From d45e57a5a4703c2f12a2d3f2bde6fd615ba8af7c Mon Sep 17 00:00:00 2001
From: Growl <uwsy1059@qq.com>
Date: Mon, 20 Apr 2026 00:00:36 +0800
Subject: [PATCH 1/2] Don't check and install bundled Boost headers if CXX_API
 not required

---
 export/CMakeLists.txt.export | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/export/CMakeLists.txt.export b/export/CMakeLists.txt.export
index 5474b1ff1..1bf97e4b2 100644
--- a/export/CMakeLists.txt.export
+++ b/export/CMakeLists.txt.export
@@ -796,7 +796,7 @@ install(CODE "
 ")
 
 # install bundled Boost headers if needed
-if (NOT LIBINT_HAS_SYSTEM_BOOST_PREPROCESSOR_VARIADICS)
+if (LIBINT2_REQUIRE_CXX_API AND NOT LIBINT_HAS_SYSTEM_BOOST_PREPROCESSOR_VARIADICS)
     install(
       DIRECTORY ${PROJECT_BINARY_DIR}/include/libint2/boost
       DESTINATION "${LIBINT2_INSTALL_INCLUDEDIR}/libint2"

From 81c457aa809e8f56447bf1170cede26e19a45200 Mon Sep 17 00:00:00 2001
From: Growl <uwsy1059@qq.com>
Date: Tue, 23 Jun 2026 11:15:10 +0800
Subject: [PATCH 2/2] CMake: Export C++ API dependencies conditionally

---
 cmake/libint2-config.cmake.in | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/cmake/libint2-config.cmake.in b/cmake/libint2-config.cmake.in
index dce83a3f4..73eaab5e2 100644
--- a/cmake/libint2-config.cmake.in
+++ b/cmake/libint2-config.cmake.in
@@ -55,6 +55,8 @@ list(PREPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR})
 # check library language component
 include(CMakeFindDependencyMacro)
 
+set(LIBINT2_REQUIRE_CXX_API @LIBINT2_REQUIRE_CXX_API@)
+if(LIBINT2_REQUIRE_CXX_API)
     if(NOT TARGET Eigen3::Eigen)
       set(Eigen3_CONFIG @Eigen3_CONFIG@)
       if (NOT Eigen3_CONFIG OR NOT EXISTS ${Eigen3_CONFIG})
@@ -65,7 +67,6 @@ include(CMakeFindDependencyMacro)
         find_dependency(Eigen3 REQUIRED HINTS "${Eigen3_DIR}")
       endif()
     endif()
-
     if (@LIBINT_HAS_SYSTEM_BOOST_PREPROCESSOR_VARIADICS@)  # LIBINT_HAS_SYSTEM_BOOST_PREPROCESSOR_VARIADICS
         # Boost headers _not_ unpacked to within `include/libint2/`
         if (NOT TARGET Boost::headers)
@@ -83,6 +84,7 @@ include(CMakeFindDependencyMacro)
             message(STATUS "Boost detected. satisfied by headers bundled with ${L2} distribution")
         endif()
     endif()
+endif()
 
 # check orderings, AM, & derivatives components
 # * LIBINT2_SHGAUSS_ORDERING = @LIBINT2_SHGAUSS_ORDERING@