From 71240850c116376edef9ab5e2ddc335ea727c46d Mon Sep 17 00:00:00 2001
From: Eduard Valeyev <eduard@valeyev.net>
Date: Sat, 15 Oct 2022 06:27:38 -0400
Subject: [PATCH] move SEQUANT_REVISION dependence into version.cpp to allow
 ccache do its job properly

---
 CMakeLists.txt         | 34 ++++++++++++++++++++++------------
 SeQuant/version.cpp    | 14 ++++++++++++++
 SeQuant/version.hpp.in | 18 ++++++++++--------
 3 files changed, 46 insertions(+), 20 deletions(-)
 create mode 100644 SeQuant/version.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 11496e06f..b5158b622 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -32,6 +32,19 @@ else (SEQUANT_PRERELEASE_ID)
     set(SEQUANT_EXT_VERSION "${SEQUANT_VERSION}")
 endif (SEQUANT_PRERELEASE_ID)
 
+# extract git revision
+if (EXISTS ${PROJECT_SOURCE_DIR}/.git)
+    find_package(Git REQUIRED)
+    execute_process(
+            COMMAND ${GIT_EXECUTABLE} rev-parse -q HEAD
+            WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+            OUTPUT_VARIABLE SEQUANT_REVISION)
+    string(REGEX MATCH "[0-9a-f]*"
+            SEQUANT_REVISION "${SEQUANT_REVISION}")
+else ()
+    set(SEQUANT_REVISION "unknown")
+endif ()
+
 # make SeQuant project
 project(SeQuant LANGUAGES CXX VERSION "${SEQUANT_VERSION}" DESCRIPTION "SEcond QUANTization toolkit")
 
@@ -170,6 +183,8 @@ add_library(SeQuant-bliss
         )
 
 add_library(SeQuant
+        ${PROJECT_BINARY_DIR}/SeQuant/version.hpp
+        SeQuant/version.cpp
         SeQuant/core/sequant.cpp
         SeQuant/core/sequant.hpp
         SeQuant/core/attr.hpp
@@ -244,6 +259,12 @@ add_library(SeQuant
         SeQuant/domain/mbpt/antisymmetrizer.hpp
         SeQuant/domain/mbpt/rdm.hpp
         )
+# feed SEQUANT_REVISION to SeQuant/version.cpp only to avoid recompiling everything
+set_property(
+        SOURCE SeQuant/version.cpp
+        PROPERTY COMPILE_DEFINITIONS
+        SEQUANT_REVISION=\"${SEQUANT_REVISION}\"
+)
 
 target_link_libraries(SeQuant PUBLIC range-v3::range-v3 Boost::regex Boost::boost SeQuant-bliss Threads::Threads)
 if (SEQUANT_HAS_EXECUTION_HEADER_STANDALONE OR SEQUANT_HAS_EXECUTION_HEADER_WITH_TBB)
@@ -255,6 +276,7 @@ if (SEQUANT_HAS_EXECUTION_HEADER_STANDALONE OR SEQUANT_HAS_EXECUTION_HEADER_WITH
 endif ()
 target_include_directories(SeQuant PUBLIC
         $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}>
+        $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}>
         $<INSTALL_INTERFACE:${CMAKE_INSTALL_PREFIX}/include>)
 target_compile_features(SeQuant INTERFACE "cxx_std_17")
 install(TARGETS SeQuant-bliss EXPORT sequant COMPONENT sequant LIBRARY DESTINATION ${SEQUANT_INSTALL_LIBDIR})
@@ -438,18 +460,6 @@ add_subdirectory(doc)
 # export SeQuant
 ##########################
 
-if (EXISTS ${PROJECT_SOURCE_DIR}/.git)
-    find_package(Git REQUIRED)
-    execute_process(
-            COMMAND ${GIT_EXECUTABLE} rev-parse -q HEAD
-            WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-            OUTPUT_VARIABLE SEQUANT_REVISION)
-    string(REGEX MATCH "[0-9a-f]*"
-            SEQUANT_REVISION "${SEQUANT_REVISION}")
-else ()
-    set(SEQUANT_REVISION "unknown")
-endif ()
-
 configure_file(
         ${PROJECT_SOURCE_DIR}/SeQuant/version.hpp.in
         ${PROJECT_BINARY_DIR}/SeQuant/version.hpp
diff --git a/SeQuant/version.cpp b/SeQuant/version.cpp
new file mode 100644
index 000000000..c412c8007
--- /dev/null
+++ b/SeQuant/version.cpp
@@ -0,0 +1,14 @@
+//
+// Created by Eduard Valeyev on 10/14/22.
+//
+
+#include <SeQuant/version.hpp>
+
+namespace sequant {
+
+const char* revision() noexcept {
+  static const char revision[] = SEQUANT_REVISION;
+  return revision;
+}
+
+}  // namespace sequant
diff --git a/SeQuant/version.hpp.in b/SeQuant/version.hpp.in
index dbf5551d4..189bf238a 100644
--- a/SeQuant/version.hpp.in
+++ b/SeQuant/version.hpp.in
@@ -5,22 +5,24 @@
 #ifndef SEQUANT_SRC_SEQUANT_VERSION_H_IN_H
 #define SEQUANT_SRC_SEQUANT_VERSION_H_IN_H
 
-/* Defines a string with the Git SHA1 revision hash tag of SeQuant */
-#define SEQUANT_REVISION "@SEQUANT_REVISION@"
-
-/* TiledArray version X.Y.Z-id */
+/* SeQuant version X.Y.Z-id */
 #define SEQUANT_VERSION "@SEQUANT_VERSION@"
 
-/* TiledArray major version */
+/* SeQuant major version */
 #define SEQUANT_MAJOR_VERSION @SEQUANT_MAJOR_VERSION@
 
-/* TiledArray minor version */
+/* SeQuant minor version */
 #define SEQUANT_MINOR_VERSION @SEQUANT_MINOR_VERSION@
 
-/* TiledArray micro version */
+/* SeQuant micro version */
 #define SEQUANT_MICRO_VERSION @SEQUANT_MICRO_VERSION@
 
-/* TiledArray prerelease id */
+/* SeQuant prerelease id */
 #define SEQUANT_PRERELEASE_ID "@SEQUANT_PRERELEASE_ID@"
 
+namespace sequant {
+/** \return a string with the Git SHA1 revision hash tag of SeQuant */
+const char* revision() noexcept;
+}  // namespace sequant
+
 #endif  // SEQUANT_SRC_SEQUANT_VERSION_H_IN_H