library is statically linked into UnityFramework (iOS `__Internal`).
+#
+# Requires the library to have been compiled with `-fno-common` (see the CI
+# workflow) so that mimalloc's tentative definitions (e.g. `_mi_page_map`) are
+# real defined symbols rather than common symbols, which cannot be localized.
+#
+# Usage: localize-apple-staticlib.sh <lib.a> <ld-arch> [sdk] [platform] [min-os]
+#   e.g. localize-apple-staticlib.sh libunienc_c.a arm64 iphoneos ios 13.0
+set -euo pipefail
+
+LIB="$1"                 # path to the .a (e.g. libunienc_c.a)
+ARCH="$2"                # ld arch name (e.g. arm64)
+SDK="${3:-iphoneos}"     # xcrun SDK (e.g. iphoneos)
+PLATFORM="${4:-ios}"     # -platform_version platform name (e.g. ios)
+MIN_OS="${5:-13.0}"      # -platform_version minimum OS version
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+EXPORTS="$SCRIPT_DIR/../../InstantReplay.Externals/unienc/crates/unienc_c/apple-exports.txt"
+
+if [ ! -f "$LIB" ]; then
+  echo "ERROR: static library not found: $LIB" >&2
+  exit 1
+fi
+
+LIB_ABS="$(cd "$(dirname "$LIB")" && pwd)/$(basename "$LIB")"
+SDK_VER="$(xcrun --sdk "$SDK" --show-sdk-version)"
+WORK="$(mktemp -d)"
+trap 'rm -rf "$WORK"' EXIT
+
+# Extract every archive member as a loose object. We deliberately do NOT use
+# `ld -r -force_load <archive>`: the modern linker (ld-prime) localizes *all*
+# symbols of a force-loaded archive, which would strip the `_unienc*` exports
+# too. Passing loose objects makes `-exported_symbols_list` behave as intended.
+( cd "$WORK" && ar x "$LIB_ABS" )
+member_count="$(ar t "$LIB_ABS" | grep -Ec '\.o$' || true)"
+extracted_count="$(find "$WORK" -maxdepth 1 -name '*.o' | wc -l | tr -d ' ')"
+if [ "$member_count" != "$extracted_count" ]; then
+  echo "ERROR: extracted $extracted_count objects but archive lists $member_count (duplicate member names?)" >&2
+  exit 1
+fi
+
+# Partial link into a single object.
+#   -exported_symbols_list : demote every global NOT matching `_unienc*` to a
+#                            private-extern symbol.
+#   -r (without -keep_private_externs) : convert those private-externs (and the
+#                            ones already produced by `-fvisibility=hidden`) into
+#                            true local symbols.
+#   -platform_version : required by ld-prime even for a `-r` link.
+( cd "$WORK" && xcrun --sdk "$SDK" ld -r -arch "$ARCH" \
+    -platform_version "$PLATFORM" "$MIN_OS" "$SDK_VER" \
+    -exported_symbols_list "$EXPORTS" \
+    *.o -o merged.o )
+
+rm -f "$LIB_ABS"
+xcrun libtool -static -o "$LIB_ABS" "$WORK/merged.o"
+
+# --- Verify (CI gate; also guards against future linker behaviour changes) ---
+echo "=== exported (global) symbols after localization ==="
+nm -gU "$LIB_ABS" | sort -u
+
+# (a) No mimalloc symbol may remain external or private-external. `nm -gU` lists
+#     both (private-externs still coalesce), so it must contain zero of them.
+if nm -gU "$LIB_ABS" | grep -iE '_mi_|_heap_main|_theap_main|mi_unity_'; then
+  echo "FAIL: mimalloc symbols are still (private-)external -> would coalesce with Unity" >&2
+  exit 1
+fi
+
+# (b) FFI entry points must remain global.
+if ! nm -gU "$LIB_ABS" | grep -q '_unienc_UnityPluginLoad'; then
+  echo "FAIL: _unienc_UnityPluginLoad is no longer exported" >&2
+  exit 1
+fi
+
+echo "Localization OK: $(nm -gU "$LIB_ABS" | grep -c '_unienc') unienc symbols exported, 0 mimalloc symbols external"

.github/workflows/build-unienc.yml

@@ -128,6 +128,21 @@ jobs:
       - run: rustup default stable
       - run: rustup target add ${{ matrix.arch }}-apple-ios
       - run: cargo build --target ${{ matrix.arch }}-apple-ios --profile ${{ env._RUST_BUILD_CONFIG == 'debug' && 'dev' || env._RUST_BUILD_CONFIG }} ${{ matrix.variant == 'unity' && '-F unity,mimalloc' || '' }}
+        env:
+          # Turn mimalloc's tentative definitions (e.g. _mi_page_map) into real
+          # BSS definitions. Common symbols cannot be localized, so without this
+          # `_mi_page_map` would remain external and still coalesce with Unity's
+          # mimalloc. Injected via cc-rs's target CFLAGS so no submodule change
+          # is needed. Only aarch64 is built for iOS (see matrix).
+          CFLAGS_aarch64-apple-ios: -fno-common
+      # Localize the bundled mimalloc so it does not coalesce with Unity 6.5's
+      # built-in mimalloc when statically linked into UnityFramework.
+      - name: Localize non-exported symbols (Unity variant only)
+        if: matrix.variant == 'unity'
+        working-directory: InstantReplay.Externals/unienc/target/${{ matrix.arch }}-apple-ios/${{ env._RUST_BUILD_CONFIG }}
+        run: |
+          chmod +x "$GITHUB_WORKSPACE/.github/scripts/localize-apple-staticlib.sh"
+          "$GITHUB_WORKSPACE/.github/scripts/localize-apple-staticlib.sh" libunienc_c.a arm64 iphoneos
       - uses: actions/upload-artifact@v4
         with:
           name: ${{ matrix.variant }}-${{ matrix.arch }}-apple-ios

InstantReplay.Externals/unienc/crates/unienc_c/apple-exports.txt

@@ -0,0 +1,11 @@
+# Symbols that must stay globally visible when libunienc_c.a is statically
+# linked into UnityFramework (iOS). Consumed via `ld -r -exported_symbols_list`.
+#
+# Everything NOT listed here (all mimalloc `mi_*`/`_mi_*`/`heap_main` symbols and
+# Rust internals) is demoted to a local symbol, so the bundled mimalloc no longer
+# coalesces with Unity 6.5's own built-in mimalloc.
+#
+# All FFI entry points (csbindgen `unienc_*` + the iOS `unienc_UnityPluginLoad` /
+# `unienc_UnityPluginUnload` registered by RegisterPlugin.mm) share the `_unienc`
+# Mach-O prefix, so a single wildcard covers them and any future additions.
+_unienc*