nng-sys: upgrade to NNG 2.0.0-alpha.6 (#34)

* nng-sys: upgrade to NNG 2.0.0-alpha.6

BREAKING CHANGES:
- nng_init() must be called before using any NNG functions
- nng_close() renamed to nng_socket_close()
- nng_send_aio()/nng_recv_aio() renamed to nng_socket_send()/nng_socket_recv()
- Many functions now return nng_err enum instead of c_int
- ZeroTier transport removed (NNG_AF_ZT, nng_sockaddr_zt, nng_zt_*)
- nanomsg compatibility layer removed (compat feature and headers)
- NNG_FLAG_ALLOC removed
- Many option getter/setter functions removed or renamed
- TLS must now be configured via nng_tls_config_* functions
- URL structure is now opaque with accessor functions

For the complete migration guide, see:
https://github.com/nanomsg/nng/blob/master/docs/ref/migrate/nng1.md

Changes:
- Bump nng-sys version to 0.4.0+v2.0.0-alpha.6
- Bump nng-sys/nng submodule to v2.0.0-alpha.6
- Regenerate bindings for NNG 2.0 API
- Simplify wrapper.h (now just nng.h and http.h)
- Remove compat.h and supplemental.h
- Update build.rs: remove compat feature handling, bump pkg-config to 2.0.0
- Add NNG_AF_ABSTRACT to nng_sockaddr_family conversion
- Update README with NNG 2.0 warning, migration guide, and fixed examples
- Update tests for NNG 2.0 API (nng_init, nng_socket_close, nng_err)

Note: The `links = "nng"` attribute is temporarily commented out because
anng and nng crates still depend on nng-sys 0.3.0 from crates.io.

* Update CI to build NNG 2.0 from submodule for non-vendored tests

- Build NNG from nng-sys/nng submodule instead of Debian packages (v1.x)
- Update linux-sys 'system + bindgen' job to build NNG from source
- Update linux-nng job to build NNG from source
- Update macOS jobs to build NNG from submodule (consolidate to 2 configs)
- Remove compat and supplemental test jobs (features don't exist in NNG 2.0)

* Fix Windows MSVC build: always enable stats

WORKAROUND: MSVC doesn't allow empty structs in C (error C2016), and
NNG has a bug where nng/src/core/stats.h defines an empty nni_stat_item
struct when NNG_ENABLE_STATS is OFF.

Until this is fixed upstream, we must always enable stats when building
with MSVC to avoid the empty struct compilation error.

* Fix macOS CI: add library search path for /usr/local/lib

On macOS, /usr/local/lib is not in the default library search path.
When we install NNG to /usr/local, the linker can't find libnng
unless we explicitly tell Rust where to look.

Add RUSTFLAGS=-L native=/usr/local/lib to the macOS system nng job.

* Refactor CI: extract NNG build script

Create .github/scripts/build-nng.sh to handle OS-specific NNG build
from the submodule. This reduces duplication between Linux and macOS
jobs - the script auto-detects the OS and handles:
- Install prefix (/usr on Linux, /usr/local on macOS)
- Parallel job count (nproc vs sysctl -n hw.ncpu)
- ldconfig on Linux only

* rename install script

* ci: build NNG from source in feature-powerset check

Replace apt-installed libnng1/libnng-dev packages with building NNG from
the nng-sys/nng submodule. This ensures the hack job tests against the
exact NNG version tracked in the repository when checking all feature
combinations.

* fix comment

* extend link comment

* add comment wht nng v1 is used for testing the nng crate

* ci: run cargo hack per-package to handle NNG v1/v2 split

nng-sys v0.4 targets NNG v2, while nng and anng still depend on
nng-sys v0.3 (NNG v1). Running feature-powerset on the entire
workspace fails since these packages require incompatible NNG versions.

This workaround runs cargo hack on each package individually:
- nng-sys: Install NNG v2 from submodule, set NNG_DIR=/usr
- nng/anng: Use vendored NNG v1 (builds from source, no NNG_DIR needed)

* remove dbg!

