detect: Use weakref instead of dlsym

.github/.cspell/project-dictionary.txt

@@ -15,6 +15,7 @@ atxmega
 Auxinfo
 auxv
 auxvec
+balign
 bitops
 BOOKE
 braich
@@ -29,6 +30,7 @@ ccmp
 cdsg
 cgrjh
 cgrjl
+chericap
 clgr
 clgrjh
 clgrjhe
@@ -60,15 +62,16 @@ cxchgweak
 devkitc
 devkitm
 devtmpfs
-dlfcn
 dlsym
 ecall
 Espressif
 espup
 exynos
+fdpic
 fild
 fistp
 FPSR
+FUNCDESC
 getauxval
 getisax
 getpid
@@ -157,12 +160,16 @@ osxsave
 outputdir
 phdr
 picolibc
+popsection
 poweroff
 prctl
 prefetcher
 PRIMASK
+progbits
 PSRAM
 pstq
+purecap
+pushsection
 quadword
 rcpc
 rdinit
@@ -229,9 +236,11 @@ wfxt
 wokwi
 xadd
 xchg
+XCOFF
 xgetbv
 xmegau
 xmmword
+XPLINK
 xsave
 xsub
 zaamo

.github/workflows/ci.yml

@@ -206,13 +206,13 @@ jobs:
 
       # {,no-}outline-atomics
       # portable_atomic_no_outline_atomics only affects x86_64, AArch64, Arm, powerpc64, and RISC-V Linux.
-      # outline-atomics is disabled by default on AArch64/powerpc64 musl with static linking, and AIX.
+      # outline-atomics is disabled by default on AIX.
       # powerpc64le- (little-endian) is skipped because it is pwr8 by default
       - run: tools/test.sh -vv --tests ${TARGET:-} ${BUILD_STD:-}
         env:
           RUSTDOCFLAGS: ${{ env.RUSTDOCFLAGS }} --cfg portable_atomic_no_outline_atomics
           RUSTFLAGS: ${{ env.RUSTFLAGS }} --cfg portable_atomic_no_outline_atomics
-        if: startsWith(matrix.target, 'x86_64') || ((startsWith(matrix.target, 'aarch64') || startsWith(matrix.target, 'arm64')) || startsWith(matrix.target, 'powerpc64-')) && !(contains(matrix.target, '-musl') && matrix.flags == '') || startsWith(matrix.target, 'armv4t') || startsWith(matrix.target, 'armv5te') || matrix.target == 'arm-linux-androideabi' || startsWith(matrix.target, 'riscv')
+        if: startsWith(matrix.target, 'x86_64') || ((startsWith(matrix.target, 'aarch64') || startsWith(matrix.target, 'arm64')) || startsWith(matrix.target, 'powerpc64-')) || startsWith(matrix.target, 'armv4t') || startsWith(matrix.target, 'armv5te') || matrix.target == 'arm-linux-androideabi' || startsWith(matrix.target, 'riscv')
       # powerpc64 and RISC-V are skipped because tested below.
       - run: tools/test.sh -vv --tests ${TARGET:-} ${BUILD_STD:-}
         env:
@@ -508,6 +508,9 @@ jobs:
           - target: aarch64-unknown-openbsd
             os: openbsd
             version: '7.9'
+          - target: aarch64-unknown-openbsd
+            os: openbsd
+            version: '7.5' # no elf_aux_info
           - target: aarch64-unknown-illumos
             os: omnios
     runs-on: ubuntu-24.04
@@ -558,9 +561,10 @@ jobs:
         if: matrix.toolchain != ''
       - uses: taiki-e/cross-platform-actions-action@63e3c031895caac4783f1f778f3e2e0e409353b3 # dev # zizmor: ignore[stale-action-refs]
         env:
+          OS_VERSION: ${{ matrix.version }}
           TOOLCHAIN: ${{ matrix.toolchain }}
         with:
-          environment_variables: CARGO_INCREMENTAL CARGO_NET_RETRY CARGO_TERM_COLOR RUST_BACKTRACE RUST_TEST_THREADS RUSTDOCFLAGS RUSTFLAGS RUSTUP_MAX_RETRIES PORTABLE_ATOMIC_DENY_WARNINGS TEST_FEATURES TOOLCHAIN
+          environment_variables: CARGO_INCREMENTAL CARGO_NET_RETRY CARGO_TERM_COLOR RUST_BACKTRACE RUST_TEST_THREADS RUSTDOCFLAGS RUSTFLAGS RUSTUP_MAX_RETRIES PORTABLE_ATOMIC_DENY_WARNINGS TEST_FEATURES OS_VERSION TOOLCHAIN
           operating_system: ${{ matrix.os }}
           architecture: ${{ matrix.os == 'omnios' && 'x86_64' || 'aarch64' }}
           version: ${{ matrix.os == 'omnios' && 'r151058' || matrix.version }}

