Allow linking the system SQLite on Linux

.github/workflows/ci.yml

@@ -58,6 +58,25 @@ jobs:
       - name: Test
         run: swift test -v
 
+  linux-system-sqlite:
+    name: Linux (system SQLite)
+    runs-on: ubuntu-latest
+    container: swift:6.3.3
+    env:
+      SWIFT_BUILD_SYSTEM_SQLITE: '1'
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install SQLite
+        run: |
+          apt-get update
+          apt-get install -y --no-install-recommends libsqlite3-dev pkg-config
+      - name: Swift version
+        run: swift --version
+      - name: Build
+        run: swift build -v
+      - name: Test
+        run: swift test -v
+
   android:
     runs-on: ubuntu-latest
     steps:

Package.swift

@@ -6,10 +6,44 @@ import class Foundation.ProcessInfo
 // get environment variables
 let environment = ProcessInfo.processInfo.environment
 let dynamicLibrary = environment["SWIFT_BUILD_DYNAMIC_LIBRARY"] == "1"
+let systemSQLite = environment["SWIFT_BUILD_SYSTEM_SQLITE"] == "1"
 
 // force building as dynamic library
 let libraryType: PackageDescription.Product.Library.LibraryType? = dynamicLibrary ? .dynamic : nil
 
+// Linux uses the embedded SQLite build by default, like the other non-Darwin
+// platforms. Set `SWIFT_BUILD_SYSTEM_SQLITE=1` to link the system SQLite
+// (`libsqlite3-dev` / `sqlite-devel`) there instead.
+let embeddedSQLitePlatforms: [Platform] = systemSQLite
+    ? [.android, .windows, .wasi, .openbsd]
+    : [.linux, .android, .windows, .wasi, .openbsd]
+
+var sqliteDependencies: [Target.Dependency] = [
+    .product(
+        name: "SQLCipher",
+        package: "swift-sqlcipher",
+        condition: .when(platforms: embeddedSQLitePlatforms)
+    )
+]
+
+var sqliteTargets: [Target] = []
+
+if systemSQLite {
+    sqliteDependencies.append(
+        .target(name: "CSQLite", condition: .when(platforms: [.linux]))
+    )
+    sqliteTargets.append(
+        .systemLibrary(
+            name: "CSQLite",
+            pkgConfig: "sqlite3",
+            providers: [
+                .apt(["libsqlite3-dev"]),
+                .yum(["sqlite-devel"])
+            ]
+        )
+    )
+}
+
 let package = Package(
     name: "SQLite",
     products: [
@@ -21,26 +55,21 @@ let package = Package(
     ],
     dependencies: [
         // Darwin platforms link the system SQLite3.framework; everywhere else
-        // has no system SQLite, so this package's embedded copy is used instead.
+        // uses this package's embedded copy, unless Linux opts into the system
+        // libsqlite3 with `SWIFT_BUILD_SYSTEM_SQLITE=1`.
         .package(
             url: "https://github.com/PureSwift/swift-sqlcipher",
             from: "0.1.0"
         )
     ],
-    targets: [
+    targets: sqliteTargets + [
         .target(
             name: "SQLite",
-            dependencies: [
-                .product(
-                    name: "SQLCipher",
-                    package: "swift-sqlcipher",
-                    condition: .when(platforms: [.linux, .android, .windows, .wasi, .openbsd])
-                )
-            ],
+            dependencies: sqliteDependencies,
             swiftSettings: [
                 .define(
                     "SQLITE_SWIFT_SQLCIPHER",
-                    .when(platforms: [.linux, .android, .windows, .wasi, .openbsd])
+                    .when(platforms: embeddedSQLitePlatforms)
                 )
             ]
         ),

README.md

@@ -18,7 +18,24 @@ DSL.
 - `Blob`, `Data`, `UUID`, and `Date` binding conversions
 - Cross-platform: uses the system `SQLite3` on Apple platforms and the embedded
   [swift-sqlcipher](https://github.com/PureSwift/swift-sqlcipher) build
-  everywhere else (Linux, Android, Windows, WASI, OpenBSD)
+  everywhere else (Linux, Android, Windows, WASI, OpenBSD), with Linux able to
+  link the system `libsqlite3` instead
+
+## System SQLite on Linux
+
+Linux uses the embedded SQLite build by default. To link the system SQLite
+instead, install the development package and build with
+`SWIFT_BUILD_SYSTEM_SQLITE=1`:
+
+```sh
+apt-get install libsqlite3-dev pkg-config   # Debian / Ubuntu
+dnf install sqlite-devel pkgconf-pkg-config # Fedora / RHEL
+
+SWIFT_BUILD_SYSTEM_SQLITE=1 swift build
+```
+
+`pkg-config` is required in addition to the headers, since the system library
+target resolves its flags through it.
 
 ## Installation
 

Sources/CSQLite/module.modulemap

@@ -0,0 +1,5 @@
+module CSQLite [system] {
+    header "shim.h"
+    link "sqlite3"
+    export *
+}

Sources/CSQLite/shim.h

@@ -0,0 +1 @@
+#include <sqlite3.h>

Sources/SQLite/AggregateFunction.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/Backup.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/Collation.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/Connection.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/Constants.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/Error.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/Function.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/IncrementalBlob.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/PreparedStatement.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/Statement.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/TypeAffinity.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/WAL.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif

Sources/SQLite/WindowFunction.swift

@@ -10,7 +10,7 @@ import sqlite3
 #elseif SQLITE_SWIFT_SQLCIPHER
 import SQLCipher
 #elseif os(Linux)
-import SwiftToolchainCSQLite
+import CSQLite
 #else
 import SQLite3
 #endif