QVAC-25104 fix: stop publishing platform-dependent values in fabric's package config

packages/fabric/CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## [Unreleased]
+
+### Removed
+
+- The CMake package config no longer publishes `QVAC_FABRIC_ABI_VERSION` or
+  `QVAC_FABRIC_OWNS_CXX_RUNTIME`. Both described the platform they were
+  configured for, and the config is not per-platform: it installs to
+  `share/qvac-fabric/cmake`, which every prebuild leg writes, and the artifact
+  merge keeps one copy in the published package. So the pair described whichever
+  leg finished last — `ON` from either Linux leg, `OFF` from Android, empty from
+  darwin, iOS or win32 — and a consumer had no way to tell a value meant for it
+  from one that was not. `0.16.0` shipped `ON` by that ordering rather than by
+  construction, and `0.16.1` still published them.
+
+  Consumers asserting the pin read the node, and whether this build exports a
+  runtime to pin to at all, out of the `.bare` for their own triplet instead;
+  `__cxa_throw` is either defined there under a version node or it is not. The
+  in-tree addon template moved to that before this removal, so nothing in the
+  repository reads either variable. `QVAC_FABRIC_ABI_VERSION` remains as a build
+  variable, stamped onto the version node so the name and the script cannot
+  drift.
+
 ## [0.16.1] - 2026-09-17
 
 ### Fixed

packages/fabric/CMakeLists.txt

@@ -224,26 +224,17 @@ endif()
 # to keep the host's libstdc++ from answering for that C++ ABI, so the links
 # without the block keep the anonymous node symbols.map ships.
 if(UNIX AND NOT APPLE)
-  # Whether consumers should expect to import their C++ runtime from this
-  # module. True only for the link that embeds libc++; Android links
-  # libc++_shared.so and the ASan build links libc++.so.1, so there the runtime
-  # is shared by other means and a consumer that pinned it here would find
-  # nothing to pin. Published through the package config so the addon template
-  # can tell "fabric does not own the runtime" apart from "fabric is too old".
-  if(QVAC_FABRIC_LIBCXX_ARCHIVE)
-    set(QVAC_FABRIC_OWNS_CXX_RUNTIME ON)
-  else()
-    set(QVAC_FABRIC_OWNS_CXX_RUNTIME OFF)
-  endif()
   # symbols.map ships anonymous, which is what the links above need. The link
   # that owns the C++ runtime gets the ABI block spliced in and the node named,
   # the two halves of the same guarantee: the name is what makes consumers
   # record a DT_VERNEED, and the DT_VERNEED is what keeps the host's libstdc++
   # from answering for the block. symbols.map carries the full rationale.
   set(_fabric_version_script "${CMAKE_CURRENT_SOURCE_DIR}/symbols.map")
-  if(QVAC_FABRIC_OWNS_CXX_RUNTIME)
-    # Declared here so the name reaches consumers through the package config.
-    # This is its only definition: the script below is stamped from it.
+  if(QVAC_FABRIC_LIBCXX_ARCHIVE)
+    # Named here so the script below can be asserted against it and the two
+    # cannot drift. Build-internal: consumers read the node they have to pin to
+    # off this module's exports, not off anything published here, because the
+    # package config is shared by every platform's prebuild leg.
     set(QVAC_FABRIC_ABI_VERSION "QVAC_FABRIC_ABI_1")
     set(_fabric_cxx_runtime_map
       "${CMAKE_CURRENT_SOURCE_DIR}/symbols-linux-cxx-runtime.map")
@@ -277,11 +268,6 @@ if(UNIX AND NOT APPLE)
     file(WRITE "${_fabric_version_script}" "${_fabric_symbols}")
     set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS
       "${CMAKE_CURRENT_SOURCE_DIR}/symbols.map" "${_fabric_cxx_runtime_map}")
-  else()
-    # Nothing to publish: this link's node stays anonymous, so a consumer has no
-    # version to record a DT_VERNEED on. Empty rather than unset so the package
-    # config says "this build shares its runtime" instead of going missing.
-    set(QVAC_FABRIC_ABI_VERSION "")
   endif()
   target_link_options(${qvac-fabric}_module PRIVATE
     -Wl,--version-script=${_fabric_version_script})

packages/fabric/cmake/qvac-fabricConfig.cmake.in

@@ -2,18 +2,13 @@
 
 include("${CMAKE_CURRENT_LIST_DIR}/qvac-fabricTargets.cmake")
 
-# The ELF version node this build stamped on its exports, empty on platforms
-# that use no version script. A consumer linking the module with -nostdlib++
-# must end up with a DT_VERNEED on this version for every C++ runtime symbol it
-# imports; without one, the dynamic linker satisfies them from whichever C++
-# runtime the host process loaded first, and typed catches across the fabric
-# boundary stop matching. See arch/qips/linux-fabric-libcxx-ownership.md.
-set(QVAC_FABRIC_ABI_VERSION "@QVAC_FABRIC_ABI_VERSION@")
-
-# Whether this build embeds and exports the C++ runtime for its consumers to
-# import. OFF where a shared libc++ provides it instead (Android, the ASan
-# build) and on the non-ELF platforms. Always defined, so a consumer can tell
-# that apart from an older fabric whose config predates these variables.
-set(QVAC_FABRIC_OWNS_CXX_RUNTIME "@QVAC_FABRIC_OWNS_CXX_RUNTIME@")
+# Nothing platform-dependent belongs in this file. It installs to
+# share/qvac-fabric/cmake, which every prebuild leg writes and the artifact
+# merge collapses to a single copy in the published package, so a value that
+# differs per platform would describe whichever leg finished last -- and a
+# consumer reading it would be wrong without any way to tell. Keep it to facts
+# that hold for every triplet; a consumer that needs to know how this build
+# links its C++ runtime reads that out of the module for its own triplet, the
+# way cmake/qvac-addon/assert-fabric-cxx-runtime.cmake does.
 
 check_required_components(qvac-fabric)