Cargo.toml

@@ -101,8 +101,12 @@ unexpected_cfgs = { level = "warn", check-cfg = [
     'cfg(target_arch,values("loongarch32"))', # 1.89+ https://github.com/rust-lang/rust/pull/142053
     'cfg(target_os,values("trusty"))', # 1.82+ https://github.com/rust-lang/rust/pull/129490
     'cfg(target_os,values("psx"))', # 1.84+ https://github.com/rust-lang/rust/pull/131168
+    'cfg(target_os,values("cygwin"))', # 1.86+ https://github.com/rust-lang/rust/pull/134999
     'cfg(target_os,values("zos"))', # https://github.com/rust-lang/compiler-team/issues/992
     'cfg(target_env,values("psx"))', # pre-1.84 https://github.com/rust-lang/rust/pull/131168
+    'cfg(target_abi,values("pauthtest"))', # 1.98+ https://github.com/rust-lang/rust/pull/155722
+    'cfg(target_abi,values("purecap"))', # https://github.com/kent-weak-memory/rust
+    'cfg(target_abi,values("fdpic"))', # https://github.com/llvm/llvm-project/issues/146959
     'cfg(target_feature,values("lse2","lse128","rcpc3"))', # 1.82+ https://github.com/rust-lang/rust/pull/128192
     'cfg(target_feature,values("quadword-atomics"))', # 1.83+ https://github.com/rust-lang/rust/pull/130873
     'cfg(target_feature,values("zaamo","zabha"))', # 1.83+ https://github.com/rust-lang/rust/pull/130877
@@ -112,7 +116,7 @@ unexpected_cfgs = { level = "warn", check-cfg = [
     'cfg(target_pointer_width,values("128"))',
     # Known custom cfgs, excluding those that may be set by build script.
     # Public APIs, considered unstable unless documented as stable in readme.
-    'cfg(portable_atomic_no_outline_atomics,portable_atomic_outline_atomics,portable_atomic_unstable_f16,portable_atomic_unstable_f128)',
+    'cfg(portable_atomic_outline_atomics,portable_atomic_unstable_f16,portable_atomic_unstable_f128)',
     # Not public API.
     'cfg(portable_atomic_test_detect_false,portable_atomic_test_no_std_static_assert_ffi,qemu,valgrind,valgrind_cross)',
 ] }

