ALPSim · Ooolab · Aug 1, 2026 · Jul 25, 2026 · Jul 25, 2026
diff --git a/ALPS_VERSION.txt b/ALPS_VERSION.txt
@@ -0,0 +1 @@
+2.3.4
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -70,13 +70,17 @@ if(ALPS_BUILD_LIBS_ONLY)
   set(ALPS_BUILD_APPLICATIONS OFF)
 endif()
 
+# Sets ALPS_VERSION_CORE from ALPS_VERSION.txt. Included by full path because
+# CMAKE_MODULE_PATH is not set up until after project().
+include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/ALPSVersion.cmake)
+
 if(ALPS_BUILD_FORTRAN)
-  project(alps C CXX Fortran)
+  project(alps VERSION ${ALPS_VERSION_CORE} LANGUAGES C CXX Fortran)
   if (APPLE)
    set (CMAKE_Fortran_RUNTIME_LIBRARIES "-lgcc_s.1")
   endif(APPLE)
 else(ALPS_BUILD_FORTRAN)
-  project(alps C CXX)
+  project(alps VERSION ${ALPS_VERSION_CORE} LANGUAGES C CXX)
 endif(ALPS_BUILD_FORTRAN)
 
 set(CMAKE_CXX_STANDARD 14)
@@ -118,25 +122,35 @@ list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
 ######################################################################
 # Version information
 ######################################################################
-set(ALPS_YEAR 2026)
-set(ALPS_VERSION_MAJOR 2)
-set(ALPS_VERSION_MINOR 3)
-set(ALPS_VERSION_PATCH 3)
-set(ALPS_VERSION_BUILD "")
-
-if(ALPS_VERSION_BUILD)
-  set(ALPS_VERSION "${ALPS_VERSION_MAJOR}.${ALPS_VERSION_MINOR}.${ALPS_VERSION_PATCH}-${ALPS_VERSION_BUILD}")
-else(ALPS_VERSION_BUILD)
-  set(ALPS_VERSION "${ALPS_VERSION_MAJOR}.${ALPS_VERSION_MINOR}.${ALPS_VERSION_PATCH}")
-endif(ALPS_VERSION_BUILD)
+# The numeric components come from project() above, which took its version from
+# ALPS_VERSION.txt. Do not hardcode them here.
+set(ALPS_VERSION_MAJOR ${PROJECT_VERSION_MAJOR})
+set(ALPS_VERSION_MINOR ${PROJECT_VERSION_MINOR})
+set(ALPS_VERSION_PATCH ${PROJECT_VERSION_PATCH})
+
+# Prerelease label, e.g. "beta.2" for the v2.3.4-beta.2 tag. Display only: it is
+# deliberately kept out of the numeric version that drives SOVERSION and
+# find_package() matching. Set by the release process, not checked in.
+set(ALPS_VERSION_PRERELEASE "" CACHE STRING
+    "Prerelease label for this build, e.g. beta.2 (affects version strings only)")
+mark_as_advanced(ALPS_VERSION_PRERELEASE)
+
+if(ALPS_VERSION_PRERELEASE)
+  set(ALPS_VERSION "${ALPS_VERSION_CORE}-${ALPS_VERSION_PRERELEASE}")
+else()
+  set(ALPS_VERSION "${ALPS_VERSION_CORE}")
+endif()
 set(ALPS_VERSION_STRING "ALPS Libraries version ${ALPS_VERSION}")
-MESSAGE(STATUS "ALPS version: ${ALPS_VERSION}") 
+message(STATUS "ALPS version: ${ALPS_VERSION}")
+
+# Derived, never hardcoded. string(TIMESTAMP) honours SOURCE_DATE_EPOCH, so
+# distro and conda reproducible builds still get a stable year.
+string(TIMESTAMP ALPS_YEAR "%Y" UTC)
 
 set(ALPS_CONFIG_HOST unknown)
 set(ALPS_CONFIG_USER unknown)
 
 set(ALPS_PREFIX "${CMAKE_INSTALL_PREFIX}")
-set(ALPS_SRCDIR "${CMAKE_SOURCE_DIR}")
 set(libdir "${CMAKE_INSTALL_PREFIX}/lib")
 set(bindir "${CMAKE_INSTALL_PREFIX}/bin")
 
@@ -396,6 +410,14 @@ endif(HDF5_LIBRARIES)
 configure_file(cmake/ALPSConfig.cmake.in ${PROJECT_BINARY_DIR}/cmake/ALPSConfig.cmake @ONLY)
 configure_file(cmake/include.mk.in ${PROJECT_BINARY_DIR}/cmake/include.mk)
 
+# Without this file find_package(ALPS <version>) accepts any version it finds
+# and silently discards the constraint. SameMinorVersion: patch releases within
+# a minor series are drop-in, a minor bump is not guaranteed to be.
+include(CMakePackageConfigHelpers)
+write_basic_package_version_file(
+  ${PROJECT_BINARY_DIR}/cmake/ALPSConfigVersion.cmake
+  COMPATIBILITY SameMinorVersion)
+
 
