packaging/aix: bundle libunwind derived from GCC runtime libgcc_s.a

packaging/aix/sitecustomize.py

@@ -1,21 +1,22 @@
-# AIX: preload libc++abi.a so that __xlcxx_personality_v0 is available
-# when pydantic_core's libunwind.a(libunwind.so.1) dependency is resolved.
+# AIX: best-effort preload of libc++abi.a with RTLD_GLOBAL.
 #
 # Background:
-#   pydantic_core is a Rust extension module compiled against AIX's libunwind.a.
-#   libunwind.so.1 declares __xlcxx_personality_v0 as an undefined symbol,
-#   expecting the IBM XLC++ C++ ABI runtime (libc++abi.a) to provide it.
-#   Python is compiled with GCC, so libc++abi.a is not loaded at Python startup.
-#   Without this preload, "import pydantic" raises:
-#     ImportError: rtld: 0712-001 Symbol __xlcxx_personality_v0 was referenced
-#     from module /usr/lib/libunwind.a(libunwind.so.1), but a runtime definition
-#     of the symbol was not found.
+#   Some C++ extensions compiled with IBM XLC++ declare __xlcxx_personality_v0
+#   as an undefined symbol, expecting the IBM XLC++ ABI runtime (libc++abi.a)
+#   to provide it. Python is compiled with GCC and does not load libc++abi.a
+#   automatically, so those extensions fail to import without this preload.
 #
-# Fix: load libc++abi.a with RTLD_GLOBAL before any checks run so the symbol
-# is available to all subsequently loaded shared modules.
+#   pydantic_core previously triggered this via a dependency on the IBM-provided
+#   /usr/lib/libunwind.a(libunwind.so.1), which needs __xlcxx_personality_v0.
+#   pydantic_core now uses a bundled libunwind derived from the GCC runtime
+#   (libgcc_s.a), which has no libc++abi.a dependency, so pydantic_core no
+#   longer requires this preload. It is kept as a best-effort safety net for
+#   any other XLC++-compiled extension that might be loaded at runtime.
 #
-# AIX 7.2 TL5+ / AIX 7.3: /usr/lib/libc++abi.a(libc++abi.so.1) ships with the OS.
-# AIX 7.2 TL4 and earlier: this file is absent; the except clause silently continues.
+# Outcome: either the load succeeds (libc++abi.a is present, RTLD_GLOBAL makes
+# __xlcxx_personality_v0 available to all subsequent modules) or the except
+# clause silently continues (file absent — AIX 7.2 TL4 and earlier — and no
+# extension that needs it is present, so nothing breaks).
 import ctypes as _ctypes
 
 try:

packaging/aix/stages/01-native-libs.sh

@@ -76,6 +76,7 @@ READLINE_VERSION="8.2"     # yum install readline-devel
 SQLITE_VERSION="3.53.0"    # built from source (amalgamation)
 GDBM_VERSION="1.23"        # yum install gdbm-devel
 LIBICONV_VERSION="1.17"    # yum install libiconv
+LIBUNWIND_VERSION="1.0"    # derived from /opt/freeware/lib/libgcc_s.a (GCC runtime)
 
 # ─── Helpers ──────────────────────────────────────────────────────────────────
 
@@ -521,6 +522,35 @@ done
 stage_toolbox_lib libiconv "$LIBICONV_VERSION" \
     /opt/freeware/lib/libiconv.a
 
+# ── libunwind (derived from GCC runtime libgcc_s.a) ──────────────────────────
+#
+# pydantic_core links against libunwind.a(libunwind.so.1). We build this
+# archive by extracting the shared object from the GCC runtime libgcc_s.a
+# (which contains all _Unwind_* symbols) and re-packaging it under the
+# libunwind.so.1 member name that pydantic_core expects.
+#
+# This avoids the IBM XL C++ Runtime version (/usr/lib/libunwind.a) which
+# needs __xlcxx_personality_v0 from libc++abi.a — absent on AIX 7.2 TL2-TL4.
+# The GCC-derived version only depends on libc.a, making it fully portable.
+if lib_done libunwind "$LIBUNWIND_VERSION"; then
+    log "libunwind ${LIBUNWIND_VERSION} already staged — skipping"
+else
+    log "Staging libunwind ${LIBUNWIND_VERSION} (from libgcc_s.a)"
+    GCC_LIBGCC_S=/opt/freeware/lib/libgcc_s.a
+    if [ ! -f "$GCC_LIBGCC_S" ]; then
+        log "ERROR: $GCC_LIBGCC_S not found — install GCC from the AIX Toolbox"
+        exit 1
+    fi
+    _tmpdir="$BUILD_DIR/build/libunwind-tmp"
+    rm -rf "$_tmpdir" && mkdir -p "$_tmpdir"
+    (cd "$_tmpdir" && ar -X64 -x "$GCC_LIBGCC_S" shr.o)
+    cp "$_tmpdir/shr.o" "$_tmpdir/libunwind.so.1"
+    ar -X64 -rcs "$EMBEDDED_DESTDIR/lib/libunwind.a" "$_tmpdir/libunwind.so.1"
+    rm -rf "$_tmpdir"
+    lib_mark libunwind "$LIBUNWIND_VERSION"
+    log "libunwind ${LIBUNWIND_VERSION} staged"
+fi
+
 # ─── Ensure standard directories exist ────────────────────────────────────────
 
 log "Ensuring standard embedded directories exist"