* improve version parsing

* add link to upstream issue

* add TODO for path dependencies

* fix manifest formatting

* rename build_nng to install_nng and remove false cases

* remove "from submodule" comments

* add CFLAGS

* improve TODO comment for removing install_nng flag and action

* remove support for abstract sockets from socket familiy conversion

* update version of nng-sys to 0.4.0-v2pre.1+v2.0.0-alpha.6

* update tls link

* revert version example

* remove migration notes and just reference the release notes and the migration guide

* remove invalid comment

* fix readme

* revert version change

* add a bold warning about the use of alpha nng v2

* fix version in readme

* add CFLAGS and RUSTFLAGS to v2 cargo hack run

---------

Co-authored-by: Felix Obenhuber <felix.obenhuber@helsing.ai>

Author: flxo

.github/scripts/install-nng.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+# Build and install NNG from the nng-sys/nng submodule source.
+# This script handles OS-specific differences between Linux and macOS.
+set -ex
+
+cd nng-sys/nng
+mkdir -p build && cd build
+
+# OS-specific settings
+if [[ "$OSTYPE" == "darwin"* ]]; then
+    PREFIX="/usr/local"
+    JOBS=$(sysctl -n hw.ncpu)
+else
+    PREFIX="/usr"
+    JOBS=$(nproc)
+fi
+
+cmake -DCMAKE_INSTALL_PREFIX="$PREFIX" -DBUILD_SHARED_LIBS=ON \
+      -DNNG_TESTS=OFF -DNNG_TOOLS=OFF ..
+make -j"$JOBS"
+sudo make install
+
+# Linux needs ldconfig to update the shared library cache
+if [[ "$OSTYPE" != "darwin"* ]]; then
+    sudo ldconfig
+fi

.github/workflows/build-configurations.yml

@@ -18,8 +18,15 @@ jobs:
         include:
           - name: system + bindgen
             features: # no-default-features, so this won't vendor, and system implies bindgen
-            # system nng, clang-dev for bindgen
-            apt: libnng1 libnng-dev libclang-dev
+            # clang and cmake for installing NNG, clang-dev for bindgen
+            apt: clang cmake libclang-dev
+            # until nng v2 is available via apt, we need to manually install nng
+            # for the checks that expect nng to be installed in the system
+            # 
+            # TODO(flxo): remove the manual installation of nng and replace with
+            # a `apt install libnng2 libnng-dev` or similar, once the apt
+            # packages are available. Same applies for `brew` and others.
+            install_nng: true
             env: {}
           - name: vendored + bindgen
             features: --features vendored,bindgen
@@ -48,24 +55,16 @@ jobs:
             # link against mbedtls.
             apt: clang cmake libmbedtls-dev
             env: {}
-          - name: vendored with compat (bindgen implied)
-            features: --features compat
-            # to generate compat, we need to run bindgen since bundled do not
-            # include compat. bindgen feature is implied by compat.
-            apt: libnng1 libnng-dev libclang-dev
-            env: {}
-          - name: vendored with supplemental (bindgen implied)
-            features: --features supplemental
-            # ditto for supplemental
-            apt: libnng1 libnng-dev libclang-dev
-            env: {}
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # tag=v6.0.1
         with:
           submodules: true
       - name: Install dependencies
         run: |
           sudo apt-get install -y ${{ matrix.apt }}
+      - name: Build and install NNG
+        if: matrix.install_nng
+        run: .github/scripts/install-nng.sh
       - name: Install stable
         uses: dtolnay/rust-toolchain@f7ccc83f9ed1e5b9c81d8a67d7ad1a747e22a561 # branch=master
         with:
@@ -80,6 +79,7 @@ jobs:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # tag=v6.0.1
         with:
           submodules: true
+      # the nng crate is not yet upgraded to nng v2. install nng v1.x (libnng1 and libnng-dev)
       - name: Install dependencies
         run: |
           sudo apt-get install -y libnng1 libnng-dev
@@ -119,16 +119,15 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - name: brew-provided nng + CFLAGS
+          - name: system nng
             features:
-            brew: nng
+            brew: cmake
+            install_nng: true
             env:
-              CFLAGS: -I/opt/homebrew/include
-              RUSTFLAGS: -L native=/opt/homebrew/lib
-          - name: brew-provided nng
-            features:
-            brew: nng
-            env: {}
+              # /usr/local/include is not a standard C compiler search path
+              CFLAGS: -I/usr/local/include
+              # /usr/local/lib is not in the default library search path on macOS
+              RUSTFLAGS: -L native=/usr/local/lib
           - name: vendored
             features: --features vendored
             brew: cmake
@@ -140,6 +139,9 @@ jobs:
       - name: Install dependencies
         run: |
           brew install ${{ matrix.brew }}
+      - name: Build and install NNG
+        if: matrix.install_nng
+        run: .github/scripts/install-nng.sh
       - name: Install stable
         uses: dtolnay/rust-toolchain@f7ccc83f9ed1e5b9c81d8a67d7ad1a747e22a561 # branch=master
         with:

.github/workflows/check.yml

@@ -120,11 +120,35 @@ jobs:
       # since we're trying every combination here, we need to ensure we have
       # all the various tools installed already.
       - name: install tools
-        run: sudo apt-get install -y libclang-dev libnng1 libnng-dev clang cmake ninja-build libmbedtls-dev
+        run: sudo apt-get install -y libclang-dev clang cmake ninja-build libmbedtls-dev libnng1 libnng-dev
+      # Run cargo hack per-package because nng-sys v0.4 targets NNG v2, while
+      # nng and anng still depend on nng-sys v0.3 (NNG v1). Running feature-powerset
+      # on the entire workspace fails since these require incompatible NNG versions.
+      # The effect of the failure (when running `hack` on the workspace) is here:
+      # https://github.com/nanomsg/nng-rs/actions/runs/20988550343/job/60328143824
+      #
+      # TODO: Remove this workaround once nng and anng are migrated to nng-sys v0.4/NNG v2
+      # and revert to:
+      # - name: cargo hack
+      #   run: cargo hack --feature-powerset check --skip source-update-bindings
+      #
       # intentionally no target specifier; see https://github.com/jonhoo/rust-ci-conf/pull/4
       # --feature-powerset runs for every combination of features
-      - name: cargo hack
-        run: cargo hack --feature-powerset check --skip source-update-bindings
+      - name: cargo hack nng
+        run: cargo hack -p nng --feature-powerset check
+      - name: cargo hack anng
+        run: cargo hack -p anng --feature-powerset check
+      - name: remove NNG v1
+        run: sudo apt-get remove -y libnng1 libnng-dev
+      - name: build and install NNG v2 for nng-sys
+        run: .github/scripts/install-nng.sh
+      - name: cargo hack nng-sys
+        run: cargo hack -p nng-sys --feature-powerset check --skip source-update-bindings
+        env:
+          # add /usr/local/include to the C compiler search path for NNG headers
+          CFLAGS: -I/usr/local/include
+          # add /usr/local/lib to the linker search path for NNG libraries
+          RUSTFLAGS: -L native=/usr/local/lib
   msrv:
     # check that we can build using the minimal rust version that is specified by this crate
     runs-on: ubuntu-latest

Cargo.lock

@@ -28,7 +28,8 @@ lazy_static = { version = "1.5.0", optional = true }
 
 [dependencies.nng-sys]
 version = "0.3.0"
-path = "../nng-sys"
+# TODO(flxo): use path dependency once anng is updated to use nng-sys v0.4
+# path = "../nng-sys"
 default-features = false
 
 [features]

anng/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nng-sys"
-version = "0.3.0+1.11.0"
+version = "0.4.0-v2pre.1+v2.0.0-alpha.6"
 authors = [
     "Nathan Kent <nate@nkent.net>",
     "Jake W <jeikabu@gmail.com>",
@@ -15,7 +15,18 @@ repository = "https://github.com/nanomsg/nng-rs"
 readme = "README.md"
 edition = "2018"
 rust-version = "1.82.0" # unsafe extern blocks in generated bindings
-links = "nng"
+# TODO(flxo): temporary comment the `links` attribute because `anng` and `nng`
+# are not yet upgraded to nng-sys v0.4.0. cargo doesn't allow multiple crates in
+# the ws dependency tree that link the same lib:
+#
+# error: failed to select a version for `nng-sys`.
+#     ... required by package `anng v0.1.3 (.../nng-rs/anng)`
+# versions that meet the requirements `^0.3.0` (locked to 0.3.0+1.11.0) are: 0.3.0+1.11.0
+# 
+# package `nng-sys` links to the native library `nng`, but it conflicts with a previous package which links to `nng` as well:
+# package `nng-sys v0.4.0+v2.0.0-alpha.6 (.../nng-rs/nng-sys)`
+# Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the `links = "nng"` value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.
+# links = "nng"
 
