[native] Use a raw pointer for the CoreCLR host's Timing instance

[simonrozsival]

Part of #12533.

Host::_timing is a process-lifetime singleton: it is created once, when fast timing is enabled, and never released. Holding it in a std::shared_ptr bought us nothing but a control block allocation and atomic refcount traffic on every get_timing () call — the call sites even bound the returned shared pointer to a const& to dodge the refcount, with a comment apologising for it:

// Technically a reference here is against the idea of shared pointers, but
// in this instance it's fine since we know we won't be storing the pointer
// and this way things are slightly faster.
std::shared_ptr<Timing> const &timing = Host::get_timing ();

Store a plain Timing* instead.

Effect

This removes the last std::shared_ptr from the CoreCLR host, dropping all five std::__ndk1::__shared_weak_count references plus one static initialisation guard pair:

	undefined libc++ symbols in libnet-android.release-static-release.a
before	55
after	48

For reference, the NativeAOT host is already at 0, which is the target for CoreCLR.

The allocation itself is deliberately unchanged — removing the remaining new/delete calls is a separate cause, tracked in #12533.

[Copilot]

Pull request overview

This PR is part of #12533 and continues the effort to remove libc++ dependencies from the CoreCLR host by eliminating std::shared_ptr usage for the Timing singleton and replacing remaining C++-stdlib-heavy formatting/logging patterns (e.g., std::format, std::string_view-based formatting) with snprintf/printf-style logging and fixed-buffer helpers. It also adjusts runtime pack composition so NativeAOT no longer ships/links libc++ archives, while CoreCLR continues to.

Changes:

• Replace the CoreCLR host’s Host::_timing from std::shared_ptr<Timing> to a raw Timing* process-lifetime singleton.
• Reduce libc++ surface area by removing std::format usage across several native host/runtime components, switching to snprintf + log_*f APIs and fixed-buffer formatting helpers.
• Adjust packaging/build logic so libc++/unwind archives are treated as C++ assets and shipped only for CoreCLR; update APK baseline descriptors to reflect size changes.

Show a summary per file

File	Description
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Resources/Base/BuildReleaseArm64XFormsDotNet.CoreCLR.R8.apkdesc	Update baseline package contents/sizes after native host changes.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Resources/Base/BuildReleaseArm64XFormsDotNet.CoreCLR.apkdesc	Update baseline package contents/sizes after native host changes.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Resources/Base/BuildReleaseArm64SimpleDotNet.CoreCLR.R8.apkdesc	Update baseline package contents/sizes after native host changes.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Resources/Base/BuildReleaseArm64SimpleDotNet.CoreCLR.apkdesc	Update baseline package contents/sizes after native host changes.
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.NativeAOT.targets	Stop linking/shipping libc++ for NativeAOT; keep libstdc++compat.a rationale documented.
src/native/native.targets	Runtime pack file selection: ship libc++ archives only for CoreCLR.
src/native/mono/shared/log_types.hh	Remove std::string_view logging helper to avoid C++ stdlib dependencies.
src/native/mono/shared/helpers.cc	Add Helpers::abort_applicationf to replace std::format-based abort paths.
src/native/mono/runtime-base/android-system.hh	Add fixed-buffer system-property retrieval helper overloads.
src/native/mono/runtime-base/android-system.cc	Implement fixed-buffer system-property retrieval to avoid dynamic string types.
src/native/mono/monodroid/monodroid-glue.cc	Replace dynamic string building with stack/heap formatting helpers for timing “more info”.
src/native/common/runtime-base/timing-internal.cc	Replace std::format/string-heavy timing output with snprintf/buffer formatting; improve TMPDIR handling.
src/native/common/include/runtime-base/timing-internal.hh	Refactor timing message formatting to fixed buffers and explicit ownership of “more info”.
src/native/common/include/runtime-base/system-loadlibrary-wrapper.hh	Switch std::format-style logging to log_*f APIs.
src/native/common/include/runtime-base/mainthread-dso-loader.hh	Remove <format>, convert to abort_applicationf/log_*f, and make pipe write EINTR-safe.
src/native/common/include/runtime-base/dso-loader.hh	Convert std::format-style logging to log_*f with length-limited string formatting.
src/native/clr/runtime-base/util.cc	Replace dynamic strings with stack/heap buffer pattern for directory creation.
src/native/clr/runtime-base/logger.cc	Refactor log-category parsing to use std::string_view and fixed-buffer property reads.
src/native/clr/runtime-base/android-system.cc	Replace std::format logging and refactor DSO-path building to fixed-buffer formatting.
src/native/clr/runtime-base/android-system-shared.cc	Refactor system property reads to fixed buffers and remove dynamic string helpers.
src/native/clr/pinvoke-override/precompiled.cc	Remove <format> and switch abort/logging paths to abort_applicationf/log_*f.
src/native/clr/include/shared/log_types.hh	Remove stdlib-heavy log macro definitions, leaving shared log function surface.
src/native/clr/include/runtime-base/util.hh	Add fixed-buffer helpers for DSO name formatting.
src/native/clr/include/runtime-base/monodroid-dl.hh	Convert logging to log_*f and remove std::format usage.
src/native/clr/include/runtime-base/logger.hh	Remove dependency on strings helper types and adjust category parsing signature.
src/native/clr/include/runtime-base/android-system.hh	Replace dynamic-string system property reads with fixed-buffer overload; refactor override-dir formatting.
src/native/clr/include/host/typemap.hh	Replace std::string_view constants with const char* for debug labeling.
src/native/clr/include/host/pinvoke-override-impl.hh	Use new DSO-name formatting helper and convert logging to log_*f.
src/native/clr/include/host/os-bridge.hh	Include shared C++ utility header for common helpers.
src/native/clr/include/host/host.hh	Switch Timing singleton storage from std::shared_ptr to raw pointer.
src/native/clr/include/host/assembly-store.hh	Remove unused strings helper include.
src/native/clr/host/typemap.cc	Replace std::format logging and dynamic string building with fixed-buffer formatting helpers.
src/native/clr/host/internal-pinvokes-clr.cc	Update timing calls to use raw Timing* from host.
src/native/clr/host/host.cc	Replace std::format logging, switch timing singleton allocation to new Timing(), and convert many logs to log_*f.
src/native/clr/host/fastdev-assemblies.cc	Replace std::format abort/logging with abort_applicationf/log_*f.
src/native/clr/host/bridge-processing.cc	Convert GC summary/logging to log_*f.
src/native/clr/host/assembly-store.cc	Remove std::format usage and replace with snprintf/log_*f, including store-id formatting.
build-tools/scripts/Ndk.targets	Reclassify libc++/unwind redistributables as C++ assets for selective packing.
build-tools/create-packs/Microsoft.Android.Runtime.proj	Pack libc++/unwind assets only for CoreCLR runtime packs.

Review details

• Files reviewed: 39/39 changed files
• Comments generated: 2
• Review effort level: Lite

[simonrozsival]

Superseded by #12545.

#12545 removes Host::_timing entirely — the instance became a static inline Timing and get_timing () returns a reference — so the std::shared_ptr this PR was replacing with a raw pointer disappears there instead. The raw pointer was only ever an intermediate state.

Nothing is lost by dropping this: rebasing the rest of the stack straight onto #12534 still lands at 38 libc++ refs, the same as with this PR in the chain. The progression is now 55 → 47 (#12541) → 38 (#12545) instead of 55 → 48 → 40 → 38.

[simonrozsival]

Superseded by #12545 — see the earlier comment. The stack is now #12534 → #12541 → #12545.