Build on libmongoc 2.0–2.2 (Ubuntu 26.04) and drop the misleading apt hint

.github/workflows/ci.yml

@@ -48,6 +48,28 @@ jobs:
           export LD_LIBRARY_PATH=$(dirname $(find /opt/mongoc -name 'libmongoc2.so' | head -1))
           swift test
 
+  linux-apt:
+    # The oldest libmongoc we support, from the distribution package the README recommends.
+    name: Linux (Ubuntu 26.04, apt libmongoc)
+    runs-on: ubuntu-24.04
+    container: swift:6.4-resolute
+    services:
+      mongo:
+        image: mongo:8
+    env:
+      MONGODB_URI: mongodb://mongo:27017
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Install libmongoc from apt
+        run: |
+          apt-get update
+          apt-get install -y --no-install-recommends pkg-config libmongoc-dev libbson-dev
+          echo "libmongoc $(pkg-config --modversion mongoc2)"
+
+      - name: Test
+        run: swift test
+
   macos:
     name: macOS (build + server-independent tests)
     runs-on: macos-15

Package.swift

@@ -32,16 +32,18 @@ let package = Package(
 			name: "PerfectCBSON",
 			pkgConfig: "bson2",
 			providers: [
-				.brew(["mongo-c-driver"]),
-				.apt(["libbson-dev"])
+				// No apt provider: SwiftPM can't vary it by release, and libmongoc-dev is 2.x only on
+				// Ubuntu 26.04+ / Debian forky+; on Ubuntu 24.04 it installs 1.x. See the README.
+				.brew(["mongo-c-driver"])
 			]
 		),
 		.systemLibrary(
 			name: "PerfectCMongo",
 			pkgConfig: "mongoc2",
 			providers: [
-				.brew(["mongo-c-driver"]),
-				.apt(["libmongoc-dev"])
+				// No apt provider: SwiftPM can't vary it by release, and libmongoc-dev is 2.x only on
+				// Ubuntu 26.04+ / Debian forky+; on Ubuntu 24.04 it installs 1.x. See the README.
+				.brew(["mongo-c-driver"])
 			]
 		),
 		.target(

README.md

@@ -35,7 +35,7 @@ targets: [
 
 ## Requirements
 
-libmongoc **2.x** must be installed where pkg-config can find `mongoc2` and `bson2`.
+libmongoc **2.x** must be installed where pkg-config can find `mongoc2` and `bson2`. Tested with 2.2.2 and 2.5.5.
 
 **macOS** ([Homebrew](https://brew.sh)):
 
@@ -45,9 +45,15 @@ brew install mongo-c-driver
 
 On Apple silicon, if SwiftPM can't find the library, set `PKG_CONFIG_PATH=/opt/homebrew/lib/pkgconfig`.
 
-**Linux:** most distributions still package libmongoc 1.x (for example Ubuntu's `libmongoc-dev`), which
-this version doesn't support. Build libmongoc 2 from source, as the CI workflow in
-`.github/workflows/ci.yml` does:
+**Linux:** whether your distribution's package is new enough depends on the release:
+
+| Distribution | `libmongoc-dev` version | What to do |
+|---|---|---|
+| Ubuntu 26.04 LTS and later | 2.2 or later | `apt-get install libmongoc-dev libbson-dev` |
+| Debian forky / sid | 2.5 | `apt-get install libmongoc-dev libbson-dev` |
+| Ubuntu 24.04 LTS (used by the `swift:*-noble` images), Debian 13 and older | 1.x, not supported | Build from source (below) |
+
+To build libmongoc 2 from source, as the CI workflow in `.github/workflows/ci.yml` does:
 
 ```sh
 apt-get install cmake libssl-dev libsasl2-dev libzstd-dev

README.zh_CN.md

@@ -33,7 +33,7 @@ targets: [
 
 ## 环境要求
 
-必须安装 libmongoc **2.x**，并确保 pkg-config 能找到 `mongoc2` 和 `bson2`。
+必须安装 libmongoc **2.x**，并确保 pkg-config 能找到 `mongoc2` 和 `bson2`。已在 2.2.2 和 2.5.5 上测试。
 
 **macOS**（[Homebrew](https://brew.sh)）：
 
@@ -43,8 +43,15 @@ brew install mongo-c-driver
 
 在 Apple 芯片的 Mac 上，如果 SwiftPM 找不到该库，请设置 `PKG_CONFIG_PATH=/opt/homebrew/lib/pkgconfig`。
 
-**Linux：** 大多数发行版仍只提供 libmongoc 1.x（例如 Ubuntu 的 `libmongoc-dev`），本版本不支持。请参照
-`.github/workflows/ci.yml` 中 CI 的做法，从源码编译 libmongoc 2：
+**Linux：** 发行版自带的软件包是否够新取决于版本：
+
+| 发行版 | `libmongoc-dev` 版本 | 做法 |
+|---|---|---|
+| Ubuntu 26.04 LTS 及更新版本 | 2.2 或更新 | `apt-get install libmongoc-dev libbson-dev` |
+| Debian forky / sid | 2.5 | `apt-get install libmongoc-dev libbson-dev` |
+| Ubuntu 24.04 LTS（`swift:*-noble` 镜像所用）、Debian 13 及更早版本 | 1.x，不支持 | 从源码编译（见下文） |
+
+参照 `.github/workflows/ci.yml` 中 CI 的做法，从源码编译 libmongoc 2：
 
 ```sh
 apt-get install cmake libssl-dev libsasl2-dev libzstd-dev

Sources/PerfectCBSON/shim.h

@@ -1,2 +1,14 @@
 #define BCON_H_
 #include <bson/bson.h>
+
+// libbson 2.3 added bson_append_array_unsafe_begin and deprecated bson_append_array_begin
+// (same signature and behaviour). Use whichever this libbson has, so the package builds
+// warning-free on current libbson and still builds on 2.0-2.2 (e.g. Ubuntu 26.04's 2.2.2).
+static inline bool _perfect_bson_append_array_begin(bson_t *bson, const char *key, int key_length, bson_t *child)
+{
+#if BSON_CHECK_VERSION(2, 3, 0)
+	return bson_append_array_unsafe_begin(bson, key, key_length, child);
+#else
+	return bson_append_array_begin(bson, key, key_length, child);
+#endif
+}

Sources/PerfectMongoDB/BSON.swift

@@ -472,7 +472,7 @@ public class BSON: CustomStringConvertible {
         guard let doc = self.doc, let cdoc = child.doc else {
             return false
         }
-		return bson_append_array_unsafe_begin(toOpaque(doc), k, -1, toOpaque(cdoc))
+		return _perfect_bson_append_array_begin(toOpaque(doc), k, -1, toOpaque(cdoc))
 	}
 
     /**

Sources/PerfectMongoDB/BSONCodable.swift

@@ -219,7 +219,7 @@ public struct BSONEncoder: Sendable {
 		case .array(let storage)?:
 			let child = UnsafeMutablePointer<bson_t>.allocate(capacity: 1)
 			defer { child.deallocate() }
-			guard bson_append_array_unsafe_begin(doc, key, -1, child) else {
+			guard _perfect_bson_append_array_begin(doc, key, -1, child) else {
 				throw MongoError("could not start array '\(key)'")
 			}
 			for (index, box) in storage.boxes.enumerated() {