 [features]
 default = ["vendored", "vendored-stats", "std"]
@@ -46,14 +57,6 @@ vendored-stats = []
 # Emits additional cargo directives for linking against mbedtls.
 tls = []
 
-# nanomsg compatibility layer
-# NOTE: this changes (adds to) the bindings as well
-compat = ["bindgen"]
-
-# supplemental utilities
-# NOTE: this changes (adds to) the bindings as well
-supplemental = ["bindgen"]
-
 ## Development features (for working with the source code)
 # Update `src/bindings.rs` with all features enabled
 source-update-bindings = ["bindgen"]

nng-sys/Cargo.toml

@@ -6,23 +6,27 @@ Rust FFI bindings to [NNG](https://github.com/nanomsg/nng):
 [![crates.io](http://img.shields.io/crates/v/nng-sys.svg)](http://crates.io/crates/nng-sys)
 ![MIT License](https://img.shields.io/badge/license-MIT-blue.svg)
 
+> [!WARNING]
+> This crate wraps [NNG v2](https://github.com/nanomsg/nng), which is still in alpha.
+> For [NNG v1 bindings](https://github.com/nanomsg/nng/tree/stable), see the [v1.xx branch](https://github.com/nanomsg/nng-rs/tree/v1.xx).
+
 ## Usage
 
 To use the latest version of this crate, add the following to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-nng-sys = "0.3.0"
+nng-sys = "0.4.0-v2pre"
 ```
 
 If you need TLS support:
 