build.rs

@@ -63,7 +63,7 @@ fn main() {
         // Custom cfgs set by build script. Not public API.
         // grep -F 'cargo:rustc-cfg=' build.rs | grep -Ev '^ *//' | sed -E 's/^.*cargo:rustc-cfg=//; s/(=\\)?".*$//' | LC_ALL=C sort -u | tr '\n' ',' | sed -E 's/,$/\n/'
         println!(
-            "cargo:rustc-check-cfg=cfg(portable_atomic_atomic_intrinsics,portable_atomic_disable_fiq,portable_atomic_force_amo,portable_atomic_ll_sc_rmw,portable_atomic_llvm_16_or_later,portable_atomic_llvm_17_or_later,portable_atomic_no_asm,portable_atomic_no_asm_maybe_uninit,portable_atomic_no_asm_syscall,portable_atomic_no_atomic_64,portable_atomic_no_atomic_cas,portable_atomic_no_atomic_load_store,portable_atomic_no_atomic_min_max,portable_atomic_no_cfg_target_has_atomic,portable_atomic_no_cmpxchg16b_intrinsic,portable_atomic_no_cmpxchg16b_target_feature,portable_atomic_no_const_mut_refs,portable_atomic_no_const_raw_ptr_deref,portable_atomic_no_const_transmute,portable_atomic_no_core_unwind_safe,portable_atomic_no_diagnostic_namespace,portable_atomic_no_strict_provenance,portable_atomic_no_strict_provenance_atomic_ptr,portable_atomic_no_stronger_failure_ordering,portable_atomic_no_track_caller,portable_atomic_no_unsafe_op_in_unsafe_fn,portable_atomic_old_miri,portable_atomic_pre_llvm_16,portable_atomic_pre_llvm_18,portable_atomic_pre_llvm_20,portable_atomic_s_mode,portable_atomic_sanitize_thread,portable_atomic_target_cpu,portable_atomic_target_feature,portable_atomic_unsafe_assume_privileged,portable_atomic_unsafe_assume_single_core,portable_atomic_unstable_asm,portable_atomic_unstable_asm_experimental_arch,portable_atomic_unstable_cfg_target_has_atomic,portable_atomic_unstable_isa_attribute)"
+            "cargo:rustc-check-cfg=cfg(portable_atomic_atomic_intrinsics,portable_atomic_disable_fiq,portable_atomic_force_amo,portable_atomic_ll_sc_rmw,portable_atomic_llvm_16_or_later,portable_atomic_llvm_17_or_later,portable_atomic_no_asm,portable_atomic_no_asm_maybe_uninit,portable_atomic_no_asm_syscall,portable_atomic_no_atomic_64,portable_atomic_no_atomic_cas,portable_atomic_no_atomic_load_store,portable_atomic_no_atomic_min_max,portable_atomic_no_cfg_target_has_atomic,portable_atomic_no_cmpxchg16b_intrinsic,portable_atomic_no_cmpxchg16b_target_feature,portable_atomic_no_const_mut_refs,portable_atomic_no_const_raw_ptr_deref,portable_atomic_no_const_transmute,portable_atomic_no_core_unwind_safe,portable_atomic_no_diagnostic_namespace,portable_atomic_no_outline_atomics,portable_atomic_no_strict_provenance,portable_atomic_no_strict_provenance_atomic_ptr,portable_atomic_no_stronger_failure_ordering,portable_atomic_no_target_abi,portable_atomic_no_track_caller,portable_atomic_no_unsafe_op_in_unsafe_fn,portable_atomic_old_miri,portable_atomic_pre_llvm_16,portable_atomic_pre_llvm_18,portable_atomic_pre_llvm_20,portable_atomic_purecap,portable_atomic_s_mode,portable_atomic_sanitize_thread,portable_atomic_target_cpu,portable_atomic_target_feature,portable_atomic_unsafe_assume_privileged,portable_atomic_unsafe_assume_single_core,portable_atomic_unstable_asm,portable_atomic_unstable_asm_experimental_arch,portable_atomic_unstable_cfg_target_has_atomic,portable_atomic_unstable_isa_attribute)"
         );
         // TODO: handle multi-line emit_target_feature_fallback
         // grep -F 'emit_target_feature_fallback("' build.rs | grep -Ev '^ *//' | sed -E 's/^.*emit_target_feature_fallback\(//; s/",.*$/"/' | LC_ALL=C sort -u | tr '\n' ',' | sed -E 's/,$/\n/'
@@ -127,6 +127,19 @@ fn main() {
     if !version.probe(74, 2023, 8, 23) {
         println!("cargo:rustc-cfg=portable_atomic_no_asm_maybe_uninit");
     }
+    // #[cfg(target_abi)] stabilized in Rust 1.78 (nightly-2024-02-26): https://github.com/rust-lang/rust/pull/119590
+    if !version.probe(78, 2024, 2, 25) {
+        println!("cargo:rustc-cfg=portable_atomic_no_target_abi");
+        if target_arch == "aarch64"
+            && (env::var("CARGO_CFG_TARGET_ABI")
+                .unwrap_or_default()
+                .split(',')
+                .any(|abi| abi == "purecap")
+                || target.ends_with("-purecap"))
+        {
+            println!("cargo:rustc-cfg=portable_atomic_purecap");
+        }
+    }
     // #[diagnostic] stabilized in Rust 1.78 (nightly-2024-03-09): https://github.com/rust-lang/rust/pull/119888
     if !version.probe(78, 2024, 3, 8) {
         println!("cargo:rustc-cfg=portable_atomic_no_diagnostic_namespace");
@@ -175,6 +188,13 @@ fn main() {
             // The part of this feature we use has not been changed since nightly-2020-06-21
             // until it was stabilized, so it can safely be enabled in nightly for that period.
             println!("cargo:rustc-cfg=portable_atomic_unstable_asm");
+            if (target_arch == "aarch64"/* test-only: || target_arch == "arm" */)
+                && (!rustflags.is_allowed_feature("global_asm") || !version.probe(54, 2021, 5, 19))
+            {
+                // weakref macro needs global_asm! and extended_key_value_attributes
+                // (stabilized in 1.54 (nightly-2021-05-20): https://github.com/rust-lang/rust/pull/83366).
+                println!("cargo:rustc-cfg=portable_atomic_no_outline_atomics");
+            }
             if (target_arch == "riscv32" || target_arch == "riscv64")
                 && !version.probe(56, 2021, 8, 15)
             {
@@ -226,7 +246,7 @@ fn main() {
         }
     }
 