 # installation
 ######################################################################
@@ -429,6 +451,7 @@ add_subdirectory(cmake)
 
 install(FILES cmake/UseALPS.cmake
         ${PROJECT_BINARY_DIR}/cmake/ALPSConfig.cmake
+        ${PROJECT_BINARY_DIR}/cmake/ALPSConfigVersion.cmake
         ${PROJECT_BINARY_DIR}/cmake/include.mk
         cmake/run_test.cmake
         cmake/run_test_mpi.cmake

diff --git a/cmake/ALPSConfig.cmake.in b/cmake/ALPSConfig.cmake.in
@@ -20,11 +20,14 @@ set(ALPS_LIBRARY_DIRS "@ALPS_LIBRARY_DIRS_CONFIG@")
 # of runtime binaries for each configuration type.
 set(ALPS_RUNTIME_LIBRARY_DIRS "@ALPS_RUNTIME_LIBRARY_DIRS_CONFIG@")
 
-# The ALPS version number.
+# The ALPS version number. ALPS_VERSION carries the prerelease label when there
+# is one; ALPS_VERSION_CORE is always plain MAJOR.MINOR.PATCH and is what
+# ALPSConfigVersion.cmake compares against.
 SET(ALPS_VERSION_MAJOR "@ALPS_VERSION_MAJOR@")
 SET(ALPS_VERSION_MINOR "@ALPS_VERSION_MINOR@")
 SET(ALPS_VERSION_PATCH "@ALPS_VERSION_PATCH@")
-SET(ALPS_VERSION_BUILD "@ALPS_VERSION_BUILD@")
+SET(ALPS_VERSION_PRERELEASE "@ALPS_VERSION_PRERELEASE@")
+SET(ALPS_VERSION_CORE "@ALPS_VERSION_CORE@")
 SET(ALPS_VERSION "@ALPS_VERSION@")
 
 # The location of the UseALPS.cmake file.

diff --git a/cmake/ALPSVersion.cmake b/cmake/ALPSVersion.cmake
@@ -0,0 +1,41 @@
+#  Copyright ALPS collaboration 2026.
+#   Distributed under the MIT licence; see LICENSE.txt.
+#
+# Single source of truth for the ALPS release version.
+#
+# ALPS_VERSION.txt holds the numeric release core (MAJOR.MINOR.PATCH) and
+# nothing else. Two constraints force that:
+#
+#   * project(VERSION ...) rejects anything non-numeric, so "2.4.0-beta.1"
+#     fails to configure.
+#   * find_package() version matching and the library SOVERSION have no notion
+#     of prerelease ordering.
+#
+# A prerelease label such as "beta.2" therefore lives in ALPS_VERSION_PRERELEASE
+# (see the version block in the top-level CMakeLists.txt), where it affects the
+# display string only -- never the numeric version used for ABI and
+# find_package() decisions.
+#
+# This file is included by full path before project(), so it cannot rely on
+# CMAKE_MODULE_PATH or PROJECT_SOURCE_DIR.
+
+set(_alps_version_file "${CMAKE_CURRENT_LIST_DIR}/../ALPS_VERSION.txt")
+
+if(NOT EXISTS "${_alps_version_file}")
+  message(FATAL_ERROR "Cannot read the ALPS version file: ${_alps_version_file}")
+endif()
+
+file(STRINGS "${_alps_version_file}" ALPS_VERSION_CORE LIMIT_COUNT 1)
+string(STRIP "${ALPS_VERSION_CORE}" ALPS_VERSION_CORE)
+
+# Fail loudly here rather than letting project() emit "VERSION format invalid",
+# which gives no hint about which file is at fault.
+if(NOT ALPS_VERSION_CORE MATCHES "^[0-9]+\\.[0-9]+\\.[0-9]+$")
+  message(FATAL_ERROR
+    "${_alps_version_file} must contain exactly MAJOR.MINOR.PATCH, but reads "
+    "'${ALPS_VERSION_CORE}'. Prerelease labels belong in "
+    "ALPS_VERSION_PRERELEASE, and the leading 'v' of a release tag is not "
+    "part of the version.")
+endif()
+
+unset(_alps_version_file)
diff --git a/src/alps/version.h.in b/src/alps/version.h.in
@@ -30,34 +30,46 @@
 #ifndef ALPS_VERSION_H
 #define ALPS_VERSION_H
 
+// Plain #define for everything the build always sets: the cmakedefine directive
+// emits an "undef" when its value is false-y, and CMake counts 0 as false-y, so
+// a zero component (2.4.0) would vanish. It is used below only where the macro
+// is genuinely optional. (configure_file matches that directive even inside a
+// comment, hence no leading '#' on it here.)
+
 // ALPS version
-#cmakedefine ALPS_VERSION "@ALPS_VERSION@"
+#define ALPS_VERSION "@ALPS_VERSION@"
+
+#define ALPS_VERSION_MAJOR @ALPS_VERSION_MAJOR@
+#define ALPS_VERSION_MINOR @ALPS_VERSION_MINOR@
+#define ALPS_VERSION_PATCH @ALPS_VERSION_PATCH@
 