 ```toml
 [dependencies]
-nng-sys = { version = "0.3.0", features = ["tls"] }
+nng-sys = { version = "0.4.0-v2pre", features = ["tls"] }
 ```
 
-This will bundle [mbedTLS](https://tls.mbed.org/). See the [NNG TLS documentation](https://nng.nanomsg.org/man/v1.10.0/nng_tls.7.html) for details.
+This will bundle [mbedTLS](https://tls.mbed.org/). See the [NNG TLS documentation](https://github.com/nanomsg/nng/blob/main/docs/man/nng_tls.7.adoc) for details.
 
 ### Library Discovery
 
@@ -82,7 +86,7 @@ This crate uses the format `<crate version>+<nng version>` following [Semantic V
 | Patch fix in crate bindings | `0.3.1+1.11.0`  | Bug fixes, no API changes                                                                  |
 | Update to newer NNG version | `0.3.2+1.12.0`  | Compatible update to the NNG library                                                       |
 | Breaking change in bindings | `0.4.0+1.12.0`  | Breaking API changes introduced by e.g. a `bindgen` upgrade (pre-1.0, minor acts as major) |
-| NNG major version update    | `0.5.0+2.0.0`   | A backwards-incompatible NNG release also results in a major version bump                                      |
+| NNG major version update    | `0.5.0+2.0.0`   | A backwards-incompatible NNG release also results in a major version bump                  |
 
 **Note:** Cargo ignores the `+<nng version>` build metadata suffix when resolving dependencies,
 so version `0.3.0+1.11.0` and `0.3.0+1.12.0` are considered equivalent by Cargo and cannot coexist.
@@ -92,16 +96,14 @@ This legacy format has been replaced to allow for proper semantic versioning of
 
 ## Features
 
-| Feature | Default | Description |
-|---------|---------|-------------|
-| `vendored` | ✓ | Build NNG from bundled sources using CMake |
-| `vendored-stats` | ✓ | Enable NNG stats (`NNG_ENABLE_STATS`) when building vendored NNG |
-| `std` | ✓ | Enable standard library support |
-| `static` | | Force static linking (default: static for vendored, dynamic for system) |
-| `bindgen` | | Generate bindings at build time (uses pre-generated by default) |
-| `tls` | | Enable TLS support (`NNG_ENABLE_TLS`, requires mbedTLS) |
-| `compat` | | Bindings for nanomsg-compatible API (implies `bindgen`) |
-| `supplemental` | | Bindings for supplemental utilities (implies `bindgen`) |
+| Feature          | Default | Description                                                             |
+| ---------------- | ------- | ----------------------------------------------------------------------- |
+| `vendored`       | ✓       | Build NNG from bundled sources using CMake                              |
+| `vendored-stats` | ✓       | Enable NNG stats (`NNG_ENABLE_STATS`) when building vendored NNG        |
+| `std`            | ✓       | Enable standard library support                                         |
+| `static`         |         | Force static linking (default: static for vendored, dynamic for system) |
+| `bindgen`        |         | Generate bindings at build time (uses pre-generated by default)         |
+| `tls`            |         | Enable TLS support (`NNG_ENABLE_TLS`, requires mbedTLS)                 |
 
 **Note:** Features that control NNG build options (`vendored-stats`, `tls`) only affect vendored builds.
 When using a system-provided NNG library, ensure it was built with the features you need.
@@ -110,13 +112,13 @@ When using a system-provided NNG library, ensure it was built with the features
 
 ### Quick Reference
 
-| Variable | Purpose | Example |
-|----------|---------|---------|
-| `NNG_DIR` | Root NNG installation directory | `/usr/local` |
-| `NNG_LIB_DIR` + `NNG_INCLUDE_DIR` | Separate library and header paths | `/opt/nng/lib`, `/opt/nng/include` |
-| `NNG_STATIC` | Force static (`1`) or dynamic (`0`) linking | `1` |
-| `NNG_NO_VENDOR` | Prohibit vendored builds (error if system lib not found) | `1` |
-| `{TARGET}_NNG_*` | Target-specific override (cross-compilation) | `AARCH64_UNKNOWN_LINUX_GNU_NNG_DIR` |
+| Variable                          | Purpose                                                  | Example                             |
+| --------------------------------- | -------------------------------------------------------- | ----------------------------------- |
+| `NNG_DIR`                         | Root NNG installation directory                          | `/usr/local`                        |
+| `NNG_LIB_DIR` + `NNG_INCLUDE_DIR` | Separate library and header paths                        | `/opt/nng/lib`, `/opt/nng/include`  |
+| `NNG_STATIC`                      | Force static (`1`) or dynamic (`0`) linking              | `1`                                 |
+| `NNG_NO_VENDOR`                   | Prohibit vendored builds (error if system lib not found) | `1`                                 |
+| `{TARGET}_NNG_*`                  | Target-specific override (cross-compilation)             | `AARCH64_UNKNOWN_LINUX_GNU_NNG_DIR` |
 
 ### Build Control
 
@@ -147,6 +149,9 @@ use std::{ffi::CString, os::raw::c_char, ptr::null_mut};
 
 fn example() {
     unsafe {
+        // Initialize NNG (required in NNG 2.0)
+        nng_init(null_mut());
+
         let url = CString::new("inproc://nng_sys/tests/example").unwrap();
         let url = url.as_bytes_with_nul().as_ptr() as *const c_char;
 
@@ -178,8 +183,15 @@ fn example() {
         // Can't do this because nng uses network order (big-endian)
         //assert_eq!(val, *(nng_msg_body(recv_msg) as *const u32));
 
-        nng_close(req_socket);
-        nng_close(rep_socket);
+        nng_socket_close(req_socket);
+        nng_socket_close(rep_socket);
     }
 }
 ```
+
+## Migration from NNG 1.x
+
+This version wraps **NNG 2.0.0-alpha.6**, which is a major breaking release from
+NNG 1.x. See the [NNG 2.0 release
+notes](https://github.com/nanomsg/nng/releases) and the [NNG 1.x Migration
+Guide](https://github.com/nanomsg/nng/blob/master/docs/ref/migrate/nng1.md) for details.