-    // feature(cfg_target_has_atomic) stabilized in Rust 1.60 (nightly-2022-02-11): https://github.com/rust-lang/rust/pull/93824
+    // cfg(target_has_atomic) stabilized in Rust 1.60 (nightly-2022-02-11): https://github.com/rust-lang/rust/pull/93824
     if !version.probe(60, 2022, 2, 10) {
         if version.nightly
             && version.probe(40, 2019, 10, 13)
@@ -404,6 +424,32 @@ fn main() {
             if is_apple || rustflags.target_cpu.map_or(false, |cpu| cpu.starts_with("apple-")) {
                 println!("cargo:rustc-cfg=portable_atomic_ll_sc_rmw");
             }
+
+            if target_os == "linux"
+                && env::var("CARGO_CFG_TARGET_ABI")
+                    .unwrap_or_default()
+                    .split(',')
+                    .any(|abi| abi == "pauthtest")
+            {
+                let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap_or_default();
+                // The compiler normally rejects crt-static for pauthtest ABI, but check just in case.
+                // https://github.com/rust-lang/rust/blob/0844f35a32c98882d77e39da8c2a872ec74615cd/compiler/rustc_session/src/session.rs#L1510
+                // crt-static is not shown in CARGO_CFG_TARGET_FEATURE when enabled by default, but fine in this case.
+                if !cfg!(feature = "std")
+                    && target_env == "musl"
+                    && env::var("CARGO_CFG_TARGET_FEATURE")
+                        .unwrap_or_default()
+                        .split(',')
+                        .any(|f| f == "crt-static")
+                    || target_env == "uclibc"
+                {
+                    // Do not use weakref on pauthtest ABI due to:
+                    // - LLD bug: https://github.com/llvm/llvm-project/issues/173296
+                    // - There is no good way to recognize `-Z pointer-authentication=-calls`
+                    // Note: There is no builtin targets can reach this.
+                    println!("cargo:rustc-cfg=portable_atomic_no_outline_atomics");
+                }
+            }
         }
         "arm" => {
             // For non-Linux/Android pre-v6 Arm (tier 3) with unsafe_assume_single_core enabled.
@@ -633,11 +679,22 @@ fn main() {
             {
                 // Cell Broadband Engine SPU syscalls support a subset of powerpc64 syscalls with the exact semantics: https://github.com/torvalds/linux/blob/v7.1/arch/powerpc/platforms/cell/spu_callbacks.c#L17
                 // but have a different syscall sequence: https://github.com/mirror/newlib-cygwin/blob/newlib-4.4.0/libgloss/spu/linux_syscalls.c#L37
-                // GCC 10 (https://gcc.gnu.org/gcc-9/changes.html) and LLVM 3.3.0 (https://releases.llvm.org/3.3/docs/ReleaseNotes.html#non-comprehensive-list-of-changes-in-this-release)
+                // Note: There is no builtin SPU targets. And GCC 10 (https://gcc.gnu.org/gcc-9/changes.html)
+                // and LLVM 3.3.0 (https://releases.llvm.org/3.3/docs/ReleaseNotes.html#non-comprehensive-list-of-changes-in-this-release)
                 // removed support for SPU, so this is unlikely to be supported in rust-lang/rust: https://github.com/rust-lang/compiler-team/issues/614
                 // Note: code referring this cfg is currently used only for testing.
                 println!("cargo:rustc-cfg=portable_atomic_no_asm_syscall");
             }
+            if env::var("CARGO_CFG_TARGET_POINTER_WIDTH")
+                .expect("CARGO_CFG_TARGET_POINTER_WIDTH not set")
+                == "32"
+            {
+                // Do not use weakref on PowerPC64 ILP32 due to LLVM bug:
+                // - https://github.com/llvm/llvm-project/issues/52826
+                // - https://github.com/llvm/llvm-project/issues/169283
+                // Note: There is no builtin PowerPC64 ILP32 targets.
+                println!("cargo:rustc-cfg=portable_atomic_no_outline_atomics");
+            }
         }
         "s390x" => {
             let mut arch9_features = false; // z196+