Swift: add a test case for symlinks

swift/integration-tests/posix-only/symlinks/.gitignore

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+*/Sources/A.swift

swift/integration-tests/posix-only/symlinks/Files.expected

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+| file://:0:0:0:0 |  |
+| main.swift:0:0:0:0 | main.swift |
+| preserve/Package.swift:0:0:0:0 | preserve/Package.swift |
+| resolve/Package.swift:0:0:0:0 | resolve/Package.swift |

swift/integration-tests/posix-only/symlinks/Files.ql

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+import swift
+
+from File f
+select f

swift/integration-tests/posix-only/symlinks/main.swift

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+public struct preserve {
+    public private(set) var text = "Hello, World!"
+
+    public init() {
+    }
+}

swift/integration-tests/posix-only/symlinks/preserve/Package.swift

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+// swift-tools-version: 5.7
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "preserve",
+    products: [
+        .library(
+            name: "preserve",
+            targets: ["preserve"]),
+    ],
+    targets: [
+        .target(
+            name: "preserve",
+            path: "Sources"),
+    ]
+)

swift/integration-tests/posix-only/symlinks/resolve/Package.swift

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+// swift-tools-version: 5.7
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "resolve",
+    products: [
+        .library(
+            name: "resolve",
+            targets: ["resolve"]),
+    ],
+    targets: [
+        .target(
+            name: "resolve",
+            path: "Sources"),
+    ]
+)

swift/integration-tests/posix-only/symlinks/test.py

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+from create_database_utils import *
+import os
+
+symlinks = ['preserve/Sources/A.swift', 'resolve/Sources/A.swift']
+
+for s in symlinks:
+    try:
+        os.symlink(os.getcwd() + '/main.swift', s)
+    except:
+        pass
+
+run_codeql_database_create([
+    'swift package clean --package-path resolve',
+    'swift build --package-path resolve',
+    'swift package clean --package-path preserve',
+    'env CODEQL_PRESERVE_SYMLINKS=true swift build --package-path preserve'
+], lang='swift', keep_trap=True)
+
+for s in symlinks:
+    os.unlink(s)