-#cmakedefine ALPS_VERSION_MAJOR @ALPS_VERSION_MAJOR@
-#cmakedefine ALPS_VERSION_MINOR @ALPS_VERSION_MINOR@
-#cmakedefine ALPS_VERSION_PATCH @ALPS_VERSION_PATCH@
-#cmakedefine ALPS_SVN_REVISION @ALPS_WC_REVISION@
+// ALPS version as a single integer, for preprocessor comparisons:
+//   #if ALPS_VERSION_NUMBER >= ALPS_VERSION_NUM(2, 3, 4)
+#define ALPS_VERSION_NUM(major, minor, patch) \
+  ((major) * 100000 + (minor) * 100 + (patch))
+#define ALPS_VERSION_NUMBER \
+  ALPS_VERSION_NUM(ALPS_VERSION_MAJOR, ALPS_VERSION_MINOR, ALPS_VERSION_PATCH)
 
 // ALPS version (full string)
-#cmakedefine ALPS_VERSION_STRING "@ALPS_VERSION_STRING@"
+#define ALPS_VERSION_STRING "@ALPS_VERSION_STRING@"
 
 // latest publish year of ALPS
-#cmakedefine ALPS_YEAR "@ALPS_YEAR@"
+#define ALPS_YEAR "@ALPS_YEAR@"
 
 // install path of ALPS
-#cmakedefine ALPS_PREFIX "@ALPS_PREFIX@"
-
-// source directory of ALPS
-#cmakedefine ALPS_SRCDIR "@ALPS_SRCDIR@"
+#define ALPS_PREFIX "@ALPS_PREFIX@"
 
 // XSLT PATH
-#cmakedefine ALPS_XML_DIR "@ALPS_XML_DIR@"
+#define ALPS_XML_DIR "@ALPS_XML_DIR@"
+
+// Optional Windows fallback for the 32/64-bit "Program Files" split. Never set
+// by the build, and guarded by #ifdef in parser/xslt_path.C.
 #cmakedefine ALPS_XML_ALTERNATE_DIR "@ALPS_XML_ALTERNATE_DIR@"
 
 // hostname where configure script was executed
-#cmakedefine ALPS_CONFIG_HOST "@ALPS_CONFIG_HOST@"
+#define ALPS_CONFIG_HOST "@ALPS_CONFIG_HOST@"
 
 // username who executed configure script
-#cmakedefine ALPS_CONFIG_USER "@ALPS_CONFIG_USER@"
+#define ALPS_CONFIG_USER "@ALPS_CONFIG_USER@"
 
 #endif // ALPS_VERSION_H
diff --git a/test/hdf5/CMakeLists.txt b/test/hdf5/CMakeLists.txt
@@ -38,6 +38,11 @@ FOREACH (name hdf5_complex hdf5_copy hdf5_real_complex_vec hdf5_real_complex_mat
     set_property(TEST ${name} PROPERTY LABELS hdf5)
 ENDFOREACH(name)
 
+# Reads a reference .h5 file from the source tree; see the note in
+# test/numeric/CMakeLists.txt.
+target_compile_definitions(hdf5_fortran_string
+                           PRIVATE ALPS_SRCDIR="${PROJECT_SOURCE_DIR}")
+
 IF (ALPS_ENABLE_OPENMP AND OPENMP_FOUND)
     add_executable(hdf5_omp hdf5_omp.cpp)
     add_dependencies(hdf5_omp alps)

diff --git a/test/numeric/CMakeLists.txt b/test/numeric/CMakeLists.txt
@@ -30,5 +30,12 @@ if(LAPACK_FOUND)
     add_alps_test(${name})
     set_property(TEST ${name} PROPERTY LABELS numeric)
   ENDFOREACH(name)
+
+  # This test reads a reference .h5 file from the source tree. That path is a
+  # property of this build, not of the installed library, so it is a private
+  # definition on the one target that needs it rather than a macro in the
+  # installed alps/version.h.
+  target_compile_definitions(matrix_deprecated_hdf5_format_test
+                             PRIVATE ALPS_SRCDIR="${PROJECT_SOURCE_DIR}")
 endif(LAPACK_FOUND)
 
diff --git a/tool/pconfig.C b/tool/pconfig.C
@@ -35,7 +35,6 @@
 int main() {
   std::cout << "ALPS version:          " << alps::version() << std::endl
             << "Boost version:         " << BOOST_LIB_VERSION << std::endl
-            << "source directory:      " << ALPS_SRCDIR << std::endl
             << "installed at:          " << ALPS_PREFIX << std::endl
             << "configured on:         " << alps::config_host() << std::endl
             << "configured by:         " << alps::config_user() << std::endl