Move the package version to version.txt.

This change moves the definition of Swift Testing's version to a new file,
version.txt. This file doesn't represent a standard, _per se_, but it is common
for open-source projects to list their version info in such a file. And by
putting our version info in this file, we can share it between package builds
and CMake builds.

Author: grynspan

Package.swift

@@ -470,12 +470,6 @@ extension Array where Element == PackageDescription.CXXSetting {
 
     // Capture the testing library's commit info as C++ constants.
     if let git {
-      if let tag = git.currentTag {
-        result.append(.define("SWT_TESTING_LIBRARY_VERSION", to: #""\#(tag)""#))
-      } else {
-        result.append(.define("SWT_TESTING_LIBRARY_VERSION", to: "0"))
-      }
-
       result.append(.define("SWT_TESTING_LIBRARY_COMMIT_HASH", to: #""\#(git.currentCommit)""#))
       if git.hasUncommittedChanges {
         result.append(.define("SWT_TESTING_LIBRARY_COMMIT_MODIFIED", to: "1"))

Sources/_TestingInternals/CMakeLists.txt

@@ -9,7 +9,6 @@
 set(CMAKE_CXX_SCAN_FOR_MODULES 0)
 
 include(GitCommit)
-include(LibraryVersion)
 include(TargetTriple)
 add_library(_TestingInternals STATIC
   Discovery.cpp

Sources/_TestingInternals/Versions.cpp

@@ -10,11 +10,33 @@
 
 #include "Versions.h"
 
+#include <mutex>
+
 const char *swt_getTestingLibraryVersion(void) {
 #if defined(SWT_TESTING_LIBRARY_VERSION)
+  // The current environment explicitly specifies a version string to return.
   return SWT_TESTING_LIBRARY_VERSION;
+#elif __has_embed("../../version.txt")
+  // Read the version from version.txt at the root of the package's repository.
+  static char version[] = {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wc23-extensions"
+#embed "../../version.txt" suffix(, '\0')
+#pragma clang diagnostic pop
+  };
+
+  // Trim any trailing whitespace.
+  static std::once_flag once;
+  std::call_once(once, [] {
+    auto i = std::find_if(std::begin(version), std::end(version), std::isspace);
+    if (i != std::end(version)) {
+      *i = '\0';
+    }
+  });
+
+  return version;
 #else
-#warning SWT_TESTING_LIBRARY_VERSION not defined: testing library version is unavailable
+#warning SWT_TESTING_LIBRARY_VERSION not defined and version.txt not found: testing library version is unavailable
   return nullptr;
 #endif
 }

cmake/modules/LibraryVersion.cmake

@@ -1,15 +1,10 @@
 # This source file is part of the Swift.org open source project
 #
-# Copyright (c) 2024 Apple Inc. and the Swift project authors
+# Copyright (c) 2024–2025 Apple Inc. and the Swift project authors
 # Licensed under Apache License v2.0 with Runtime Library Exception
 #
 # See http://swift.org/LICENSE.txt for license information
 # See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 
-# The current version of the Swift Testing release. For release branches,
-# remember to remove -dev.
-set(SWT_TESTING_LIBRARY_VERSION "6.3-dev")
-
-message(STATUS "Swift Testing version: ${SWT_TESTING_LIBRARY_VERSION}")
-add_compile_definitions(
-  "$<$<COMPILE_LANGUAGE:CXX>:SWT_TESTING_LIBRARY_VERSION=\"${SWT_TESTING_LIBRARY_VERSION}\">")
+# The library version is now tracked in version.txt at the root directory of the
+# repository. This file will be removed in a future commit.

version.txt

@@ -0,0 +1,9 @@
+6.3-dev
+
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2025 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See http://swift.org/LICENSE.txt for license information
+# See http://swift.org/CONTRIBUTORS.txt for Swift project authors